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Physicists drive antihydrogen breakthrough at CERN

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81–90 of 96 posts

Re: Physicists drive antihydrogen breakthrough at CERN

#81
post #55
post #53

Earlier quoted context omitted.

> Fusion energy is really the only counterexample in history, which makes me think we are still missing some crucial physics about how it works This is magical thinking. We know how fusion works in great detail. And “reliably triggered with minimal energy” is essentially not a thing, unless by minimal energy you mean something like 10 million times the energy of an air particle at room temperature, for every particle…

> at the core of a star - which is powered by gravity That is what I meant, I doubt we really understand what 'powered by gravity' means. You could win a Nobel prize or two by discovering all the details involved here. You would also win a Nobel prize by definitively proving that nothing special happens, you just have high temperatures and high pressures. The way we are trying to study fusion is like rubbing larger a…

We have an extremely good understanding of how gravity operates, both inside and outside of stars. There are no Nobel prizes waiting for things you describe, because that’s all well-established and settled science.

Quantum physics tells us exactly why high temperatures and pressures are needed, and predicts numerically what values are needed. We have a great deal of confidence in its correctness, especially because classical physics predicted values that were far too high - it’s only with quantum tunneling that we get values that match observations.

> The way we are trying to study fusion is like rubbing larger and larger rocks to produce more fire.

This is an incorrect opinion borne of ignorance of the very well-understood physics involved.

Re: Physicists drive antihydrogen breakthrough at CERN

#82
post #69
post #48

Earlier quoted context omitted.

It's a pretty fundamental prediction though, and it's been derived in many different ways, all of which give the same prediction. It's closely related to the Unruh effect, which is a direct consequence of pure QFT. The Unruh effect describes how an accelerated observer sees a different vacuum from an inertial observer - they see radiation that the inertial observer doesn't. Hawking radiation is essentially this same…

A lot of great science progress followed after some "fundamental prediction" turned out to be wrong :). Wouldnt it be awesome to learn that blackholes, in fact, do not evaporate at all? That would be exciting

> A lot of great science progress followed after some "fundamental prediction" turned out to be wrong

For example? What I mean by “fundamental” is that we have very strong reasons to believe in the correctness of a prediction, because e.g. it follows mathematically from more than one model (in this case), and doesn’t involve dependence on uncertain physics.

> Wouldnt it be awesome to learn that blackholes, in fact, do not evaporate at all? That would be exciting

These kinds of attitudes don’t seem to me to involve an interest in science. You don’t appear to actually have much understanding or knowledge of what we’re discussing. You’re just looking for a fix.

Re: Physicists drive antihydrogen breakthrough at CERN

#87
post #85

Earlier quoted context omitted.

Please, no. We detached this comment from https://news.ycombinator.com/item?id=46075749 and marked it off topic.

Okey doke. Still not wrong.

It’s not clever or profound to note this. Yes indeed, countless things are both true and deeply vile. HN if for people who have much higher standards than this.

Re: Physicists drive antihydrogen breakthrough at CERN

#88
post #81
post #55

Earlier quoted context omitted.

> at the core of a star - which is powered by gravity That is what I meant, I doubt we really understand what 'powered by gravity' means. You could win a Nobel prize or two by discovering all the details involved here. You would also win a Nobel prize by definitively proving that nothing special happens, you just have high temperatures and high pressures. The way we are trying to study fusion is like rubbing larger a…

We have an extremely good understanding of how gravity operates, both inside and outside of stars. There are no Nobel prizes waiting for things you describe, because that’s all well-established and settled science. Quantum physics tells us exactly why high temperatures and pressures are needed, and predicts numerically what values are needed. We have a great deal of confidence in its correctness, especially because c…

I'm amused at your confidence in stating that we have a good understanding of what's literally the most prominent open problem in physics, gravity at small/particle scales.

Re: Physicists drive antihydrogen breakthrough at CERN

#89
post #65

Earlier quoted context omitted.

It's much easier to make a fission reactor than a fission bomb, and much easier to make a fusion bomb than a fusion reaction. They are not even that similar.

It's way easier to make a fission bomb than a fission reactor. I reactor has to stay in the very narrow window where it's critical but not prompt critical. Even pure fission bombs can be marvels of engineering but the simplest gun-type bomb is easier to build than the simplest nuclear reactor.

Without a precisely timed neutron initiator you'll get a fizzle. Either way, gun-type bombs require highly enriched uranium. A simple reactor can be literally just brickwork of natural uranium and graphite.

Reactors are much much simpler to pull off, which is why US had the first reactor whole 2.5 years before a nuclear bomb.

Re: Physicists drive antihydrogen breakthrough at CERN

#90
post #66

Earlier quoted context omitted.

The biggest problem is that if you're creating it with lasers, you're only going to get the energy out that you put in. You really want to be able to feed it matter, which would effectively make it an anything-to-gamma-radiation converter, which means you have to feed it quite a lot of matter, against the radiation pressure of all that energy coming out. The paper mentioned assumes a worst case of not being able to f…

Does anyone address the fact that a black hole will be falling towards the center of the earth at 1g? How do you handle a black hole?

Use it for interstellar spacecraft, as far away from Earth as possible.
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