Ask Ethan #15: The Universe's Most Massive Black Holes

Quote from post:- "The speed is important, because if you compress something slowly, its temperature tends to stay constant but its entropy rises, while if you compress it quickly, its entropy stays constant but the temperature goes up!"

I find that interesting. Is there a link that explains this in greater detail? I looked up the various classical laws of gases, but none of them use time.

The wikipedia pages for "adiabatic" (quick compression) and "isothermal" (slow compression) should help a lot.

Running combinations of adiabatic and isothermal expansion and compression is the very essence of a heat engine operating under the Carnot cycle; this is very powerful, but also very fundamental stuff!

Have we ever observed black holes colliding? Sounds like that would be the ultimate lab to test quantum gravity / string theory models!

Odd that you should ask at this time:

http://www.jpl.nasa.gov/news/news.php?release=2013-345

I'm having some trouble in piecing this all together in terms of masses, times, and mechanics. Something seems to be off, or (if) some steps were skipped then that might be what I don't understand.

This is what I've been able to find so far:

- according to Wiki H & He clouds need some 10-15 million years for grav. collapse to form proto-stars.
- on wiki and on arxiv I couldn't find anything about even theoretical 1000 solar mass stars (population III). I did find papers proving it's impossible to make anything beyond 150s.m... but that was disproved once the star in tarantula nebula was found. But even with that, most people seem to be thinking around 200-400 solar masses for population III. This is very far from 1000 or beyond, which Ethan states in the article. Any info on this would be welcoming

- Even if we take a hypothetical 500solar masses star going meganova.. wouldn't the shockwave blast things nearby so far from singularity that any mega accretion is impossible? Even with tens or hundreds of millions of years, IMO it seems that we require so much stuff around BH, and all of it falling perfectly inside, to get from 500 s.m. to billions of solar masses. And all of that in first 1 billion years, because...
- according to wiki again: A major constraining factor for theories of supermassive black hole formation is the observation of distant luminous quasars, which indicate that supermassive black holes of billions of solar masses had already formed when the Universe was less than one billion years old.

So the image I have in terms of time and what happens is this...
t= 0 -> 0.5mil. y. - nothing much
t= 0.5 mil. years -> 12 million years - hydrogen and helium clouds collapse to form first proto-stars (to be main sequence pop.III stars)

Now at t=15 mill. years.. seems everything is happening... pop.III protostars create main sequence popIII stars, who go nova only after 1-2 million years (in this time scale, almost instantly). Now after only 1-2 million years we have smaller stars going their marry way, with some (wonder about the % here..10, 20, 50%.? don't know) mega stars now being 500 solar masses black holes.
They move around.. interact.. stuff fliles in.. flies away.. Yet a billion solar masses BH is like a furnace needing constant intake to get it from 500 to 5.000.000.000 s. m. It needs millions of suns to just fly in or millions of black holes.. however you look at it.. no orbits no nothing... and only has about 900 million years to do so. Don't know.. just doesn't seem to add up somehow.

p.s.
... to not get trolled :)
when I say "t= 0 -> 0.5mil. y. – nothing much", I mean in terms of stars and black holes. Not in terms of cosmology or early universe, where of course, lots of things are going on at that same period :)

SL, Ethan talks about 1000 solar mass stars making 1000 solar mass black holes, not insisting that 1000 solar mass stars exist, so you're jumping the gun here a bit and extrapolating.

I'd done some 20 years ago a study into super massive (>60So) stellar objects and there were then hints that stellar bodies over 120So were observed (given the observations were correctly interpreted) and a potential of @260So, with a best guess of 160So mass stars in places.

At that time, HOW they could be stable (rather than collapsing immediately into a core of greater than 1.4So which inevitably collapses into a black hole before it can ignite and overcome the inertia of the infalling matter to attain some semblance of stability.

It took several years to come up with a mechanism, which is the pair production and several more to be able to do the maths in such a way as to find a solution.

I think that the self-disintegration form Ethan begins here is very much more recent, so not finding anything about it isn't really odd and that your search not finding anything showing many hundreds to thousands of solar mass objects being at least temporarily stable allowing the mass to retreat to within the Schwartschild radius before runaway nuclear reactions throw it out is merely that this is at the cutting edge and hard to find in *accessible* research.

@ Wow
"SL, Ethan talks about 1000 solar mass stars making 1000 solar mass black holes, not insisting that 1000 solar mass stars exist, so you’re jumping the gun here a bit and extrapolating."

His sentence is: "... A 260 solar mass star would create a 260 solar mass black hole, a 1000 solar mass star would make a 1000 solar mass black hole, etc. And so if we can make a star that exceeds that limit here...."

I didn't extrapolate anything.

You did.

one elephant will eat 1ton of hay a week. ten elephants will eat 10 tons of hay a week.

Neither say I have any elephants.

(NOTE: consumption rate of a pachyderm is pulled from arse since it is irrelevant to the point being made)

@wow

I have no idea what you are talking about. You misread plural when it was in singular.

Ethan proposes a 1000 solar mass star that goes supernova and creates a 1000 solar mass black hole, which is a seed for supermassive black hole. Not stars (plural).. but star.. one.
I said I couldn't find any reference that 1000solar mass star is even possible.

What do elephants and hey have to do with all of this....

"I have no idea what you are talking about. "

OK, so what level reading age should I work for?

That was only age-6 there, so there's not a lot lower than that I can go without getting Dr Seuss in on the picture.

"Ethan proposes a 1000 solar mass star WHICH goes supernova WOULD create[s] a 1000 solar mass black hole"

Just because you want to put different words in that make your assertions right doesn't mean your assertion over the words that are there right.

Should be:

"Ethan proposes THAT a...

To clarify, because there seems to be some confusion:

I propose -- and it is not an original proposal by me -- any star with a mass that exceeds a certain limit, probably in the ballpark of 250 solar masses, will, when it runs out of hydrogen fuel in its core (and exceeds that critical mass when it runs out of core fuel) simply collapse completely to a black hole.

I am not claiming that a 1,000 solar mass Pop III star can form via monolithic collapse, but Pop III stars in excess of 100 solar masses can be (relatively) very common, and stellar mergers can also be somewhat common. Reaching 1,000 solar masses is not unheard of; indeed that's about the largest number that those who study it bandy about these days.

But let's be clear: there is no supernova for stars above this mass threshold, just runaway collapse.

Ethan, thanks for replying. We got stuck on my first question, without anyone addressing other things.

My main worry is how a 200-500, doesn't matter.. solar mass black hole gets to several billion masses in such a short time (less than 1 billion years). That's roughly one solar mass per year.. give or take a few... needed every year for billion years. Are conditions in the Universe at that point such that this is in fact the case? I am just not sure there enough matter to allow for that at such rapid scale.

Weather or not 1000 solar mass star is possible or not is not so much an issue.

SL, I did address more than you then continued to obsess on:

I’d done some 20 years ago a study into super massive (>60So) stellar objects and there were then hints that stellar bodies over 120So were observed (given the observations were correctly interpreted) and a potential of @260So, with a best guess of 160So mass stars in places.

At that time, HOW they could be stable (rather than collapsing immediately into a core of greater than 1.4So which inevitably collapses into a black hole before it can ignite and overcome the inertia of the infalling matter to attain some semblance of stability.

It took several years to come up with a mechanism, which is the pair production and several more to be able to do the maths in such a way as to find a solution.

I think that the self-disintegration form Ethan begins here is very much more recent, so not finding anything about it isn’t really odd and that your search not finding anything showing many hundreds to thousands of solar mass objects being at least temporarily stable allowing the mass to retreat to within the Schwartschild radius before runaway nuclear reactions throw it out is merely that this is at the cutting edge and hard to find in *accessible* research.

" they can fuse all the hydrogen in their cores into helium in mere millions — or in extreme cases, possibly only hundreds of thousands — of years" Is there a formula or a list somewhere that relates mass to H-He? 1sol 10Byrs, and so what is the time for 2sols, 4sols, 8sols, 16sols, 32sols, 64sols, 128sols, 256sols for example, and the other way too: 0.5sols, 0.25sol - down to the 8.3%sol - the smallest mass above brown dwarfs

So the idea is a >250 SM star collapses into a BH without creating a huge amount of energy, which would serve to blow away surrounding gas clouds ending star formation. So presumably you get a bunch of intermediate mass BHs in a small space, that might resemble a globular cluster, but instead of stars most of the objects are intermediate mass BHs? Then you got to get lots of BH mergers.

I think part of the reason large stars are scarce once pop III has done its thing is metals. They increase opacity, which means that the effect of radiation pressure per unit mass of gas goes up. I think that leads to higher mass stars pushing away their outer layers as radiation pressure exceeds gravitational attraction? The thing about the LMC, is that it presumably had very little star formation until it got disturbed by recent tidal interaction with the MIlkWay, so the stars in places like R136 formed from low Z gas, which we don't normally find in modern galaxies. Is this right?

@ Wow

Please show which parts of what you've written correspond to my other questions?

you've written that
1. you've done study on >60So objects (I assume So means Solar mass).
2. found that they exist
3. found that they can be as massive as 260 So
4. found that they can be stable

... ok. No one refutes this. What does this have to do with rest of my questions? Such as wouldn't the shockwave blast material far away from singularity, rate of accretion etc. etc... I read everything you wrote the first time. You needn't spam with duplicate posting.

SL, you accused Ethan of saying there were 1000So mass stars.

You were wrong.

I pointed out that you were wrong and that claim was you extrapolating what was said into something not said.

I then talked about my knowledge of supermassive stellar objects from quarter of a century ago.

Then talked about how it had changed.

Then talked about how the lack of confirmation of a claim never made may be pending because such claims would be the cutting edge and not available in easily accessible sources.

Now, what questions do you think that the above must have been an attempt to answer?

David, not a lot that's easy to get unless you get some "taken on faith" undergraduate textbooks or work at the post-doc level information.

Partly because H-H fusion burns at a rate proportional to (IIRC) T^6 and solving T for the mass of a star requires hydrostatic equilibrium with photon pressure (from the burn rate), and the available mass to fuse with, THEN it goes and starts running He-He burning which goes as T^8, but there's an outer shell still able to burn H-H.

Then it goes a bit bang and then you have C-C burning, He-He burning and probably still some H-H burning, with a lot of mass ejecting, but only if it's less massive than a certain amount.

Which means that your calculations are very convoluted.

Approximate answers based on simplifying assertions are here:

http://www.astronomy.ohio-state.edu/~pogge/Ast162/Unit2/mainseq.html

Sinisa Lazarek

"My main worry is how a 200-500, doesn’t matter.. solar mass black hole gets to several billion masses in such a short time (less than 1 billion years). "

Yep, that is a good question.
And yep, it doesn't seem to matter much whether we start 1000 Solar mass, 260 or less than 130 solar mass stars; hence black holes.

However, one of the links that Ethan points us to this
http://www.dailygalaxy.com/my_weblog/2013/11/mystery-of-supermassive-bl…
Nov 8, 2013 article begins, "An enduring mystery is the existence of supermassive black holes in the early universe—such black holes would have formed less than one billion years after the Big Bang.." And then (I think, I defer to experts) this article goes on to describe a computer simulation (of the physical processes that Ethan summarizes). And this particular simulation requires 260 and 1000 solar mass stars as part of the initial conditions of its explanation. And also this particular simulation has figured out a way for these big hypothetical stars to be stable; hence the importance of the observation of a 265 solar mass star. Very nice, one observation is enough to confirm that such stars exists.

But the article goes on to waffle that, "Although the study involved computer simulations and is thus purely theoretical, in practice, (yada yada yada).. which was first predicted by Albert Einstein in his general theory of relativity; future space-borne gravitational-wave observatories, Reisswig says, will be necessary to detect the types of gravitational waves that would confirm these recent findings." ahh!

I think that means that this particular explanation (of supermassive black holes in a short period of time) can not be confirmed (as correct) without successful gravitational astronomy, e.g. LIGO. OK.

Which means that we still have a very important big unanswered cosmological question.

Meaning we do not have enough information (astronomical data) to evaluate the correctness or not of the various current hypothetical explanations to the astronomical question:
How could supermassive black holes form one billion years after the big bang?

We don't know but we are working on some promising hypotheses.

That's my paraphrase.

I defer to the experts; because there is an awful lot in the (yada yada yada) that frankly; I have no idea what the experts are talking about.

Something I don't get about the pair production instability. Photons that create electron/positron pairs don't destroy energy, those pairs will recombine shortly. The only thing I would think they would do is increase the heat capacity, as these electrons/positrons add degrees of freedom to the mix of gas/photons/nuclei/electrons. Unless they get involved with nuclear reactions and neutrinos are produced which can carry energy out of the star, they oughtn't be an energy sink.

@OKThen

thanx for the link to that. Found the arxiv pdf
http://arxiv.org/pdf/1304.7787v2.pdf

At the beginning the author's say: "...Sufficient initial
seed mass could be offered by the theoretical possibility
of supermassive stars (SMSs) with masses 10^4 - 10^6 Solar Masses..."

Am I reading this right? 10.000 solar mas and 1 million solar mass star???

the more I read the paper, the more it seems it's really about modeling how a black hole (or holes in this cases) would form if such an object existed. Can't really say I'm please with this line of reasoning. Want a billion solar mass BH.. no problem, just start with million solar mass star and make it colapse. Don't mind how it's made or can it be made...

#24 Sinisa Lazarek
"Can’t really say I’m please with this line of reasoning."

Well yes and no. I mean, we got some data (I assume) evidence that 13 billion light years away (distance in the nomenclature of a 13.7 billion light year radius universe) that even so long ago there were supermassive black holes.

OK, I'm not sure of the evidence but I accept that there is such evidence. And this means we have a mystery to explain.

Well we only got the astrophysics and physics that we understand. And so, they make their best explanation(s). And they have to be pausable.

But since we have only so much observational data and only have various accepted theories; we can only go so far in our explanation(s). And this is one of the promising imperfect explanations within conventional accepted theories of cosmology.

Of course, the great lingering question, the elephant in the room is?????

Get ready to pounce upon me.
Well if the big bang is wrong i.e. is only an apparent big bang?
That is to say,
What if the universe is only apparently expanding. i.e. if the cosmic red shift has been misinterpreted.
What if there is only apparently dark matter and apparently dark energy.
And of course all of this is an enormous BIG IF
And of course such a BIG IF would imply a lot of other different interpretations of the various other unsolved problems of physics and astronomy.
But if all of this BIG IF; well then our visible universe would only apparently be 13.7 billion years old.
And therefore, we'd more time maybe even an infinite amount of time in which to build supermassive black holes at the center of galaxies.
And so on and so on and so forth. And that's a lot of BIG IFs.

But even a village idiot, like me, couldn't possibly consider the possibility of such a BIG IF; could I??

I mean, we do all believe that at the end of the day (end of this century) we will find an elephant in the room. I mean, we all expect that physics will identify the 95% of the universe (the dark matter and dark energy) that is missing. Right?

-- So elephant is in the room; dark matter and dark energy fill the observable universe. or
-- BIG IF, no elephant in the room. Complete revolution in our understanding of cosmology and physics (e.g. maybe extra dimensions, supersymmetryishness, stringy ness, quantumy gravity, or some suchness)

Personally, as the village idiot, I do not se much difference between
-- an unseen elephant in the room (i.e. unseen dark matter and unseen dark energy), versus
-- unseen extra dimensions and unseen supersymmetries.

But science is not a popularity contest. And we shall see what can be seen (i.e. experimentally/theoretically determined).

Amazingly, I must say, we have seen a 265 solar mass star. Absolutely amazing. The theorizing could have gone this and versus that way for quite a long time (maybe 13.7 billion years even). But one definitive observation.

Wow: your #20 responding to my #15: I knew things would not be simple but anyway thank you for some pointers.

" Photons that create electron/positron pairs don’t destroy energy, those pairs will recombine shortly."

No, most cases will see the two never meet again. For a start, pair production requires a mass nearby to allow momentum to be conserved as well as energy. Conserving both is not possible without another body to take the hit.

So you now have a mass that could be taking on one of those.

The pair are also really fast, in general, and they have more kinetic energy than they have electrostatic binding energy, so there's no energetic reason for them to come back together.

If they did collide, you'd get two photons not one. IIRC on this one, required to ensure energy and momentum are conserved again in the absence of a mass.

Lastly, both are charged particles and can be moved by electric and magnetic fields (like you get in a star) and this can both move them apart and cause them to give off photons by being turned (requires acceleration).

So they won't produce a post-event that removes all the energy for several reasons.

"Am I reading this right? 10.000 solar mas and 1 million solar mass star???"

Yup, but you seem to be forgetting one really rather important word to make this a fake observation:

theoretical

.

A dense gas cloud will collapse quicker and therefore any masses accumulating may be bigger and fewer and closer together.

If an open cluster of 10^6So collapses, then it's the weight of the rest of the galaxy that pulls them apart.

In the middle of a galaxy, that's less relevant. And if they're black holes accumulating mass from dust and losing energy in the group by gravitational collapse, they're not going to pass out and spread through the galaxy, but eventually merge.

And they will, at the beginning, even if that million solar mass cloud doesn't turn into one single black hole, but a thousand of them a thousand solar masses each, they will still be ~10ly across and non-radiating as a group except by accretion disk emissions.

So, given all this, why do you think that a million solar mass black hole is impossible?

"couldn’t possibly consider the possibility of such a BIG IF; could I??"

No, anyone can pursue a chain of big ifs. You need education to find out if the ifs are plausible and their consequent and discriminatory features detailed for experimental testing, but think through the big ifs is no problem.

This is something that has no thread, so it's OT, but you need to consider what effect is making the redshift. It has to accord to the current observations that support the current meme and explain why the universe is older than it appears. Previous attempts fail because the fine structure constant would have to change for those other theories to be right, and a change there would make the absorption spectra of stars different, and that's not seen.

And after you get all that, that's just one of the big ifs. You haven't shown that any of the rest of the ifs, required for the observation to prove the overall hypothesis, are correct.

It's one reason science tends to be conservative until a paradigm shift, and even then it merely jogs along, going back over the past knowns to see how or even if they change (thermodynamics didn't change a jot with QM, for example). And that takes time.

Nice article Ethan. Well written. Good organisation illuminated and divided into digestible lumps by the pictures. Evidential and factual and nicely salted with caveats where appropriate. Pulls the reader along so effortlessly it's a disappointment to get to the end. Couldn't fault it. Yep, that's the way to write a blog.

OKThen: there is a big difference between dark matter/energy and some of the other things you mentioned. Look to relativity. Space has its vacuum energy. That energy has a mass equivalence. And space is dark.

@ Wow

why do you keep misreading or misunderstanding me???

"So, given all this, why do you think that a million solar mass black hole is impossible?"

Where did I say that?? Star man! Not black hole! Please read carefully what has been written.

No one is questioning the existance of supermassive black holes. We have experimental evidence.

This is about 1 million solar mass population III star. Not a 10^6 So cloud or a cluster or anything that you are thinking I'm talking about. The issue is a very "if if" scenario.. nothing even close to such masses evenly remotely observed... and yet it's the key ingredient. Without it their simulation fails. It's a far cry from 200So observed star and 10^6 So hypothetical star.

"why do you keep misreading or misunderstanding me??? "

Possibly because you're posting incoherent babble. Consider the option, for variety's sake, if nothing else.

"“So, given all this, why do you think that a million solar mass black hole is impossible?”

Where did I say that??"

You didn't say that, but that is the conclusion of what you DID say, dear:

“Am I reading this right? 10.000 solar mas and 1 million solar mass star???”

Why are you disbelieving not only something written down, but something you quoted, if you thought it was not impossible?

What is the question mark for?

Why does it exist?

What does it mean?

?

"No one is questioning the existance of supermassive black holes"

So is your assertion that 10^6So is not super massive?

You see, the question mark there? Here it is used to denote a rhetorical question. You know what rhetorical means, don't you.

So, yes, 10^6So is supper massive.

But you question the evidence of your eyes that such a thing is said to be possible by someone else.

Why is that?

you're funny when you incoherently troll like that.

"This is about 1 million solar mass population III star. Not a 10^6 So cloud or a cluster or anything that you are thinking I’m talking about. "

This was also about 10,000So.

But you wish to preclude anything that is not supportive of your bafflement that your babble is not understood or acknowledged by anyone else in a state of mental stability.

Or is this you were incredulous only of 10^6 but not 10^4 and you included both values in the same sentence of intense incredulity at your own visual acuity because...? You're dumb?

I'm not saying that's the answer, but it's a possible one, yes? The only one who knows what you're babbling on about is you, but apparently you have no idea what it is either, so you must be having "thinks" that your own brain can't follow. And we're left guessing as to what's going on on the other end of the internet.

Ah, I see, SL, "I can't answer, so you must be trolling".

Doesn't work, dearie.

Lolz..oki doki. By the way, am not your deary grandpa. so buzz of

No, that doesn't work either, SL.

When you are asked a question as to what you were using the question mark for in the statement "Am I reading this right? 10.000 solar mas and 1 million solar mass star???”, the answer is neither "U Troll, bro?" nor "You not ma dadday".

Well, not if you're sane, anyway.

Wow @27. I didn't mean they'd find each other to recombine with, but we are talking about a super hot dense plasma, they'd find other electrons/positrons in very short order. In fact the density/energy distribution should be determined by thermodynamics, and the photon distribution would be as given by Plank.
I did look this up in wikipedia, the claim isn't so much that this process absorbs energy, but that is changes the dynamics of collapse such that is doesn't stop. I think that means the plasma still heats up as it is compressed, but the pressure doesn't increase enough to make up for greater gravitational forces. So I guess once the density/temperature gets high enough nuclear reaction rates become so high that everything fuses with a few seconds while the star is blowing apart.

I just wonder how gentle a >250 SM star collapsing into a BH would be. If there is rotation involved, then it could spin up an accretion disk and do the gamma-ray burst thing. Presumably those would heat the surrounding gas enough to blow it away and shut off star formation. AFAIK massive star formation is self limiting, as energy released for supernovas and gamma ray bursts push away the gas clouds -probably as far as out of the proto galaxy.

Ok, Wow.. will try to put this to your senile level:

1. "Possibly because you’re posting incoherent babble. "
- that would be you

2. "Consider the option, for variety’s sake, if nothing else."
- correct, consider that yourself, for change

3. "You didn’t say that, but that is the conclusion of what you DID say, dear:"
- you're projecting grandpa... your own misguided conclusions

4. What is the question mark for?
- people put question marks when they question something grandpa... In this case, the existance of such massive stars in early Universe.

5. So is your assertion that 10^6So is not super massive?
- lolz.. no.. again... see the pattern of your dilusion?

6. This was also about 10,000So.
- 10.000So what? chocolate, flowers, stones.. 10.000So of what? Or did you forget already?

... and so on and on...

What is in question here, is your ability to follow conversation. Sad realy

"but we are talking about a super hot dense plasma, they’d find other electrons/positrons in very short order."

Which will have different energies, so any result will be a different energy photon it had before (even before splitting into two), so the end result is not a system identical to the one before.

High energy posi/elec-tron pairs are more likely to find a partner of a lower energy and this will mean that you get a cascade of energy down from high to low energies.

"So I guess once the density/temperature gets high enough nuclear reaction rates become so high that everything fuses with a few seconds while the star is blowing apart."

No, it blows up too late to happen outside the event horizon, therefore no explosion as far as we can tell.

It'll just collapse.

No boom.

Just wink out.

"1. “Possibly because you’re posting incoherent babble. ”
- that would be you"

So you're not posting, I'm doing it under your name?

Your attempt to do the schoolyard "I'm rubber, you're glue" is incoherent. Still.

"2. “Consider the option, for variety’s sake, if nothing else.”
- correct, consider that yourself, for change"

I did consider the option. See above for the result.

"3. “You didn’t say that, but that is the conclusion of what you DID say, dear:”
- you’re projecting grandpa… your own misguided conclusions"

So the question mark was there for what reason? You still avoid saying, petulant child.

"4. What is the question mark for?
- people put question marks when they question something grandpa… In this case, the existance of such massive stars in early Universe. "

So you were questioning whether the existence of such massive stars was impossible?

If that were the case, why did you say when I said that:

““So, given all this, why do you think that a million solar mass black hole is impossible?”

Where did I say that??”

Are you so desperate to make an obvious twat of yourself that you will pretend you didn't disbelieve the statement when you did disbelieve it and then avoid for ages saying that you actually did disbelieve the statement to begin with?

Why?

"5. So is your assertion that 10^6So is not super massive?
- lolz.. no.. again… see the pattern of your dilusion?"

Ah, I see. Rhetorical is a word you've never come across. You have good typing skills for someone in kindergarden.

What, precisely, is your problem? Is it congenital or acquired?

"So you’re not posting, I’m doing it under your name?"
- no, under your name.

"So you were questioning whether the existence of such massive stars was impossible?"
- I was questioning whether the existence of such a massive star was possible.

" ““So, given all this, why do you think that a million solar mass black hole is impossible?”

Where did I say that??”"

Because... and for the last time, I do not think a million solar mass black hole is impossible!!!!!!!!!!! Why would I think that when we have astronimical observations of them. For hell's sake, this entire post is about them. The question is how they came to be so big!!! Or did you miss the entire point of the entire post?!
Author's of the above paper, and in turn Ethan's post based on that paper, is that a billion masses black hole came to be from a million masses star. I question if a million solar mass star is possible. Because if it's not, the rest of the paper is irrelevant.

I can't put it much more simpler than that.

"Because… and for the last time, I do not think a million solar mass black hole is impossible"

Then why so incredulous that someone mentioned it?

Yet more incoherency of a moron desperately digging a hole to fill the hole they've dug themselves into.

Sad, really, that such a being is counted among homo sapiens.

"Then why so incredulous that someone mentioned it?"
- Because, moron, they mentioned a star that big.. not a black hole. All your moronic BS is based on you reading "black hole" when it was written "star"...

"Yet more incoherency of a moron desperately digging a hole to fill the hole they’ve dug themselves into.
Sad, really, that such a being is counted among homo sapiens."
- couldn't have put a better description of your last 5-6 posts on this topic, even if I tried. Thumbs up

"- Because, moron, they mentioned a star that big.."

So why is a star that big impossible?

Or is that too hard a question?

And why is a million solar mass black hole acceptable, but a million solar mass star that will form into a million mass black hole not acceptable?

Both form from the accretion of a million solar masses of hydrogen.

Sinisa Lazarek and Wow

This is really a sad state of affairs. Both of you are science minded, bring intelligent thoughts, good questions, healthy skepticism, curiosity to the table.

And yet, look how this discussion has degenerated.
And yes I is tempting to take sides. Well maybe not; what's the point when the conversation is completely broken.

I may have told this story before.

I was in a key shop trying to get a key made for an old lock. I brought the old lock. And the lock smith took the lock looked at it for a minute and told me it would be a waste of money to get a key made for this old lock.

The lock smith handed the lock back to me. But now the lock was in two pieces. Whereas when I had handed it to him, my lock was in one piece.

I said something relatively innocent like, "What'd you do? My lock is broken now."

And the conversation deteriorated quickly to the point where the locksmith said to me, "get out of my store. And don't come back again."

I stopped. Looked at the locksmith realizing how insane our conversation had gotten about a stupid old lock. I said to him, "You know the world is a really fucked up place. Everybody fighting and killing everybody else about stupid things like this lock. And you know, there is really no hope for this world; if you and I can't discuss this old lock. So let me first apologize to you because I never meant to offend you. I am sorry. And if you are willing, maybe we could start this conversation all over again."

And waited and looked at the locksmith while he thought a moment. To his credit, the locksmith looked at me and said, "I am sorry too. I just felt you were accusing me of breaking your lock. Which I would never do. But this lock is old. It is made out of cast iron. And when cast iron gets old; it gets brittle. May I show you." He reached for the lock.

I gave him the lock. He tapped it on the counter lightly and he said, "see now it is in more pieces. So you don't want to lock any doors that have this lock; because the slightest tap just the right way and the lock will be broken and you wouldn't be able to unlock your door."

I picked up the collection of broken lock and said, "I didn't know that cast iron got brittle with age. You're right. I don't want to lock any of these doors that have these old cast iron locks. thank you."

Then he said, "But if you ever decided to lock a door. Just a simple skeleton key like this is how you do it."

I asked, "How much are your skeleton keys?"

He said, "$1."

I said, "I have no intention of locking any of these doors; but I'll buy three skeleton keys."

I never used those skeleton keys for anything but to hang on a nail and remember that locksmith who I only saw that one time 20 years ago. There was always someone else in his shop on the few times when I returned for a different key or lock or such.

So Sinisa Lazarek and Wow; this conversation, this lock that you are passing back and forth, can continue to be broken in more and more pieces as you pass more insults back and forth. And pretty soon, no one that is following these comments will be able to tell that it started with a simple lock; because well the lock will have deteriorated not into 1 or 2 pieces or even 1000 or 10^6 pieces. Yep all that will remain of this conversation will be puffs of an Avogadro's number of insult dust swirling back and forth.

And you know Sinisa Lazarek and Wow; if you two (intelligent inquisitive men) cannot fix this and your next and your conversations; then there is not much hope for this world.

When someone tries the fake incredulity so as to avoid actually specifying what their issue is with the quoted text, then they're not really that intelligent, are they?

"Am I reading this right?"

Answer 1:

NO.

This would be sarcasm since the text was quoted, therefore it has to exist to be quoted.

Answer 2:

YES.

This would therefore be a non answer that has only confirmed that text written was actually written.

Therefore the only position to take is to assume that the query was not about whether the person is insane and imagining text but that there was some issue with the claim.

However, after having tried that, SL decided to get shit flinging rather than coherent.

@OKThen & WOW

From #5 onwards I have tried my best to document and explain my chain of thoughts and to ask for more information from the people in the field. What I got is one answer from wow which is interesting historicaly, but didn't give me the answers to the questions I had. His second and third post were already starting to become rude and offensive, weather or not it's because I didn't say "oh thank you wow for answering all my questions" or for some other reason... I don't know.

After that, OKThen, you provided a link for an article that helped me find the scientific paper which tackles this problem. In it, the authors say that not even 1000solar mass star is enough, but 10.000-1.000.000 solar mass star is needed for a seed. And yes, I was very incredulous of what I've read. From 265 solar mass star that is observed, to a 1k star that might be... to a very hypothetical 1 million sol. mass star. Yes I am sceptical, and wanted to know what physicists think about this. Wow never actually bothered answering that. He was to busy writing vulgarities.

And I asked all this, and honestly tried to explain when I was met with waves of insults from wow... for what reason? To ridicule and conjure some grammar or spelling mistakes as to show off his overwhelming intelect?? or what?

In his comments it is clearly shown that he misread ethan's sentance firstly. Misread most of my posts. Seriously doubt he even bothered opening the linked paper. Just bashed insult after insult. And that's his right. Maybe he doesn't know, doesn't care... it's his right.

But someone else might know, and I won't just back down when someone is insulting me and accusing me of things I haven't done or said. No matter if he's an astronomer or whatever... I tried to keep my tone and manner decent and civilized. I broke after 3rd or 4th batch of insults. I will not be talked in that way and keep saying " oh thank you master"...

If I wasn't clear in my questions, and others also share Wow's "interpretation" of my question. I can accept that, apologize and will try to rephrase. But I don't think my handling of english is the problem here.

p.s.
And after everything, the question is still open... how does one end up with 10^6 solar mas star? What would prevent a cloud to form many smaller stars instead, as is the case.

And I've tried to show you that your train of thought is incomprehensible because you prefer to imply a query you will not voice and to pretend words that aren't there.

Ethan never said that there was observation of 1000So stars, yet your complaint was predicated on him saying so.

The paper said that a theoretical 10^4-10^6So star would explain the black holes, yet your complaint was predicated on these not being theoretical and being impossible.

EVERY SINGLE MISTAKE you've made has been to read "this is observed" when no such statement is made, then to whine and whinge yet more unstated queries absent of any actual content, then whine and whinge yet more when guesses as to what the fuck you're on about THIS time do not accord to what you wanted to imply but assiduously avoided saying.

Then make out that's all my fault.

If I wasn’t clear in my questions, and others also share Wow’s “interpretation” of my question.

Since you never said what you query WAS, of course I will need to interpret them to an actual frigging question you retarded little shitstain. Interpretation is required when you avoid any content but imply some is there, NO BLOODY SCARE QUOTES NEEDED.

"Am I reading this right?"
"No, you're insane and imagining the text. Next question"
"Oh, that wasn't the question I was asking!!!!"

FFS.

I note you still cannot say why you think 10^6So is impossible.

Argument from incredulity?

Jesus christ on a stick.

SL earlier:

At the beginning the author’s say: “…Sufficient initial seed mass could be offered by the theoretical possibility of supermassive stars (SMSs) with masses 10^4 – 10^6 Solar Masses…”

SL more recently:

the authors say that not even 1000solar mass star is enough, but 10.000-1.000.000 solar mass star is needed for a seed.

So "10^4-10^6 is enough to explain it" becomes "10^3 can't!".

See what I mean about reading something not there (or omitting something relied upon to make incredulity).

"And after everything, the question is still open… how does one end up with 10^6 solar mas star? "

When you get 10^6 solar masses of hydrogen collapsing into one object, you get a 10^6 solar mass star.

And where the hell was that question first? Even looking for "how does one" brings up NO previous query of that form.

For a question to "still be open", IT HAS TO HAVE ALREADY BEEN ASKED.

"I notice that a question I'm making now still hasn't been asked. Why haven't any of you answered it before?".

Hey,

I hate having to moderate grown adults, but I guess it's necessary here. Here goes.

If someone asks an ill-posed question, it doesn't necessarily mean they're dense, trolling, looking for a fight or something else malicious. It also doesn't mean they're deserving of ridicule or cruelty, even if the ill-posed question is ridiculous. Sometimes a question is simply ill-posed.

And sometimes, whether the question is ill-posed or not, the answer is still not conclusively known. We know very little about the first stars in the Universe, to be frank, and that's part of why the James Webb Space Telescope is such an important tool.

There's a good overview of the theory here, where you'll note that even the "typical" size of a star-forming Pop III region exceeds the mass of the Tarantula Nebula, and some recent simulation work here.

I myself am not aware of a good mechanism to achieve ultramassive ( > 1000 M_Sun ) stars, but I am also not convinced that they are required to seed supermassive black holes. One important lesson I've taken away from cosmology is that we tend to vastly underestimate how quickly nonlinear growth occurs.

That said, cut out the petty bickering; you're all real people behind your names/pseudonyms. I'd break you up if I saw you behaving like this in public in the streets, and I mean to do just that on this blog right now. Knock it off.

Seriously? I haven't asked the questions?

# 5 "- on wiki and on arxiv I couldn’t find anything about even theoretical 1000 solar mass stars (population III)" - this was answered in part by you, ethan and okthen

#5 " Even if we take a hypothetical 500solar masses star going meganova.. wouldn’t the shockwave blast things nearby so far from singularity that any mega accretion is impossible?"

#14 "My main worry is how a 200-500, doesn’t matter.. solar mass black hole gets to several billion masses in such a short time (less than 1 billion years)...Are conditions in the Universe at that point such that this is in fact the case?"

#23 "Am I reading this right? 10.000 solar mas and 1 million solar mass star???" - this is when I found a paper that now theorizes 10^6 s.m. star. And the question mark was there because I could imagine it being a typo or me not reading it right (not a physicists). And at that point I was looking for the answer here. Either: a) yes, sinisa, 1 million solar mass star is indeed very possible, because it can be formed if such and such happens under such and such, we have good evidence for it. or b) hmmm.. that is very strange and the authors seem to speculate a bit since we have no evidence that they can be so big.

#42 " I was questioning whether the existence of such a massive star was possible."

#52 "What would prevent a cloud to form many smaller stars instead, as is the case."

... wow, you ca post as much as you want and as in many messages as you want. But at least don't spin it.

Sorry Ethan,

thank you for the links. Won't post about this in that manner again.

One more thing, that I think either I wasn't clear enough about or that was overlooked:

Stars between about 130-250 M_Sun will go supernova catastrophically at the end of their lives, and that will, indeed, work to quench (suppress) star formation. But stars above that number will indeed work to burn off interstellar gas-and-dust while they're burning in their core, but there is no supernova explosion when they run out of core fuel. (And these are the first and fastest stars to run out of their core fuel.) Instead, the pair production I talked about -- which reduces the pressure -- causes the entire star to implode and collapse to a black hole, with no explosion, and no quenching of star / accretion disk formation.

In other words, although there's no proof, there's good reason to believe that the most massive stars that form these many-hundred (or above) solar mass black holes -- commonly known as IMBHs (Intermediate Mass Black Holes) -- could reasonably serve as the seeds of SMBHs. That's my best guess as to where they come from, but that is still only a guess; we don't know with the level-of-certainty I usually reserve for entries on this blog.

Thanks again Ethan :) The link to caltech's site was helpful in learning more about popIII stars. One thing it gave an idea about is DM, which I overlooked completely. Some of that mass certainly played a role somehow

What I liked most was the the overview at the end :) One theory says they were mostly small stars, second says they were large, third says they were small and large, and the forth sais... hey guys, there were no stars :))) That' cool :)

I will have to dig deeper into pair production instability. At first glance seems so amazing and bizarre that a star would just disappear in a blink. If nothing "goes out", and whole star just ends up behind swartz. radius, to an outside observer it would just be here on moment and gone the other. Strange image.

"If someone asks an ill-posed question, it doesn’t necessarily mean they’re dense"

But it does mean it was ill posed.

But that isn't what got me riled. It was the "Oh, your guess as to what I meant was wrong" just kept bloody dogpiling on on top of yet more needing to guess with the inevitable "your guess as to what I meant was wrong".

"And the question mark was there because I could imagine it being a typo or me not reading it right (not a physicists)"

So ask "Was that a typo?". Not "Did I read that right?".

But why would a typo get in there? Why would it be more likely a typo when it's merely saying "theoretical". Theoretically, there's no problem with a 10^20So star. The rest of the universe would be pretty damn boring and empty.

If you've got a question and it seems people can't work it out and you've not stated what your question was (you did not ask "is that a typo?" or anything even vaguely similar), then just ask the damn question you meant.

"I haven’t asked the questions?"

You haven't asked the question: "how does one end up with 10^6 solar mas star? ” until you claimed it was "still open".

# 5 “- on wiki and on arxiv I couldn’t find anything about even theoretical 1000 solar mass stars (population III)”

Answered in #7:
I think that the self-disintegration form Ethan begins here is very much more recent, so not finding anything about it isn’t really odd ... it out is merely that this is at the cutting edge and hard to find in *accessible* research.

” Even if we take a hypothetical 500solar masses star going meganova.. wouldn’t the shockwave blast things nearby so far from singularity that any mega accretion is impossible?”

Answered by Ethan ATL and by me to Ohmega.

No. It falls within its event horizon before the boom.

…Are conditions in the Universe at that point such that this is in fact the case?”</blockquote?

No, because we weren't there. Hard enough to get "this is in fact the case" about things already in front of us, never mind 13By ago.

#23 “Am I reading this right? 10.000 solar mas and 1 million solar mass star???” – this is when I found a paper that now theorizes 10^6 s.m. star.

Yes, they do. This is nothing like a problem. What are you expecting? Everyone to laugh at the paper? There's nothing impossible about it.

#42 ” I was questioning whether the existence of such a massive star was possible.”

By not saying you were questioning whether it was possible, but acting incredulous that your optic systems were working.

It was answered with "Yes" and explanation of the methods by which such a thing isn't really impossible. Thousands is easy. Why not tens, hundreds or thousands times bigger?

#52 “What would prevent a cloud to form many smaller stars instead, as is the case.”

In the case where it forms many, then it's prevented from making only one by the fact of having made many, but the case of making many is not the only case. So drop the "as is the case". Then the question is not begging the question as it currently is, but asking a query to which answer is "there is nothing preventing it making one big star".

Nothing prevents it from taking all the mass, except the speed at which other things take the mass it can accumulate from its grasp.

Sinisa Lazarek and Wow
This blog is not just Ethan's. It is ours also to make into a place for intelligent discussion on scientific matters.

so re: Sinisa Lazarek's question 2nd paragraph #51 above.

My answer would be.
Once you get over the 250 solar mass threshold; apparently the mathematics gets stable solutions all the way up to 10,000 or even 1,000,000 solar masses. And then the bigger the star, the faster it burns, so the faster it enters its end stage of being a very big black hole. Hence, most all of those superbig stars just are gone out of existence. We're lucky to have found a single 265 solar mass star that is still in existence (though I would like to know its estimated age).

Now having said this, do I believe that this will turn out to be the correct physical answer as astronomers and mathematical astrophysicist get better observations and do better simulations?

Well NO. And not because of any crackpot theory that I personally might hold. I say NO; because going from 265 solar masses to 10,000 solar masses and to 1,000,000 solar masses is 4 orders of magnitude. And a lot of interesting and unpredictable new physics and instability can happen with each increase in oder of magnitude. By stability, I mean the ability of such a superstar to smoothly transition to a super black hole without blowing itself to smithereens (i.e. instability).

But I am an amateur; Wow you are a professional.
And truthfully, I know that you Wow can offer a more physically insightful answer/explanation of the astrophysical processes involved in this discussion than I can.

I for one, would greatly appreciate it Wow; if you would give your best shot at answer/explanation/point of view to Sinisa Lazarek.

And then Sinisa Lazarek say, Thank you.

And then end this much too long and too exasperating discussion. It hurts to listen too it. Yes I am a baby, a village idiot. fine.

But then again, silence NOW is an OK answer too.
Sometimes silence is the best answer.
Just walk away from the uncomfortable discussion.

" I say NO; because going from 265 solar masses to 10,000 solar masses and to 1,000,000 solar masses is 4 orders of magnitude. And a lot of interesting and unpredictable new physics and instability can happen with each increase in oder of magnitude."

The paper was talking about theoretical. And there's no theory that makes it impossible, even though you're correct that it's possible that it IS impossible.

There are three really new things going on in the early universe:

1) no metals. Changes the mechanics of stellar formation into a fusing entity.
2) Warmer universe. Can cause small inhomogeneities to fail to turn into bigger ones: the heat breaks the stuff up easily.
3) Smaller. Gas clouds are denser and therefore have more mass nearby.
4) No other stars. Here a lot of star formation is the result of another star going boom, and the shockwave will cause many places to condense, potentially into stars. Absent them, it would be less likely for a star to form, reducing competition for the mass in the cloud when condensing actually happens somewhere.

We don't know any reason why 10^6So wont collapse as expected without mass loss into a BH, but it could exist.

Similarly for 10^7, 10^8 or 10^9.

Just the size of the expected available cloud here isn't easy to get: it has to be pretty dense to get that much mass within reach so it falls in rather than hangs about wondering what all the fuss is.

"I for one, would greatly appreciate it Wow; if you would give your best shot at answer/explanation/point of view to Sinisa Lazarek."

I did.

What did I get?

"I have no idea what you are talking about."

"Please show which parts of what you’ve written correspond to my other questions?"

Note: I'm not a professional, though some of my lucky compatriots still are. But in this climate, it's probably for the best: I would refuse to go to the USA or via it today.

#67 Wow

What you get is: thank you very much for that education and perspective from me.

I hope that with #67 that Sinisa Lazarek, reflects and says thank you also.

It is so easy to misunderstand one another; and then like the locksmith and me. Well things get out of control. Tragic really how our various qualities collude in a negative way.

I can't find my copy of David Bohm's book On Dialogue. But look at this there is a copy of it online. http://sprott.physics.wisc.edu/chaos-complexity....../dialogue.pdf
"Discussion is almost like a Ping-Pong game, where people are batting the ideas back and forth and the object of the game is to win or to get points for yourself.. In a dialogue, however, nobody is trying to win. Everybody wins if anybody wins. There is a different sort of spirit to it. In a dialogue, there is no attempt to gain points, or to make your particular view prevail. Rather, whenever any mistake is discovered on the part of anybody, everybody gains. It's a situation called win-win, in which we are not playing a game against each other but with each other. In a dialogue, everybody wins. ' from 3nd and 4th paragraph on page 2 which is the first page. Science at its best is like this and in my opinion a particularly good example of institutionalized long term dialogue.

And from bottom of page 4
"But if people were to think together in a coherent way, it would have tremendous power. That's the suggestion. If we have a dialogue situation - a group which has sustained dialogue for quite a while in which people get to know each other, and so on - then we might have such a coherent movement of thought, a coherent movement of communication."

It seems to me that Ethan has created in his blog the potential for a group of people to get to know each other and so have dialogue.

Sigh, unfortunately, dialogue requires that we each try to be an adult, make the effort to understand each other. It is hard, as all of us who have friends and families know.

"And there’s no theory that makes it impossible, ..."

Actually there are many theories that put mass cut-off on stellar formation. And all of them below 1k. Some bizare merger of i.e. 2 300So mass stars might be possible.

www.chara.gsu.edu/~wiita/CAOUpperMassLimit.doc

http://www.nature.com/nature/journal/v434/n7030/abs/nature03293.html

http://www-star.st-and.ac.uk/~kw25/teaching/stars/STRUC10.pdf

http://www.astro.caltech.edu/~george/ay20/eaa-stellarmasses.pdf

Even tough there is no definate theory, or fully understood mechanisms, they all seem to agree that anything above 500So masses is, if not impossible, then extremely unlikely. There is much reason to question validity of a 10^4-10^6 star theory as a solution to SM BH's.

As for #67, thank you. Altough I disagree with your view that there's nothing preventing such extreme mass build-up in just one place.

"Actually there are many theories that put mass cut-off on stellar formation."

First: Not Available.

Second one: "Here I report an absence of stars with initial masses greater than 130 M circle dot in the Arches cluster, whereas the typical mass function predicts 18."

Yeah. It's observation in a cluster.

Third one: standard stars, as per indication that the maximum is 50So. You know, wrong thing, dude. You're really stretching, you know that, right?

Last one: same as third one: talking about how stars can't be heavier than 60So...

Actually, Last one: actually says the same as Ethan ATL: 440So but predicated on Eddington's work in the 20's.

Do try to keep up, SL. There's a dear.

Thanks for acknowledging #67.

Bring on the Rainbow theory so we can have some brightly colored arguments for a change !

By the way, most of the conversation between SL and Wow; I did not understand. For example, wow's remarks #73 and #74 are beyond my understanding. But I have no dougt that Wow is correct and that if I was interested and searched on key words and such I would gain a partial insight of what Wow understands on this area to science. And I know full well that it would take me years of dedicated study alone or in graduate school to achieve his clear thinking and insight and judgement on this topic (not that Ethan or Wow or whoever are some kind of super authority to me). No but they have earned my respect.

That being said, I allow myself my own skepticism. But I don't pretend that my skepticism is based on a more detailed more correct understanding of something. No I must acknowledge what I do not know in the detail. (Yes, even though I am the village idiot; I must acknowledge that). But even then I allow myself to right, to listen to my own reasoning upon the various conflicting data and conclusions and say, "I reserve judgement on this or that; or I still think this or that may one day prove to be a more correct direction that yes science may take."

But I don't hold that position as a believe or as a dogma. I hold that position because for me that position serves me as a guide in my inquiry into how this world works. But when (and I mean when because) my hypothesis will break in my own eyes; then it is time for me to throw it away because it has served its purpose for my learning.

On the other hand if I defend my idea regardless of evidence and my learning of contradictory data and theories; and I can never be moved from my position; then I have ceased to learn, ceased to be science minded. My hypothesis are then not just useful strawmen in my learning to develop my idea; then my hypotheses have become statues, golden idols if you will.

So Sinisa Lazarek, you must always trust and use your own judgement e.g. #71. And if you remain unconvinced; that is fine. Because well you are struggling with a picture that is bigger than the definitive detail that is known to be correct today. And those ideas of yours will lead you to understand physics and astronomy and the world better; because you are using these ideas to learn and to question.

And we must question right from the beginning. We do not leave the questioning to the wise men. No my 6 year old son questions me and I listen and allow him to grow. And my 32 year old son questions me; but he allows me to learn and to grow. And it is up to each of us to be self honest enough whether 6 year old, or 32 year old or yes I am 64 years old; to know that I am not conning and deceiving myself. And even if I can't express it very well; I am trying to understand both how the world works and yes I am willing to have my favorite idea my best idea (my best lock) broken by well some evidence (even if not the experts evidence).

I guess what I am saying is this.
Wow and Sinisa Lazarek, I consider you both online friends that I respect a lot. And in my mind, you are both right. Wow is right in this case about the details; and you Sinisa Lazarek are right about still questioning the overall narrative. And depending how you need to learn, at various times it is sometimes important to focus and understand the details and it is sometimes important to question from a bigger picture and different perspective.

You hear my various assertions of skepticism. And you also hear my various assertions of accepting a current understanding. the important thing; I think is learning which means not having a static understanding. Being totally indeifferent to being wrong. Thank you very much for finally clarifying that to me; because I get no pleasure in misunderstanding the world.

Wow and Sinisa Lazarek, you are to of the best people out here and others; you are part of a dialgue group such as David Bohm discusses. I hope I am part of that Ethan's dialogue group too.

That's why it hurt me, yes hurt me so much to hear you too at such words.

Ethan, as someone whose aspirations to be an astrophysicist were derailed 40 years ago, I'd like a description (sparing modeling) of how the collapse of a 250 SM star differs from the (core) collapse of a 25SM star. The later is presumed -at least in cases with sufficient rotation (I think) to generate gamma ray bursts, whilst the big one is alleged to be a very clean eater (to turn around the phrase about BHs being messy eaters). Is it that in the smaller stellar collapse, the core collapses into a compact object so fast the outer part of the star can't keep up? I hope its no because people only did 1-D models for the heavier star! I suspect a collapse of anything with spin leads to a dynamo effect, which given the energies involved might generate magnetic fields of ludicrous strength.

"And if you remain unconvinced; that is fine."

Of *course* it's flipping fine! Look at the evidence and be unconvinced, especially when it's just theoretical and not even an observationally tested one!

Just don't point at irrelevant information and claim that as support of the counter.

You don't have to be convinced to be unconvinced. Unconvinced is the default state. So you don't need evidence to be unconvinced.

You need evidence that the evidence given is not sufficient, mind. That's a different problem. The evidence for gravity is pretty strong.

And refusing to accept that something is possible is not being unconvinced, it's being mulish. Whilst refusing to accept something "impossible" in the colloquial sense because there's a quantum-level chance of something being true is as bad. For the same reason: it kills progress in its tracks.

Wow #80
I particularly liked
"Unconvinced is the default state."
Boom right between the eyes. Nice.
And yes, yes, yes elsewhere, well said.

"Do try to keep up, SL. There’s a dear."

You have to provoke, don't you?.. truly pathetic

Piss of, kid, you wanted to go there, so we got there.

lol

ORLY?

The Lion and the Boar

Articles like this one are for the most part, silly. You can stack all the math you like on top of a theory, but if the theory itself is bogus, everything that follows is nonsense as well.
My reasoning goes as follows: What is a black hole? Unless you know this, and can decide what qualities it will possess, you will have no idea what you are looking for is, or how to match your observation with your desired subject.
* To begin with: Black holes in fact, are a mathematical artifact of a purely mathematical space proposed first by David Hilbert using a Ric=0 Space time model within the theoretical framework of General Relativity with the energy momentum tensor set to zero. This space time model contains no matter, lasts forever (not compatible with big bang), and is asymptotically flat (no curvature). All black hole derivations pertain to this highly non-linear model with zero or only one mass (as a singularity without physical extension) and which contain no matter (this is called a contradiction). Because the field equations are highly-nonlinear, you can not insert additional matter. In other words, the equations can not be solved for a space time containing two or more masses (There are no known solutions). A modeled universe containing one or no masses is not anything like our universe (look around the room if you don't believe me), it's useless for the purpose of making predictions about our universe that contains just a little bit more than one mass, as gravity requires something to act upon to even be considered or observed. I'm not even getting into the parts of the math that require division by zero (a singularity) causing the metric to "blow up" (not a very scientific concept, mathematicians may explode, but math does not). Division by zero is undefined (you can't calculate it), and no one, not David Hilbert, certainly not even Stephen Hawking can hand wave this away for their convenience. What are you left with then? Not much. You have a dysfunctional mathematical model that requires contradiction, No more than one mass, the mass it can contain must be of zero size and infinite density (not logical, possible, or measureable), and division by zero (not mathematically possible) is required to do the calculations, just to get off the ground. This black hole model (and all it's variations) is not only useless, it isn't even wrong since it would require you linearize the non linear equations of General Relativity to try and do anything with it, which is also a another big no-no. At this point, I'm going to propose that if the math is this hinky just to get a theoretical concept off the ground, it has little or no useful merit, except as a so-so Star Trek plot device or a bad Disney movie concept.
Sooo, what happens if you stack other theories and even more complicated math on top of this mess? You certainly don't get science, valid math, or even a prediction that could be used to predict anything in our universe.
**If you want to look over the nitty gritty details of how badly fudged the math and theory is, check out Stephen J. Crothers various articles or lectures. He is very good at laying out the mathematical arguments the black hole depends upon.

That would be the world famous crank Stephen Crothers? Sorry, pass on that waste of time.

"What is a black hole?"

It is an extremely dense collection of matter such that gravity ensures that no information can leave.

Done.

" you will have no idea what you are looking for is"

Tautology alert! You need to know what you're looking for before you know what you're looking for?

"or how to match your observation with your desired subject."

Who "desires" this subject? Black holes are a theory. Observations of extremely dense collections of matter are also observed and these observations are in agreement with the black hole and not in agreement with any other known form of matter.

Oh, and the "three body problem" shows that we have had "you cannot add another body" in our science before. Didn't stop us sending probes to the outer solar system on target.

So don't see what your words are trying to prove here.

"Division by zero is undefined (you can’t calculate it),"

No, we do it all the time.

The mass of a photon is an example. gamma =0. relativistic mass = rest mass/gamma. A division by zero.

X/X=1 for all values of X. Even if X=0. Despite being a divide by zero.

And so on.

CFT: I think you're being too harsh. Ethan didn't mention "singularity". Have a read of Kevin Brown's Formation and Growth of Black Holes and note that he talks about two interpretations. The one he doesn't favour is the frozen-star interpretation. IMHO that's the correct interpretation because as you're doubtless aware that the coordinate speed of light varies in a gravitational field, and goes to zero at the black hole event horizon. It can't go any lower than that. Also see this:

http://diracseashore.wordpress.com/2009/02/19/black-holes-as-frozen-sta…

Interestingly the frozen-star black hole interpretation bears some resemblance to the gravastar which features a void in the fabric of space and time. Look at the black-hole image by Alain Riazuelo on French Wiki to get a feel for it. Drop a dimension and think of the balloon analogy for space. See the hole in space? IMHO with the correct interpretation of GR, black holes do exist. They are black, and they really are holes.

#88 CFT
Nice nonsense, particularly your promotion of a famous antiscience crank.

Yes in Aesop's story of The Lion and the Boar; the third character was the. Hmm? Was it the Antiscience Crank or was it the Vulture? I can't remember.

Sorry CFT, I got distracted.

Here's an idea. Next time CFT, that you want to pretend that you understand science (even if your intent is to disparage it) quote a scientist not an antiscience crank. Then you might be able to impress someone.

But now we know how deep your thought is. Not just the Crothers reference; but also right there in the middle you say, "I’m not even getting into the parts of the math that require division by zero ."

Oh my goodness, I can't imagine what you might say if you "got into the parts of the math that require division by zero ."

But before you do "get into the parts of the math that require division by zero; " may I recommend that you
a) read an introductory calculus book
b) read an introductory physics book
c) keep coming to this blog; but don't pretend to be an expert; just come to learn.
d) keep quoting Crother's nonsense somewhere else. And there is a place on this blog where you may discuss Crother's and any other psuedoscience, antiscience nonsense. http://scienceblogs.com/startswithabang/2012/09/23/weekend-diversion-yo… Please go there, read and understand Ethan's comment policy and follow it.

Thank you

“Division by zero is undefined

This is the only thing cft had correct. In math we never define division by 0 in the basic method of arithmetic, even if the numerator is zero - any meaningful results are (essentially) the results of limiting operations.

@John Duffield,
Thank you, I will look at that, it does look interesting. I'm not against any such idea of gravitationally dense objects, blackbody, neutron star etc., but I am quite harsh on zero sized entities with 'infinite' whatever.
@OKThen,
Sweetie ,
calling someone an 'anti-science crank' or saying they do "pseudo science" is ad hominem, especially without even a single specific example to back your insult. You offered no actual counter argument, except lots of condescending smug, verbal hand waving, allusions to what you think you know of my understanding, and a possible self admission of attention deficit disorder. If this had been a debate class, you would not have scored. I would point out that Crothers lays out his argument quite logically, with the mathematical details clearly shown, and then provides examples and illustrations of the concepts involved in the mathematical artifact you are calling a black hole. He does know his subject, and disagreement with his conclusions is fine, if you can actually provide one. If you are contending that in fact division by zero is not taking place in Hilbert's and Hawking's math, or are contending you can in fact insert additional matter into the non linear equations of GR which describe a theoretical black hole, please have the nerve to say so in order to challenge the argument on some logical grounds, elsewise, you have no argument, just a bunch of snark. Yes, please, do examine Ethan's comment policy (as I did) and note that you did not follow it when you failed to offer counterargument or refutation, but did offer up ad hominem and name calling. In full disclosure, I did call you sweetie in response to your disgruntled but otherwise empty commentary, which could be considered a mild diminutive.
As for my suggestions,
a.) Take a basic logic course. Pay extra special attention to 'logical fallacies' in argument.
b.) Read "Not Even Wrong" by Peter Woit.
c.) Read "Trouble with Physics" by Lee Smolin .
d.) Come up with a good counter argument the next time you darken my doorstep, or I will feed you to the wolves. Figuratively of course.
@Dean and Wow, I'm sorry, you are just so cool. Once again, smug ain't an argument, evidence, or interesting, even on this blog. Same goes for 'crank', if this word is your argument, you lose. As for your equations, I'm quite aware mathematicians and physicists think they are clever, it's why they keep making stuff up and having pissing contests over who knows the most buzzwords. Both my parents were mathematicians however, so I'm not terribly impressed by terminology.

CFT,

You could go up to the top of the page and use the "Search this blog" feature if you were looking for the answer to that question. Interestingly enough, if you put "Stephen Crothers" into the search bar, you get back this lovely post: http://scienceblogs.com/startswithabang/2009/11/18/are-black-holes-forb…

If you enjoy that post, you might also enjoy the post linked to in comment number 2, which is a post by Sabine Hossenfelder on evidence for the black hole event horizon.

And whether you choose to make substantive arguments and stick around here or not, you are not going to feed anyone to the wolves on my blog.

Actually, as my x/x shows, even arithmetic (well, algebra, but nobody would exclude it in a discussion about arithmetic when it's used colloquially, especially since the only one saying arithmetic is you, dean) allows a divide by zero.

It can do so, in the same way as limits do in a more rigorous fashion, by looking at HOW you get to zero.

"@Dean and Wow, I’m sorry, you are just so cool. Once again, smug ain’t an argument, evidence, or interesting"

Ah, so you are wrong and shown where and then decide that this must be the "moral error" of those pointing it out.

Sorry, doesn't work.

You can argue AND be smug at the same time. They are orthogonal issues in a response.

It appears that you merely make these things up as you go along. This is not a useful method of disputation. Please try something else.

"As for your equations, I’m quite aware mathematicians and physicists think they are clever"

As for you, you think you're even more clever.

And you call us "smug"?!?

Accusations of smugidity is not a refuation of a counterclaim, dear.

"Both my parents were mathematicians however, so I’m not terribly impressed by terminology."

But describing your parents study specialities indicates no presumption of the same possibility for knowledge on their offspring.

Unless you're a Lamarkian.

Just noticed the funny thing about two of the quotes I took from CBT:

1) “As for your equations, I’m quite aware mathematicians and physicists think they are clever”

2) “Both my parents were mathematicians however, so I’m not terribly impressed by terminology.”

I believe the internet term is LOL.

I have two questions:

1. Once a star collapses to within its Schwarzschild radius, is there a known mechanism that might prevent its further collpase to a singualrity?

2. Does black hole have a surface, or must we speak of it in terms of an event-horizon?

@CFT: My pleasure. I don't like zero sized entities with infinites either. Do have a read of Ethan's article on black holes though, which IMHO is fair enough. But be more cautious about other articles. Sabine's isn't bad, and at the bottom she links to the frozen star piece I linked to. But watch out for little things like this: If the gravitational force on the surface gets so strong not even light can escape. Gravitational force doesn't stop light escaping. A vertical light beam doesn't slow down. And gravitational force relates to the "local slope" of gravitational potential, which relates to the slope of your plot of the coordinate speed of light, which is zero at the event horizon, and can't be less than zero. Think about it! A great question to ask on a website is why a vertical light beam doesn't get out of a black hole. Some will tell you about the "waterfall" analogy, wherein space is falling inwards. That's tantamount to saying the sky is falling in, and to be blunt, it's wrong. This sort of thing takes you places with eg Hawking radiation and the black hole information paradox and the "firewall". Check out a guy called Friedwardt Winterberg for that. All interesting stuff. But all said and done, it's still a black hole even without the point singularity. Only more so.

Nova:

1) No.
2) It has no surface, you have to talk of the event horizon, since that is all you have that could be considered "surface".

Actually, as my x/x shows, even arithmetic (well, algebra, but nobody would exclude it in a discussion about arithmetic when it’s used colloquially, especially since the only one saying arithmetic is you, dean) allows a divide by zero.

No, division by zero is never defined, again, even when the numerator is zero. Sometimes the mechanics you reference give the correct result, sometimes not. 0/0 is an undefined ("indeterminate") term in mathematics.

No, division by zero is defined.

X/X is a division by zero when X = 0. And it's always equal to 1.

0/0 is undefined because you haven't said HOW they got the zeros.

@Wow

Thanks. :)

Nova: read The Formation and Growth of Black Holes by Kevin Brown. He talks about two interpretations. One yields the point-singularity black hole where total collapse is inevitable. The other yields the original frozen-star interpretation where collapse grinds to a halt due to infinite gravitational time dilation. Most people including Kevin Brown will say the former is correct, but note this quote about an infalling body: "In other words, the object goes infinitely far into the 'future' (of coordinate time), and then infinitely far back to the 'present'". Then see this New Scientist stub about the elephant and the black hole: "If his calculations are correct, the elephant must be in more than one place at the same time". The point-singularity black hole features an infalling body that goes to the end of time and back, and is in two places at once. This sounds a stretch, so if the frozen-star interpretation is correct instead, the answers to your questions would be yes and yes.

"Limits of the form
\lim_{x \to 0} {f(x) \over g(x)}
in which both ƒ(x) and g(x) approach 0 as x approaches 0, may equal any real or infinite value, or may not exist at all, depending on the particular functions ƒ and g " wikipedia

Also
"Any number system that forms a commutative ring — for instance, the integers, the real numbers, and the complex numbers — can be extended to a wheel in which division by zero is always possible; however, in such a case, "division" has a slightly different meaning." wikipedia

Aye, mathematician for "How did you get to zero?" :-)

@John Duffield

I have only a layman's understanding of physics [maybe not even that], but i looked up frozen stars, and it seemed to me that the reason they were called thus was because it was thought that they would APPEAR frozen just beyond their Schwarzschild radius to an outside observer ... and not as if the collapse would actually stop at this point.

nyway, i think the operative word here was "known mechansism", something Wow got on to at once. :)

@Wow, my initials aren't CBT, please try not to be disgusting, I know what it means and so do you. That is close to sexual harassment or name calling, and if Ethan doesn't pick up on it, and chide you, I should chide him.
**
As for the rest of your 'argument', I'm certain that any mathematican worth his sheepskin on the wall can make a mathematical argument with zero in the denominator, and then fudge (bullshit) around with it until the metric 'explodes' (a la Hawking)... But this isn't physics, or descriptive of reality in any way. This is why I never confuse reality with math, because they are NOT equivalent. You can describe something, more or less accurately with math, but at no time is the math anything more than a description of the subject, it isn't the thing itself. If you do feel the math somehow 'informs' reality, you are subscribing to a philosophy called 'mathematical platonism', which is not science, it's actually a branch of metaphysics, which I will assume you aren't trying to embrace. I have nothing against metaphysics, because it can be examined philosophically, just not with science or actual physics which have different logical limitations by their very definition.
* With physics you have to discard certain solution sets because they do not pertain to reality, though they may be possible mathematically (i.e. a negative value can't be a negative distance). When you are plugging things into equations in physics, it's not just numbers anymore, it's physical relationships, measurements, and ratios of measurement which are trying to model something. If you play with numbers in a way that isn't physically possible, like claiming you can take the velocity of something at a point you are basically saying you can make a calculation with zero period of distance or time , which contradicts what a velocity is. A contradiction in terms almost always mean your initial premise, your argument, or both, are wrong. This is why I don't allow singularities in physics as physical objects. A singularity is not a small, very small, or super super planck length sized small physical object, it is a geometric abstraction of zero size (zero physical extension). Without a physical extension, you can not assign density to it, or mass for that matter. There simply is nothing there to hang your hat on. If you have no physical cross section, you have no volume, thus you can have no density with which to relate your mass to. If you are going to claim your point or singularity is a mathematical point, please realize it isn't the same as a physical point. Mathematical points exist only inside of the diagrammed math, and have as many dimensions as you like (such as a matrix)). You can have no mathematical point without at least one dimension (a number line, x), and you can pile on as many as you like (a matrix, x,y,z, etc)). You can have no physical point with any dimension other than zero, or it isn't a point anymore by definition. This is why terms must be carefully considered and defined logically and contextually before you muck about with them in physics (no matter how complex your operation) or you make gross logical mistakes which supersede the math you are using.

"my initials aren’t CBT, please try not to be disgusting"

Uh, three letters are disgusting to you?

Wow, thin skinned or what?!? Especially to a moron who blammed on stage to proclaim everyone else a moron with no clue of what science really is.

Sorry QBT, I don't know what your three letters mean, you're not, in the scope of things, all that important.

You're just a blowhard.

"and not as if the collapse would actually stop at this point."

You're correct, Nova.

"blow·hard, noun
1. a person who blusters and boasts in an unpleasant way.
"a bunch of pompous blowhards trying to get on the news""

"point, noun
1. the tapered, sharp end of a tool, weapon, or other object.
"the point of his dagger"
2. a dot or other punctuation mark, in particular a period."

CFT "You can have no physical point with any dimension other than zero, or it isn’t a point anymore by definition. "

Well actually, it is a geometric point which has no dimension (or property) by definition except for it's location (co-ordinates). But a physical point whether the point of a dagger or the singularity of a black hole is a point with dimensions or properties (if it is physical). All points in physics have dimensions and properties or else we are just talking about mathematical geometry (e.g. Euclidean), not physics.

As well, in geometry (e.g. Euclidean) a point is a primitive notion, an object without properties (by definition). But the idea of a geometric point is very different than any physical idea of very small dimensions. In physics, the tiniest objects (e.g. even of "empty spaces") imaginable do not follow the definition of geometric point (e.g. Euclid); they follow the experimentally verified equations of quantum mechanics.

Nova: Yes, it's all relative.

Keep in mind this includes the Event Horizon. An Event Horizon is a surface beyond which events that occur cannot influence you. Where that is depends on your relative acceleration and velocity. If you were to fall into a black hole you would never cross any Event Horizon, because from your point of view the Event Horizon is constantly receding as you accelerate towards it. When you crossed the point where you had previously calculated the Event Horizon to be when you were well outside of and stationary relative to the black hole, nothing would happen.

Well, except the ongoing process of spaghettification.

Well, except the ongoing process of spaghettification.

May His Noodly Appendage Touch You.

"If you were to fall into a black hole you would never cross any Event Horizon, because from your point of view the Event Horizon is constantly receding as you accelerate towards it. "

CB, This seems like nonsense; please provide a reference.

Ethan, some expert; please clarify this point.
Thank you.

Thanks CB

May His Noodly Appendage Touch You.

On the noddle side, i hope. :)

Nova: when you look up frozen star you sometimes get some misinformation. The collapse doesn't just "appear" to stop. It stops. The known mechanism is gravitational time dilation, which goes infinite at the event horizon. So the event horizon is always in your future. You never cross it. What CB said is right. See this from the Kevin Brown article: the event horizon is in the future of every locus of constant Schwarzschild coordinate time. It's like Zeno's paradox in reverse. It's like the kid in the car who says Are we there yet? And the answer is no. It's no today, it's no tomorrow, it's no in a billion years time. The answer is always no.

Take a look at this page from Misner/Thorne/Wheeler. On the picture on the left, the vertical axis is the time axis, and the horizontal axis is the space axis. This is where the infalling body goes to the end of time and back and is in two places at once. It's nonsense I'm afraid. There's a dreadful schoolboy error here wherein a stopped observer is assumed to see a stopped clock ticking as normal. He doesn't. He doesn't see anything.

@John Duffield

Are you sure, sir, that you have understood your own words correctly? Because to me at least they [the first paragraph] seemed to suggest quite the contrary of what you imply by them, i.e., that the collapse would never EVER stop.

As to the rest, i believe it is true that the "singularity' poses several problems; and i don't know how we cannot discuss it — it does seem to me the elephant in the room, though i could be wrong — when discussing black holes, since it is to be "unavoidable". I did read Ethan's post where he wrote that "the 'singularity' is not essential for the black hole to exsts", but i couldn't find anything on if it is also avoidable.

Best.

"Erratum", above: As to the rest, i believe it is true that the “singularity" poses several problems; and i don’t know how we cannot [NOT] discuss it...

@ Nova

Singularities in black holes arise from general relativity. Hence from mathematics. We do not know if gravitational singularities "really" exist in nature. For example, you could in theory have large enough mass in small enough space to allow gravity to overpower speed of light. Yet such an object could have finite size (given, of course, you don't use relativity).

As a simple example I would offer loop quantum gravity where there is no singularity inside black hole. Whether or not this is a correct model of reality is a different matter. Too early to say.

So it means only more work, i.e., to improve our understanding of the reality, that's all. I think i get it. Thanks Sinisa. :)

It is OK that no one answered my question #114; because.. well every understanding about the inside of a black hole is seriously hypothetical and every proposed explanation seems to run into this or that paradox. And also, my question (despite my best intentions) might be ambiguous; or a non sequitur.

So let me point to partial answers to my own question.
First here is an examples of the paradox and difficulty of clear thinking even for the best black hole scientists from December, 2012 http://www.scientificamerican.com/article.cfm?id=black-hole-firewalls-c…

Second here is the standard answer to the question What happens to you if you fall into a black hole? http://math.ucr.edu/home/baez/physics/Relativity/BlackHoles/fall_in.html

By the way, much of chapter 32 and 33 of MTW's Gravitation is online in Google Books http://books.google.com/books?id=w4Gigq3tY1kC&printsec=frontcover&dq=gr… But most of it is unreadable to me; except pg 908 in which an advanced civilization's garbage shuttle is described which dumps its garbage into a black hole and also gets energy back from a black hole. Nice. I also read once about a suitcase size black hole as a convenient garbage disposal (yes it was comedy).

But Kip thorne does write a readable book Black Holes & Time Warps 1994 and says on page 451, "Imagine an astronaut falling feet fist into.. a black hole.. the larger the hole the lond=ger he can survive.. billion solar masses. Then the falling astronaut crosses the event horizon and enters the hole about 20 hours before his final death (I assume this is from the astronauts point of view), but as he enters, he is still too far from the singularity to feel its tidal gravity.. just 1 second before the singularity, he begins to feel it (tidal gravity) stretching his feet and head apart and squeezing him from sides."

So those are the best partial answer that I can find.

@ OKThen

I don't think CB is correct in saying that location of event horizon is dependent on observers velocity and acceleration. Especially that you never reach it.

My understanding is that event horizon is the same thing as schwartzschild radius. And that only depends on the mass and size of the object that undergoes a collapse.

Also I don't think this sentence is correct. "If you were to fall into a black hole you would never cross any Event Horizon."

In fact, I would put it exactly the opposite. Only when you cross the event horizon, will you be falling into the black hole. Everything outside event horizon is still causally linked to the rest of the universe, thus not part of BH.

But am not an expert.

Nova: I do understand my own words. Imagine you drop a pencil, only it falls slower and slower and s l o w e r and never hits the ground. Not today, not tomorrow. Not in a billion years, not in a zillion years. Not ever.

Ethan was right to say the point singularity is not essential for the black hole to exist. See what I said to CFT in #90 and #99. The black hole really is a "hole" once you get rid of the point singularity. What Sinisa sounds pretty good, but I would add that it's one particular interpretation of general relativity that gives rise to the point singularity.

OKThen: re your question in post #114, it isn't nonsense. I can't offer you any credentials to back this up. But hopefully I can offer you clear explanations that you can understand, and that nobody can show to be wrong. The rest is down to you. As for what happens really happens when you fall into a black hole, think on this:

The coordinate speed of light varies with gravitational potential. As you fall faster and faster the coordinate speed of light is getting lower and lower. There comes a point when a crossover would have to occur, and you would be falling faster than the local speed of light. That isn't going to happen. Check out Friedwardt Winterberg and gamma-ray bursters. Have a look at an old wiki article on the black hole firewall. There's Winterberg given priority. He's been removed from the latest version of the article. Look at the "talk" page for more details. It isn't just some priority dispute, it concerns the very nature of black holes.

No, division by zero is defined.

X/X is a division by zero when X = 0. And it’s always equal to 1.

0/0 is undefined because you haven’t said HOW they got the zeros.

No, again, division by zero is not defined.

Sinisa Lazarek#122
I tend to agree with you. But I am also no expert.

John Duffield #123

You said, " I can offer you clear explanations that you can understand, and that nobody can show to be wrong." Nice, but then neither your words nor your links offered any explanation (clear or unclear) upon my question #114.

And I really tried to find your promised explanation.
Winterberg's ideas are not standard theory. Nevertheless, I followed your links; and I even found and read Winterberg's viXra paper that you referenced. None of your links or even Winterberg's paper address my question.

You say, "The coordinate speed of light varies with gravitational potential. As you fall faster and faster the coordinate speed of light is getting lower and lower." I am no expert on coordinate speed of light; but I can find no reference supporting your understanding. On the contrary, your understanding expressed in those words seem to be a misunderstanding or misinterpretation of what I do find.

What I find about the coordinate speed of light is that "The local velocity of light is always c" This is from page 219 of Relativity and the Nature of Spacetime by Vesselin Petkov. And that page is referenced by wikipedia as their only source of their tiny discussion of the coordinate speed of light. On google books online, Petrov further emphasizes pg 185, "It should be stressed, however, that it is the average coordinate velocity of light between two points that is different than c; the local speed of light at a point is always c." And it is this idea John that you seem to misinterpret. You're words imply that the coordinate speed of light is a local observable; it is not.

It seems to me that when we are talking about someone falling into a black hole (from their own point of view) we are talking about the local velocity of light from that persons point of view; and that is always c. So from what I understand, the coordinate speed of light has nothing to do with my question posed in #114. It has been an interesting diversion; but not relevant.

Finally, I must admit that I surely do not fully understand what I have read and must defer to experts only.

John Duffield, I'd much prefer, that when you have something to say, that you try to use your own words. That would be much clearer and more helpful. Regards.

OKThen: when I google on "coordinate speed of light" this is top of the list:

http://en.wikipedia.org/wiki/Propagation_of_light_in_non-inertial_refer…

See where it says "at the event horizon of a black hole the coordinate speed of light is zero". That's the speed of light as measured by observers at a great distance. Like us. So if we had a gedanken telescope and could see Ethan in a bubble of artistic licence with a torch at the event horizon, the speed of the light coming out of his torch would be zero.

Like your Petkov reference, this Wikipedia article also says "the local instantaneous proper speed of light is always c". But think about it. Ethan is trying to measure the local speed of light. Only light isn't moving where he is. So he can't see. And electrochemical signals in his brain aren't moving either. So he can't think. So how long does it take him to measure the local speed of light? Forever. He never measures it.

It's like this: if you put a slowed-down observer with his slowed-down clock in front of slowed-down light, he will measure the local speed of light to be the same. But if you put a stopped observer with his stopped clock in front of stopped light, he doesn't measure the local speed of light to be the same. He doesn't measure anything. Not ever. People who advocate Kruskal-Szekeres coordinates make the mistake of thinking he does.

@John Duffield #127: You are conflating two different things, and thereby confusing both the issue and apparently yourself. You cannot (indeed, must not) assume that the measurements of a "distant observer" in relativity correspond to the actual state of affairs in a different reference frame. Doing so, without applying all of the appropriate transformations, is what leads to every one of the so-called "paradoxes" of SR and GR.

You are making this elementary mistake here, when you claim that because a distant observer measures the coordinate speed of light near the event horizon as zero, then the true local speed of light there must also be zero. That is just wrong.

The local observer ALWAYS sees the local speed of light as 'c'. Period. The local observer doesn't see the event horizon of a black hole as anything particularly special, other than in how her view of the outside Universe is distorted and then, as I recall, eliminated. (Of course, such a local observer will be "spaghettified" near a small BH before getting to the horizon, but one can assert a "sufficiently small" observer to avoid tidal effects).

In free fall through the horizon, I can set up my nifty Fizeau cogwheel and laser pointer, and measure the speed of light all the way through, and my digital scope will tell me 299792458 m/s every time. A distant observer will see my cogwheel spin slower and slower and slower, but that's _their_ problem, not mine.

John #127, thank you for that explanation. Now we can follow your thinking.

Truthfully, I find it difficult to think clearly on the co-ordinate speed of light; so I won't try to analyze starting in paragraph 2 where; in my mind you get mixed up. Because frankly, I will get my brain tied in a knot too. But, I agree with Michael Kelsey; unlike my thinking on this topic or yours; his thinking is clear.

As always, Michael Kelsey #128 thank you for your clear explanation. At first I thought that the second half of your third paragraph was in correct; I needed to read several times to agree with the second half of your third paragraph; finally I agreed with the explanation or understood and thought, "oh I did not know that." Thanks

@Michael: I really don't think I'm wrong about this. When speaking of the actual state of affairs, note that a reference frame is an abstract thing. You can't point up to the clear night sky and say "look at that reference frame". Also note that there is no transformation you can do to make a stopped clock tick. Putting a stopped observer in front of it isn't going to make it start ticking "in his frame". Fooling yourself about this leads to paradox. See this page from MTW. See the picture on the left. The infalling body goes to the end of time and back,and is in two places at once. Like the elephant. You might want to think about this some more before dismissing the original frozen-star black hole interpretation as some "elementary mistake".

OKThen: with respect, Michael gave an assertion, not an explanation. Don't fall for it. Instead think for yourself and ask searching questions of him. Put him at the event horizon next to Ethan and ask him have you measured that 299,792,458 m/s yet? Wait for an answer, and there is no answer. Because the answer is no. Ask him again in a billion years and it's still no. It's always no. He doesn't measure the same old thing. He doesn't measure anything. Ever.

#130 John Duffield
Michael Kelsey's assertions are always well reasoned. I don't fall for anyone. As my answer to you (my #126); I give people the benefit of the doubt. I follow their reasoning and determine if it is reasonable or not. Michael has earned my benefit of the Doubt; you have not.

However, John Duffield, I will give you an explanation; I will try to carefully point out some of the things that you say that are inbcorrect in your comment John Duffield #127.

re: #127
Your first paragraph Is correct.

This sentence
"Like your Petkov reference, this Wikipedia article also says “the local instantaneous proper speed of light is always c”."
is also correct.

"But think about it. Ethan is trying to measure the local speed of light. " correct
Yes, in your description Ethan is at the event horizon of the black hole and he is trying to measure the speed of light locally.

"Only light isn’t moving where he is."
Incorrect. Ethan is in an inertial frame of reference, he falling from the accelleration due to the supermassive black hole. And locally as Petrov states, as wikipedia quotes and as you agree, with “the local instantaneous proper speed of light is always c”. And this is the only speed of light that "the Ethan in your description" can locally measure.

Now it doesn't matter if "the Ethan in your description" is at the event horizon of a supermassive black hole such as Ethan Siegel discusses in his post or if "the Ethan in your description" is at the event horizon of a tiny black hole such as Michael Kelsey #128 describes. In either case the only speed of light that "the Ethan in your description" can measure is c.

This is where you have made your mistake.

Let me analyze your words "Only light isn’t moving where he is." a little more. Here is another problem or confusion with your words. Light is bosonic matter, i.e. energy, it is always moving where we are. (There are exceptions where in a particularly manipulated baryonic medium, the speed of light is slowed to much less than c in that medium; but that is not what we are talking about here). So the light is always moving at speed c relative to "the Ethan in your description at the event horizon of a black hole".

Then you say, "So he can’t see." No. He can see, in his reference frame (yes, which is time dilated from his point of view; BUT NOT FROM HIS OWN POINT OF VIEW. FROM HIS OWN POINT OF VIEW EVERYTHING IS NORMAL.)

Then you say, "And electrochemical signals in his brain aren’t moving either. So he can’t think. " This is redundant with your previous statement, i.e. same mistaken logic.

Then you say, "So how long does it take him to measure the local speed of light? Forever. He never measures it." Here, you have mistaken the time as measured by a distant observer with the time as measured by "the Ethan in your description at the event horizon of a black hole". The time as measured by me a distant observer is forever; but the time as measured by "the Ethan in your description at the event horizon of a black hole" is finite. And it is a finite amount of time before "the Ethan in your description at the event horizon of a black hole" (from his own point of view) collides is ripped apart by tidal gravitational forces and only a little later when his particles collide with the singularity. So "the Ethan in your description at the event horizon of a black hole" can make the measurement of the local speed of light and will determine that it is c; experimental measure can be done quickly with modern equipment.

Now I will not comment upon you last paragraph in #127 which is mostly a repeat plus some extra stuff upon what you have said.

Now some personal comments.
John Duffield
I know exactly what it is to have personal hypotheses that disagrees with the current best hypothesis. (And yes we know that inside a black hole is pretty much open to speculation because we can't measure anything from within a black hole.)

Nevertheless, I divide the world (of my understanding) into 3 categories
- the current best professional working hypotheses (there may be 1 or a few)
- the current underdog professional hypotheses (there may be 1 or a few). These are generally not even in the running by most professional physicists. Fred Cooperstocks explanations of dark matter fall in this category.
- my (or your) personal speculative hypothesis; which is at best in my mind an insightful learning hypothesis that is useful in my learning. But I warn anyone who is listening to my personal explanations that they are considered bogus, nonsense for this or that reason. Most important I do not want to mislead anyone; even by my own sincere opinions and biases!!

Now in #130 you ask, me to ask Ethan.
I don't have to ask Ethan; because I have already answered for myself. I have said above, let me repeat, "So "the Ethan in your description at the event horizon of a black hole" can make the measurement of the local speed of light and will determine that it is c; experimental measure can be done quickly with modern equipment. "

Now this is my understanding of the current best accepted hypotheses at the event horizon of black holes.

I defer to experts, e.g. Michael Kelsey, on this matter because; I am not arguing or even discussing my own personal point of view here. (this is not the place, nor will I point to it today, I've done that enough times). So I defer to Michael Kelsey because; if I am to have a credible understanding of my own personal learning hypotheses; I (in my opinion) need to first understand clearly the standard theory. How else will I know where I disagree and why?

I will say only this personally. The event horizon of a black hole, in my opinion, is likely to be a place where quantum gravity will be found to be very important and the theory of general relativity is found not to apply. But I will not defend or argue this. This opinion, yes this village idiots personal opinion, is not what we are discussing!!!

We are discussing current understanding based on an understanding of general relativity. Period!!

So John, read what I have said, and decide:
- do you agree mine and Michael Kelsey's explanations are current best theory
- do you disagree that your John Duffiled's explanation is current best theory (then show a reference)
- do you disagree that your John Duffiled's explanation is a current underdog theory (then show a reference also)
- do you disagree that your John Duffiled's personal explanation is best theory (then acknowledge this as your personal bias; do not discuss it as if it is accepted science.)

I do think for myself. And Most important that requires the intellectual honesty and self integrity not to mislead myself or especially another. I am very excited when one of my strongest held personal hypothesis is busted.

Yikes, the world doesn't work that way; well I'm glad I now understand that aspect of the world a little better. I most certainly do not want to deceive myself!

I said,
No. He can see, in his reference frame (yes, which is time dilated from his point of view; BUT NOT FROM HIS OWN POINT OF VIEW. FROM HIS OWN POINT OF VIEW EVERYTHING IS NORMAL.)

I meant to say
No. He can see, in his reference frame (yes, which is time dilated from A DISTANT OBSERVER'S point of view; BUT NOT FROM HIS OWN POINT OF VIEW. FROM HIS OWN POINT OF VIEW EVERYTHING IS NORMAL.)

By the way, I defer to Michael or Wow or any expert that tells me I misspoke and mixed up my ideas on this.

This is my last comment on this post.
Ciao!

OKThen: Ethan isn't "in an inertial frame of reference". A reference frame is an abstract thing. You can't point up to the clear night sky and say "look at that reference frame". You can point up to the centre of the galaxy and show me the fast-orbiting stars and say there's something small and massive there, that there's a black hole there. You can show me clocks and GPS and explain gravitational time dilation. You can explain to me that gravitational time dilation goes infinite at the event horizon. But when you point to the stopped clock, then you must accept that Ethan is stopped too. And then you cannot assert that Ethan sees everything as normal. Light is stopped. Ethan sees nothing. Ever. He has no view. He is a popsicle forever.

And get this: he is not something falling any more. You can work this out for yourself. You know that the coordinate speed of light varies with gravitational potential. You know that the coordinate speed of light is zero at the event horizon. You know that the coordinate speed of light can't go less than zero. And you know that the coordinate speed of light varies with gravitational potential. So the gravitational potential doesn't go any lower. So Ethan is falling anywhere any more.

This is not some personal hypothesis. This is the original frozen-star black hole interpretation. The one that goes back to Oppenheimer. And unless you'd rather believe in elephants going to the end of time and back and being in two places at once, unless you'd rather let somebody else do your thinking for you, it's the right interpretation.

Tsk:

Ethan isn't falling anywhere any more.

I will paste here a part of Ted Bunn's article on Black Holes, from Berkley's cosmology page FAQ, that clearly explains what is going on. In a way, both John and OKThen are correct as far as viewing BH goes. What John writes about reference frame is just silly... same as it would be writing that "physical system" doesn't exist. Yes, you can't buy it in a store, but it is as real as we need it.. just this blog isn't real but is in fact a bunch of abstract mathematical data being run as another mathematical formula's input to create certain output... But back to reality

... here is the section dealing with coordinate systems and local vs. far away observer.

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http://cosmology.berkeley.edu/Education/BHfaq.html

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What would happen to me if I fell into a black hole?

Let's suppose that you get into your spaceship and point it straight towards the million-solar-mass black hole in the center of our galaxy. (Actually, there's some debate about whether our galaxy contains a central black hole, but let's assume it does for the moment.) Starting from a long way away from the black hole, you just turn off your rockets and coast in. What happens?

At first, you don't feel any gravitational forces at all. Since you're in free fall, every part of your body and your spaceship is being pulled in the same way, and so you feel weightless. (This is exactly the same thing that happens to astronauts in Earth orbit: even though both astronauts and space shuttle are being pulled by the Earth's gravity, they don't feel any gravitational force because everything is being pulled in exactly the same way.) As you get closer and closer to the center of the hole, though, you start to feel "tidal" gravitational forces. Imagine that your feet are closer to the center than your head. The gravitational pull gets stronger as you get closer to the center of the hole, so your feet feel a stronger pull than your head does. As a result you feel "stretched." (This force is called a tidal force because it is exactly like the forces that cause tides on earth.) These tidal forces get more and more intense as you get closer to the center, and eventually they will rip you apart.

For a very large black hole like the one you're falling into, the tidal forces are not really noticeable until you get within about 600,000 kilometers of the center. Note that this is after you've crossed the horizon. If you were falling into a smaller black hole, say one that weighed as much as the Sun, tidal forces would start to make you quite uncomfortable when you were about 6000 kilometers away from the center, and you would have been torn apart by them long before you crossed the horizon. (That's why we decided to let you jump into a big black hole instead of a small one: we wanted you to survive at least until you got inside.)

What do you see as you are falling in?

Surprisingly, you don't necessarily see anything particularly interesting. Images of faraway objects may be distorted in strange ways, since the black hole's gravity bends light, but that's about it. In particular, nothing special happens at the moment when you cross the horizon. Even after you've crossed the horizon, you can still see things on the outside: after all, the light from the things on the outside can still reach you. No one on the outside can see you, of course, since the light from you can't escape past the horizon.

How long does the whole process take? Well, of course, it depends on how far away you start from. Let's say you start at rest from a point whose distance from the singularity is ten times the black hole's radius. Then for a million-solar-mass black hole, it takes you about 8 minutes to reach the horizon. Once you've gotten that far, it takes you only another seven seconds to hit the singularity. By the way, this time scales with the size of the black hole, so if you'd jumped into a smaller black hole, your time of death would be that much sooner.

Once you've crossed the horizon, in your remaining seven seconds, you might panic and start to fire your rockets in a desperate attempt to avoid the singularity. Unfortunately, it's hopeless, since the singularity lies in your future, and there's no way to avoid your future. In fact, the harder you fire your rockets, the sooner you hit the singularity. It's best just to sit back and enjoy the ride.

My friend Penelope is sitting still at a safe distance, watching me fall into the black hole. What does she see?
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Penelope sees things quite differently from you. As you get closer and closer to the horizon, she sees you move more and more slowly. In fact, no matter how long she waits, she will never quite see you reach the horizon.

In fact, more or less the same thing can be said about the material that formed the black hole in the first place. Suppose that the black hole formed from a collapsing star. As the material that is to form the black hole collapses, Penelope sees it get smaller and smaller, approaching but never quite reaching its Schwarzschild radius. This is why black holes were originally called frozen stars: because they seem to 'freeze' at a size just slightly bigger than the Schwarzschild radius.

Why does she see things this way? The best way to think about it is that it's really just an optical illusion. It doesn't really take an infinite amount of time for the black hole to form, and it doesn't really take an infinite amount of time for you to cross the horizon. (If you don't believe me, just try jumping in! You'll be across the horizon in eight minutes, and crushed to death mere seconds later.) As you get closer and closer to the horizon, the light that you're emitting takes longer and longer to climb back out to reach Penelope. In fact, the radiation you emit right as you cross the horizon will hover right there at the horizon forever and never reach her. You've long since passed through the horizon, but the light signal telling her that won't reach her for an infinitely long time.

There is another way to look at this whole business. In a sense, time really does pass more slowly near the horizon than it does far away. Suppose you take your spaceship and ride down to a point just outside the horizon, and then just hover there for a while (burning enormous amounts of fuel to keep yourself from falling in). Then you fly back out and rejoin Penelope. You will find that she has aged much more than you during the whole process; time passed more slowly for you than it did for her.

So which of these two explanation (the optical-illusion one or the time-slowing-down one) is really right? The answer depends on what system of coordinates you use to describe the black hole. According to the usual system of coordinates, called "Schwarzschild coordinates," you cross the horizon when the time coordinate t is infinity. So in these coordinates it really does take you infinite time to cross the horizon. But the reason for that is that Schwarzschild coordinates provide a highly distorted view of what's going on near the horizon. In fact, right at the horizon the coordinates are infinitely distorted (or, to use the standard terminology, "singular"). If you choose to use coordinates that are not singular near the horizon, then you find that the time when you cross the horizon is indeed finite, but the time when Penelope sees you cross the horizon is infinite. It took the radiation an infinite amount of time to reach her. In fact, though, you're allowed to use either coordinate system, and so both explanations are valid. They're just different ways of saying the same thing.

In practice, you will actually become invisible to Penelope before too much time has passed. For one thing, light is "redshifted" to longer wavelengths as it rises away from the black hole. So if you are emitting visible light at some particular wavelength, Penelope will see light at some longer wavelength. The wavelengths get longer and longer as you get closer and closer to the horizon. Eventually, it won't be visible light at all: it will be infrared radiation, then radio waves. At some point the wavelengths will be so long that she'll be unable to observe them. Furthermore, remember that light is emitted in individual packets called photons. Suppose you are emitting photons as you fall past the horizon. At some point, you will emit your last photon before you cross the horizon. That photon will reach Penelope at some finite time -- typically less than an hour for that million-solar-mass black hole -- and after that she'll never be able to see you again. (After all, none of the photons you emit *after* you cross the horizon will ever get to her.)

Not bad Sinisa. That gives a mixed viewpoint siding towards the point-singularity, but not totally. I think to the question to ask is "Is he there yet?". Imagine Ted had started falling into his black hole in 1995 when he wrote the article. According to him it takes 8 minutes 7 seconds to reach the singularity. But "is he there yet?" No. The answer is always no.

Interesting topic, isn't it?

The answer is "no" from our point of view, not his. Regardless of your view of reference frames, the fact is we do measure time differently. So arguing that both ted and distant observer would measure the same things is just wrong. Experimental evidence is to the contrary. We can argue theory, but when experiment shows that different observers measure different things, arguing is pointless.

Sinisa: you're missing the point, which is this: he has no point of view.

Imagine the SR situation where Ted is moving so close to the speed of light that we can't measure any difference. He is subject to what we'd say was infinite time dilation. He might claim that "in his frame" everything is normal. But it takes him forever to measure anything or see anything. So he doesn't measure anything or see anything. He's a popsicle. He doesn't see the evolving universe. He doesn't see stars going nova. He doesn't see the galaxies rotating, he hasn't had time to measure the CMBR anisotropy yet. And he doesn't see the asteroid we put in his way: BLAM.

Now try applying the same logic to GR infinite time dilation. What does he see? Nothing.

@ John

just, in the case we are talking about, he's not moving even close to "c". So what again is your point? No infinite time dilation for Ted.

p.s. One thing I am curious about is why are you so desperately relying on relativity in such extreme cases, when it is clear to all that the theory itself breaks down at those scales.

I personally believe that there are no singularities in this Universe. I have no proof of that of course, so I am not arguing about it very much. Yet you have no proof whatsoever that they do exist, and yet are proposing one extreme view of it as a "de facto" state of reality. I find that very bizzare to be honest.

Sinisa: if Ted is at the event horizon, he's subject to infinite gravitational time dilation. Check this by asking around elsewhere. Re your curiosity, IMHO general relativity doesn't break down. Instead people misunderstand it, and then make claims about point-singularities and infalling observers who travel to the end of time and back and are in two places at once. I don't think it's bizarre to point out that this is bizarre! Again see the formation and growth of black holes. Note this bit:

"...Remember that historically the two most common conceptual models for general relativity have been the 'geometric interpretation' (as originally conceived by Einstein) and the 'field interpretation' (patterned after the quantum field theories of the other fundamental interactions)..."

There are two ways of applying GR. One way leads to the bizarre, the other way doesn't. And actually it's this other way that's the Einstein way. Like I said, interesting stuff.

@ John

" if Ted is at the event horizon, he’s subject to infinite gravitational time dilation"

ONLY if you use schwartzschild coordinates. And you don't have to. Thus your point of view becomes biased. Like I said in my previous message, you chose one "path". And that's ok. But it's not an only path.

dean: "No, again, division by zero is not defined."

And I shall say again what I've said but youve never seen, dean:

Division by zero CAN BE DEFINED by how you get to zero.

Indeed, dividing any real number that isn't zero by zero will result in infinity, so your claims can ONLY apply if you mean dividing the abstract numeric zero by the abstract numberic zero gives a number that is not defined by that division.

However, if that zero for both is defined as algebraic X, then the division of X/X gives 1 even if X is zero.

How you get to zero will define what number you get.