Kurzgesagt – In a Nutshell
1 HN recommender · recommended in 3 months, 2024
11:44 · 9.6M views · May 21, 2024
Kurzgesagt explores the idea that black holes could create universes and that we might live inside one. It builds up the physics of how density falls as black holes get larger.
HN refers to it for the notion that big black holes are not very dense and that universes could form inside black holes.
5 comments from Hacker News
You might enjoy this if you haven't already seen it: this video - TL;DW black hole density decreases with increasing radius, and the average density of the observable Universe is potentially greater than that of an equivalent-sized black hole, so maybe the whole Universe is inside one...
Yes, the effective mass of a photon is determined by E=mc^2 even though it has no mass, but it's sort of by definition because nothing with mass can reach the speed of light. Also anything moving at the speed of light doesn't perceive the passage of time, because from its perspective we're so time-dilated that the universe comes and goes in an instant as it crosses that expanse. So an argument could be made that only one photon exists, forming a frozen 4D crystal with the shape of every photon's path through the universe. A black hole's average density decreases by increasing radius. So theoretically a black hole could be formed from a gas like air, and in fact IRAS 20100-4156 with a mass of 3.8 billion suns and a diameter of about 10 billion km (according to the video below) has the same density as air: this video Also from the video, if we take the average density of the universe and consider it a uniformly distributed gas, we find that it fits within a black hole 10 times larger than the radius of the visible universe, which is 45 billion light years. So I believe that we're inside of a giant black hole and that the expansion of the universe is driven by Hawking radiation at the event horizon causing it to evaporate, which lowers the radius, which from our perspective looks like galaxies slipping away from us faster than the speed of light as they pass that velocity due to the Hubble constant multiplied by that distance. So technically a black hole could be created by just ph
I would think the most difficult part is figuring out if it's even possible to tweak the universe to be more favorable to life than it already is. Maybe it is possible to form more stars, but the same tweak would also form too many sterilizing supernovae? In any case, I'm inclined to believe that other universes exist simply due to how easy they are to find by extending a penrose diagram [1], and that the "natural selection" of "universe reproduction" eventually leads to a universe with parameters that enable life and consciousness. [2] Unfortunately, this method still can't tell us how often alternate universes are capable of life or how much the parameters can vary. [1] [LINK] [2] this video
> Maybe the big bang was a result of the birth of another black hole somewhere else, and that the rapid expansion rate of the early universe was due to the a huge amount of matter converted into dark energy by this black hole There is actually a theory that black holes create universes inside them, and that our universe could be underneath countless layers of black holes forming universes that form black holes ad infinitum. There is a Kurzgestadt video[0] that discusses the theory in more detail. Granted, this is in the realm of science where we have no idea if this is remotely true, but that's part for the course when black holes are involved. [0] this video
If the ring rotated, and black hole density decreases with size ( this video ), could a rotating Gödel universe exist within our universe? Could a region of space be engineered to allow for a limited form of time travel?