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ALPHA observes light spectrum of antimatter for first time

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Re: ALPHA observes light spectrum of antimatter for first time

#61

Post by paulmd »

euyyn wrote: post #58
bmh100 wrote: post #40

In case anyone is wondering about what antimatter actually is, antimatter is basically like normal matter, but the electrical charges are reverse. Take hydrogen for example. It is a massive, positive particle (the proton), orbited by a light, negative particle (the electron). Anti-hydrogen is a massive, negative particle (the antiproton) orbited by a light, positive particle (the positron) [1]. Why do matter and anti…

"Falling into the nucleus", as stated in that Stack Exchange question, is a classical (as in "wrong" :) ) way to look at it. The 1s orbital of the electron is spherically symmetric, with non-zero probability of the electron being right in the center of the atom (so within the nucleus), and decreasing probability of it being farther away. So e.g. a good approximation of the He atom is of two neutrons, two protons, and…

> At the end of the day, there are interactions that are seen in Nature and interactions that aren't.

That's provably false. Every reaction occurs in nature, even the vanishingly improbable ones, just at an extremely low reaction coefficient. They're still there, just at a probability of 10^-14 or whatever.

Re: ALPHA observes light spectrum of antimatter for first time

#62

Post by pranjalv123 »

paulmd wrote: post #61
euyyn wrote: post #58

Earlier quoted context omitted.

"Falling into the nucleus", as stated in that Stack Exchange question, is a classical (as in "wrong" :) ) way to look at it. The 1s orbital of the electron is spherically symmetric, with non-zero probability of the electron being right in the center of the atom (so within the nucleus), and decreasing probability of it being farther away. So e.g. a good approximation of the He atom is of two neutrons, two protons, and…

> At the end of the day, there are interactions that are seen in Nature and interactions that aren't. That's provably false. Every reaction occurs in nature, even the vanishingly improbable ones, just at an extremely low reaction coefficient. They're still there, just at a probability of 10^-14 or whatever.

What? There are interactions that can never occur because they're forbidden by the laws of physics - you'll never violate conservation of [energy, baryon number, momentum, etc.] even with probability 10^-14.

Re: ALPHA observes light spectrum of antimatter for first time

#63

Post by ianai »

jcoffland wrote: post #11
cshimmin wrote: post #8

Earlier quoted context omitted.

Actually his story was about trying to explain the difference between left and right in terms of nuclear spin experiments. You also explain that humans greet by shaking their right hands. If you meet the alien and he extends his left hand to shake, he must be made of antimatter (since the combination of parity and antimatter conjugation is a symmetry of the universe). edit: jess is correct, and that's the whole point…

Assuming a two handed alien of course.

I'm just proud when a physicist assumes a cows not a perfect spheroid.

Re: ALPHA observes light spectrum of antimatter for first time

#64

Post by [deleted] »

grkvlt wrote: post #55
kirykl wrote: post #44

Earlier quoted context omitted.

Would antimatter interact with gravity opposite that of matter, prohibiting an alien (or anything) from being made of antimatter ?

No, it interacts identically. This is a good question - so much so that there was an experiment[0] done at CERN before this one to find the answer. You are in good company asking this, despite downvotes! [0] https://en.wikipedia.org/wiki/Gravitational_interaction_of_a...

[deleted]

Re: ALPHA observes light spectrum of antimatter for first time

#65

Post by Retra »

glandium wrote: post #46

So, if antimatter has the same light spectrum as matter, what makes us theorize that there is currently more matter than antimatter in the universe?

If there were more antimatter than theorized, we'd expect to see much more radiation due to matter-antimatter annihilation. If we don't see this, then there must be a heavy bias in one direction or the other.

Re: ALPHA observes light spectrum of antimatter for first time

#66

Post by jessriedel »

tbabb wrote: post #60
jessriedel wrote: post #14

Earlier quoted context omitted.

> combination of parity and antimatter conjugation is a symmetry of the universe It's only an approximate symmetry. Look up CP symmetry violations.

CPT still holds, though, right?

Yes

Re: ALPHA observes light spectrum of antimatter for first time

#67

Post by stan_rogers »

jcoffland wrote: post #11
cshimmin wrote: post #8

Earlier quoted context omitted.

Actually his story was about trying to explain the difference between left and right in terms of nuclear spin experiments. You also explain that humans greet by shaking their right hands. If you meet the alien and he extends his left hand to shake, he must be made of antimatter (since the combination of parity and antimatter conjugation is a symmetry of the universe). edit: jess is correct, and that's the whole point…

Assuming a two handed alien of course.

In Feynman's story, the "alien" we meet is an artificial human (a biological Locutus, if you will) built using a description we sent them rather than a coincidentally humanoid life form. For a throw-away illustration taking only a couple of minutes in the middle of a lecture about symmetry, the guy filled in a lot of the obvious gaping holes.

Re: ALPHA observes light spectrum of antimatter for first time

#68

Post by neikos »

euyyn wrote: post #58
bmh100 wrote: post #40

In case anyone is wondering about what antimatter actually is, antimatter is basically like normal matter, but the electrical charges are reverse. Take hydrogen for example. It is a massive, positive particle (the proton), orbited by a light, negative particle (the electron). Anti-hydrogen is a massive, negative particle (the antiproton) orbited by a light, positive particle (the positron) [1]. Why do matter and anti…

"Falling into the nucleus", as stated in that Stack Exchange question, is a classical (as in "wrong" :) ) way to look at it. The 1s orbital of the electron is spherically symmetric, with non-zero probability of the electron being right in the center of the atom (so within the nucleus), and decreasing probability of it being farther away. So e.g. a good approximation of the He atom is of two neutrons, two protons, and…

As someone who hasn't studied this (yet) does that mean that the reason protons and electrons don't annihilate is because their Baryon Number wouldn't sum up to zero? (With Protons having 1 and Electrons 0 if I understood correctly)

Re: ALPHA observes light spectrum of antimatter for first time

#69

Post by tokenizerrr »

paulmd wrote: post #61
euyyn wrote: post #58

Earlier quoted context omitted.

"Falling into the nucleus", as stated in that Stack Exchange question, is a classical (as in "wrong" :) ) way to look at it. The 1s orbital of the electron is spherically symmetric, with non-zero probability of the electron being right in the center of the atom (so within the nucleus), and decreasing probability of it being farther away. So e.g. a good approximation of the He atom is of two neutrons, two protons, and…

> At the end of the day, there are interactions that are seen in Nature and interactions that aren't. That's provably false. Every reaction occurs in nature, even the vanishingly improbable ones, just at an extremely low reaction coefficient. They're still there, just at a probability of 10^-14 or whatever.

I'm very interested in seeing that proof.

Re: ALPHA observes light spectrum of antimatter for first time

#70

Post by [deleted] »

tokenizerrr wrote: post #69
paulmd wrote: post #61

Earlier quoted context omitted.

> At the end of the day, there are interactions that are seen in Nature and interactions that aren't. That's provably false. Every reaction occurs in nature, even the vanishingly improbable ones, just at an extremely low reaction coefficient. They're still there, just at a probability of 10^-14 or whatever.

I'm very interested in seeing that proof.

[deleted]
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