Are they connected somehow?
Or is quantum foam just describing what quantum fluctuations in the Planck scale looks like...its "foamy"?
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Are they connected somehow?
Or is quantum foam just describing what quantum fluctuations in the Planck scale looks like...its "foamy"?
Order of Kilopi
The second is my understanding.Originally Posted by Platinum Rhymer
Order of Kilopi
I am adding this so as not to have to edit my prior message:
However, quantum foam is drastically reduced in SuperString theory, since the elementary particles are no longer 0-dimensional points, but 1-dimensional strings.
IMHO: quantum foam is just a mathematical quirk due to the limitations of the standard model and is not to be taken literally.
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I'd disagree with this statement. Can you explain why you think this would be the case, or provide a link suggesting that string theorists actually support this point of view?
To some extent, I suppose one could consider all subatomic particles to have a certain hypotheticalness, but I tend to think that when the models describe what we do observe well, that's usually a sign that we've gotten something right. I'd like to point out that the theory which predicts the existence of virtual particles (QED) makes very specific predictions about some of the effects these virtual particles should have. These predictions are borne out by experiment, to quite a few decimal places. It's possible, of course, that some other theory could explain these effects in some other way, but I'd say that such excellent experimental results lend a lot of credence to the idea that such virtual particles are real.
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As to your first question, this is covered in Briane Greene's latest book, "The Fabric of the Cosomos". for example, in the chapter "Jitters and their discontent", page 333ff.I'd disagree with this statement. Can you explain why you think this would be the case, or provide a link suggesting that string theorists actually support this point of view?
To some extent, I suppose one could consider all subatomic particles to have a certain hypotheticalness, but I tend to think that when the models describe what we do observe well, that's usually a sign that we've gotten something right. I'd like to point out that the theory which predicts the existence of virtual particles (QED) makes very specific predictions about some of the effects these virtual particles should have. These predictions are borne out by experiment, to quite a few decimal places. It's possible, of course, that some other theory could explain these effects in some other way, but I'd say that such excellent experimental results lend a lot of credence to the idea that such virtual particles are real.
As far as your second question is concerned, I never said paritcles do not exist, I just maintain that 0-dimensional particles are mathematical constructs, and IMHO do not exist. Particles certainly exist, but what their form is, who knows.
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So since virtual particles/quantum fluctuations are proven to exist...does the quantum foam exist?
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We will never manage to prove that quantum foam exists, the Planck length is much too small. According to Briane Greene, it is the postulated existance of this quantum foam which causes GR problems. SuperString theory manages to unite GR and QM by smoothing out the quantum foam, since GR needs a smooth space structure.
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I see, so amongst the scientists is the theory of quantum foam popular?
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I'd say, it depends what model they believe in. Those who are still skeptical of M-theory will believe in quantum foam.
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So if they believe in M-Theory they likely wont believe in quantum foam?, is M-Theory against quantum foam or something?
Order of Kilopi
M-theory smoothes out the quantum foam. This is the only way to accomodate GR.
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Sorry I didn't respond to this earlier.
I haven't had a chance to read this, but Greene's work is usually good. I'll take a look next time I'm at the library.
Well, what you said was that quantum foam is just a mathematical construct, not that zero dimensional particles were, and you still seem to be implying that from your later comments. Quantum foam is just a description of the sea of virtual particles, and doesn't depend on whether they're mathematical points, or strings in 11 dimensions, or something weirder still.
I still think this is misleading at best. If by "smoothes out" you just mean "more mathematically tractable", then that's true. But if you're implying that there are fewer virtual particles popping into existence, then I think you're mistaken. Even under M theory, there are still scads of virtual particles (technically, infinitely many!) involved in any given interaction, it's just that those particles are string-like rather than point-like, which solves some of the renormalization issues. If you feel like virtual particles are just a mathematical trick, it's hard for me to imagine not thinking the same thing about string theory.
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My understanding is that if you model fundamental paricles to be 0-dimensional points, when you get down the Planck length, space becomes extremely turbulent.
Since GR needs smooth space, this cause difficulties in reconciling GR with QM in these extreme conditions.
Greene mentions that since the 1930's, physicists have been looking for alternative mathematical structures on which to base fundamental particles. 1 dimensional strings appartently cause space at the Planck length to be smoother, alowing an integration between GR and QM.
IMHO we are not there yet, since strings are also idealized constructs, especially if they are modelled as being 1 dimensional.
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No, I think foam and fluctuations are different. Foam is the shape of spacetime itself when you get down near the Planck length. The foam is more like the medium that gives rise to the virtual particle quantum fluctuations. Apologies to Einstein, but when spacetime gets really small, it is just not smooth and continuous. Efforts to theoretically (or mathematically) "smooth it out" may produce good estimates, but I think it is GR that will have be modified to meet QM at least half way, else the resulting unified theory will only be based on an estimation of reality rather than on reality itself.The second is my understanding.
Everyone is entitled to his own opinion, but not his own facts.
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In Greene's The Fabric of the Cosmos; Space, Time, and the Texture of Reality [2004], he speaks of the "Higgs ocean," which may be intimately related to these issues.
Everyone is entitled to his own opinion, but not his own facts.
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Isn't this a chicken and egg situation? I thought that the massive virtual particle quantum fluctuations at the Planck length cause a chaotic space fabric?No, I think foam and fluctuations are different. Foam is the shape of spacetime itself when you get down near the Planck length. The foam is more like the medium that gives rise to the virtual particle quantum fluctuations. Apologies to Einstein, but when spacetime gets really small, it is just not smooth and continuous. Efforts to theoretically (or mathematically) "smooth it out" may produce good estimates, but I think it is GR that will have be modified to meet QM at least half way, else the resulting unified theory will only be based on an estimation of reality rather than on reality itself.The second is my understanding.
edited to add: due to gravitational warping of space
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I don't know, but I like your new sig pic.
Everyone is entitled to his own opinion, but not his own facts.
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Thanks. It was inspired by yours. Mine is one of my many paintings of big cats I have made.
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So who is right, Cougar or gzhpcu? or are you both wrong lol
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If you read Brian Greene's book, under the heading "Why Does String Theory Work?":
He goes on to say that the wild frenzy at the Planck length arises from applying the uncertainty principle to the gravitational field, on smaller and smaller scales the fluctations in the gravitational field get larger and larger. The uncontrollable quantum fluctuations arise only when we consider quantum uncertainty on distances shorter than the Planck length. This occurs if the theory is based on zero-sized point particles, but in string theory (since the strings are of Planck length), you can not go smaller than the Planck length. There is still quantum foam, but it is mild compared to a point-based theory, and thereby allows GR and QM to be united.The main new feature of string theory is that it basic ingredient is not a point particle - a dot of no size - but instead an object that has spatial extent. This difference is the key to string theory's success in merging gravity and quantum mechanics.
So, I would say Cougar is right: there is a quantum foam, but not nearly as chaotic a quantum foam under superstring theory at the Planck length.
edited to include: red text
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So foam and fluctuations are different?
So if quantum foam is thought to give rise to virtual particles and virtual particles effect has been proven already...does that mean quantum foam is real, it exists? or is just a theory?
Order of Kilopi
How about this, Quantum Foam is word used for the shape of space, at scales less than the Planck lentgh. The probability of each shape is determined by the fluctuations within that space.
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And we cant prove it exist because we cant see that small, even with today's tech...??
Order of Kilopi
We're talking about the geometry of essentially nothingness that has any meaning at all only at roughly 20 orders of magnitude less than "today's tech" can muster. Count to a billion, then count to a billion again a billion times, and it's still smaller than 1 part out of that whole. And then what do you expect to "see"? It ain't gonna be an ultra-small version of Gillette Foamy shaving cream.
Everyone is entitled to his own opinion, but not his own facts.
Order of Kilopi
To be clear: Quantum foam is a distortion of space due to gravitational effects. The cause is the quantum fluctuation caused by applying the uncertainty principle to small spaces which allows for frenzied virtual particles to appear/disappear.
Order of Kilopi
That is a lot more elegant than the way I put it. =D>
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