mass
dr. dolittle | July 2, 2015 Image of a Mexican Jay selecting peanuts from www.sci-News.com
I just listened to a neat podcast from Scientific American's Karen Hopkin in which she described a new study published in the Journal of Ornithology that suggests Mexican Jays (Aphelocoma ultramarina) pick which peanut to eat only after literally weighing their options. The researchers modified some peanuts to remove the contents. The Mexican Jays were then offered unmodified nuts along with the empty shells. Perhaps not surprisingly, the birds snubbed the empty shells. Rather, they only chose shells that contained nuts. In…
esiegel | July 17, 2013"These neutrino observations are so exciting and significant that I think we're about to see the birth of an entirely new branch of astronomy: neutrino astronomy." -John Bahcall
You've been around here long enough to know about the Big Bang. The vast majority of galaxies are speeding away from us, but more than that, the farther away they are from us, the faster they appear to be receding.
Image credit: ESA/Hubble, NASA and H. Ebeling.
But it's more than that; when you look at a distant galaxy, because the speed of light is finite, you're actually looking at it in the distant past. Since…
esiegel | July 10, 2013"It followed from the special theory of relativity that mass and energy are both but different manifestations of the same thing — a somewhat unfamiliar conception for the average mind." -Albert Einstein
You've heard and seen it plenty of times: Einstein's most famous equation, E = mc2. I've taken you inside this equation before, which lays out how much energy is stored in matter-at-rest, and tells you how much energy you need to create matter in the first place.
Image credit: Niels Madsen, ALPHA / Swansea / CERN.
That's right, you can create matter directly from energy; we do it all the…
esiegel | June 17, 2013“God put me on this earth to accomplish a certain number of things. Right now I am so far behind that I will never die.” -Bill Watterson
Welcome back to another Messier Monday, only here on Starts With A Bang! With each new Monday, we take an in-depth look at a prominently visible random object from Messier's catalogue of 110 deep-sky curiosities, objects that range from stellar corpses to star-forming regions, to open clusters, globular clusters, distant galaxies, and even a few anomalies!
Image credit: Wikimedia Commons users Jim Cornmell and Zeimusu.
The objects in Messier's catalogue…
esiegel | November 16, 2012"Other than the laws of physics, rules have never really worked out for me." -Craig Ferguson
Earlier this week, evidence was presented measuring a very rare decay rate -- albeit not incredibly precisely -- which point towards the Standard Model being it as far as new particles accessible to colliders (such as the LHC) go. In other words, unless we get hit by a big physics surprise, the LHC will become renowned for having found the Higgs Boson and nothing else, meaning that there's no window into what lies beyond the Standard Model via traditional experimental particle physics.
Image credit:…
esiegel | July 5, 2012"We knew that we had indeed done something that was very different and very exciting, but we still didn't expect it to have something to do with physical reality." -Gerald Guralnik, co-developer of the Higgs mechanism
Might as well make this entire week "Higgs week" here on Starts With A Bang, given how important yesterday's discovery/announcement was! It isn't every day, after all, that you see a theoretical physicist on the 7PM news. (Video here.)
Image credit: KGW.com.
(So proud of Portland, OR's local TV station, KGW NewsChannel 8, for being willing to promote science to the whole city…
esiegel | July 4, 2012"This is evidently a discovery of a new particle. If anybody claims otherwise you can tell them they have lost connection with reality." -Tommaso Dorigo
You've probably heard the news by now: the Higgs boson -- the last undiscovered fundamental particle of nature -- has been found.
The fundamental types of particles in the Universe, now complete.
Indeed the news reports just keep rolling in; this is easily the discovery of the century for physics, so far. I'm not here to recap the scientific discovery itself; I wrote what to expect yesterday, and that prediction was pretty much exactly what…
esiegel | May 28, 2012"Everyone must leave something behind when he dies, my grandfather said. A child or a book or a painting or a house or a wall built or a pair of shoes made. Or a garden planted. Something your hand touched some way so your soul has somewhere to go when you die, and when people look at that tree or that flower you planted, you're there." -Ray Bradbury
Today is Memorial Day here in the United States, where we honor all the soldiers who have fought and fallen for our country. The peace and prosperity that I have enjoyed my entire life is because of a price paid, many times over, mostly by people…
drorzel | July 15, 2010In the comments following the silly accelerator poll, onymous wrote:
[T]he point of the LHC isn't to discover the Higgs. No one in their right minds would build a 14 TeV pp collider if their only goal was to discover the Higgs.
While it's true that the ultimate goal of the LHC is to discover more exotic particles that may or may not exist (blah, blah, supersymmetry, blah) most of the hype has focussed on the Higgs, which is the one thing they're pretty sure they'll find (comments later in that thread notwithstanding). This is one of the potential problems with the way the machine has been…
rallain | June 10, 2010In the last episode of MythBusters, they wanted to see if a tornado could make some glass cut off a person's head. The first attempt was just to take some glass and through it at a simulated human neck. Clearly, this wasn't quite the same as a tornado.
So, here was their plan. If they want to simulate glass moving at 300 mph, they could get a bigger piece of glass and put it on a truck moving at 80 mph. The result would give a piece of glass with the same kinetic energy as a smaller piece moving at 300 mph. Their calculations look to be correct. However, the question is: would this make…
rallain | March 23, 2009I have always wanted to ask a question like this - but never found the right test for it. Perfect for a blog.
Question:
Suppose you are in your car at a stop light behind a truck. The truck is pulling a trailer with a rollable tractor on it.
When the light turns green, the truck starts to accelerate. However, the cable holding the tractor to the trailer breaks and the tractor starts to roll off the trailer. You are right behind the trailer. What do you do?
Do you have an answer yet? You should probably come up with one quickly. That tractor is rolling off now. I will put the answer…
rallain | February 3, 2009People say I am picky. Ok, sometimes I am. But somebody has to stand up for what is right and just. Maybe I am that person.
Please stop using the word force if you don't know what it is.
There. I said it. You can attack me now.
It wasn't just one thing that got me fired up. It was two things. First, I read this article on physics and football (Physics of 'The Hit' from the NY Times). If it was just this article, I would have let it go and moved on. But no. One of my kids just happened to be watching MythBusters (We all love MythBusters) and there was a discussion that used the term…
rallain | December 30, 2008Just to be clear, Newton probably didn't have a portable video camera. I do. I have one of these Flip Mino pocket cameras. Very nice. You can put it in your pocket. However, there is a problem with cameras like these (think of video from camera phones). The problem is the mass, it is too small.
Video from a camera phone or small portable camera looks too jerky (unless you are careful). Sometimes it is jerky to the point that it makes me feel barfy. The reason this happens is that with a small mass, a force can cause a significant acceleration. Let me draw a picture (you know I like…
esiegel | May 16, 2008This has been all over my inbox since the press release came out yesterday; it's been on slashdot (thanks Brian), it's been at space.com, and there's a mediocre writeup on Universe Today. What's the big news? Black Holes don't destroy information after all!
What is this whole information thing, anyway? Take a look at all the normal stuff in the Universe: photons, protons, neutrons, and electrons, for example. They have lots of different properties each. They move around one another, they get bound and unbound from one another, they exert forces on one another, etc. They're aware of one…
esiegel | May 8, 2008Let's say we're having a nice day here on Earth; the Sun is shining, the clouds are sparse, and everything is just looking like a peach:
And then Lucas goes and tells me,
Oh my God, Ethan! It's Armageddon! An asteroid is coming straight for us! You've got to stop it!
Really? Me? Well, how would I do it? Let's say we've got some reasonably good asteroid tracking going on, and we've got about 2 months before the asteroid is actually going to hit us. We'd like to do something with the situation on the left, to avoid the situation on the right:
Well, what we really have to do is change the…
esiegel | May 6, 2008(This is adapted from my public lecture, Afraid of the Dark: How We Know What We Can't See.)
Let's go back over 200 years ago, to 1781. William Herschel (left) discovered the planet Uranus, noticing that an object, as bright as a star, was actually moving relative to the other stars. The other five inner planets (besides Earth) were known for over 2000 years before that. But it was thought for a long time that Saturn was the farthest one.
But it clearly isn't; as you can see with modern telescopes, Uranus is a super-interesting planet, rotating on its side, surrounded by rings and moons.…
esiegel | May 5, 2008Hector writes in and asks about someone from Sheffield in the UK who says that the Large Hadron Collider (LHC) will create Dark Matter:
The massive ATLAS detector will measure the debris from collisions occurring in the Large Hadron Collider (LHC) which recreates the conditions found in the early universe during the Big Bang when Dark Matter was first created. If the LHC does indeed create such particles then it will be the first time that the amount of Dark Matter in the universe has increased since the Big Bang - the LHC will effectively be a Dark Matter 'factory'.
Well, Hector basically…
esiegel | April 16, 2008Ahh, stars. Giant furnaces of nuclear fusion. Doing the stuff our Sun does, burning hydrogen fuel into helium (among other things) and emitting lots of visible light and energy in the process.
But when we take a look at brown dwarfs, they aren't like normal (i.e., main sequence) stars like our Sun. Instead of burning hydrogen into helium for their fuel, brown dwarfs don't generate enough pressure to make that happen; they can only burn hydrogen into deuterium.
Let's go over what the differences here are. A hydrogen nucleus is just a proton, with a mass of 938.272 MeV/c2. (I use these units…
esiegel | April 7, 2008What's going to happen to all the stars in the Universe as they get older? Well, just as nothing can live forever, stars can't live forever also. Why? Because they run on fuel: burning hydrogen into helium, for example. When they run out of fuel, something's gotta give. Barbara Ryden reminds us of an excellent and appropriate quote by Dylan Thomas:
Do not go gentle into that good night.
Rage, rage against the dying of the light.
But what exactly happens to the star depends very sensitively on what the mass of the star is.
If you've got a tiny little star, less than about 40% of the mass of…