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The strange fate of a person falling into a black hole

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Re: The strange fate of a person falling into a black hole

#101

Post by guard-of-terra »

ars wrote: post #91
monocasa wrote: post #77

So I've had a question about stellar mass black holes that I can't seem to be able to get answered (the question was deleted for /r/askscience). How does a stellar mass black hole actually form a singularity given the fact that there's gravitational time dilation? Wouldn't the heart of a black hole slow down relative to an outside observer as mass is added to it so that you never actually reach infinite density? It s…

I reached the same conclusion years ago, and the answer is very simple (and controversial): Black holes do not exist. If they existed they could exist, but it's impossible for them to form. I've asked many many physicists this very same question, and none could answer me (or I've gotten hand-wavy non answers). It's like no one wants to be the first to declare this well accepted thing as non-existing. The black holes…

I've wondered the same, found this:

http://physics.stackexchange.com/questions/21319/how-can-any...

"The objects that can be very similar to black holes are called collapsars. They are virtually indistinguishable from actual black holes after a very short time of the formation. They consist only of matter outside the radius of the event horizon of a BH with the same mass. This matter is virtually frozen on the surface like with actual BH, due to high gravity level.

Such collapsars possibly can become BHs for a short time due to quantum fluctuations and thus emit hawking radiation.

Astrophysicists do not separate such collapsars from actual black holes and call all them BHs due to practical reasons because of their actual indistinguishability."

Re: The strange fate of a person falling into a black hole

#102

Post by jessaustin »

DannoHung wrote: post #94
jessaustin wrote: post #86

Earlier quoted context omitted.

This is not an insightful response. Of the people I know who watched the movie, those who objected the most to the science were those with little scientific training. (Similar to a relative of mine who is certain that we will "never" have self-driving cars...) If you are knowledgeable, and have specific objections, those might be more insightful.

Nah. Someone should've realized Miller's world was a bad idea before they went down there and made the whole thing a screw up. Oh, or what about the fact that they "solve" Gravity and decide to leave Earth. HELLO, YOU NOW HAVE INFINITE ENERGY! YOU CAN FIX ANY PROBLEM WITH BRUTE FORCE!

Well considering they were looting really old Indian Air Force drones for parts at the beginning, and they have giant self-sustaining luxury habitats at arbitrary points in the Solar system at the end, I'd say energy utilization has increased a bit.

Re: The strange fate of a person falling into a black hole

#103

Post by gus_massa »

I really don't understand this sentence:

> So Anne takes her bit, A, and puts it through her handy entanglement-decoding machine, which spits out an answer: either B or C.

(Note: I have a Ph.D. in Math and half a major in Physics that include a few quantum mechanics curses (for example, with the Sakurai book))

What is a entanglement-decoding machine? You cant use entanglement to send information. Just repeat after me: You cant use entanglement to send information. This is one of the most common misunderstandings about entanglement.

When you make the measurement and get the collapse, you only get a random value (with a weighted probability). It's not possible to use that to get information about B or C.

Re: The strange fate of a person falling into a black hole

#104

Post by peter303 »

peter303 wrote: post #98

There are minimal tidal forces for very large black hole. You would not be torn apart approaching or crossing the event horizon then. You would be unable to leave or signal out of the hole.

Note the observable universe has an event horizon 13.8B years in time or 92GLY wide in space which we cannot communicate across. Some speculate the observable universe may also have the mass-energy of a black hole with an event horizon of that size. But the observable universe is not a singularity with all the mass-energy concentrated at a infinitely small "center". So in conclusion the observable universe SOME of the characteristics of being inside a black hole, but not all of them.

Re: The strange fate of a person falling into a black hole

#105

Post by pcl »

gus_massa wrote: post #103

I really don't understand this sentence: > So Anne takes her bit, A, and puts it through her handy entanglement-decoding machine, which spits out an answer: either B or C. (Note: I have a Ph.D. in Math and half a major in Physics that include a few quantum mechanics curses (for example, with the Sakurai book)) What is a entanglement-decoding machine? You cant use entanglement to send information. Just repeat after me…

half a major in Physics that include a few quantum mechanics curses

I'm sure you meant "courses" but I like it more the way you wrote it.

Re: The strange fate of a person falling into a black hole

#106

Post by dvdkhlng »

amluto wrote: post #90

I don't think this article is representative of current serious thought about black holes. I'm a bit out of date on this stuff, and I was never any sort of expert, but let's see: 1. This reality splitting thing sounds wrong. I've never heard of it. Ignoring quantum effects, if you fall into a black hole and survive crossing the horizon, Anne will see you get closer and closer to the horizon, but she won't see you get…

I think the "current serious thought about black holes" is about quantum theoretical effects at the event horizon. Seems there are some problems with reconciling quantum entanglement at the horizon with the fact that nothing can return from beyond the event horizon apart from Hawking radiation. This results in the "Firewall Paradox" [1]. One of the proposed resolutions of the paradox is the claim that directly at the event horizon, invisible to outside observers, a kind of ultra-thin particle inferno exists due to the breakdown of entanglement. This would make it effectively impossible to enter any black hole. (I don't really understand any of this, consult wikipedia and the referenced articles for more correct explanations).

[1] https://en.wikipedia.org/wiki/Firewall_%28physics%29

Re: The strange fate of a person falling into a black hole

#107

Post by CookieMon »

monocasa wrote: post #77

So I've had a question about stellar mass black holes that I can't seem to be able to get answered (the question was deleted for /r/askscience). How does a stellar mass black hole actually form a singularity given the fact that there's gravitational time dilation? Wouldn't the heart of a black hole slow down relative to an outside observer as mass is added to it so that you never actually reach infinite density? It s…

I wouldn't think it could matter to an outside observer whether the mass inside an event horizon had converged to a point of infinite density or not, there just needs to be enough mass collapsed to an area small enough to create an event horizon.

If the outside observer were to cross the event horizon to check whether there was a singularity in the middle, they'd approach the same frame of reference, no longer be affected by the time dilation, and find the singularity.

/notaphysicist

Re: The strange fate of a person falling into a black hole

#108

Post by monocasa »

CookieMon wrote: post #107
monocasa wrote: post #77

So I've had a question about stellar mass black holes that I can't seem to be able to get answered (the question was deleted for /r/askscience). How does a stellar mass black hole actually form a singularity given the fact that there's gravitational time dilation? Wouldn't the heart of a black hole slow down relative to an outside observer as mass is added to it so that you never actually reach infinite density? It s…

I wouldn't think it could matter to an outside observer whether the mass inside an event horizon had converged to a point of infinite density or not, there just needs to be enough mass collapsed to an area small enough to create an event horizon. If the outside observer were to cross the event horizon to check whether there was a singularity in the middle, they'd approach the same frame of reference, no longer be aff…

Sure, it doesn't matter really to an outside observer, I just threw that in to hit home the time dilation aspect.

You seem to be assuming a preexisting singularity. My question is how does that singularity get there if the compaction itself that would form the singularity continually pushes the goal post down the line?

Re: The strange fate of a person falling into a black hole

#109

Post by Thrymr »

PuffinBlue wrote: post #43

I always assumed the differing 'views' of what would happen crossing into a black hole was a product of the interplay of the equivalence principle and 'relativity of simultaneity' that Special/General relativity already accounts for. I had thought that upon reaching the event horizon the outside observer sees time 'stand still' because no light from your continued motion the other side of the event horizon can reach…

> Is this line of reasoning incorrect - I'm assuming it is - why?

You're trying to reason about black holes with special relativity, rather than general relativity. Special relativity explicitly ignores acceleration (and equivalently, gravitation). You mention the equivalence principle, which is relevant, but "spacetime curtavure of velocity c" makes no sense, because the curvature leads to acceleration, not velocity directly.

Re: The strange fate of a person falling into a black hole

#110

Post by jerf »

amluto wrote: post #90

I don't think this article is representative of current serious thought about black holes. I'm a bit out of date on this stuff, and I was never any sort of expert, but let's see: 1. This reality splitting thing sounds wrong. I've never heard of it. Ignoring quantum effects, if you fall into a black hole and survive crossing the horizon, Anne will see you get closer and closer to the horizon, but she won't see you get…

"This reality splitting thing sounds wrong. I've never heard of it."

It's a strange scientific truth filtered through at least one scientist filtered through at least one journalist filtered through at least one editor. The reality is stranger... even if there's no firewall, there's still only one reality, with all the observers seeing all the different things.

As for your 2, yes, it is likely there isn't a single black hole in the universe that meets our criteria for being able to "safely" fall into it, but at least in theory such a beast could exist, and barring any other unexpected existence failures, such a beast may exist in the far, far, far future. There's a lot of future and most of it is pretty boring....

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