Hawking Radiation not limited to BHs?, if due to gravitational tidal force

I won't go into great detail but the mechanism behind Hawking Radiation wouldn't seem limited to solely occuring along the threshold of an event horizon for a black hole (the exact location of which is even subjective depending of where the observation of the black hole is made from).

The idea of gravitational tidal forces separating virtual particles in space would apply to non-black hole gravitational sources as well. If you took a mass 1/4th the necessary density to create a black hole but moved twice as close to it, it would no longer be a black hole yet (I believe the scaling is correct, but I assume we'd be working with the second derivative of the gravitational field, and this might make the scaling incorrect but either way - you just move closer until you experience the same tidal force as you would near a black hole) that area of space would be subjected to the same level of tidal gravitational forces as being twice as far away from a black hole of 4 times the mass.

So the point is that these virtual particles, unless specifically tied to the mass of a black hole, wouldn't seem to know the difference between one gravitational field and the other and would be separated by non-black holes in the same manner as Hawking Radiation operates for a black hole. Assuming this is true it would seem that even something as small as a single atom would have some of this effect operating near it also.

Please let me know if I'm missing anything.

The Unruh effect seems to be relevent.

http://en.wikipedia.org/wiki/Unruh_effect

And Casimir force

http://en.wikipedia.org/wiki/Casimir_force

seems to belong in the same basket and is detected.


If you like the Unruh effect then black body radiations starts to get interesting.

http://hyperphysics.phy-astr.gsu.edu/hbase...phodens.html#c1

Once you've read these references you know as much (or more) than I do.

Best wishes,

C2.

Those are great and appropriate links. I admit half of it is like reading a foreign language (for me) but the half that I got the gist of kept me busy with a whole bunch of other ideas ... and that's always the fun part. Thank you.

Hey guys! First post here in quite a long time. Be gentle! Here goes...

IIRC, the "definition" of what makes a dense object a black hole, as opposed to just something really dense and massive, is based on a frame-independent measurement (I think it's a ratio of two radiuses which change proportionately under space deformations). Meaning that, if something is a black hole in one frame, it is a black hole in any other frame. The density may appear to shift as you move relative to it, but never to the extent that the object would suddenly shift from being a black hole to not being one, or vice versa. In short, I'm pretty sure it requires an actual physical change in the massive system in order for it to become a black hole, or stop being one. It's not a completely observational phenomenon.

I believe it is the strange and mysterious nature of thet event horizon boundary, where tidal forces overcome light speed on one side, but not the other, that allows the quantum requirement of energy being "given back" to the vacuum, to be overcome. (And you only get the even horizon with a "true" black hole.) The energy is given back, but not by immediate annihilation. I don't understand the exact mechanism of it, but it's what I have been told by other, more knowledgeable people.

It's definitely true, but I suppose, the true reason of Hawking mechanism is rather the gravitational gradient, which changes the probability of virtual pair recombination across such gradient. Surprisingly enough, such mechanism is pretty close to the recombination mechanism of charge carriers inside the common Light Emitting Diodes (so called "LEDs") in the gradient of so called volume charge field (just electromagnetic, not the gravitational one).



It means, the Hawking radiation should appear at the presence of EACH massive body and particle making it thermodynamically unstable in contact with vacuum, just by the very subtle way. Maybe more interesting is the indicia, such gradient should appear inside the black hole too by such a way, the black holes should radiate from outside to inside! It gives an interesting possibility to measure the Universe size by internal observer from inside just using the wavelength of Hawking radation suppose the Universe is formed by gravastar (i.e. the sort of giant black hole), too.

Unfortunately, the wavelength of such radiation at the case of observable Universe should be large by immeasurable way, too. Well, at least everybody can make sure by such way, the Universe size isn't quite small...

This post has been edited by Zephir on Jun 30 2006, 05:56 PM

Has Hawking radiation ever been detected, or is it simply that because we can't disprove the idea so it must happen?

The theory behind Hawking radiation to me is sound, but is this all that supports it? And as far as looking for it, perhaps aiming to detect the signals from a pulsar in the breaks between the pulses would be an idea.

Hawking radiation is currently completely theoretical. There are various ways of deriving it through. There's .... (/goes to get lecture notes) .... equating the black hole area with temperature since dA = ... gives an equation much like dE = ... in thermodynamics or you can consider a Euclideanised metric and a canonical ensemble partition function with a Green's function.

If such radiation is ever observed Hawking will probably get the Nobel Prize. I doubt it'll be done in his lifetime though.

I'm afraid, despite the theoretical importance of Hawking radiation, from the practical perspective of BH lifetime the Hawking radiation mechanism is solely insignificant. By me the BH are losing it's energy by the number of mechanisms, where the Hawking's one is the most unimportant at all.

But I suppose, the observation observation of proton decay can be considered as some evidence of Hawking mechanism too.

This post has been edited by Zephir on Jun 30 2006, 09:01 PM

If Hawking Radiation isn't only a product of black holes but instead of curvatures in the gravitational field then it might not be necessary to wait for a black, nor would a black hole probably even be the best place to look. I'm certain you could generate much larger gradients at closer distances to smaller masses than a black hole. The event horizon for a black hole is actually rather large in comparison to a neutron star below this threshold.

The gradient, that effectively uses gravity to separate masses and expand space would be the derivative of the gravitational force. Ignoring scaling factors, we have:

g(force) = m/d^2 or m*d^-2

differentiating this over distance and ignoring scaling, we have:

g'(force) = m*d^-3

So the tidal forces increase in effect faster than the gravitational force as you get closer to a mass. I assume this is why Hawking Radiation is greater (not simply relative to the mass but in absolute energy output) for a small black hole. The change in the gravitational field per unit distance is greater very close to a small black hole than it is far from a larger one.

But the same would be true for masses that weren't black holes and you could get much closer to these masses also. So Hawking Radiation, if it exists, is likely visible as some other property near masses that we have probably already encountered, as some of you have already posted. In fact, other than for a very small and rapidly decaying black hole, it would likely be more easily witnessed for ordinary matter than large black holes as the larger tidal forces near the mass wouldn't be obstructed from view by an event horizon.

Yes, this is an interesting idea I was thinking about before. Though this doesn't give a clear explaination for why black holes are assumed to evaporate. At face value this would seem to even provide a source of energy to grow a black hole (though I assume in reality these virtual particles aren't virtual but instead mass from within a black hole that actually does temporarily violate light speed limits due to quantum effects).

This post has been edited by StevenA on Jul 1 2006, 01:37 AM

Any radiation at the event horizon would be zero energy. Light would be infinitely red shifted. This infinity must be addressed.

I am posting out of my league here.. please forgive if wrong..
I absolutely agree with you in principle.
The oddity about an event horizon is that there is (by definition) no way back from the other side of it. Anywhere else there is the probability to repair the virtual particle (pair) anomaly within a short interval of time.
-C2.

Yes, if it came from exactly on the event horizon, but that isn't what Hawking said. The pair production happens just above the horizon.

The only infinity that needs to be addresses if your infinite apathy for actually learning any of this.

By Aether Wave theory the event horizon prohibits just the passing of photons and photon derived hadrons from inside out.
The neutrino leptons and weak force interaction spreading shouldn't influenced by the event horizon at all.

Why does this occur?

Because the event horizon affects just the path of light, forming a total reflection barrier for light spreading. The total reflection depend on the black hole curvature and the wavelength of radiation. The wavelength of gauge bosons is well below 10-18 meters, whereas the light of such wavelength is materialized into hadrons readily. The Aether Wave theory (AWT) supposes, underneath the light event horizon lies another one for gauge bosons.



The gauge bosons and neutrinos can escape from the space in between, because can pass through light event horizon freely. Under normal conditions, the length of gauge bosons free path is pretty low (i.e. no more than 10-15 meter) due to it's instability, but at higher gravitational field they're forming a considerable amount of energy and it's stability increases. As the result, the black hole can lose a considerable amount of its mass in the form of neutrino flux and this is a one of testable predictions of AWT.

You can see an analogy of such phenomena in passing of X-ray through diamond cut. The diamond strongly reflects the visible light due the total reflection, but the X-ray radiation is passing through it like through air due the considerably smaller wavelength.

This post has been edited by Zephir on Jul 1 2006, 10:49 PM