[a.nikhil]

when light enters black hole,is it converted into matter[mass]
i've read that energy exists all over the universe and when it is denser it is called matter.

i mean does it become as dense as matter or does it become as dense as the black hole itself or nothing happens?

[csmyth3025]

a.nikhil, on 7 September 2011 - 02:28 PM, said:

when light enters black hole,is it converted into matter[mass]
I've read that energy exists all over the universe and when it is denser it is called matter.

i mean does it become as dense as matter or does it become as dense as the black hole itself or nothing happens?

About the only thing known with any confidence about light (or anything else) crossing the event horizon of a black hole is that it will end up in the center where there is a "singularity". This is a point in space where the gravity is so great that we don't have any equations to describe the conditions there. It's not likely that light is converted into matter at this point because matter itself collapses into something we don't know how to describe except to say that it's a singularity.

In a way, you're right that when energy is denser, it's called matter. The details aren't so simple, though. You can find a simplified explanation in the Wikipedia article "Matter Creation", here:
http://en.wikipedia....Matter_creation

Chris

[questionposter]

csmyth3025, on 8 September 2011 - 05:28 AM, said:

About the only thing known with any confidence about light (or anything else) crossing the event horizon of a black hole is that it will end up in the center where there is a "singularity". This is a point in space where the gravity is so great that we don't have any equations to describe the conditions there. It's not likely that light is converted into matter at this point because matter itself collapses into something we don't know how to describe except to say that it's a singularity.

In a way, you're right that when energy is denser, it's called matter. The details aren't so simple, though. You can find a simplified explanation in the Wikipedia article "Matter Creation", here:
http://en.wikipedia....Matter_creation

Chris

Wait, but the light moves to a really low energy potential, so it would get red-shifted a lot, and since matter is quantized, wouldn't a singularity not be able to absorb it unless it did in fact become matter? Maybe in the future there can be a test to see if the event horizon of a mini-black hole increases as you shine gamma-rays into it. A singularity isn't even normal matter, how could it interact with light as to just "absorb" it?

This post has been edited by questionposter: 9 September 2011 - 12:20 AM

[csmyth3025]

questionposter, on 9 September 2011 - 12:19 AM, said:

Wait, but the light moves to a really low energy potential, so it would get red-shifted a lot, and since matter is quantized, wouldn't a singularity not be able to absorb it unless it did in fact become matter? Maybe in the future there can be a test to see if the event horizon of a mini-black hole increases as you shine gamma-rays into it. A singularity isn't even normal matter, how could it interact with light as to just "absorb" it?

First, matter can absorb light:

Quote

Electrons can absorb energy from photons when irradiated, but they usually follow an "all or nothing" principle. All of the energy from one photon must be absorbed and used to liberate one electron from atomic binding, or else the energy is re-emitted. If the photon energy is absorbed, some of the energy liberates the electron from the atom, and the rest contributes to the electron's kinetic energy as a free particle.

(ref. http://en.wikipedia....ssion_mechanism )

Second, light moving toward a source of gravity is blue-shifted, not red-shifted.

Third, by definition the event horizon of a black hole marks the "point of no return" for anything that crosses inside - this includes light as well as matter.

Fourth, since matter and energy are essentially two aspects of the same "thing" (think E=mc²), if you shine gamma rays into a black hole the radius of the event horizon will, indeed, increase (the black hole will gain mass). Physicists are keen to conduct exactly the sort of controlled experiment you propose.

Chris

[ajb]

csmyth3025, on 9 September 2011 - 03:51 AM, said:

Fourth, since matter and energy are essentially two aspects of the same "thing" (think E=mc²), if you shine gamma rays into a black hole the radius of the event horizon will, indeed, increase (the black hole will gain mass).

Mass and energy are quite complicated things in general relativity, but for the case of black holes you are indeed correct. The space-times that describe black holes are asymptotically flat and so we can apply more or less the ideas from special relativity when it comes to mass and energy. More complicated space-times things will be much harder.

[questionposter]

csmyth3025, on 9 September 2011 - 03:51 AM, said:

First, matter can absorb light:


(ref. http://en.wikipedia....ssion_mechanism )

Second, light moving toward a source of gravity is blue-shifted, not red-shifted.

Third, by definition the event horizon of a black hole marks the "point of no return" for anything that crosses inside - this includes light as well as matter.

Fourth, since matter and energy are essentially two aspects of the same "thing" (think E=mc²), if you shine gamma rays into a black hole the radius of the event horizon will, indeed, increase (the black hole will gain mass). Physicists are keen to conduct exactly the sort of controlled experiment you propose.

Chris

So going into a lower gravity potential gives a photon more potential energy even though matter going into a lower gravitational potential has less potential energy?
Also, are you saying energy can distort the fabric of space itself?
And wait, wtf, did you not think that I thought normal matter absorbs light even though it can reflect it and not absorb it as well? And did you also think I didn't know the event horizon is where the gravitational well becomes so steep that light cannot escape it? Otherwise idk why you commented on those.

This post has been edited by questionposter: 9 September 2011 - 12:44 PM

[csmyth3025]

questionposter, on 9 September 2011 - 12:42 PM, said:

So going into a lower gravity potential gives a photon more potential energy even though matter going into a lower gravitational potential has less potential energy?
Also, are you saying energy can distort the fabric of space itself?
And wait, wtf, did you not think that I thought normal matter absorbs light even though it can reflect it and not absorb it as well? And did you also think I didn't know the event horizon is where the gravitational well becomes so steep that light cannot escape it? Otherwise idk why you commented on those.

As a photon, or a baseball, falls deeper into the gravitational well of a massive body it will lose (gravitational) potential energy and gain kinetic energy.

Yes, I'm saying that energy can distort space-time (it's called the energy-stress-momentum tensor)

As to the rest, I apologize if I misunderstood your post.

Chris

[Big Nerd]

anybody know why all the THES are highlighted.

im real confused about black holes. matter cant be created or destroyed. no matter what, it will exist as matter or gases or watever. but if blackholes make evertything disappear, where does the stuff go? and also, its not possible to count pla=nets or black holes. the universe goes on and on AND ON. but it cant end. there is no nothing in this world.

matter cant absorb light. light is light. it cannt just disapper. the light has to go somewhere. unless, things really can disappear

[Schrödinger's hat]

Big Nerd, on 24 September 2011 - 01:12 AM, said:

anybody know why all the THES are highlighted.

im real confused about black holes. matter cant be created or destroyed. no matter what, it will exist as matter or gases or watever. but if blackholes make evertything disappear, where does the stuff go? and also, its not possible to count pla=nets or black holes. the universe goes on and on AND ON. but it cant end. there is no nothing in this world.

Well it becomes part of the black hole.

Quote

matter cant absorb light. light is light. it cannt just disapper. the light has to go somewhere. unless, things really can disappear

Every time light hits something it gets absorbed and turned into other forms.
It just carries spin and some energy-momentum. These things are conserved but the light itself is not. Examples of this are the sunlight hitting your arm, it gets wam (absorbs the energy) and if you had very very sensitive instruments you'd feel it pushing ever so slightly. If it was circularly polarized light (all with the same spin) you'd also feel it twisting even more subtly.

[Genius13]

in the inflation model gravity works the other way around and works like a energy that compels matter to floute away from eachouther..
so why doesnt this hapen in black holes??

[MigL]

The inflation model makes use of pressure as the driving force behind the 'negative' gravity, but not in the way you would think.

We all know pressure is a form of energy and so, a compressed spring will weigh a miniscule amount more than a relaxed spring. In effect this pressure contributes to the stress-energy tensor, increases the local space-time curvature and increases the gravitational force felt in its vicinity. We can then assume the opposite to be also true. If the pressure is decreased so is the stress-energy tensor, the space-time curvature and the gravitational force. In fact, if it is decreased enough, it actually can become negative and we would have repulsive gravity.

In the inflationary model the energy of the vacuum falls to a non-zero state, before slowly dropping from this false state to the real zero energy state. It is while the universe is hung up in this false zero energy state that it can be shown to have a negative pressure, and through the method outlined above, this negative pressure overcomes the gravitational attraction and results in repulsive gravitation. This leads to the inflationary period, where for the brief time that it takes for the universe to fall from the false, non-zero vacuum energy to the real zero level energy, the universe is believed to have expanded by 10^30 to 10^100 in size.

[IM Egdall]

Rollin78, on 2 November 2011 - 07:11 AM, said:

Regarding Einstein, he statedthat gravity can cause space and time to bend. Massive objects can cause thecurvature to become visible.

Per Einstein's general relativity, gravity does not cause space and time to bend -- gravity IS the bending of space and time. Or more properly, gravity is spacetime curvature.

And mass/ernergy is the source or cause of gravity, of spacetime curvature. More properly mass/energy and its movement (momentum) are the source of spacetime curvature.

This post has been edited by IM Egdall: 4 November 2011 - 10:44 PM

[superball]

IM Egdall, on 4 November 2011 - 10:44 PM, said:

Per Einstein's general relativity, gravity does not cause space and time to bend -- gravity IS the bending of space and time. Or more properly, gravity is spacetime curvature.

And mass/ernergy is the source or cause of gravity, of spacetime curvature. More properly mass/energy and its movement (momentum) are the source of spacetime curvature.

cherry pie, that certainly is the best answer.

cheers.

IM Egdall, on 4 November 2011 - 10:44 PM, said:

Per Einstein's general relativity, gravity does not cause space and time to bend -- gravity IS the bending of space and time. Or more properly, gravity is spacetime curvature.

And mass/ernergy is the source or cause of gravity, of spacetime curvature. More properly mass/energy and its movement (momentum) are the source of spacetime curvature.

cherry pie, that certainly is a great answer.

cheers.