Why Does the Universe Expand?(cosmicave.org) |
Why Does the Universe Expand?(cosmicave.org) |
https://en.wikipedia.org/wiki/Event_horizon
I also understand that there is a cosmological (event) horizon, where galaxies freeze, then rapidly redshift in the same way. This happens because these distant objects are accelerated away from us faster than light.
It appears to me that we are seeing black hole event horizons from the outside, and the cosmological event horizon is seen from the inside.
The similarities do give one pause.
The mechanisms are different; one is gravity, and the other is dark energy.
Perhaps similar to somebody more famous like Harari in that respect.
The author appears to be legitimate in his scientific background but the repeated implications of the revolutionary nature of his work are somewhat crankish; this is a personal blog so possibly he just needs a good editor (he says he is published elsewhere).
Just something to bear in mind as you read - not that there isn't anything to gain from it; but the boundary between well-grounded theory and speculative philosophic beliefs may not be clear - which to be fair arguably comes somewhat with the territory here.
But how is the "dials" that the author describes, which "science" use to make the theory fit the facts of observation, more grounded?
And there is also one huge reason to not think such models are viable. The Wikipedia article skates right by it:
"According to such scenarios, our observable universe was born in a black hole existing in a larger universe, where this black hole may, at some point, appear as a white hole."
The problem with this is, a white hole has a past horizon. In other words, it is an isolated system with a horizon around it, and infinite empty space outside the horizon. We have no evidence for any such thing, and how would it be possible anyway? The past horizon would have had to be "built in" to the universe from the start. It's not something that can be produced by a physical process, the way a black hole, with its future horizon, can be formed by gravitational collapse.
Absolutely wild, thanks for sharing.
> 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.
> 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.
So what then, is it black holes all the way down?
> “In physics, description is explanation” (author quoting his PhD advisor)
Yes, i have always hated this about physics. It is the only scientific field that apparently feels no responsibility to explain “why”, deciding that “what” is sufficient.
I wish the author all success so that i can someday read a satisfying answer to some of the “whys” of physics.
Psychology explains why you feel tired by pointing to biology. Biology explains why cells need ATP by pointing to chemistry. Chemistry explains why ATP releases energy by pointing to physics. Physics explains that by pointing to some higher level form of physics like thermodynamics, which points to statistical mechanics, which point to quantum laws. When you get down to a certain level you simply have nothing left to punt to. You simply accept it because it's what's observed and makes reproducible predictions or you don't and go study philosophy or religion or something.
So they goes round and round, using more and more "dials" to stay within their framework, always kicking the can down the road a bit (its turtles all the way down), but never really answering the core questions...
When I think about things at this scale, it really makes me feel minuscule.
That or that it's all a fractal!
Inflation is accelerating because as the black hole grows it eats more.
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.
No scientist can explain the why, and most can't even explain the how (Heisenberg uncertainty, for one accessible example).
Einstein GR → Friedmann eqns → universe can be expanding or contracting
Rest of this amounts to "what about initial conditions? things become divergent at t→0"
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.
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.
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.
I guess because every code monkey in Silicon Valley has wet dreams about overthrowing the hidebound physics establishment for some reason
Would Ramanujan's unsolicited letter to Hardy be one of the kind that you describe here?
Only in models that actually have such an initial singularity. Not all models do. Eternal inflation models, for example, do not.
While this is true, it's also true that out of all of his published work in physics (which you can find at the "Google Scholar" link on the Author page of his log), none of it, as far as I can see, is about the hypothesis described in this article. All his writings about that appear on his blog. Which means that, if he has tried to get any of this published in peer-reviewed journals, he's failed.
This could mean that he is a visionary whose insight is not recognized by the establishment, which is the story he tells. It could also mean that his speculations actually don't lead anywhere useful. My Bayesian prior is heavily on the latter.
Too much focus on the tech in Star Trek when you're a kid, I imagine. Shoulda focused on the morality.
Sounds lot like you are using appeal to authority.