Comment by bmitc | Hacker News Reader

Comment by bmitc | Hacker News Reader

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That doesn't really follow, because it seems that people were and are wanting black holes to be something else that they are both not observed to be and not described by any theory of them.

Also, I think it gets lost in physics that theories are models of reality. They are not reality themselves. General relativity is about as good as a model gets. Alongside the standard model, it's one of the most tested models around.

A singularity has a meaning in physics in terms of math, which is dividing by zero or something approaching zero in the denominator. A singularity has a physically modeled aspect in that it's the name assigned to whatever becomes of the matter that gets squished down. A black hole is effectively not a thing in itself but rather an effect of what happens when mass is squeezed beyond all known limits.

What's inside a black hole is not the only thing in the universe we can't see. The actual universe is far bigger than the visible universe, but we can't see outside of the visible universe due to how light works. So it basically doesn't even matter what's going on there. The question is if anything happening at the boundaries can tell us something about that which we can't see. It doesn't make sense to dismiss what we observe on the outside based upon what we literally cannot know of the inside.

And after all, general relativity is a classical theory. Is it really all that "weird"? It all feels somewhat mechanical and natural as you start learning it and turn off your biased intuition.

We have observed one black hole from the inside, the big bang. The reality we see today doesn't really look like what general relativity math says the inside of a black hole should look like.

The pro singularity people must then believe the black hole evaporated really quickly into a big bang to rejoin the out universe, but a more rational answer is that the big bang is what happens inside black holes rather than a singularity forming. Space inflation after the big bang would just be the black hole expanding as it ate more material in its near vicinity.

That seems more like a fun sci-fi speculation

So here is the evidence: We know the big bang fulfilled the math criteria of being a black hole. We also know how black holes work from the outside from observations today. The simplest theory explaining both of those is that the math for the inside of the black hole is wrong, while it is right for the outside, and that we observe in our own universe/black hole is what really happens inside. Any other explanation simply has less evidence behind it.

Speculating that there is some strange singularity there is just as much sci fi as speculating that there isn't and that what we observe from the big bang is the normal state. Any theory saying that the black hole has a singularity inside would need to explain why the universe isn't a singularity, otherwise its provably wrong, since we know the universe isn't a singularity.

The only evidence against the universe and the big bang being a black hole is that it lacks a singularity, everything else adds up to it being a black hole. Ignoring that evidence is more unscientific imo. Also saying that the universe expands due to "dark eneregy" is also baseless sci-fi in that case.

Anyway, if black holes do become big bangs like that then it could be testable by looking at distributions after a big bang etc and compare that with some different ways of calculating black holes sucking up mass in different scenarios to see if it is reasonable. Science starts with speculating about stuff, speculation is not non-science. At least this is more testable than stuff like dark energy.

Edit: I've also studied all the math and physics in college for the testable parts of GR, I haven't studied string theory, at that point I no longer felt the physics made sense, I don't think it is wrong for me to hold alternative theories to the untested ones.

It's all science fiction, stuff I like to think about just before I go to sleep. But I like to pretend this is what happened to time, why it is only one way. see, once you pass the event horizon of a black hole it effectively removes a half dimension from reality(you can't go back towards the horizon) time is that half dimension we are missing.

It isn't just science fiction, the Schwarzschild radius of the universe is massively larger than the universe itself, we are living in a black hole according to current math.

And in theory a black hole whose density gets lower than the density of the universe will grows its event horizon to fill the entire universe. Such a large black hole doesn't have strong tidal forces, so you wouldn't even notice as you entered it, from the outside it would look like the black hole disappeared and the internals popped out rather than you entering it.

At least that is what the math says. Likely there are some more strangeness as you enter the event horizon, since at that point you effectively pass the speed of light barrier, creating infinite time dilation (a gravitational difference is equivalent to a speed difference in relativity, and the anent horizon is when that becomes the speed of light). That means we have no math to explain how time inside the black hole is related to time outside.

So while the space tidal forces wont rip you apart space wise, the time dilation difference between your different parts would be infinite, since at the event horizon one part of you will see the other part as having infinite time dilation, I'm not sure how you could get through that unscathed. The particles might still be next to each other, but you might turn to dust from infinite time passing resulting in infinite particle decay, basically resetting the state of your matter.

I did study all this math in a masters degree, I am not a working physicist but I think this is a much more reasonable interpretation and also more testable than the prevailing ones about black holes. All the math of the testable parts adds up, while the prevailing theories are wrong since the universe isn't a singularity.

Edit; Note that extremely few physicists are even researching GR seriously, barely any work has been done on it since the Einstein days, quantum field theory is where all the useful applications and hence money is at, it also has way more testable results, so almost all physicists are approaching the problem from that angle. The few who do study GR are mostly focusing on the raw math and not interpretations, since math is publishable and interpretations are not, also since GR requires so high level math that basically only those who love math over nature even wants to study it.

Case in point, Einstein himself didn't understand GR math, today he wouldn't be able to publish any GR research even though he invented the theory.

But wouldn't that mean it's black holes all the way down? If in our universe, another universe is inside every black hole, then aren't those universes quite small due to their total mass being the same as the black holes'? The mass of black holes can be quite modest. Then the universes inside those universes' black holes would be even smaller, and so on.

Also, it's my understanding that black holes shrink over the time, so they aren't expanding and certainly not at increasing rates like our universe is. The ones in the center of galaxies "gobble" up gas, but most black holes aren't at the centers of galaxies.

> The ones in the center of galaxies "gobble" up gas, but most black holes aren't at the centers of galaxies.

Most black holes aren't as large as our universe, although if that theory is true we can't say much about what a typical black hole would be like in the larger universe.

It is also possible our universe ate the entire outer universe. At a certain size the black holes density is less than the universe density, at that point its event horizon will expand forever and eat the whole universe. That could happen to our universe as well. That probably wouldn't destroy the outer universe though, since entering such a large black hole doesn't rip you apart, so in a way that is a theoretical way to "exit" a black hole, although technically you make the outer universe enter it.

Edit: Back in college I intend to go into theoretical physics, but once I got to string theory etc I no longer believed in it, and continuing from there would mean I'd have to study that sort of nonsense for half a decade just to enter the field. That makes theoretical automatically turn away anyone who have alternate interpretations, so you wont find them form working physicists. I know all the math from the tested parts of GR, the rest are just untested theories, mine are as good as any there.

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