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Eldar Black Holes

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Re: Eldar Black Holes

#91

Post by joemag »

metaobject wrote: post #23
grondilu wrote: post #19

Earlier quoted context omitted.

> So how do black holes gain any mass then? Well, from our point of view all incoming mass gets stuck very close to the event horizon. That's not too surprising considering the amount of information of a black hole is proportional to its surface area. So from a far away observer a black hole is more like a sticky sphere than an hollow ball.

Doesn't the surface area increase as the BH takes on more mass?

Yes, the radius of its event horizon is directly proportional to its mass. The relationship is described by the Swartzchild equation.

Re: Eldar Black Holes

#92

Post by simonh »

IntronExon wrote: post #81
olegkikin wrote: post #77

Earlier quoted context omitted.

> The crew of a 99.9% lightspeed ship doesn’t experience time dilation until they return home. That's not true. They see the universe around them moving much faster. Time dilation has nothing to do with "returning home".

Seeing the universe around them is comparing clocks with another frame of reference. On the ship, life at 99.9% and life at 1% of c is identical. By the same token, if you fell into an (inactive) supermassive black hole, your watch would trick the same way into and past the event horizon. You would in fact live inside the hole for hours until you were torn asunder.

The point is, the crew onboard the ship can compare clocks with those in different frames of reference at any time. All they have to do is observe the period of a pulsar for example, or measure the orbits of binary star systems, etc. It would be quite apparent to them that there is a time dilation effect for them with respect to most of the rest of the universe. See Tau Zero, by Poul Anderson. It has a few mistakes, but it's still a great read.

Re: Eldar Black Holes

#93

Post by hinkley »

grondilu wrote: post #8

There is a fascinating PBS Space Time video[1] about black holes that questions the very existence of whatever is "inside" a black hole. They point out that as you approach a black hole, your proper time is advancing slower and slower when compared to an observer located far away from the black hole (like us, on Earth). That means that from the point of view of this far observer, nothing happens inside a black hole u…

I’ve wondered this too but I just had a thought. I ended up asking myself why any black hole is ever bigger than critical mass if this is true.

Take a black hole that’s been slurping matter in and it’s all at the event horizon because as you say, it takes forever to cross. But as that mass builds and builds doesn’t the event horizon move? Take the scene to the limit. Say a black hole never absorbs anything. The amount of mass parked just above the horizon becomes so great that another black hole forms. Now you have two overlapping horizons, which can’t stay that way. What really happens is that the density of mass inside the radius near the black hole is sufficient to be a black hole of a larger diameter and then it just... is.

I think that what this means is that you never get to the event horizon, but the horizon comes to you.

Re: Eldar Black Holes

#94

Post by v_lisivka »

LoSboccacc wrote: post #4

Wonder if they also explored the possibility that we are in a black hole and the universe structure is recursive. Maybe the background radiation is the part of the hawking radiation that falls inward. And we perceive it infinite but it’s the dilatated space between the hevent horizon and the naked singularity at the center. And the big bang was the supernova that left the black hole. Trippinng!

We are inside of infinite number of recursive black holes. We are inside infinite number of Homer heads. But we are too small to view whole picture even for level above.

Re: Eldar Black Holes

#95

Post by v_lisivka »

neilsimp1 wrote: post #83
LoSboccacc wrote: post #4

Wonder if they also explored the possibility that we are in a black hole and the universe structure is recursive. Maybe the background radiation is the part of the hawking radiation that falls inward. And we perceive it infinite but it’s the dilatated space between the hevent horizon and the naked singularity at the center. And the big bang was the supernova that left the black hole. Trippinng!

I've always liked toying with the idea (in my own head, not an astrophysicist) that space is cyclical, or in your words, recursive. I love animations where it zooms out farther and farther into space, until it gets to the point where galaxies start to resemble molecular structures. And then of course The Simpson's did a couch gag where exactly this happens and they zoom out and out into space until it finally zooms o…

Drop me line at vlisivka@gmail.com if you want to talk further about that.

Re: Eldar Black Holes

#96

Post by Balgair »

analog31 wrote: post #40
grondilu wrote: post #8

There is a fascinating PBS Space Time video[1] about black holes that questions the very existence of whatever is "inside" a black hole. They point out that as you approach a black hole, your proper time is advancing slower and slower when compared to an observer located far away from the black hole (like us, on Earth). That means that from the point of view of this far observer, nothing happens inside a black hole u…

Here's something I've wondered about black holes, related to what's inside. Simplistically, there must be mass inside, i.e., every black hole has a mass that can somehow be measured, e.g., by orbital velocities of satellites. And the mass-energy has to equal the mass-energy that has fallen in. So far so good. But the stuff that falls in is not purely described by its mass. It also has angular momentum, electrical cha…

The main issue is that you cannot just put a voltmeter or other devices/methods near a BH. Not that you can't do it in a Gedankenexperiment way, of course, but in a relativistic way. Because of General & Special Relativity, things like volts and amps, charge and mass, they get 'bent' in this weird non-intuitive way. In our own (slow) world, electro-magnetism is one of those 'weird things' that comes out of special relativity [0] for example. So, trying to take our 'classical' world and apply it to a General Relativistic world is going to have 'weird' results.

There is a TON of work done on BHs and the formulations to try to bend our knowledge of QM and 'classical' physics to them. If you really want to get into the nitty gritty of it start with this [1]. It's a HARD road, but the proofs and knowledge in the field is mindblowingly cool. Go for it!

[0]https://en.wikipedia.org/wiki/Relativistic_electromagnetism

[1]https://www.amazon.com/Classical-Electrodynamics-Third-David...

Re: Eldar Black Holes

#97

Post by Balgair »

wcarss wrote: post #18
grondilu wrote: post #8

There is a fascinating PBS Space Time video[1] about black holes that questions the very existence of whatever is "inside" a black hole. They point out that as you approach a black hole, your proper time is advancing slower and slower when compared to an observer located far away from the black hole (like us, on Earth). That means that from the point of view of this far observer, nothing happens inside a black hole u…

off-topic a bit: does anyone have suggestions for paths for the layperson toward being able to reason and intuit about this stuff at one level beyond pop physics claptrap? I have heard "the theoretical minimum" suggested in the past, but I haven't heard from anyone who has actually used it to go from zero to say, general relativity, only people who think it sounds good. It also seems like a steep investment -- I just…

Honestly, the best place to do so is an astrophysics undergrad followed by an astrophysics grad program with a good PI. It'll get you there faster and better than any library or self-taught schedule. If you need to choose the self-taught route, look at a course catalog and then research the books they use.

For Example: http://astro.cornell.edu/undergraduate-studies.html

Re: Eldar Black Holes

#98

Post by gooseyard »

grondilu wrote: post #8

There is a fascinating PBS Space Time video[1] about black holes that questions the very existence of whatever is "inside" a black hole. They point out that as you approach a black hole, your proper time is advancing slower and slower when compared to an observer located far away from the black hole (like us, on Earth). That means that from the point of view of this far observer, nothing happens inside a black hole u…

If you've not come across Lee Smolin's (speculative) writing on the Fecund Universes theory, you'll probably also love it. Don't have any links as I've only read about it in one of his books, but it's a fascinating idea.

Re: Eldar Black Holes

#99

Post by tritium »

If the universe expands in a big bang, collapses in a big crunch, and then expands in another big bang, then it’s not a different universe.

The black hole wouldn’t be older than the universe. The black hole is just older than the last, most recent big bang, and the big bang doesn’t explain anything anymore.

It’s disproven as an event of creation. The big bang just becomes different parlance for turtles all the way down.

Re: Eldar Black Holes

#100

Post by pbhjpbhj »

visarga wrote: post #80
dustingetz wrote: post #57

Earlier quoted context omitted.

Between reality and maths, the maths are the more fundamental thing that is used to explain reality. What you call reality is just some circumstances that your brain got used to.

On the contrary, maths are just approximations of reality, not something fundamental to it.

I think the jury is still out on mathematical realism. Our current physics is almost certainly an imperfect description/model however.
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