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The strange fate of a person falling into a black hole

bbc.com

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

#81

Post by logfromblammo »

strictnein wrote: post #62
jetskindo wrote: post #30

What a coincidence that I finish watching interstellar and the minute I check my phone this is the number one post. Maybe I made that happen.

Surprisingly, they only snuck in one Interstellar reference, and it was pretty vague: > "Alright, a l r i g h t, a l r i…" https://www.youtube.com/watch?v=FiTaK3Fyj0k

By my count, there are three.

> What happens here, no one knows. Another universe? Oblivion? The back of a bookcase? It's a mystery.

The back of a bookcase. That might also be a reference.

> Let's start by asking your space companion — we'll call her Anne — who watches in horror as you plunge toward the black hole, while she remains safely outside.

Perhaps the outside observer's last name is Hathaway?

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

#82

Post by jessaustin »

ceejayoz wrote: post #58
tjake wrote: post #57

sounds cool, except before you even got close close to the black hole you would be ripped apart by the tidal forces.

http://en.wikipedia.org/wiki/Spaghettification > The point at which tidal forces destroy an object or kill a person will depend on the black hole's size. For a supermassive black hole, such as those found at a galaxy's center, this point lies within the event horizon, so an astronaut may cross the event horizon without noticing any squashing and pulling, although it remains only a matter of time, as once inside an ev…

That is the best word for a scientific phenomenon, ever.

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

#83

Post by dvdkhlng »

antimagic wrote: post #28
dvdkhlng wrote: post #20

Earlier quoted context omitted.

There aren't any stable orbits within the event horizon of a black hole (due to General Relativity): https://en.wikipedia.org/wiki/Schwarzschild_metric#Orbital_m...

Not so, only one of the two solutions is unstable: https://en.wikipedia.org/wiki/Schwarzschild_geodesics#Circul... Also, this applies only to circular orbits, and does not indicate that a powered ship could not maintain orbit.

BTW most of what I know about black hole physics is from Greg Egan's novel "Incandescence". Which covers quite a lot of science for a work of fiction (and overall extremely inspiring).

http://gregegan.customer.netspace.net.au/INCANDESCENCE/Incan...

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

#84

Post by jessaustin »

PaulHoule wrote: post #48

Talk about the moral decay of theoretical physics... This is just like one of those miller lite ads where somebody smacks a beer bottle on the table and on the TV they see a mix of dog racing and bikini mud wrestling. The trouble is that it is so hard to get established that the field is dominated by old fogies; as a kid in the 80s I was aware of this contradiction but it was censored from the physics literature. Ins…

The trouble is that it is so hard to get established that the field is dominated by old fogies...

That's interesting. Do you think it's better or worse in this respect than other sciences or other academic fields?

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

#85

Post by contravariant »

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…

Indeed you won't ever be able to ever see something fall into it, but when you get down to it that's just because the light will take an infinitely long time to reach you. There are coordinate systems that are able to describe stuff falling past the event horizon in finite time, you just won't be able to see this happening until you fall into it yourself.

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

#86

Post by jessaustin »

ekianjo wrote: post #34
Avalaxy wrote: post #23

Earlier quoted context omitted.

Very interesting if you want some more background is the book 'the science of Interstellar'.

interstellar was more a pile of nonsense than Science.

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.

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

#87

Post by monocasa »

contravariant wrote: post #85
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…

Indeed you won't ever be able to ever see something fall into it, but when you get down to it that's just because the light will take an infinitely long time to reach you. There are coordinate systems that are able to describe stuff falling past the event horizon in finite time, you just won't be able to see this happening until you fall into it yourself.

My question isn't along the lines of how visible it is to an outside observer, it's more of how can a singularity itself form? It seems like you can't reach infinite density in finite time given gravitational time dilation.

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

#88

Post by digsmahler »

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've been wrestling with this same problem, and can't find a satisfying answer. One problem I have with the usual description of a black hole is that the singularity is at the center. But it seems to me that if the escape velocity is the speed of light at the Schwarzschild radius, then the singularity should be there. More of a spherical asymptote than a point mass in the center.

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

#89

Post by digsmahler »

contravariant wrote: post #85
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…

Indeed you won't ever be able to ever see something fall into it, but when you get down to it that's just because the light will take an infinitely long time to reach you. There are coordinate systems that are able to describe stuff falling past the event horizon in finite time, you just won't be able to see this happening until you fall into it yourself.

Are there such coordinate systems that "describe stuff falling bast the event horizon in finite time"? How does that not violate general relativity?

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

#90

Post by amluto »

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 there. She won't see you burnt up and she certainly won't collect your ashes. The only fundamental difference between what you see and what Anne sees is that by the time she gets bored of watching, you will only have perceived a tiny amount of time passing.

2. Free fall doesn't protect you from burnination. If the horizon is surrounded by enough fire and brimstone and you free fall through it, you're still going to burn to a crisp.

3. If I remember my old problem set correctly, a black hole big enough for you to live your life in would be truly huge. IIRC the supermassive black hole at the center of the Milky Way would give you about 0.1 ms before you hit the singularity.

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