The race for antihydrogen
December 7, 2005 8:54 AM   Subscribe

ALPHA and ATRAP are two collaborations of physicists racing to trap and study antihydrogen. To the winner most likely goes a Nobel Prize. The proposed comparison of hydrogen to antihydrogen promises to give an extremely senstive test of CPT invarience. Why do we care? Thats a whole Noether matter...
posted by ozomatli (10 comments total) 1 user marked this as a favorite
 
For you history buffs, here is a copy of Noether's seminal paper. In German of course...
posted by ozomatli at 8:56 AM on December 7, 2005


When I clicked on the second link, I'm ashamed to admit that a small part of me hoped to see a shocked Admiral Ackbar staring back at me.
posted by robocop is bleeding at 9:04 AM on December 7, 2005


I'm not sure whether to cheer for CPT violation or preservation on this one. Either one has deep consequences.

Its always struck me how fundamental these symmetries are to our world and, even more so, how all of the sub-symmetries (e.g. P violation) manage to be almost exactly true in our universe, except for a few small exceptions. Why some small exceptions? Why do these symmetries almost work? Its a deep question and one I know that really troubled Feynman, who, like Einstein thought the Noether theorems were one of the most beautiful things to emerge from 20th century physics.

Is the reason that your average physics-interested layman knows nothing about them because they were developed by a woman?
posted by vacapinta at 9:09 AM on December 7, 2005


Vacapinta, you could be right about that. This is certainly the first time i've heard of her and I've been reading about physics off and on for many years. She's got an amazing story.

But maybe her obscurity is because of the attitudes at the time she was working. It looked like she had to deliver her papers through a third party and she never attained scientific insidership. If we couple that with the esoteric nature of the work...

How is her story different I wonder from Marie Curie? Is Curie more famous because her work is more understandable? Why did Curie manage to get a Nobel Prize even in those incredibly restrictive times?

Either way, I predict that Noether will get her deserved due. A story like that doesn't stay buried for long.
posted by storybored at 10:06 AM on December 7, 2005


Great post, thanks.
posted by Rothko at 10:14 AM on December 7, 2005


Weird coincidence... After the recent spate of physics-related FPPs, I intended to make an FPP about Noether's theorem too.

Lagrangian Mechanics [PDF] was my favourite course in school exactly because the conservation and symmetry principles being applied to classical mechanics could actually be used in quantum mechanics (least action, hamiltonians, etc). Deep stuff.
posted by growli at 10:27 AM on December 7, 2005


Well, I'm going to dumb it down but one of the things Noether did was show that Conservation principles are tied to symmetry laws. Its a beautiful piece of work.

What that means is that what we call Conservation of Energy in a system is tied to the fact that our universe mostly obeys Time-symmetry with respect to natural laws. Succinctly, an experiment I perform today at SLAC should have the same results as if I perform it tomorrow. We take this for granted.

Likewise, Conservation of Momentum is tied in with Space symmetry. If I move all of SLAC 10 cm to the left - again it shouldnt affect the experiment.

So, Energy is tied closely to Time. And Momentum is tied closely to Space. This shows up again in the Heisenberg Uncertainty principles (there are two) which also tie these two operators together. It all arises naturally out of Noether's conception of the universe.

Finally, the CPT stuff is pure beauty in itself. These are all symmetry observations about our universe. C symmetry asks: What if we replaced every particle with its anti-particle? Would the universe behave the same? The answer is No.

P symmetry asks: What if we reflected the whole Universe in a mirror? Would the universe behave the same? The answer is No.

T symmetry asks: What if we ran the universe backwards? Would the physical laws and processes of that universe (not macro behaviour obviously) remain the same? The answer is No.

Then we started asking: Ok, what about, say CP symmetry? That is, flip antimatter and matter and mirror-image everything too!! The answer is still No.

the only combo which seems to hold is CPT which says: If we a) reverse matter with antimatter and b) mirror it and c) run it backwards in time then and only then can we get the physics back. Strange stuff.
posted by vacapinta at 10:32 AM on December 7, 2005


Feynman talks about the importance of symmetry in Nature in the book "Six Not So Easy Pieces".
posted by growli at 10:41 AM on December 7, 2005


This is all great stuff. I need to do mucho reading. thanks vaca and growli.

Growli, if you wanted to make an FPP on Noether, i'd say go for it! I'd love to read it.
posted by storybored at 2:44 PM on December 7, 2005


Great post.

Terrible pun.
A whole noether mater?

Not only is it a pun on another, but "no aether" is exactly what the Photoelectric effect and the MM experiements finally resulted physicists believing in, leading to QM and CPT theory. Ahhh punning!
posted by lalochezia at 5:33 PM on December 7, 2005


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