I understand that, for a stationary black hole without spin (which does not exist), an object that falls into it will freeze, then the image will redshift until it disappears.
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.
Note this website appears to be based around the personal theories of a scientist rather than a presentation of the consensus of the field.
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.
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.
What the Wikipedia article calls "evidence" is not actually evidence. It's not things we actually observe that are predicted by this model. It's just stuff that can be made to sound plausible in the model, if you assume for the sake of argument that the model is true.
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.
I'd heard that hypothesis, but not that we seem to have evidence for it too.
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.
> “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.
It's not that physics feels no responsibility to explain why, it's that all other fields of science answer the why by punting to some lower level of science that is taken as an assumption until you get down to physics which has nothing lower level to punt to.
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.
There is philosophy, but common physicists does not like going there, unless for rare cases like the author or Max Tegmark or Roger Penrose...
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...
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.
When I think about things at this scale, it really makes me feel minuscule.
I've always thought it would be interesting if the universe also operated on the principles of lazy evaluation, and the deeper you point the telescope, the more is rendered.
I like that too. It fits with the "there's no such thing as infinity, there's just really big numbers". So space is not infinite, it just doesn't have edges.
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).
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.
I doubt very much the universe is expanding. The CMB doesn't present as a uniform field and is probably just noise from galaxies. There is too much vested religious interest in a finite and non-eternal universe for preconceptions not to cloud scientific observation. I call bullshit.
> The standard cosmological model affords no such explanation
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
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.
One red flag that jumped out at me was, not a single link to a published paper, or even an arxiv preprint. Just other blog posts. Actual physics isn't done in blog posts. What has actually been published about all this for other physicists to critique? It's easy to make anything sound plausible if no one else but you gets to speak.
Physics/cosmology-related HN submissions tend to have poor comment quality, so this being upvoted to the front page isn’t too surprising, unfortunately.
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
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.
I understand that, for a stationary black hole without spin (which does not exist), an object that falls into it will freeze, then the image will redshift until it disappears.
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.
https://en.wikipedia.org/wiki/Cosmological_horizon
I mean they’re similar because it’s the same thing happening… light not being able to reach us.
Maybe dark energy is inside-out gravity
Note this website appears to be based around the personal theories of a scientist rather than a presentation of the consensus of the field.
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.
>between well-grounded theory...
But how is the "dials" that the author describes, which "science" use to make the theory fit the facts of observation, more grounded?
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.
Because our universe is actually the inside of a blackhole.
https://en.wikipedia.org/wiki/Black_hole_cosmology#Evidence
What the Wikipedia article calls "evidence" is not actually evidence. It's not things we actually observe that are predicted by this model. It's just stuff that can be made to sound plausible in the model, if you assume for the sake of argument that the model is true.
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.
I'd heard that hypothesis, but not that we seem to have evidence for it too.
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.
Wow speaking of asymmetries https://academic.oup.com/mnras/article/538/1/76/8019798?logi...
But our universe also has black holes.
So what then, is it black holes all the way down?
Why there are anothder blackhole? Is there blackhole inside our blackhole?
Whew, really fantastic article!
> “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.
It's not that physics feels no responsibility to explain why, it's that all other fields of science answer the why by punting to some lower level of science that is taken as an assumption until you get down to physics which has nothing lower level to punt to.
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.
There is philosophy, but common physicists does not like going there, unless for rare cases like the author or Max Tegmark or Roger Penrose...
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...
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.
When I think about things at this scale, it really makes me feel minuscule.
I've always thought it would be interesting if the universe also operated on the principles of lazy evaluation, and the deeper you point the telescope, the more is rendered.
That or that it's all a fractal!
I like that too. It fits with the "there's no such thing as infinity, there's just really big numbers". So space is not infinite, it just doesn't have edges.
Attempts to tackle why in science are actually, underneath, just a how-it-really-happens, or what-happens answers.
No scientist can explain the why, and most can't even explain the how (Heisenberg uncertainty, for one accessible example).
The fact that i am being downvoted on my previous comment means i am on to sth. Truth maybe?
I didn't really understand what you wrote in your comment above. Re-phrase a bit maybe?
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).
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.
I doubt very much the universe is expanding. The CMB doesn't present as a uniform field and is probably just noise from galaxies. There is too much vested religious interest in a finite and non-eternal universe for preconceptions not to cloud scientific observation. I call bullshit.
It’s not expanding. It’s rotating in the 4th dimension.
Tomayto, tomahto? Mathematically speaking, I mean.
is pointless to say the universe expands. We don't even know where it ends or begins
> The standard cosmological model affords no such explanation
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
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.
One red flag that jumped out at me was, not a single link to a published paper, or even an arxiv preprint. Just other blog posts. Actual physics isn't done in blog posts. What has actually been published about all this for other physicists to critique? It's easy to make anything sound plausible if no one else but you gets to speak.
> this is called the Big Bang singularity, GR breaks down there.
Only in models that actually have such an initial singularity. Not all models do. Eternal inflation models, for example, do not.
Physics/cosmology-related HN submissions tend to have poor comment quality, so this being upvoted to the front page isn’t too surprising, unfortunately.
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
> The author is a physicist
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.
> I guess because every code monkey in Silicon Valley has wet dreams about overthrowing the hidebound physics establishment for some reason
Too much focus on the tech in Star Trek when you're a kid, I imagine. Shoulda focused on the morality.