Comments on: Antimatter Astronomy

By: Brian Koberlein

Brian Koberlein — Mon, 20 Feb 2017 14:10:00 +0000

Most interstellar gas is hydrogen, so that would react with anti-hydrogen. In principle gold and anti-gold would also annihilate, but exactly how that would occur is something I don’t think we know. It might break apart first, who knows.

By: Robert Crowley

Robert Crowley — Mon, 20 Feb 2017 12:34:42 +0000

As far as I am aware, there is no antiphoton, as it’s nature doesn’t allow for a charge, just an energy level. But is there any theoretical variation in light emitted by antimatter in non-annihilation interactions that would be observable? Perhaps a differently polarized nature from what we would observe in a matter interaction? Say, from a star made of anti-H, He?
Also, and I am revealing my ignorance with this question, so please don’t be too harsh if this is a goofy question, but do antiatoms have to encounter their matter opposites to annihilate? For instance, will an antihydrogen atom annihilate if it encounters an atomic of gold? And will only the corresponding number of particles in the gold atom be consumed, or will the entire gold atom be destroyed in the process? Well, destroyed as in split into separate lighter atoms, instead of only transforming into Platinum due to the loss of a single proton?

By: sjastro

sjastro — Sun, 08 Jan 2017 00:35:36 +0000

Antimatter is distinctly different from matter when examined at a quantum mechanical level.
Reactions between particles and antiparticles not only require properties such as energy or charge to be conserved, but other properties which are quantum mechanical in nature and differentiate matter from anti matter, such as baryon and lepton number.
Gamma radiation produced through matter/antimatter annihilation is a signature for the conservation of baryon and lepton number.

Then there are the specific physical properties.
For example neutrons and anti neutrons have the same neutral charge and mass but have opposite magnetic moments of the same magnitude.

By: Brian Koberlein

Brian Koberlein — Sat, 07 Jan 2017 15:50:34 +0000

The names we use aren’t really that important. It’s the process and relation between the two that matters, and that wouldn’t change.

By: Brian Koberlein

Brian Koberlein — Sat, 07 Jan 2017 15:49:31 +0000

You might. It would be really faint, though.

By: David Simmons

David Simmons — Sat, 07 Jan 2017 01:27:29 +0000

Is antimatter a matter of definition? I mean can we define matter to be made of positive and negative matter particles? That way we can drop the antimatter term. This would make some radioactive reactions make sense e.g. positron decay. Surely, the radioactive isotope isn’t really creating antimatter; or is it?

By: Beat Toedtli

Beat Toedtli — Fri, 06 Jan 2017 23:29:50 +0000

What happens it you consider CP-violating processes in distant galaxies? Are they observable? I could imagine that they would be able to tell the difference between matter and antimatter.

By: LocalFluff

LocalFluff — Wed, 04 Jan 2017 13:25:43 +0000

Have really no matter/anti-matter annihilations been observed in the universe?
Anti-matter form, in tiny quantities, by cosmic radiation in Earth’s upper atmosphere or magnetosphere, I’ve heard. I suppose that it is known because it annihilates and emits characteristic gamma rays. But beyond that.

Is the mass really annihilated, or could it remain as a shadow in the shape of dark matter, undetectable in labs?

By: Brian Koberlein

Brian Koberlein — Tue, 03 Jan 2017 14:33:38 +0000

Gamma rays produced by antimatter would have a specific signature. Just seeing gamma rays isn’t enough to support antimatter.

By: Brian Koberlein

Brian Koberlein — Tue, 03 Jan 2017 14:32:27 +0000

You have to take that quote in context. It seems reasonable to assume, however, we should look at things more closely (which is done in the rest of the post). To use your flat earth analogy. It’s reasonable to assume the Earth is flat, however … and then point out that detailed evidence shows the Earth is round.

By: usarian

usarian — Tue, 03 Jan 2017 14:07:42 +0000

“any small amounts of matter from the intergalactic wind would annihilate with antimatter on the outer edges of the galaxy and produce gamma rays”

what about the Gamma ray halo around our galaxy, or the extragalactic cosmic rays we know so little about, or even those mysterious gamma ray bursts?

By: usarian

usarian — Tue, 03 Jan 2017 13:53:18 +0000

I don’t understand this statement:

”
In all of our interactions, both in the lab and when we’ve sent probes to other planets, things are made of matter. So we can assume that most of the things we see in the Universe are also made of matter.
”

As far as I can tell, that’s a logical fallacy.. a big one in fact, in the same vein as the original flat earth paradigm.. how can tests here on earth and in our immediate local vicinity justify the presumption that the entire vastness of the universe is identical?

It seems to me like the best we can do right now is shrug – we need at least some info from other star systems and galaxies before making any assertion at all