Comments of the Week #146: From zero gravity to our Solar System's end

“I hope that in this year to come, you make mistakes. Because if you are making mistakes, then you are making new things, trying new things, learning, living, pushing yourself, changing yourself, changing your world. You’re doing things you’ve never done before, and more importantly, you’re doing something.” -Neil Gaiman

Another week, another slew of fantastic stories down here at Starts With A Bang! If you've been wondering about what the Starts With A Bang Podcast is going to be about this month, wonder no longer! It's on the expanding Universe, and what's still so controversial about all of it. Have a listen!

• Is zero gravity really a thing? (for Ask Ethan),
• Colliding asteroids to blame for Earth's meteors (for Mostly Mute Monday),
• Nobody knows where a black hole's information goes (a wonderful guest contribution by Sabine Hossenfelder),
• World's largest telescope will revolutionize the future of astronomy,
• How the anthropic principle became the most abused idea in all of science, and
• How our Solar System will end in the far future.

For those of you around Salem, OR on Wednesday, February 1st, come by Chemetka Community College and hear me speak to the Nightsky45 astronomy club (at the 45th parallel), and for everyone else, it's onto our comments of the week!

Prokaryotic, single-celled bacteria may seem boring, but are they? Image credit: E. Coli bacteria, retrieved from http://scitechdaily.com/bacteria-replicate-closely-to-the-actual-thermo….

From Denier about the boring billion: "The first dominant life form on Earth was the green and purple photosynthetic bacteria. They ruled for 2 b-b-b-Billion years. That they can still be found to this very day in Stromatolites shows they didn’t toxify themselves into extinction. The climate was stable and evolutionarily resulted in what is referred to as the Boring Billion."

You must remember that what looks boring to you may not actually be boring in the same terms you want it to be. Yes, prokaryotic, single-celled organisms may indeed still be single-celled, prokaryotic organisms, but that doesn't mean evolution didn't happen. It doesn't mean their genomes didn't get more complex. It doesn't mean that they didn't become, by whatever metric you'd like to measure, more evolutionarily advanced and well-adapted. We might compare bacteria to fungi, plants, animals and protists as the "least evolved" kingdom, but there are multiple kingdoms of bacteria that are just as different from one another as they are from any plant or animal.

Evolution doesn't stop because conditions are stable, but mass extinctions do bring about periods of great, accelerated change. Would humanity have evolved without the snowball Earth catastrophe? Doubtful. But would something just as interesting as us have emerged instead? Perhaps.

An artist's illustration of large, rapid masses emerging from a point origin in space. Public domain image by Pixabay user Yuri_B.

From eric on how to test for scientific literacy: "You think someone [needs] to show appreciation for science and scientists to be literate. Okay, so what question would you ask to tell the difference between someone who met your criteria and someone who didn’t? Come up with a bunch of questions like that. Also come up with a bunch of simple yes-no or multiple-choice questions about science. Give both sets of questions to a sample population. Find out which of the simple questions correlate with the more complicated questions you really want to ask. Then you can use the simple questions to survey the population.
Surely there is some empirical way to distinguish between the people you think meet your #1 and #2, and the people who don’t?"

Even if there were, I don't know how this would accomplish anything other than to self-satisfy those of us who pass such a test... and alienate further those that don't. The whole reason I wrote that people should have an awareness and an appreciation for science is that those are both positions that are difficult to argue against are objective goods, and they're something that every reasonable person ought to be on board with. It's hard to argue that being more knowledgeable is a bad thing; it's hard to argue against science and technology having made our world better for the vast majority of us; it's hard to argue that investing in those things further won't continue to benefit humanity as a whole. Telling someone, "you are not scientifically literate," and being right... what good can that accomplish?

This is an image that ran in a real newspaper in the USA, but is not factually nor scientifically correct. Image credit: Boise Weekly, via http://www.boiseweekly.com/boise/idahos-epidemic-of-fear-vaccination-li….

From dean on anti-vaccination claims: "For comparison: we have a strong infestation of anti-vaccination people in this part of Michigan, and occasionally some will bring up discussions about the “studies” that “prove autism is caused by vaccinations” in the stat courses I teach. Even after the flaws in those “arguments” are pointed out, in detail, and it’s been demonstrated that the standard anti-vac stuff is baseless, the response yes “Well yes, but …” and nothing has changed. Just like the climate change deniers do repeatedly here"

There are a lot of motivators, and while you'd hope that demonstrable facts can change anyone's mind about any topic, almost all of us have our own ideologies and things we believe so strongly that they would be incredibly difficult to change. A great many of us arrive at a position from whatever means we arrive at it, and then will pick and choose the facts we like (and dismiss the ones we don't) to defend it. We'll pick science with conclusions reached by Lindzen and Lewis and Curry and dismiss it from all other climate scientists. We'll claim there's a conspiracy to suppress the real facts and know that we have the true story like Mike Adams, Joe Mercola, Dr. Oz, Andrew Wakefield or the Fluoride Action Network has dug up. We'll dismiss the AMA, the CDC or an entire branch of science to suit our own prejudices. We all have them, but it's up to us to be vigilant in fighting them and re-assessing the evidence objectively, as best we can, and to gain competency in doing so. It's a tough fight, and I am sure we all have our own ways where we fail. That's as much a flaw in our wiring as it is in us as individuals.

Astronauts, and fruit, aboard the International Space Station. Note that gravity isn't turned off, but that everything -- including the spacecraft -- is uniformly accelerated, resulting in a zero-g experience. Public domain image.

From Joshua W Davies Jr on zero gravity: "Until the theoretical quantum of mass, as the segment of infinite pure energy is reached, particles as waves will persist until the quark gluon plasma condenses into objects that we, within our own plane of reference, can see."

How you interpret the quantum Universe, thankfully, has absolutely no impact on the zero gravity you experience. Anything with mass or energy experiences gravitation, and even things that are "in zero gravity" experience gravitation. The Earth pulls on astronauts in space just as surely as it pulls on you here on the ground. But because the astronauts are in free-fall, they don't experience the normal force of the space station pushing them back up. Someday, we'll implement some sort of artificial gravity in space, and then, perhaps, our bodies won't decay like they do in zero-gravity.

Black holes can devour anything in the Universe, but getting the information out again still proves elusive. Image credit: ESO, ESA/Hubble, M. Kornmesser.

From Naked Bunny with a Whip on black hole information: "Susskind’s hypothesis is that the sock turns to lint that is smeared across the event horizon of the lint filter. The sock is still there, but there’s no practical way to put it back together."

Sock jokes aside (I keep hoping that someday, my mismatched ones show up in the dryer, mysteriously), the information of something falling into the black hole should get imprinted or encoded on the event horizon. The problem is, when the black hole decays, the quantum regime is very small, and there's no way we can conceive of to encode all of the information of what fell into the black hole over its entire history onto such a tiny event horizon; the math doesn't add up. So where does all the information go? Is it somehow encoded into the Hawking radiation? (Maybe.) Is it truly destroyed, and do we not understand information after all? (Maybe.) Is it somehow encoded, at a quantum level, onto that tiny, Planck-sized mass that will be revealed by quantum gravity? (Maybe.) It's a hard problem, and one where we cannot easily see where progress or a resolution will be found next.

Information may come out of the black hole at early times, but the mechanism has not been uncovered. Image credit: Petr Kratochvil.

From Sinisa Lazarek on a non-singular state inside a black hole: "What if there is no singularity but rather a [super] dense state of matter… like a super-neutron star at the center of BH. And Hawking radiation doesn’t evaporate BH into nothingness.. but at most can reveal a super dense core.. which will probably last as long as the universe, just like neutron star cores."

There was an interesting discussion that followed this, but I have to say of everyone, I think Denier came closest to getting it right. When you talk about the inside of a black hole -- Schwarzschild, Kerr, Reisser-Nordstrom, Kerr-Neumann, etc. -- there's a big problem. The only way you can move away from the singularity and a step closer to the outside of the event horizon is if you move faster than light. So the question then becomes how can something "hold itself up" against collapse? What fundamental interaction can do it?

• Electron degeneracy pressure,
• Electromagnetic radiation,
• Gravitational waves,
• Quark/gluon or gluon-gluon interactions,
• Virtual meson exchange,

all suffer from the same problem: they are interactions mediated by either massive or massless particles.

Any system in equilibrium requires that forces be balanced. But what will balance gravity inside a black hole's event horizon?

If the particle will have to move faster than light to move "outwards," which is impossible, then what will prevent the outer particles from falling in towards the singularity? I'm not saying that doesn't mean you can't have a solid, degenerate object that is stable inside a black hole; I'm saying if you do, it means that there must be some type of physics that goes beyond the physics we know and understand today. It can't simply be some exotic state of the matter we have today; if it obeys the Standard Model and General Relativity, you have a singularity at the black hole's center.

A comparison of the mirror sizes of various existing and proposed telescopes. When GMT comes online, it will be the world's largest, and will be the first 25 meter+ class optical telescope in history. Image credit: Wikimedia Commons user Cmglee, under c.c.a.-s.a.-3.0.

From Omega Centauri on GMT: "So how is the resolution, and contrast so needed for separating close objects with a great difference in brightness going to compare with its larger -but many-segmented cousins. Will this instrument have unique capabilities that they won’t?"

Well, at the rate things are going, the only other telescope that will come online that rivals GMT in size in the 2020s is the E-ELT (which may have its name shortened to ELT), which is a few years behind GMT right now. GMT will have seven mirrors, each with their own adaptive optics system. Keck is the longtime segmented champion, and E-ELT will have around 800 independent segments. They won't have their own adaptive optics systems -- one per mirror -- but will instead have to worry about edge-correction at all the interfaces between segments.

Typical PSF in the L band with Strehl ratio of up to 88%, and many diffraction rings visible. Image credit: COFFEE Paul et al., 2014.

Reconstructing the actual image based on the data you collect is the hard problem in ground-based astronomy, and so GMT -- with fewer numbers of larger mirrors but with gaps between the edges -- and a segmented telescope with smaller, more numerous gaps but more mirrors and more edges and less empty space have different hard problems to face. The thing about GMT that makes it so amazing is that of the (let's just call them) 30-meter class telescopes, it's going to be first. It's going to see first light first, it's going to take scientific data first, it's going to be fully built and operational first, and, with any luck, it'll take direct images of Proxima b first, too.

The correlation between gravitational acceleration (y-axis) and the normal, baryonic matter (x-axis) visible in an assembly of 153 galaxies. The blue points show each individual galaxy, while the red show binned data. Image credit: The Radial Acceleration Relation in Rotationally Supported Galaxies, Stacy McGaugh, Federico Lelli and Jim Schombert, 2016. From https://arxiv.org/pdf/1609.05917v1.pdf.

From Anonymous Coward on rotation curves and distant galaxies: "We had a post a few months back about how simulations like MUGS2 and others predict that the rotation curves of very distant and hence younger galaxies ought to show deviation from the SPARC acceleration law discovered by McGaugh et. al. Will this new telescope be able to measure the rotation curves of galaxies far enough away to confirm or refute this prediction of MUGS2 and other galaxy simulations?"

With enough statistics, we should be able to do exactly that. James Webb won't be able to, but GMT, E-ELT and WFIRST in the 2020s should do it. They may, however, all get scooped by the European Space Agency's EUCLID satellite! EUCLID won't go out to the high redshifts (2-3, maybe even 4) that the others will, but by getting large numbers of galaxies at z ~ 1-2, it may be able to make the first measurements to constrain dark matter/rotation curves out at high redshifts. Either way, this is science I'm very much looking forward to, and that we should start to see very rich information coming in over the next decade!

That the Universe exists and that we are here to observe it tells us a lot. But it doesn't tell us as much as some people infer. Image credit: NASA / NExSS Collaboration.

From Li D on sample size and robust conclusions: "Now look mate. If you go and dig up a single fossilized bit of bone from a couple hundred million years ago you have a sample size of one. Yeah? Well first off no you [don't] because it instantly becomes part of several sample sizes. Think of Venns. It has [comparative] value at an absolute minimum to lots of other things. And in total isolation it can yield much data besides. Do you understand this?"

When you look the cosmic microwave background, you have one Universe and a sample size of one, right? Well, kind of. If you wait long enough, the CMB will change, because the gravitational potentials you're seeing have evolved as the Universe has evolved. If you make a measurement of the Earth right now you get a single measurement only, but if you make multiple measurements over time, you can track changes quite accurately. If you do that for many bodies in the Solar System, you can track how they've changed, too. In temperature, irradiation, flux, atmospheric concentrations, etc.

Heat-trapping emissions (greenhouse gases) far outweigh the effects of other drivers acting on Earth’s climate. Source: Hansen et al. 2005, Figure adapted by Union of Concerned Scientists.

These are questions where the science can be quantified. Where we can say, "this much is due to this; that much is due to that; etc." Where the uncertainties lie is in, "how quickly will the temperature rise in the future dependent on emissions and other factors," and that is not a question with a solid answer. The thing is, there are a range of possibilities that are reasonable, and they are all bad. The question for us, as citizens of the world, is whether we're going to recognize this is a real problem, quantify the risks and hazards of inaction, and take steps to bring about the most positive outcome we can for the good of humanity. I hope the answer is yes, but so far, it hasn't been.

The Hilda asteroids (pink) and the Greeks and Trojans (green) that may be most threatening to Earth. Image credit: Petr Scheirich, 2005, of http://sajri.astronomy.cz/asteroidgroups/groups.htm.

From PJ on the far future of the Solar System: "As long as we don’t get clobbered by a giant asteroid in the meantime."

Even if we do, it's very unlikely that it will end all life on Earth. The last giant asteroid strike wiped out between 30-50% of the species on Earth; half or more survived. We -- and I mean "we" as in creatures that live on Earth -- will likely have a very good run regardless of asteroid strikes. Looking back with eyes from the far future, they're unlikely to play a major role in the fate of our Solar System.

The evolution of some of the Sun’s properties over time. Luminosity is what impacts the temperature here on Earth. Image credit: Wikimedia Commons user RJHall, based on Ribas, Ignasi (2010), “The Sun and stars as the primary energy input in planetary atmospheres”.

And finally, from G on what will: "Long before the Sun’s expansion burns Earth to a crisp, it will disrupt the carbon cycle & photosynthesis, and then boil the oceans. Complex life on Earth will have ceased. If the lineage of Earth life is to continue, we must seek to become an interstellar, multi-stellar species."

We have 1-2 billion years before that happens. 1-2 billion years to become an interstellar, multi-stellar species. Or, if we want to punt, we can terraform other worlds in our Solar System to become more hospitable to life in that time. Although all the stars will eventually die, the ones within our galaxy will burn for 10,000 times as long as our Universe has existed. If we became an interstellar species, we could spread life throughout the galaxy and seed it for the trillions and trillions of years to come. It's an interesting thought.

Thanks for sharing your thoughts, and I'll see you back here next week for more incredible science here on Starts With A Bang!