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X Particle Might Explain Dark Matter & Antimatter
cold fjord writes "Wired Science has a story on a new theory that tries to explain dark matter, and the balance of regular matter with antimatter. This theory may even be testable. From the article: 'A new hypothetical particle could solve two cosmic mysteries at once: what dark matter is made of, and why there's enough matter for us to exist at all."
What gives the X-Men their powers.
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Humans are terrible replicators of Godly things.
Yes, but why?
That's the question that needs answering. We see that there is matter, obviously, but common sense (assuming the big bang is accurate, and it has held up pretty well over the years) says their shouldn't be.
So why does matter exist? Why didn't matter and anti-matter annihilate each other evenly? They've tested it in the colliders, and sure enough, matter and anti-matter are not created equally given the conditions necessary to create them.
This is a theory to explain why what is, is. This is how science works. You take an observable fact, create a hypothesis for why it might be so, and test the hypothesis. If it works as the hypothesis describes, you're closer to knowing why the observable fact is an observable fact. When you know a bunch of reasons why observable facts exist, you start to be able to predict new things that you haven't observed yet, and you can start looking for them. If you don't find them, your theory is bunk. If you do, your theory may still be bunk, but you at least know it is pretty good.
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The paper is also available at the arXiv if you don't have a subscription to Phys. Rev. Lett.
Why, oh why can't people posting science stories on slashdot post links to the actual papers when they're publicly available? http://arxiv.org/abs/1008.2399
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Wow, haven't been following physics much, eh?
Security is mostly a superstition... Avoiding danger is no safer in the long run than outright exposure. - Helen Keller
"This theory may even be testable."
To be a theory it must be testable.
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Yes, because as we all know, the 'black' in 'black hole' is a reference to ignorance, not a reference to its light-capturing property.
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Equal amounts of X and anti-X were created in the Big Bang, and then decayed to lighter particles. Each X decayed into either a neutron or two dark-matter particles, called Y and . Every anti-X converted to an anti-neutron or some anti-dark matter.
But the hypothetical X particle would rather decay into ordinary matter than dark matter, so it produced more neutrons than dark matter. Anti-X preferred decaying into anti-dark matter, and so produced more of it.
Bold emphasis added is mine. Does this theory explain why "particle X" would rather decay into ordinary matter? Isn't that begging the question? How is that any different than moving to the larger set of all mass, and just saying "Hypothetical universe X would rather form more ordinary matter than dark matter". I understand they may be foregoing the DiffyQ's that perhaps stand behind their assertions for the word "rather" to provide for the layman, but this premise kills the theory for me unless there exist math/science/evidence/a reason besides the word "rather for this article.
'We are trying to prove ourselves wrong as quickly as possible, because only in that way can we find progress.' RPF
There's a difference between "testable in theory" and "testable in practice". Science proceeds from both ends towards the middle, where theoreticians and experimenters meet.
Theoreticians work on things that may not be testable in practice, now. They may be testable one day, and that actually happens: particle physicists build bigger colliders, astronomers get to see the views they couldn't before, paleontologists dig up the fossil they expected but didn't have.
It leaves the realm of science utterly when it's not testable even in theory. Between the two there's a gray area, where something may not be practical in the forseeable future, or may require so much time and space and energy that it's absurd to think it would ever become practical. Theoreticians run a minefield here, but it would be invalid to forbid them from going there. They might well find a way to take something absurd and make it realistic; it happens.
I'm glossing over a lot of epistemic niceties here, but the point is that a theory does not have to be testable at the moment to be science. If this one happens to be testable now or in the near future, yay; that lets us exclude a lot of territory that's currently in the mine field. But it likely would not have happened without other theoreticians having explored that space.
just put a crowbar by the testing lab
Which ones specifically? In fact, I challenge you to name even one theory that isn't testable. And String theory doesn't count. It's about as scientific as Astrology.
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To be a theory it must be testable.
Prove it.
rewriting history since 2109
In fact, I challenge you to name even one theory that isn't testable.
P = NP.
Your move.
The axiom of choice is an axiom, not a theory. Coincidentally, this is why it is not called the theory of choice.
And String theory doesn't count. It's about as scientific as Astrology.
A Slashdotter or hundreds of physicists... who's a fellow to believe?
String theory (variants thereof) conforms to observations as well as any other theory. What's lacking is an observation where the predictions diverge.
Until such time as such an observation becomes possible, if you want to knock string theory you should argue on the basis of Ockham's Razor, not on perceived parallels with astrology.
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Yes, it's because it doesn't emit (except for the Hawking radiation) but it's still a name of ignorance: the existance of the singularity proofs Einstein's general relativity as wrong but we still lack a better theory to substitute it.
Actually it's the opposite.
The existence of singularities was a major prediction of General Relativity, and the source of much skepticism towards the theory. People didn't believe a thing like that could exist in our universe. The discovery of Black Holes with many of the predicted properties was (more) proof that GR was a damn good theory.
Not that we don't need a better theory to address known flaws, or that you couldn't in some way say Black Hole is a 'name of ignorance'. Certainly, there is a lot we don't know about them. If there is any problem with relativity wrt black holes, it's that since we can't look past the event horizon, we can't tell if there really exists a mathematical discontinuity in the universe or if something else is happening.
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Physicists going old-fashioned on us, eh?
Table-ized A.I.
Well said sir! As an example, Frame-dragging was proposed as a theory in 1918 based on Einstein's theory of General Relativity but wasn't able to be tested until 1996 with a couple of special satellites and even then not accurately enough to be provable until 2006. Since we had barely left the ground let alone orbit the earth at that point I'm sure it must have seemed un-testable at the time.
whenever two WIMPs meet up in space, they annihilate each other
I'm trying to picture this in my head, and failing.
Every end has half a stick.
There are about 10^500 possible string theories. We haven't yet found any that conform to all our observations. We don't know if it's even possible to search efficiently for that needle in the 10^500-big haystack, so string theory might be like the evil hall of mirrors in a bad B-movie: "yes, my childish nemesis, you falsified THIS one, but which one is the REAL string theory? HA HA HA!".
String theory may not be on a par with astrology, but IMHO it sullies the term theory. Anyone who has defended the theory of Evolution against fundies knows that's a bad move. It wouldn't be a bad idea to rename it string physics, even though arguably it's not physics yet either.
Expected time to finish is 1 hour and 60 minutes.
"Dark matter" is not a theory. It is a label for a set of observed phenomena. Galaxies move as though they contained something that does not interact electromagnetically ("dark") but does interact gravitationally ("matter").
Warning: this article may contain humor, sarcasm, parody, and perhaps even irony. Read at your own risk.
In relativity nothing can travel beyond light speed because that would imply an infinite energy,
Not exactly. In Relativity nothing with rest mass can travel at the speed of light because that would imply infinite energy.
Nothing at all, not even information, can travel faster than light because that implies that you could create scenarios where from certain reference frames, effects appear to happen before causes. As in time travel, or causality violation, and both Relativity theories (and the rest of physics) assumes causality to hold.
Ten years after Einstein's death we discovered a universal velocity reference in the microwave background dipole, so one of the main tenets of special relativity is not true anymore.
Not true. All Special Relativity says is that there is no preferred reference frame, as in the laws of physics must appear to hold true according to every observer. There is not one "special" reference frame where causality only needs to hold for it.
There was never anything in Relativity saying that there couldn't be some convenient reference against which to measure your velocity. Which is all the CMB dipole really is, and in the sense of what it implies for Relativity is no different than arbitrarily deciding the Andromeda Galaxy is our reference.
I believe the future lies in information theory.
The present and recent past lies is information theory. Information theory, which arose from QM, is fundamental to explaining many situations encountered today, like limits on the efficiency of irreversible calculations or the decay rate of black holes. However there is nothing in Information Theory that suggests information can travel faster than light. Indeed, quite the opposite, and this limit is key to understanding things like quantum entanglement and why it cannot be used for information transfer.
Assuming observable events happen in the universe, and assuming that causality exists, i.e. that if some event causes another that relation will exist under all circumstances, then we can think on how information about different events is transported through the universe. Again, this would be a truly absolute limit, not one imposed by our limitations in measuring and calculation.
That's pretty much how it's already done -- assume causality holds for all reference frames, and you can see that information cannot travel faster than light.
However at the end of the day no matter how elegant a mathematical model you have constructed, there are going to be variables whose values in our universe must be determined experimentally. Like c. You can get c via direct measurement, you can calculate it based on other constants which must themselves be measured. Either way.
Yet as our measurements get more precise, the values for these constants becomes more precise, and doesn't suddenly change values to something outside the error bars on previous less precise measurements. We're still depending on measurement, but we aren't going to up-end physical theories at some point when we hit the 32nd digit of c and suddenly nothing works.
This only seems like a problem if it bothers you for some reason that you can't derive all physical constants from a mathematical model, and instead the only way to know what values to place in that model of the universe is by actually looking at the universe.
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