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.
And earth contains so much of heavier elements.
Physicists drive antihydrogen breakthrough at CERN
31–40 of 96 posts
Re: Physicists drive antihydrogen breakthrough at CERN
#32As 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...
There is a theory that primordial black holes formed in the very early universe. I'm not sure when this process would happen relative to the formation of atoms. But, if it actually happened, it would have been long before stars started forming.
Re: Physicists drive antihydrogen breakthrough at CERN
#33How many times does the rate need to be increased 10x before it's a problem?
Re: Physicists drive antihydrogen breakthrough at CERN
#34Earlier 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 pretty widely accepted though. He himself hated the idea so you can expect he did the calculations thoroughly.
Re: Physicists drive antihydrogen breakthrough at CERN
#35How many times does the rate need to be increased 10x before it's a problem?
If I remember correctly, 6.023x10^23 protons (with electrons) is one gram of hydrogen.
Re: Physicists drive antihydrogen breakthrough at CERN
#36Re: Physicists drive antihydrogen breakthrough at CERN
#37Re: Physicists drive antihydrogen breakthrough at CERN
#38Earlier quoted context omitted.
Depends. Do we know how to obtain a miniature black hole?
There have been several proposals. This paper proposes a feasable mechanism[1]: -"a SBH could be artificially created by firing a huge number of gamma rays from a spherically converging laser. The idea is to pack so much energy into such a small space that a BH will form." 1. https://arxiv.org/abs/0908.1803
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 feed the black hole at all, but doesn't (in my skim) address the fact that this means you have to put in all the energy you'll be using for the lifetime of the black hole at the creation of it, which seems significantly more outrageously infeasible than the bare necessity of creating a black hole at all.
Re: Physicists drive antihydrogen breakthrough at CERN
#39This piece argues that antimatter could be feasible for space propulsion and we could start developing it now: https://news.ycombinator.com/item?id=46073414
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 !
Re: Physicists drive antihydrogen breakthrough at CERN
#40As 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.
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.