https://en.wikipedia.org/wiki/Schwarzschild_radius The principle is simple. If something crosses it's Schwarzschild radius, it becomes a black hole. So if you had a very, very, obscenely large particle collider, you could start smashing heavy nuclei with enough force to get them within that radius. Then you would have to 'trap' the new micro-black hole in some way (possibly give it a charge) and 'feed' it more matter very, very quickly, before it evaporates.
The evaporation is a bit trickier, also known as Hawking radiation. It has not been observed yet, but it's one of those cases when we are pretty sure something like it must be going on. Otherwise we have even bigger hole in our understanding of the universe.
Theory is more difficult, but the practical effect is relatively obvious. Once the 'surface temperature' of black hole reaches over that of microwave background, it will begin to evaporate. The process is slow at first, but non-linear. As black hole evaporates, it loses mass, but the temperature actually rises.
Eventually, the process should end with a gamma ray burst.
There is a lot of unknown in that.
Right now we are very, very far from doing any of this. We would need to achieve much higher strength of magnetic fields before we could even consider this. It may turn out, that it's easier just to "catch" an existing micro-black hole. If they exist that is.
One way would be to make a "Kugelblitz". It works by concentrating a huge amount of energy in a very small space. Because of E=mc2, concentrating energy does the same thing as concentrating mass, and could create a black hole from which even the photons that created it can't escape, at least in theory.
In practice, probably impossible, or at least well beyond our current technological capabilities.
Nobody really knows for black holes of these sizes, because we don't have a theory of quantum gravity, but I think that answer according to general relativity would that the curvature is steep enough that escaping would require going faster than c, the universal speed limit, so it doesn't happen.
Black holes are not held together by gravity. The geometry of spacetime inside the event horizon doesn't allow anything to move away from the singularity. All possible worldlines move closer to the singularity.
Except some radiation does leave, evidently. As far as I know, no one knows how or why. I hope we find out before I die. It’s such a fascinating, confusing aspect of black holes
Well, not evidently. Rather, theoretically. We don't have any evidence of this whatsoever, but quantum field theory predicts that it should happen. On the other hand, we don't have a unified theory of quantum physics and general relativity, so it may well turn out to be pure fantasy; an artifact of the intersection of two incomplete theories.
The radiation you talk about, Hawking radiation, does not come from inside of the black hole. It is caused by the black hole but it is formed from beyond its event horizon.
Well, I’ve exposed myself. I don’t have a PhD in physics. In fact, I don’t know much about physics. Including the things I comment about on Hacker News (my bad).
I’m not sure how I made it all these years thinking the radiation came from inside.
I see now that it’s hypothesized to be some crazy interplay of particles and antiparticles within vacuums in curved space time which leads to the black hole absorbing a lesser charged particle while the higher charged particle is emitted as radiation… Which incurs some sort of mass debt for the hole due to the rules of vacuums? I will have to read about it for a few years before it makes any sense. In the meantime I’ll avoid saying dumb things about it on the internet
You didn't say anything dumb whatsoever. Your explanation of it comes from Hawking himself but it was more for illustrative purposes rather than a rigorous description of it.
At any rate, even taking your description which certainly has merit, it is still not the case that the radiation comes from the inside of the black hole, from beyond the event horizon. Rather it's that just outside of the event horizon a virtual particle anti-particle pair is produced which has a combined energy of zero. One way their energies can add up to zero is for one to have positive energy and the other to have negative energy. The explanation then goes that the virtual particle with negative energy enters the black hole and the virtual particle with positive energy escapes, which results in the mass of the black hole decreasing. But both of these particles were formed outside of the black hole, not beyond the event horizon.
So yes the black hole loses mass, and yes for illustrative purposes one can think about a thought experiment involving the production of virtual particle anti-particles, but the key principle is that nothing escaped the black hole in the sense of coming from within the event horizon.
Oh noes my friend.. Its not about negative energy, but background (void) temperature. The pair of particles (matter / anti-matter) spawn, cooling down the vacoom. Once they anihilate again, they change to energy (various photon emisions) increasing background temperature again. Thats why empty space is not at 0 kelvin. Every time such particle is absorbed by blackhole, it just increases it energy (and possibily mass). Not sure where that evaporation comes from ;)
There is no singular "it". I am responding to someone else who came to understand Hawking radiation through a thought experiment that Hawking himself described for pedagogical purposes.
A brief description of that thought experiment involving negative energy can be found here along with the appropriate citation coming from Hawking's "A Brief History of Time":
>Virtual particles can exist for a short period. When a pair of such particles appears next to a black hole's event horizon, one of them may get drawn in. This rotates its Killing vector so that its energy becomes negative and the pair have no net energy. This allows them to become real and the positive particle escapes as Hawking radiation, while the negative-energy particle reduces the black hole's net energy. Thus, a black hole may slowly evaporate.
This is not to be confused with the infrared light that’s relatively easy to detect, which isn’t leaving the black hole but is just light emitted from matter heating up due to tidal forces near the black hole.
I don’t think humanity is ever really going to know what a black hole actually is, simply because they’re too far away and the energy levels required for experiments are many many orders of magnitude beyond what we can generate on Earth. But I do expect if we could get up close and study one, we’d simply discover a lot of fascinating new physics over top of some kind of matter not that far off from neutron stars.
A lot of people don’t really get past the pop science articles about “singularities” to realize that those are just failures of our theories. We don’t know how anything behaves when gravity is strong enough to affect the quantum level, because QM has some kind of silly techniques for avoiding it under normal circumstances (called renormalization) that no longer work.
At extremely high energy levels, my guess as a guy on the internet is that the universe looks less like magical portals to Matthew McConaughey’s bookshelf, but more like regular boring space crap that destroys our notions of stuff like time, matter, energy, causality etc. And in fairness, neutron stars already kind of do this, but nobody cares for some reason.
I might also mention elections being compromised. It is another clear target for Russia with an extremely high payoff.
Feel certain they have not managed to hack the election?
> Can you recommend some resources for building and sourcing a solar setup like this?
A lot of people like Will Prowse on YouTube[1]. I've watched a few of his battery test videos and it's influenced what I'll end up buying. I haven't watched any of his solar videos.
I've been lurking in r/SolarDIY[2] as well.
I'm buying a bunch of Victron[3] gear. They have forums, HOWTOs, some videos, plus the various product sheets. They have some circuit diagrams too.
The rest is Google and reading blog posts, DIY articles, price comparisons, etc. There are books, but I haven't read any.
I've got basic electronics chops and tinker with things a bit. I'm by no means an expert.
I like https://www.redmine.org/. It’s stable, contains all features I expect from issue tracking, fast, easy to export and configure. And if you must, very easy to go into the code or database and change.
Basically, if we are soon able to accelerate at 5000g, then interstellar flight is quite possible.
In which case I would like to see the suns set on a world orbiting binary stars, please.
Well to be fair, in my country (Denmark), that is mostly the case. For normal purchases, using cash is very much not the norm.
But paying a carpenter, cleaner or similar, who will give a lower rate (and not pay income tax and VAT), that is very much the norm (though socially frowned upon). Also drugs I guess.
Love the return to text based chords/tabs (without all the other crap on top). That is all that is needed really.
This guitar/tab space is ripe for disruption if you ask me.
Yup, we need more data, and it appears the ball is somewhat rolling on this.
And meanwhile we need to try to not jump to conclusions, even though it is so very tempting for believers and sceptics alike.
But interesting is the field or subject of ufology (though I hate that word). It is so mixed with crazy people, very reasonable people, grifters, those who are maybe grifters, disinformation (maybe or just the crazy people or grifters again?) and maybe some real interesting stuff among it all.
If the issues we're talking about stem from claims David Grusch (or people in that circle) made, then enough has been disclosed already to draw some conclusions: when your key witnesses discredit themselves, that is itself a form of evidence.
I agree, it seems like there should be a traditional program on top that's filtering responses for known company secrets, conversations that go against published company guidelines, etc.
Is it a case of once you black, you never go back?