Steven Hawking changes his mind about black holes

[lowpost]

Hawking changes his mind on black holes

The end of the article explains that no comments were given on how to actually -extract- the information. Could anyone comment?

 

[Cawchy87]

wow, that is huge news! Thanks! I can't wait to hear what he has to say about that. He really had me convinced about black holes after reading his book. Also, how can anything escape from infinate gravity? Comments?

 

[DarkSarkas]

Well, just theorizing:

As things get smaller, accelerating them or maintaining their speed requires less energy (less mass and therefore less energy). So, if there is a threshold where the energy of the particle overcomes the energy that gravity asserts on the particle, theoretically it could escape the black hole. These particles would have to be infinitesimal though, and as far as I know there is nothing that has a mass that small. Not even light

 

[Chaotic42]

Wow.

If anyone here can get hold of a copy of any paper or speech, or anything he creates about this, I hope you'll post it here.

This looks huge.

 

[DarkSarkas]

Originally posted by: Chaotic42
Wow.

If anyone here can get hold of a copy of any paper or speech, or anything he creates about this, I hope you'll post it here.

This looks huge.

Seriously. I'm stoked.

 

[Sahakiel]

Originally posted by: Cawchy87
wow, that is huge news! Thanks! I can't wait to hear what he has to say about that. He really had me convinced about black holes after reading his book. Also, how can anything escape from infinate gravity? Comments?

I have heard that in physics, anytime you come up with infinity in an equation, you need a new theory.

 

[cquark]

Originally posted by: DarkSarkas
As things get smaller, accelerating them or maintaining their speed requires less energy (less mass and therefore less energy). So, if there is a threshold where the energy of the particle overcomes the energy that gravity asserts on the particle, theoretically it could escape the black hole. These particles would have to be infinitesimal though, and as far as I know there is nothing that has a mass that small. Not even light

Light has zero mass, so it's small enough, but there are two problems with your idea:

1. The speed of light is the maximum speed a particle can attain, no matter how much energy you put into it. Increasing energy doesn't change the speed of light, but rather changes the frequency of the light through the relation E = h v, where h is Planck's constant, v is frequency, and E is energy.
2. Gravity affects energy as well as mass, so while increasing energy increases speed of massive particles through the relation E = m c^2 (1-v^2/c^2)^(-1/2), it also increases the gravitational attraction of the object to the source of the field at a faster rate. Of course, for massless particles, higher energy means the same speed but a higher gravitational attraction.

wow, that is huge news! Thanks! I can't wait to hear what he has to say about that. He really had me convinced about black holes after reading his book. Also, how can anything escape from infinate gravity? Comments?

You don't need to have infinite gravity to have a black hole. You only need to have a sufficiently large gravitational field such that the escape velocity from the object is greater than the speed of light, c. The event horizon of a black hole is the boundary between two volumes of space: an inside region where the escape velocity is higher than c, and an outside region where it is less than c.

Hawking's new idea argues that there's only an apparent event horizon, but not a real one. He hasn't presented the paper yet and I haven't read enough from other papers to understand how an apparent event horizon differs from a real one yet.

 

[gigapet]

holy crap!

i dont know what any of this means. especially in terms of how it will change my comfort level or standard of living.

 

[Cogman]

Hey look everyone, He talks on my birthday (July 21). Excuss my ignorance, But what is the practical Application (if any) of been able to read what went in a black hole? I mean I dont think we will be able to get close enough to one in our lifetimes to actually study one and see what went it and whats going in.

 

[cquark]

Originally posted by: Cogman
Hey look everyone, He talks on my birthday (July 21). Excuss my ignorance, But what is the practical Application (if any) of been able to read what went in a black hole? I mean I dont think we will be able to get close enough to one in our lifetimes to actually study one and see what went it and whats going in.

Certain variants of string theory allow production of black holes in particle accelerators at not much higher energies than we can produce now. I don't think they're likely to be right, but we won't know until we do the experiments.

I'm not sure if there are any applications of reading information from a black hole, but dropping objects into the gravitational well of a black hole is the most efficient means of energy production we know, as they radiate away energy equivalent to over half their rest mass during the fall (the energy radiated is extracted from the hole itself), while matter-antimatter reactions are only about 10% efficient.

 

[DarkSarkas]

Originally posted by: cquark


Light has zero mass, so it's small enough, but there are two problems with your idea:

1. The speed of light is the maximum speed a particle can attain, no matter how much energy you put into it. Increasing energy doesn't change the speed of light, but rather changes the frequency of the light through the relation E = h v, where h is Planck's constant, v is frequency, and E is energy.
2. Gravity affects energy as well as mass, so while increasing energy increases speed of massive particles through the relation E = m c^2 (1-v^2/c^2)^(-1/2), it also increases the gravitational attraction of the object to the source of the field at a faster rate. Of course, for massless particles, higher energy means the same speed but a higher gravitational attraction.

As far as I know, light does have an effective mass, but no "rest mass" (it can never be at rest). I believe the effective mass of light would be it's kinetic energy divided by c^2, although assuming it had no mass this would give it absolutely no kinetic energy and therefore no movement potential. Correct me if I'm wrong, as I probably am, because I'm going off of a years-old understanding of physics and an understanding of string theory that is amateur at best. Photons can "fall," as it were, into a gravity well. But this could be explained by the relation between energy and matter, assuming you're correct, and because the gravity (or black hole, as it has the only known powerful enough gravity well to do so) would have to be strong enough to require an escape velocity equal to or greater than the speed of light. That's a powerful gravimetric field.

Assuming that we have absolutely no hope of ever breaking the light-speed barrier, this would the be end all of our ability to understand black holes, because the chances that we will ever actually be able to observe one in close enough proximity to really understand much of this would be greatly diminished. I believe a greater understanding of the relationship between time, energy and matter will bring many improvements to our ability to... do cool stuff

It will be interesting to see exactly what Hawking is proposing, and how he will explain the existence of an "apparent" black hole. Something leads me to believe that he's going to explain that the black hole itself, and its event horizon, do not really exist in our dimension, I suppose, and that gravity is applied across the barrier between the dimensions. Actually, I have no idea what he's going to say and I'm just theorizing. It will be interesting to say the least.

 

[Ogg]

:Q

 

[cquark]

Originally posted by: DarkSarkas
As far as I know, light does have an effective mass, but no "rest mass" (it can never be at rest). I believe the effective mass of light would be it's kinetic energy divided by c^2, although assuming it had no mass this would give it absolutely no kinetic energy and therefore no movement potential.

What you're describing is the "relativistic mass" of a photon, an idea which we discourage because people think they can drop that relativistic mass into Newton's second law, F=ma, or Newton's law of gravity, F=Gm1m2/r^2, which you can't as Newton predates special relativity by a few centuries. Newton's equations use rest mass, not relativistic mass.

In general relativity, the analog of mass is the 4-dimensional energy-momentum vector. The equations are no longer in terms of scalars like mass and distance, but are written in terms of vectors and tensors. You can explain a photon being attracted to a massive object like a star in terms of the star's energy-momentum vector coupling to the photon's energy-momentum vector instead of talking about mass.

It will be interesting to see exactly what Hawking is proposing, and how he will explain the existence of an "apparent" black hole. Something leads me to believe that he's going to explain that the black hole itself, and its event horizon, do not really exist in our dimension, I suppose, and that gravity is applied across the barrier between the dimensions. Actually, I have no idea what he's going to say and I'm just theorizing. It will be interesting to say the least.

Some types of hypothesized dark matter are effectively outside our universe, with the exception that they interact gravitationally with normal types of matter, and string theory has to hide its extra dimensions to explain our normal 4-dimensional universe, so there are plenty of odd theoretical tricks available. I'm a bit more concrete, so I want at least a potential way to test his theory before I'll accept it. We don't need more ideas like string theory, which isn't even wrong.

 

[Cawchy87]

Originally posted by: DarkSarkas

Originally posted by: cquark


Light has zero mass, so it's small enough, but there are two problems with your idea:

1. The speed of light is the maximum speed a particle can attain, no matter how much energy you put into it. Increasing energy doesn't change the speed of light, but rather changes the frequency of the light through the relation E = h v, where h is Planck's constant, v is frequency, and E is energy.
2. Gravity affects energy as well as mass, so while increasing energy increases speed of massive particles through the relation E = m c^2 (1-v^2/c^2)^(-1/2), it also increases the gravitational attraction of the object to the source of the field at a faster rate. Of course, for massless particles, higher energy means the same speed but a higher gravitational attraction.

As far as I know, light does have an effective mass, but no "rest mass" (it can never be at rest). I believe the effective mass of light would be it's kinetic energy divided by c^2, although assuming it had no mass this would give it absolutely no kinetic energy and therefore no movement potential. Correct me if I'm wrong, as I probably am, because I'm going off of a years-old understanding of physics and an understanding of string theory that is amateur at best. Photons can "fall," as it were, into a gravity well. But this could be explained by the relation between energy and matter, assuming you're correct, and because the gravity (or black hole, as it has the only known powerful enough gravity well to do so) would have to be strong enough to require an escape velocity equal to or greater than the speed of light. That's a powerful gravimetric field.

Assuming that we have absolutely no hope of ever breaking the light-speed barrier, this would the be end all of our ability to understand black holes, because the chances that we will ever actually be able to observe one in close enough proximity to really understand much of this would be greatly diminished. I believe a greater understanding of the relationship between time, energy and matter will bring many improvements to our ability to... do cool stuff

It will be interesting to see exactly what Hawking is proposing, and how he will explain the existence of an "apparent" black hole. Something leads me to believe that he's going to explain that the black hole itself, and its event horizon, do not really exist in our dimension, I suppose, and that gravity is applied across the barrier between the dimensions. Actually, I have no idea what he's going to say and I'm just theorizing. It will be interesting to say the least.

There was an interesting article in pop sci a few months ago about the possiblity of 10 dimensions, i'll have to dig it up and see if i has any relivance to this topic.

 

[DarkSarkas]

Ah. It appears that you have a much more thorough understanding of physics than I do, which isn't surprising because I've only really had a year of it so far... heh, 6 or 7 to go.

I'm not sure that I agree with you entirely about needing to have a way to really test a theory before it is introduced. String theory itself is going to be difficult to prove in its entirety, just like the theory or relativity was not actually proved until years after its inception. I guess I like to believe that's really the nature of theoretical physics.

What do you do for a living, if I might ask?

 

[cquark]

Originally posted by: DarkSarkas
Ah. It appears that you have a much more thorough understanding of physics than I do, which isn't surprising because I've only really had a year of it so far... heh, 6 or 7 to go.

I'm not sure that I agree with you entirely about needing to have a way to really test a theory before it is introduced. String theory itself is going to be difficult to prove in its entirety, just like the theory or relativity was not actually proved until years after its inception. I guess I like to believe that's really the nature of theoretical physics.

What do you do for a living, if I might ask?

Actually, I know physics despite what I do for a living, not because of it, as I, like most people with PhDs in theoretical physics, don't work in physics. If you are interested in getting a PhD in physics, which it sounds like from the 6-7 years to go above, be prepared to work in another field. I discovered in the course of my PhD that I enjoyed computer science more than physics, so I'm happier being out of physics, especially as I'm not sure that theoretical physics is going anywhere with the lack of new particle accelerators. From what I see today, astronomy or astrophysics is the growing field, with lots of new expeirmental results to explain.

 

[cquark]

The NYT has a story on Hawking's talk, but it doesn't provide a lot of detail. It sounds like we'll have to wait for his paper on the subject to come out later this summer.

 

[Jeff7]

Originally posted by: cquark

Originally posted by: Cogman
Hey look everyone, He talks on my birthday (July 21). Excuss my ignorance, But what is the practical Application (if any) of been able to read what went in a black hole? I mean I dont think we will be able to get close enough to one in our lifetimes to actually study one and see what went it and whats going in.

Certain variants of string theory allow production of black holes in particle accelerators at not much higher energies than we can produce now. I don't think they're likely to be right, but we won't know until we do the experiments.

I'm not sure if there are any applications of reading information from a black hole, but dropping objects into the gravitational well of a black hole is the most efficient means of energy production we know, as they radiate away energy equivalent to over half their rest mass during the fall (the energy radiated is extracted from the hole itself), while matter-antimatter reactions are only about 10% efficient.

Romulan Warp Core - uses a micro singularity to generate power. Be awesome if we could manage something like that. Mr. Fusion might not be such a bad idea. Nothing like fusing matter into a singularity to squish every last bit of energy out of it. Of course, if you wind up sucking the entire planet into it, that creates other problems.

 

[glugglug]

The new theory contradicts John Titor, because if information about what went in the black hole can be determined from the radiation, this means that going in doesn't actually send you to an alternate universe or "worldline".

 

[gsellis]

Originally posted by: Jeff7
Romulan Warp Core - uses a micro singularity to generate power. Be awesome if we could manage something like that. Mr. Fusion might not be such a bad idea. Nothing like fusing matter into a singularity to squish every last bit of energy out of it. Of course, if you wind up sucking the entire planet into it, that creates other problems.

Only problem with this sf idea is that there would be insufficient gravity to hold it together. If it held together, the ship would definitely be inside the event horizon.

I am glad SH finally figured this out. This is just one of those "well, duh" things. There is not magic or romance in approaching a black hole or singularity. You just make it a infintisimally bit bigger. It is still there, otherwise it would not generate the gravity well it does. I love the one about time stretching to infinity as you reach the event horizon too. No, this is Zeno's Paradox part... I lost count. You will hit bottom, face it. You will not know you hit bottom as there will be a point where you get 'mangled' on the way down. But it will be below the event horizon. The event horizon would just be the apogee for the particles that did not make it out alive Rule one, if you see the light at a black hole, it is too late.

 

[unipidity]

You will never get to the centre of a singularity. *shrug* Certainly not in anyone elses frame of reference.

I beleive that the jist of this is that the event horizon is not perfectly round/spherical but is somewhat warped. Im not sure if this is due to quantum foam, or just some random postulate. Hence information that is in a black hole could come out if the event horizon shifts inwards locally. Maybe? I really havnt read this stuff well enough, but its a guess.

I dont think it has much to do with M theory.

 

[Cawchy87]

There was a short segment on this on CNN. The physics corispondent from the Lou Dubbs show explained it like this:

"If you put an apple into a blender and chop it up you get apple sauce. Now if you try to take a bit of that out you are taking out some of the apple, but you have no idea what part of the apple it is. This is much like what happens in a black hole. Matter goes into the black hole, gets "chopped up" and then comes out in very tiny bits called hawking radiation. Advanced mathmatical calculations that Mr. Hawking was able to proform could acctully trace the path that matter takes as it enters and exits a black hole. However, what acctully goes on inside the black hole is still a mystery."

Thats all i could remember, oviously those aren't those exact words, but something close to that. (sorry that i am bad at spelling)

 

[DrPizza]

I can't wait to hear more about this.

And to add to whoever posted it above, IIRC, they expect to be creating a black hole every month or so when they start colliding protons and anti-protons in (2006?) I can't remember when it's supposed to be done.