Because our universe is actually the inside of a blackhole.<p><a href="https://en.wikipedia.org/wiki/Black_hole_cosmology#Evidence" rel="nofollow">https://en.wikipedia.org/wiki/Black_hole_cosmology#Evidence</a>
I'd heard that hypothesis, but not that we seem to have evidence for it too.<p>Absolutely wild, thanks for sharing.<p>> Any model of the observable universe being the interior of a black hole requires that the Hubble radius of the universe be equal to its Schwarzschild radius, which is proportional to its mass. This is indeed observed to be nearly satisfied, but might be a coincidence.<p>> The only way to test the idea that black holes create new universes is to measure the observable universe. Inflation generated by spin and torsion is consistent with the cosmic microwave background data from the Planck satellite.
Edward Arthur Milne's proposal was that the universe started out expanding. That is Milne cosmology, and oddly enough it's equivalent to Standard cosmology when you take out the gravitational effects of mass-energy. What's odd about that is that in Milne cosmology you have a big bang at one point with the edge moving at arbitrarily close to c and with uniform distribution of stuff and velocities, while in Standard cosmology we speak of the big bang happening everywhere all at once. This oddity is resolved when you realize that Milne is hyperbolic, so you if you "unfurl" a Milne universe it then looks the same as Standard excluding gravity.
It’s not expanding. It’s rotating in the 4th dimension.
I kind of like the idea that as the edge of the universe is observed, it expands to fit that observation. "Observed" being in the same sense as the uncertainty principle. But there's also the idea of the universe or space as a kind of mesh that's stretching, not really growing.<p>When I think about things at this scale, it really makes me feel minuscule.
> The standard cosmological model affords no such explanation<p>Einstein GR → Friedmann eqns → universe can be expanding or contracting<p>Rest of this amounts to "what about initial conditions? things become divergent at t→0"<p>Yes, this is called the Big Bang singularity, GR breaks down there. You are not the first person to notice this. It is considered one of the biggest open problems in the field.<p>The stuff about accelerating expansion is confused (AI?) slop which eventually gets around to admitting that there's no problem at t>0 and no change to the existing problem at t=0, so I don't know why you didn't just cut it.<p>This is some real "unsolicited snail mail to physics departments"-tier content, even for HN I think it's embarrassing to have this on the front page.<p>I guess because every code monkey in Silicon Valley has wet dreams about overthrowing the hidebound physics establishment for some reason
Dunning Krueger is most prevalent in software engineers for some reason. Fortunately most of us grow out of it and begin to appreciate how hard other disciplines are.
What stuff about accelerating expansion are you referring to? The author is a physicist not just a barstool talker. He's right as you point out that there are huge interesting and unexplained phenomena that sometimes have pretty little names that discourage further question asking. It's sad to see such negativity instead of engaging with the material a bit
My favorite idea is that the universe expands because mass-energy in our 4d parent universe is falling into our universe, which is a black hole. We exist as information upon the 4d hole’s 3d event horizon, and experience its inflation as our time dimension (as well as space inflation).<p>Inflation is accelerating because as the black hole grows it eats more.<p>Don’t know how crackpot this is. From what I’ve read it actually can be coaxed into fitting observation but there’s just no possible way to test it.