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Physicists drive antihydrogen breakthrough at CERN

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Re: Physicists drive antihydrogen breakthrough at CERN

#41

Post by idiotsecant »

irjustin wrote: post #30
teleforce wrote: post #26

As a side note, it's mind boggling that overwhelming majority (more than 98%) of the visible universe's mass are only from two most lightweight of chemical elements namely Hydrogen and Helium.

> it's mind boggling that overwhelming majority is it though? I mean literally everything has to start there and the only way get to heavier elements is via stars and many-many iterations. it's not like heavier things popped into existence.... or did they...

Yes, it's a little mind boggling because the typical human context is this rocky ball of what is ultimately a very uncommon distribution of heavy elements. It's a strange feeling to know that almost everything is utterly unlike the everyday human experience. If you turn down the uhm acksshuwlly a few notches I think parent post's point is quite obvious.

Re: Physicists drive antihydrogen breakthrough at CERN

#42

Post by idiotsecant »

fooker wrote: post #12
impossiblefork wrote: post #8

Earlier quoted context omitted.

Miniature black holes would just evaporate. Antimatter wouldn't.

Not before efficiently converting a large amount of mass into usable energy.

In the same way that atomic weapons and radioisotope generators both convert mass into energy. It's just a matter of slightly different timescales.

Re: Physicists drive antihydrogen breakthrough at CERN

#43

Post by idiotsecant »

Qem wrote: post #29
manphone wrote: post #25

Earlier quoted context omitted.

Probably more like a water wheel - matter spinning around the hole can be accelerated.

A spacecraft carrying a blackhole as propulsion means probably would have poor power to weight ratio.

Not at all. It would have one of the best power to weight ratios possible.

Now as to whether you could use all that power....

Re: Physicists drive antihydrogen breakthrough at CERN

#44

Post by dmead »

IsTom wrote: post #6
modeless wrote: post #3

This piece argues that antimatter could be feasible for space propulsion and we could start developing it now: https://news.ycombinator.com/item?id=46073414

If you can electromagnetically trap enough antimatter to use it as fuel you could as well trap a miniature charged black hole that can be fed regular matter to produce power, which skips the whole inefficient part of making antimatter.

The romulan empire does this.

Re: Physicists drive antihydrogen breakthrough at CERN

#45

Post by kadoban »

analog31 wrote: post #40
codesnik wrote: post #31

Earlier quoted context omitted.

And earth contains so much of heavier elements.

As I learned it long ago in school, elements up to the mass of iron are formed by stellar fusion. That's the point where fusion is no longer exothermic. Any element on earth that is heavier than iron is the product of a supernova. So we live on a ball of supernova debris.

Most of what we live on, the vast majority, is iron or lighter. So it's more that we're sprinkled with supernova debris. But we are made out of stardust, so that's something.

Re: Physicists drive antihydrogen breakthrough at CERN

#46

Post by volemo »

doug713705 wrote: post #39
teamonkey wrote: post #16

Earlier quoted context omitted.

For those who are time-rich and knowledge-poor: https://youtube.com/watch?v=i6jMnz6nlkw (Angela is genuinely a great science communicator and that video is time well spent if you are interested in this topic.)

You can skip the first 42 minutes that are about how bad is an article titled "how antimatter space craft will work". This part is absolutely boring as hell !

Angela is great, albeit her rants can get quite windy.

Re: Physicists drive antihydrogen breakthrough at CERN

#48

Post by antonvs »

aeve890 wrote: post #24
impossiblefork wrote: post #8

Earlier quoted context omitted.

Miniature black holes would just evaporate. Antimatter wouldn't.

Minor nit-pick but Hawking Radiation hasn't been observed and remains a theoretical prediction.

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 effect, except that "acceleration" is replaced by "gravity" (Einstein's equivalence principle.) There's a bit more to it, but that's the basic intuition.

For Hawking radiation to be wrong would require some fundamental changes to GR, QFT, or both.

Re: Physicists drive antihydrogen breakthrough at CERN

#49

Post by fooker »

pfdietz wrote: post #27
modeless wrote: post #3

This piece argues that antimatter could be feasible for space propulsion and we could start developing it now: https://news.ycombinator.com/item?id=46073414

Before we get too excited, this current "breakthrough" is making less than 1 antihydrogen atom per second. This corresponds to a delivered annihilation power of less than 1 nanowatt.

Neutrons were first definitively observed in 1932.

First nuclear reactor was 1942, and bomb was 1945.

Once the science is established, we have smart engineers to make a short work out of it.

Fusion energy is really the only counterexample in history, which makes me think we are still missing some crucial physics about how it works, for example in stars. Specifically the particle physics view of how it's reliably triggered with minimal energy.

Re: Physicists drive antihydrogen breakthrough at CERN

#50

Post by fsh »

fooker wrote: post #49
pfdietz wrote: post #27

Earlier quoted context omitted.

Before we get too excited, this current "breakthrough" is making less than 1 antihydrogen atom per second. This corresponds to a delivered annihilation power of less than 1 nanowatt.

Neutrons were first definitively observed in 1932. First nuclear reactor was 1942, and bomb was 1945. Once the science is established, we have smart engineers to make a short work out of it. Fusion energy is really the only counterexample in history, which makes me think we are still missing some crucial physics about how it works, for example in stars. Specifically the particle physics view of how it's reliably trig…

The antiproton decelerator at CERN has been operational for 25 years, and they have plenty of smart engineers there. Unlike in the 1940s, the underlying physics has been well understood for many decades. I would argue that nuclear fission is the counter example that happens to be surprisingly easy to do.
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