Ping George Herold: The Lyman-alpha transition for anti-hydrogen detected

On Saturday, August 25, 2018 at 5:27:37 AM UTC-4, snipped-for-privacy@nospam.org wr ote:

I have to admit I am not up to date on my anti-matter physics. The article says they will be performing spectroscopy and gravity measurements on the antihydrogen atoms. Would they expect to measure anything different from t he same measurements on hydrogen? In fact, if they measure something diffe rent, won't that indicate a fundamental flaw in present theory?

Or do they expect to see differences and I'm a long way from current?

Rick C.

You don't know about the warp engines everyone's talking about?

I don't think it's a matter (pun!) of expecting something. It's a matter of *hoping* to see something they don't expect.

That's very much the question... whether there are differences.

One of the big unanswered questions in physics is why there is so little antimatter in the universe, compared to the amount of matter. The basic processes which create matter from energy (e.g. shortly after the Big Bang) are symmetrical, should create equal amounts of both... after which the matter and antimatter would tend to annihilate one another, leaving energy but no matter. In a fully symmetrical universe, we would simply not exist.

There must be asymmetries in the physical processes involved, somehow, which favor the creation of matter over antimatter. This may or may not show up in measurable differences between matter particles and their antiparticles. Any such differences will (I think) require extending or changing the Standard Model... they will indicate that present theory is incomplete.

Some such asymmetries have already been detected - violations of charge/parity symmetry in some particle decays. It's possible that direct measurements of antimatter particles may find others.

But what happened to the energy released when they annihilated each other?

That would have been a lot of energy. What form did it take?

The Big Bang, more-or-less. Prior to about a picosecond after the Bang everything was in some kind fashion of grand-unified force quark-gluon plasma. After about a nanosecond all the forces had separated out into about the way we know them now, but the Universe was still too hot to allow hadrons to form and quark/antiquark plasma existed happily in thermal equilibrium.

At a microsecond things have cooled enough for hadron/anti-hardrons to form, and they immediately start annihilating, releasing a huge amount of further energy but it's already way too late for it to heat things back up enough to "push the reaction back" to an earlier state, as it were. Much of that anti-matter is annihilated at one second, and matter/anti-matter proportion is basically at its current amount after one minute.

After all that it took quite a while for the Universe to cool enough become transparent to radiation, basically glowing hot like the center of a thermonuclear fireball but for half a million years.

That's cool. :^) Hanging on to anti matter is not so easy. I think it's certainly worth doing and getting the data. We expect the spectra to be the same, but who knows. Hydrogen is like the only element physics's can predict exactly with QM. And that's led to a bunch of nice physics. (One dream I have is to measure the Lamb shift in hydrogen, with today's diode lasers it's a piece of cake... well you have to make the hydrogen, that's the hard part.)

George H.

Hydrogen molecules are easy.

A hydrogen atom source does seem to be commercially available.

It doesn't look cheap.

--
Bill Sloman, Sydney

Electrolysis? My highschool physics teacher used electrolysis to make H and O gas, blew bubbles with it in soapy water that floated in the auditorium, had the kids ignite those with a lighter. You very fast learn that volume goes up exponentially with bubble size, the big ones gave a BIG bang, He was dangerous, I used to sit way back, but that was not safe either, he used the same H&O in a metal tube with a cork in it ignited by a spark plug, and shot a hole in the glass in the back of the place.

Hey, just found this link in sci.astro:

refers to paper: Apparent evidence for Hawking points in the CMB Sky Daniel An, Krzysztof A. Meissner, Roger Penrose (Submitted on 6 Aug 2018)

Have not read it yet....

Yeah you need monatomic hydrogen. The usual way to make that is with a discharge in H2 gas. But single H is rather reactive and goes away, so you have to keep making it... I'm not really sure of the details.

Me either :^).. maybe later.

George h.

Polynomially, I believe (r^3), not exponentially (x^r for some value of x).

But, yes, a big bubble can make quite an Earth-shattering kaboom.

The single proton-single electron system of neutral hydrogen, specifically, you can write out on paper.

Interestingly the Schrodinger equation works just fine in two dimensions as opposed to three, IIRC it's somewhat better behaved wrt closed-form calculation, and you can construct hypothetical two-dimensional elements and speculate on the chemistry of Flatland, though not of much practical value currently. There's a paper somewhere online about it...

One gathers that you never took undergraduate quantum, because the bound-st ate 1-D time-independent solution to the Schroedinger equation for a 1-D sq uare-well potential is about a Week 3 problem iirc. The analogous scatterin g problem is a week ot two later, maybe.

2D might be the following quarter, but is certainly undergraduate level.

Cheers

Phil Hobbs

Solutions in 2-D QM are used all the time. There's all sorts of 2-D quantum wells in layered semi-conductors, used for detectors and light sources. (not Ge and Si but all the 3/5's and 2/6 combo's)

I call the hydrogen atom a zero dimension solution to QM, the electron is contained equally in all directions. You can google quantum dots, which have similar (though different) solutions.

George H.

All zero of them? ;)

I haven't done the math in 30 years, but in the Coulomb potential the Lapla cian separates in spherical coordinates, with a radial equation giving (iir c) spherical Bessel functions and the angular equation leading to spherical harmonics.

But you certainly remember that at least as well as I do, since you do quan tum things for a living.

Cheers

Phil Hobbs

Now now, you can only squeeze so hard in one direction and the electron has to come oozing out in the others. I guess I just see 2-D as having the electron constrained in one dimension and free to move in the others. Of course it still has a wavefunction in the constrained dimension. (but you know all that.)

lacian separates in spherical coordinates, with a radial equation giving (i irc) spherical Bessel functions and the angular equation leading to spheric al harmonics.

antum things for a living. Yeah but I hardly use anything more than E = h * frequency, (and a dipole selection rule here or there.)

George H.