Singularities

>>8063019
>How do we know that they have no size?

Who said that they have no size?

When physicists/mathematicians see that their model predicts something such as an infinite energy density they
>well, this model is obviously incomplete, or potentially just wrong
but if said model seems to work for most circumstances, they will continue to use it for what it works for, and work on how to reconcile their abnormal results.

And then pop-sci mags and social media get their hands on these theories and as you know, good headlines trump everything else. Hence hurr-durr singularities hurr-durr

No respected physicists really believe anymore that things can be compressed to a 0-dimensional point, even if those models are useful for when things aren't compressed to that size.

>>8063033
So what do physicists actually think about them then?
Could they have sizes that get infinitely close to zero (but never reach?) Or maybe a singularity's size is determined by its mass, wherein the more mass it has, the smaller it is?

>>8063062
don't listen to him he's a massive retard who doesn't understand how mathematical and physical singularities fork off with respect to general relativity.

>>8063062
assuming you're talking about black holes... (nobody talks about singularities...)
the fine details and underlying structure are unknown
black holes are usually the realm of GR which very accurately tells us a lot about them on a macro scale
but when you get down to the micro scale, like usual, GR fails
This is usually where QM comes into play, but black holes are all about gravity, and gravity is the only force not explained well by QM... so...

Maybe you will study physics and research this some day. You could be the one to uncover a theory of quantum gravity which explains black holes. Good luck.

>>8063062
this is still a debated topic among physicists. Some think that the mass of a black hole is concentrated on the event horizon and nothing can actually pass through it. Some physicists do believe that the mass is concentrated in a singularity of 0 size. Most physicists believe these are both true, it just depends on your frame of reference. It doesn't matter anyway, the black hole will act as if all the mass is at a singularity because of Birkhoff's Theorem.

>>8063076
hey sorry that I didn't see your post calling me a massive retard for not knowing that GR fucks off singularities, I was too busy explaining that GR fucks off singularities

I hope you feel good about yourself

>>8063085
>Some think that the mass of a black hole is concentrated on the event horizon and nothing can actually pass through it.

Really? Interesting. I had never heard that. Everything I'd ever learned about black holes told me the event horizon was just the point at which the singularity's gravity was strong enough to keep even light from escaping.

>>8063019
Even an electron has no size. The diameter has been measured to be zero within experimental error. Crazy, right? Yet it still has mass and we interact with them every single day. The universe is mysterious.

>>8063098
I'm sure they have a size. We are just not capable of seeing / measuring things that are that small using our current technology

>>8063105
there is no technology evidence or theory that supports the idea of it having size.

>>8063098
>>8063105
The problem is that to measure the really really small things we use electron microscopes, so there's no realistic way to measure the size of an electron. Also, measuring an electron's "true size" would violate the Heisenberg uncertainty principle, so there's no meaningful way to measure it either.

>>8063111
there is no technology evidence because we do not have the technology, but there are several big theories that support the idea of an electron having a physical size:
https://gravityandlevity.wordpress.com/2015/04/11/how-big-is-an-electron/

>>8063096
Exactly. There's a few reasons why people think that the mass is concentrated on the event horizon. Firstly, when observing a blackhole, it appears that everything entering it is frozen on the event horizon until it gets redshifted into nothingness. An outside observer will never actually see anything enter the event horizon, so it's reasonable to conclude that the mass is all on the surface.

Another reason people might think that the mass is concentrated on the event horizon is because of the quantum mechanics of the blackhole. As you said the event horizon is the point at which the escape velocity is c. c isn't just the speed of light, it's the speed limit of the universe, so nothing can travel faster than c, including gravitational waves and information. So when something falls into the black hole and it gains mass, it's radius increases as well. But how could the radius increase without information from the singularity reaching the event horizon to tell it to increase? Another way of explaining this is that every interaction on the atomic level is just an exchange of a photon. So when the mass of the blackhole increases, there cannot be a photon exchange that allows the event horizon to increase in size.

Something interesting about blackholes is that as the mass increases, it's the surface are that proportionally increases, not the volume. This supports the fact that nothing ever actually enters the event horizon, it just gets infinitely pressed into itself on the edge.

>>8063134
So basically you are saying that not even gravitational waves could leave the black hole (to have their influence nearby mass) if the gravitational pull were *actually* at the speed of light? Is there anything at all that is immune to the effects of gravity?

>>8063134
>>8063181
Okay I think I get what you mean by the light not being able to get to the event horizon to tell it to get bigger (because the light would just be frozen at the singularity and wouldn't be able to cross the space between it and the event horizon to begin with.)

So if this theory is correct, would the black hole be completely solid then? Composed of this event-horizon mass?

>>8063019
Singularities have a diameter above 0. It's simply that this diameter is 1^-infinity, or infinite digits behind the decimal.

>>8063939
* 1e^-infinity