LHC might have figured out Antimatter Paradox

http://www.msnbc.msn.com/id/45347624/ns/technology_and_science-science/

For those of you non-physicists, one of the great mysteries of our day is why the universe isn't equal parts matter and anti-matter, when immediately following the Big Bang the universe should have been half and half - and if so, one half would have wiped out the other half and left the universe empty. The LHC crew might have finally answered that question, which would be a huge leap forward in our understanding of how the universe came to be. And all this right after confirming that the neutrino thing is real and that Einstein just got pwned.

Pretty exciting that they are finally making some nice payoffs after all the early disappointment!

Interesting. The "supersymmetry" (half a unit of spin) part, mainly.

Do we have a source for this? I thought it was still in unknown stage.

edited 17th Nov '11 11:24:39 PM by abstractematics

Now using Trivialis handle.

http://cosmiclog.msnbc.msn.com/_news/2011/11/17/8866223-faster-than-light-neutrinos-confirmed

Basically there's still dissent, of course, but its looking like the chances for some sort of systemic error are getting slim.

OOH.

All right, I'm bumping the other thread back up. Carry on.

Now using Trivialis handle.

I thought we already knew that charge symmetry was broken. IIRC, it was by muon decay or something like that. (A muon is slightly more likely to decay into mostly-matter than into mostly-antimatter.)

Da Rules excuse all the inaccuracy in the world. Listen to them, not me.

I thought that the universe being half antimatter and half matter wouldn't actually lead to the destruction of one half, as long as they didn't touch much? In the vacuum of space, on the boundaries, occasionally a particle of antimatter would touch matter, but that'd be about all, right? It'd just create a burst of energy. That's why there can be a thin antimatter belt around Earth without much of anything happening.

"You fail to grasp the basic principles of mad science. Common sense would be cheating." - Narbonic

Back when the universe was basically a tiny point, all the matter/antimatter would've touched in that closed space.

Oh, I get it! So even though the reaction from interactions NOW are pretty small, compared to what most people think when they think 'matter meets antimatter', the mystery is how the current situation developed in the first place?

"You fail to grasp the basic principles of mad science. Common sense would be cheating." - Narbonic

Yup.

Exactly — the question here is why the universe, having just developed from a singularity into a discrete-if-small agglomeration of matter/antimatter, would not have immediately turned itself back into energy thanks to mutual annihilation. In short, if the relative proportions of matter and antimatter were exactly 50%, we shouldn't be here.

edited 18th Nov '11 9:02:04 AM by Fighteer

"It's Occam's Shuriken! If the answer is elusive, never rule out ninjas!"

Antimatter is so cool! I never get why some people think science takes the wonder and the mystery OUT of life!

"You fail to grasp the basic principles of mad science. Common sense would be cheating." - Narbonic

Willful ignorance.

One question: Why would matter-antimatter collision destroy the universe if the universe has a big enough space?

Now using Trivialis handle.

It wouldn't - it would just convert all matter into energy. So you'd have yourself a universe, but one with nothing but photons - no stars, no planets, no peoples, no top hats, no dinosaurs, no lemon-meringue pies...just photons zipping around in empty space.

Well, if I understand the theory correctly, the energy density was so great at the start of the universe that it is very likely that much of it would have "condensed" *

back into matter... but again that same matter would immediately collide with an equivalent amount of antimatter, until the whole thing blew itself too far apart to spontaneously generate more mass. You might still have a very diffuse cloud of matter/antimatter particles floating throughout the universe, but nothing like the matter-dominant one we have now.

Superstring theory allows for the possibility of infinite combinations of universal laws and constants, each forming its own universe, so the Anthropic Principle dictates that for us to be able to exist, the laws of our universe must favor matter. The question is: what is the mechanism by which this occurs?

"It's Occam's Shuriken! If the answer is elusive, never rule out ninjas!"

Well, matter and antimatter seem to be perfectly symmetric, so isn't it just that we've labeled our type of particles "matter" and the other type "anti-matter"? There's still the question of why one dominates, but it's not like matter and anti-matter are fundamentally different. If our universe was dominated by anti-matter, we'd have just given them the opposite names, but the laws of physics would still most likely appear the same.

If they were perfectly symmetric, then our universe couldn't exist as it currently is. But otherwise, yes, it's true that what we call "matter" could just as easily be antimatter; the distinction is meaningless. It's just like the theory that the universe is symmetric across the Planck length, so something 10⁵ Planck lengths in size is identical in physical properties to something 10^-5 Planck lengths in size. We could be unimaginably tiny and we would appear exactly the same as if we were very big; and, in fact, would likely define ourselves as "big".

edited 18th Nov '11 1:04:37 PM by Fighteer

"It's Occam's Shuriken! If the answer is elusive, never rule out ninjas!"

That's how most physics works, really. Want to find the electric field of a charged sphere? Go out to infinity and treat it like a point in space. Cylinders are just lines if you are far enough away, an orbiting electron's a dipole from our point of view, etc.

They could be globally perfectly symmetric and our universe could still exist. I think I read about a theory at some point where the universe oscillates on a huge time scale between matter and antimatter or something like that. What if there's an antimatter universe out there, paired with our matter universe? It could still be symmetric.

Not suggesting this is the case, just that a priori perfect symmetry is possible.