When you run the Schwarzschild radius calculation for the universe (relating mass of a black hole to event horizon radius) you get a prediction that's close enough to the size of the universe and it's mass, so to me that's pretty good evidence our universe is an event horizon.
This means all 3D points in our space are on the horizon itself, and the time dimension is the normal vector to that "surface" (3D manifold). It explains why space is expanding, because Event Horizons always only expand (excluding considering Hawking evaporation of course, which happens too slowly to affect things)
> "Still, some folks will stubbornly insist, there has to be something deep and interesting about the fact that the radius of the observable universe is comparable to the Schwarzschild radius of an equally-sized black hole. And there is! It means the universe is spatially flat."
Sean Carroll is not really an unbiased party. He has his entire reputation staked on him being right about his own theory, so he's going to simply disagree with anything else, and he's going to disagree with anything that's not a "standard" theory.
He likely believes in the Big Bang too which is an absurd, and disproven theory. There are far too many mature galaxies that are far too old for the Big Bang theory to be correct.
> He has his entire reputation staked on him being right about his own theory
You may be thinking of someone else. I'm not aware of Carroll having "his own theory" that he's "staked his entire reputation on."
In any case, he's explained his position, even in the quote I provided. He's simply describing what general relativity says about this. If you have some issue with it, you can respond on technical grounds, without needing to resort to ad hominem.
> He likely believes in the Big Bang too which is an absurd, and disproven theory.
Big Bang is not "disproven" - the Lambda-CDM model of the Big Bang is still known as the "Standard Model of Cosmology," and nothing has replaced it as a consensus among mainstream scientists.
> There are far too many mature galaxies that are far too old for the Big Bang theory to be correct.
The issue of galaxy ages has a number of reasonable explanations in the context of Lambda-CDM. One of them could simply have to do with age estimates, which is an area that suffers from limited observational data that's difficult to interpret. Recent work on the Hubble tension may help resolve that, e.g.: https://news.uchicago.edu/story/new-webb-telescope-data-sugg...
The idea that galaxy ages "disproves" Big Bang theory is at best, a misunderstanding of pop science hype, and at worst pseudoscience. That's not how science works, especially in cosmology where most evidence is very indirect and subject to interpretation.
Hypothetically speaking, what would it mean if telescope technology were to improve to the point where we could see back to the point in time immediately after the CMB and what we saw were fully formed mature galaxies? It seems to me that there would only be a couple of possible explanations - either the CMB would have to be re-interpreted as some sort of local (but extremely large scale) event not necessarily from the formation of the entire universe or else it would be evidence of a Big Bounce where somehow parts of a previous universe survived.
That kind of observation would have a much more dramatic impact, because it would imply that the theories about what the CMB is are completely wrong.
The CMB originates from what's called the surface of last scattering. Prior to that time, density was such that photons couldn't travel very far without being absorbed. During that period, matter was in an ionized plasma state, consisting of free protons, neutrons, electrons, and some light ionized nuclei like deuterium, without any bound electrons. In this scenario, there were no objects bigger than a light nucleus. It would be impossible for stars or galaxies or even dust particles to form in that situation.
Reinterpretation would depend on what the evidence was. This isn't an area that we're particularly unsure of. There's a very comprehensive theory of the evolution of the early universe, supported by all the evidence we have for quantum theory. I recommend Steven Weinberg's book The First Three Minutes if you're interested.
The CMB was the only "evidence" for the Big Bang (and I use evidence in quotes because it's wrong actually), other than the fact that everything seems to be expanding as if from a single point.
When people still insist on believing the CMB proves it even when we now see fully formed galaxies at the edge of the observable universe, it's only because they're vested in that theory, and they know if it's wrong then they've been badly wrong for their entire lives. Only people with decades of vested belief in the Big Bang are hanging onto it for dear life, while open minded objective people correctly claim the evidence is against the Big Bang, and it was never anything but a wrong guess.
The Big Bang theory makes more assumptions and contradicts more evidence than just assuming our universe is an event horizon embedded in a higher dimensional space. The Event Horizon explains lots of things the Big Bang doesn't also, like why time is a special dimension, and why space always only expands. The Event Horizon theory explains everything that the Big Bang theory cannot explain and contradicts NONE of the evidence.
The Event Horizon theory doesn't postulate a "beginning" of everything, in the comical "it popped into existence" nonsense of the Big Bang. The EH theory doesn't try to establish a first-mover or uncaused-cause. It just describes how the universe is without trying to describe any "magical" beginnings. The Big Bang is a theory about magic, not a theory of science.
It's my own theory, which I haven't published. "Holographic Theory" (Susskind) is similar but still quite different. But others are having similar ideas, as seen in this video:
The reason scientists do peer review is captured well by the Mike Tyson quote, “Everyone has a plan until they get punched in the face,” which we can rephrase as, "Everyone has a theory until they undergo peer review."
The point is that your theory is almost certainly wrong, but you won't find out how wrong it is unless you describe it in enough detail for others to check it.
No. The point is standing outside the ring shit-talking about how you have the best punch is just BS, and you know it - otherwise you would have published something.
You're talking about an amateur conjecture that no-one has seen as though it has some relevance to a discussion about physics.
That's just nonsense. My analogy about boxing is not shit-talking, it's pointing out what you're actually doing: talking a big game with no ability to back it up.
I'm doing you a favor by pointing that out, because if you somehow don't realize it, it might help prevent you from turning into a complete crackpot.
Aw, lighten up a bit. I'm just on HN having fun discussing Physics, because it's something I love. But it's super nice of you to take so much time and effort to encourage people to publish.
There's more evidence for this Black Hole theory than there is for the Big Bang, but not it's not like there's any laboratory experiment that can be done afaik. It's all about measuring things in astronomy. Big Bang theory at this point is hilariously wrong, and doesn't fit much evidence nowadays. Big Bang is disproven.
Ok, by that comment you told me everything I wanted to know: you're pulling this out of thin air. Please provide sources whenever you make insane claims like "Big Bang is disproven". Because it's not [1]. Also you told me there's "more evidence for this Black Hole theory than there is for the Big Bang", so please link to it, that I might examine it and maybe change my mind.
The Big Bang is disproven because we see fully formed galaxies when we look out at the edge of the universe using James Webb Telescope. That's conclusive proof it's wrong.
In the context of the Big Bang theory, the 'edge' is at the distance away from us at which seeing any light from that distance would have to mean that light started traveling "before" the big bang, which is considered impossible, due to constant speed of light and hubble expansion.
Really curious, how do you quantify "close" in such numeric ranges?
Quick calculations say that ratio is 1.71:1 (https://rentry.co/k85wy696). I guess given the scale of the numbers having such a low ratio is interesting.
But my intuition says that in physics constants are scattered in a sort of logarithmic way, i.e. the orders of magnitude are uniformly scattered in some range. So small ratios between such constants not impossibly rare.
I admit I haven't run the calculation myself, nor even asked OpenAI (or other AI, which are almost certainly capable of doing it), but I heard a presentation say the number is off by a factor of 3. To me '3' is best described as "no where near an order of magnitude". Since there's no way we're measuring the radius of the universe nor the mass in it accurately, I think being off by only a factor of 3 is astoundingly "accurate". When you're dealing with many many orders of magnitude like these astronomically large numbers, and you end up being only off by 3x that's actually pretty close. Too close to be an accident. If the theory was "wrong" it would be off by many orders of magnitude.
This means all 3D points in our space are on the horizon itself, and the time dimension is the normal vector to that "surface" (3D manifold). It explains why space is expanding, because Event Horizons always only expand (excluding considering Hawking evaporation of course, which happens too slowly to affect things)