Quantum foam.
24 November 2007, 02:44 PM
#2
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As far as I can see, quantum foam is just another euphemism for something we don't really understand all that well. Other examples are dark matter, dark energy, the quantum foam is happening on the scale of the Planck length 10^-35 meters. Basically, this has to do with the vacuum not really being empty (see Heisenburg uncertainty principle). There is experimental and theoretical evidence that there is a non zero background energy. At the Planck length, their are supposedly particle/antiparticle pairs being created and destroyed on a frequent basis. This is hypothesized as being a natural quantum phenomenon.
The term quantum foam comes from a description of what one might see if it were possible to actually look at a patch of "empty space" on the scale of the Planck length. One would see a "sea of roiling seething particle interactions". The visual I keep coming up with in my mind whenever I read such descriptions is of a pot of boiling water. Where these particles keep bubbling up to the surface and then suddenly disperse releasing their load of energy.
As far as theoretical proof, I think this result has been a widely accepted result of quantum electrodynamics (QED) for some time now. On the experimental side, the Casimir effect (an attractive force felt between two very closely spaced objects) is thought to be caused by an energy imbalance due to the exclusion of certain frequencies of photons between the two objects.
Now the whole issue about wormholes being part of the quantum foam is somewhat more speculative. This is what happens when you try to get quantum mechanics and relativity to work together in regimes that neither was originally intended. As I understand it though, the energy required to open a wormhole (theoretically of course) is proportional to the size of the wormhole (energy requirements actually growing exponentially with size). So, with this seemingly abundant energy on so small a scale, I guess there have been some people who have determined that sufficient energy exists to open Planck-scale wormholes (not that they would do anybody any good). I don't know that anything has been said about the mechanism which would actually pry open the wormhole, but that may just be oversight on my part.
You have to understand that all this hypothesizing and theorizing is just an extrapolation of physical models which were originally devloped in completely different regimes. These models have been experimentally verified in their original regimes, so there is confidence in these models' accuracy, but only in the neighbourhood of the domain in which they were formulated. The physics of the universe on the Planck scale is extremely far away from the domain of relevance for relativity, and is even somewhat out of range of the quantum mechanical phenomena that we actually have good experimental evidence for. Like Einstein did for Newton, there will likely be some corrections to the existing theories which will explain the behaviour of the Planck scale universe, but not until we start obtaining experimental evidence which directly challenges the predictions of existing theories.
Until then, there is still plenty of good sci-fi material in quantum foam and singularities. If I were to write such sci-fi, the first application I can think of for a Planck scale wormhole would be for communications purposes. Instantaneous communication over great distances is the one premise I would need for any number of cool space exploration stories.
If you need any further explanation I'll be glad to help
The term quantum foam comes from a description of what one might see if it were possible to actually look at a patch of "empty space" on the scale of the Planck length. One would see a "sea of roiling seething particle interactions". The visual I keep coming up with in my mind whenever I read such descriptions is of a pot of boiling water. Where these particles keep bubbling up to the surface and then suddenly disperse releasing their load of energy.
As far as theoretical proof, I think this result has been a widely accepted result of quantum electrodynamics (QED) for some time now. On the experimental side, the Casimir effect (an attractive force felt between two very closely spaced objects) is thought to be caused by an energy imbalance due to the exclusion of certain frequencies of photons between the two objects.
Now the whole issue about wormholes being part of the quantum foam is somewhat more speculative. This is what happens when you try to get quantum mechanics and relativity to work together in regimes that neither was originally intended. As I understand it though, the energy required to open a wormhole (theoretically of course) is proportional to the size of the wormhole (energy requirements actually growing exponentially with size). So, with this seemingly abundant energy on so small a scale, I guess there have been some people who have determined that sufficient energy exists to open Planck-scale wormholes (not that they would do anybody any good). I don't know that anything has been said about the mechanism which would actually pry open the wormhole, but that may just be oversight on my part.
You have to understand that all this hypothesizing and theorizing is just an extrapolation of physical models which were originally devloped in completely different regimes. These models have been experimentally verified in their original regimes, so there is confidence in these models' accuracy, but only in the neighbourhood of the domain in which they were formulated. The physics of the universe on the Planck scale is extremely far away from the domain of relevance for relativity, and is even somewhat out of range of the quantum mechanical phenomena that we actually have good experimental evidence for. Like Einstein did for Newton, there will likely be some corrections to the existing theories which will explain the behaviour of the Planck scale universe, but not until we start obtaining experimental evidence which directly challenges the predictions of existing theories.
Until then, there is still plenty of good sci-fi material in quantum foam and singularities. If I were to write such sci-fi, the first application I can think of for a Planck scale wormhole would be for communications purposes. Instantaneous communication over great distances is the one premise I would need for any number of cool space exploration stories.
If you need any further explanation I'll be glad to help
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24 November 2007, 04:56 PM
#10
Cheers DCI that was one hell of an explanation. I managed to just about assimilate enough information to have a slightly better understanding now. One thing still bugging me is how much physical matter is crammed into the singularity? I understand it is all this physical matter that is being turned into quantum foam but how much of it is there in a given area?
24 November 2007, 04:56 PM
#11
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Try and use a source with correct spelling next time
Last edited by David Lock; 24 November 2007 at 04:59 PM.
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