Light cannot escape a black holes gravity?

[SunnyD]

Light doesn't cease to move. Gravity can end up distorting space-time, in a black hole to such an extent as to be a nearly infinite singularity. If light has to travel infinite space (even within a singularity), then it doesn't matter how fast it goes, it would never escape. Basically, within a black hole, there is so much space-time for the light to traverse that it will just about never get out. It never slows down though.

Better yet, there is the possibility that light can indeed pass through a black hole. However, in doing so, the distortion of space-time distorts and stretches out the wavelength of the light so much that it no longer has any wavelength at all, and thus no detectable properties.

 

[Coalfax]

I think the better question, that would answer the black hole problem the best, is if light is a particle or a wave.

There have been experiments that make it one, and then others that make it another. Particles can be influenced easily with a gravity well or large mass. Waves.. that's something different entirely.

 

[silverpig]

Originally posted by: jjsole

Originally posted by: SagaLore

Originally posted by: MTDEW
If the speed of light is constant, whether on earth or in space.
Wouldnt that mean the speed of light is not effected by gravity, since it travels the same speed in earths gravity as it does in space.

Has it ever even been PROVEN that light is even effected by gravity?
Or better yet, that gravity can actually stop light?
Or is it all just theory?

I know most of whats known of black holes is mostly theory, but the thought that even light cannot escape a black holes gravity has always had me skeptical, since we were always taught the speed of light was constant.

Its constant relative to spacetime. Gravity is not a "force", but rather curvature of space. Following this curve stretches time.

And this curvature is cause by...?

(mass?)

In the equations curvature is induced by something called a stress-energy tensor. The gist of it is mass or energy can curve spacetime.

 

[silverpig]

Originally posted by: GodlessAstronomer
Gravity is the curvature of spacetime. Light travels on a geodesic through spacetime at a constant speed, but if that geodesic is bent due to gravity then light will appear to bend instead of travelling straight. If the gravity is so intense that the curvature becomes (effectively) infinite, then there is no straight geodesic on which the light can travel to escape.

Eh, I'd say that the curvature becomes greater than 1 (most GR people use c = 1 units, so a photon's worldline (light cone) has a slope of 1).

 

[Fritzo]

I'm pretty well versed in astrophysics. To understand how a black hole works, you have to be able to visualize how gravity affects space. To do this, picture a trampoline. Put a bowling ball in the center and it will make a large dimple in the fabric. This is what happens to space when mass is present- it distorts the fabric of space.

If you were to roll a marble around the dimple and keep it's speed constant (moving fast enough to stay away from the bowling ball), it would "orbit" the bowling ball. The marble's velocity counteracts the slope of the dimple.

With a black hole, you have the mass of 10's to 1000's of suns squeezed into an object the size of the earth or smaller. This would be like a bowling ball so massive that the fabric of the trampoline hits the ground, goes through the earth, and never ends. Light needs a medium to travel through- space. If there's a dimple in the fabric of space with a slope so steep that the escape velocity is faster than light, guess what happens to the light?

Black holes are actually pretty well understood. What happens AFTER entering a black hole is not so clear.

 

[SunnyD]

Originally posted by: Coalfax
I think the better question, that would answer the black hole problem the best, is if light is a particle or a wave.

There have been experiments that make it one, and then others that make it another. Particles can be influenced easily with a gravity well or large mass. Waves.. that's something different entirely.

Light is both. A photon is a particle that travels in and exhibits wave-like properties. However photons have no mass, thus can not directly be affected by gravity. It is indirectly affected by gravity due to the distortion of space-time that is a property of gravity.

 

[Arkaign]

OP : one of the more recent developments that changes what was conventionally understood about light previously : http://www.news.harvard.edu/ga...1.24/01-stoplight.html

 

[Miramonti]

Originally posted by: Arkaign
OP : one of the more recent developments that changes what was conventionally understood about light previously : http://www.news.harvard.edu/ga...1.24/01-stoplight.html

They did it by passing a beam of light through a small cloud of atoms cooled to temperatures a billion times colder than those in the spaces between stars. The atom cloud was suspended magnetically in a chamber pumped down to a vacuum 100 trillion times lower than the pressure of air in the room where you are reading this.

'Kids do not try this at home.'

 

[SSSnail]

So, does a black hole ever gets filled?

 

[Fritzo]

Originally posted by: SSSnail
So, does a black hole ever gets filled?

This is what's cool- nobody knows what happens to matter once it goes over the event horizon. It might get spewed out of a white hole in an anti-universe, it may get turned into an undiscovered form of matter, it might just clump together to a infinitely dense ball of matter...we may never know.

 

[SunnyD]

Originally posted by: SSSnail
So, does a black hole ever gets filled?

If it did, how could it possibly evaporate? (They do that you know)

 

[Arkaign]

Originally posted by: SSSnail
So, does a black hole ever gets filled?

I think that would tend to violate the conventional understanding of 'infinite density' and the singularity. String theory tends to account for this very possibility though.

 

[RESmonkey]

Originally posted by: GodlessAstronomer

Originally posted by: StevenYoo
You some kind of astronomer or something?

Nah I'm just a poser I spent 2 years studying astrophysics at university before reality kicked me in the face and I decided to change majors to a field where I might be able to get a job at the end. Astrophysics is a subject I'm deeply passionate about and I intend on returning to finish a degree in it one day.

That's why I'm double majoring. EE and Physics

 

[KK]

Originally posted by: SSSnail
So, does a black hole ever gets filled?

Yes

 

[Fritzo]

Originally posted by: Kalmah

Originally posted by: polarmystery

Originally posted by: edro

Originally posted by: MTDEW
Has it ever even been PROVEN that light is even effected by gravity?

Einstein and Eddington's famous eclipse experiment proves it.
An Article
A photo

I was going to post this...

Me too.

Also, astronomers use a technique called gravitational lensing that allows us to see distant objects because their light is bent around massive objects, making the distant object seem larger and brighter. If light wasn't affected by gravity, this technique would not work.

 

[Fritzo]

Originally posted by: KK

Originally posted by: SSSnail
So, does a black hole ever gets filled?

Yes

LOL!!!!!!! 15/10 stars!!!!!

 

[PlasmaBomb]

Originally posted by: TridenTBoy3555
Highly Technical forum

We have one.

Noob.

 

[PlasmaBomb]

Originally posted by: SSSnail
So, does a black hole ever gets filled?

No they just get larger and hungrier...

kinda like Americans

 

[MTDEW]

Wow, this turned into an incredibly educational thread while i was at work.
Never underestimate the knowledge of fellow anandtech members.

So if Black Holes are pretty much understood, then has it been explained why there is one in the center of each Galaxy? (once again im just going off of what i saw on the Science Channel)
I assume they played a key role in each Galaxy's formation?

 

[Jeff7]

Originally posted by: MTDEW
Wow, this turned into an incredibly educational thread while i was at work.
Never underestimate the knowledge of fellow anandtech members.

So if Black Holes are pretty much understood, then has it been explained why there is one in the center of each Galaxy? (once again im just going off of what i saw on the Science Channel)
I assume they played a key role in each Galaxy's formation?

Seems to make sense - you've got places in the early Universe that were more dense, so they attracted lots of matter toward them. That matter was able to form stars, and you wind up with galaxies of stuff orbiting a massive object, massive enough to be termed a black hole.
Kind of like if you had a bath tub with a thin layer of bubble bath foam on it. If the tub had multiple drains, tiny whirlpools would form over them, and the bubbles would gather around in swirling masses.

And on the Insane end of the galactic spectrum are quasars. What happens when a black hole tries to get "full"? It just gets bigger, and gets a bigger appetite.

 

[The Boston Dangler]

black holes are among my most hated things, ever.

 

[Born2bwire]

Originally posted by: The Boston Dangler
black holes are among my most hated things, ever.

Even more than Jefferson Starship?

 

[MTDEW]

Originally posted by: Born2bwire

Originally posted by: The Boston Dangler
black holes are among my most hated things, ever.

Even more than Jefferson Starship?

Hey, its better than a Brown Hole. :roll:
Try to stay on topic...LOL

 

[Born2bwire]

Originally posted by: MTDEW

Originally posted by: Born2bwire

Originally posted by: The Boston Dangler
black holes are among my most hated things, ever.

Even more than Jefferson Starship?

Hey, its better than a Brown Hole. :roll:
Try to stay on topic...LOL

Nothing's Gonna Stop Us Now, we are on topic, I just want to gauge Boston's theories on the relative suckiness of various things.

 

[GodlessAstronomer]

To answer a couple of questions:
Black holes don't fill up, although recent research suggests that there is a maximum mass for black holes (a mere 10,000,000,000 solar masses). The most widely accepted hypothesis for this upper limit is that radiation from the black hole evaporation pushes back against matter that is falling towards the black hole.

I think black holes are more of a consequence of galactic formation than they are a key role. Galactic neuclii tend to be very dense by their very nature. The super massive black holes that make up galactic centers don't look much like what most people expect a black hole to look like. The density of super massive black holes can be very low - the average density of the milky way's central black hole is probably less than that of the air you're breathing. If you fell past a super massive black hole's event horizon it's likely that you wouldn't notice for quite some time - the tidal forces are very low, so you wouldn't be "spagettified" like most people expect from a black hole.