And are virtual particles somehow connected to this foam?
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And are virtual particles somehow connected to this foam?
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Thank you Platinum Rhymer for this questions about the space. It is important for me too. There are many clever guys on this Forum and they help us , I hope.
I have some ideas but I am not sure.
This virtual particle is probably an energy sum of the gravitational field and electromagnetic field. It is everywhere in our Observable Universe. Other energy will be a violation of the energy conservation law provided that the energy comes from outside to us (as in Rotating Universe).
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I see, so are is there virtual particles in my house right now? if I look close enough?
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You'd have to look pretty darn closely. :wink:Originally Posted by Platinum Rhymer
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Virtual anything blows my mind. I mean if it's "virtual" then its like pseudo-real. how can something be kind of real or not? I mean it either IS or it ISN'T. If you can only infer that virtual particles exist because if indirect evidence, then it seems to me your looking for something real, you just haven't identified it.
Indirect evidence points to an interaction. How can you interact with something thats not there?
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It goes deeper than that but maybe someone who knows more could explain, I dont think scientists are that dumb...I think its because they last for like not even a millisecond.
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I've known scientists who lasted for 70-80 years.
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Yes.
By their nature, you cannot see them no matter how closely you look.
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Yeah, but if it exists at all, no matter how short of a time, it's not virtualIt goes deeper than that but maybe someone who knows more could explain, I dont think scientists are that dumb...I think its because they last for like not even a millisecond.
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Wow, now I am confused, so they are real...but not really?
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That's why they're called virtual particles.Here's a pretty good introductory discussion of the role they play in quantum theory.
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I see so the virtual particles are basically just the potential particles?That's why they're called virtual particles.
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Calling them virtual does not mean that they are not also in some sense real. They have actual effects you can detect and are in that sense real. They simply behave in a certian way (you cannot directly detect them) and so we give them a particular name "virtual". You can replace the word "virtual" with "quijybo" if you like, its just a name for a classification.
By the way, field theorists also talk about "ghosts" in their Feynman diagrams, but I doubt they think there are spirits floating around in there
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If there is over 102 keV energy , it is possibility to create an electron-positron pair. If there is not a magnetic field enough close (momentum) we have a virtual particle only. There is enough energy but no charge for quark .
Could it be correct ?
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Well said, sabaki. And welcome to the board!
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Wheeler's quantum foam describes spacetime at the Planck length. Due to QM basing itself on zero-dimensional points, the foam is very chaotic (this results in posing a gravity for an intergration with GR) due to the Heisenberg Uncertainty principle. Spactime geometry becomes very uncertain with bubbling pairs of matter and antimatter pairs (short-lived and annihilating each other).
Whether or not things are really so extreme is questionable since Superstring theory by using one-dimensional strings manages to define much less turbulent spacetime for the Planck length (allowing an integration with gravity).
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I don't actually think that it's the zero-dimensional particle size issue that results in virtual particles or that gives us the "chaos" as you describe it. Rather, it's just a result of using an interaction model for the three forces it explains well so far, regardless of the nature of the particles. It is true that having zero size particles is part of what causes problems with unification with gravity (you get infinite values that can't be renormalized when you try to work out the math).
But if string theory turns out to be the solution for uniting gravity with quantum theory, I believe we'd still have an interaction model, so the fundamental forces would still be modeled as virtual particles. Indeeed, we'd add the graviton into the mix, so one might say that it would get even more chaotic.
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The way I understand it, the 1 dimensional nature of strings relies on quantum foam to cancel most of their mass. Strings usually have planck mass, something like the 'weight' of a peice of dust or a flea, which is pretty darned heavy for a elementary particle. The chaos down there cancels out most of the mass leaving either massless or nearly massless particles.
Sounds a little hokey at the moment, but the maths seems to work out. According to the string theorists.
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You gotta squint.
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I might have misunderstood what I read, but my understanding is that GR relies on a smooth fabric for space/time and that QM results in quantum foam at the Planck length, so that the integration of the two results in infininte values. Apparently many physiscists in the past tried to get around the problem of 0 dimensional particles by coming up with other shapes with dimensions, but the math became to complicated. I thought it was the 0 dimensional model for particles, combined with Heisenberg's uncertainty principle that resulted in a chaotic quantum foam.I don't actually think that it's the zero-dimensional particle size issue that results in virtual particles or that gives us the "chaos" as you describe it. Rather, it's just a result of using an interaction model for the three forces it explains well so far, regardless of the nature of the particles. It is true that having zero size particles is part of what causes problems with unification with gravity (you get infinite values that can't be renormalized when you try to work out the math).
But if string theory turns out to be the solution for uniting gravity with quantum theory, I believe we'd still have an interaction model, so the fundamental forces would still be modeled as virtual particles. Indeeed, we'd add the graviton into the mix, so one might say that it would get even more chaotic.
Order of Kilopi
Not really. The infinite values that arise in trying to create an interaction model of gravity is that gravity couples to itself. That is, photons are uncharged, so they don't produce an electric field of their own. But a gravitational field will actually have a gravitational effect of its own, based on its energy. So you effectively get infinite loops when trying to do the calculations. Actually, sometimes you get infinite loops when working with virtual photons, too, but it turns out to be possible to deal with them. The infinite loops for gravity turn out to be harder to handle mathematically.
No. The "quantum foam" arises from the fundamental forces being carried by virtual particles. Take a look at the link I pointed to above if you aren't familiar with Feynman diagrams and how virtual particles are involved in particle interactions. Whether the particles have a finite shape or size won't change whether or not these virtual particles are involved. Having a finite shape and size of the sort proposed by string theorists does however impose some restrictions on the way gravitons could interact, and seems to allow using this kind of model to work with gravity.
For gravity, this is certainly still unfinished (and string theory may even ultimately not work or be contradicted by experiment), but for the electromagnetic, weak, and strong forces, this picture of how things work is supported strongly by experimental agreement with predictions, including some predictions based specifically on the effects these virtual particles should have if they're"really" there.
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So could virtual particles and virtual space-time bubbles be promoted to real ones during the heat death?
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Grey,
I am familiar with the Feynman diagrams, but was always under the impression he had just invented those virtual particles in his diagrams to make things work.
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Um, I suppose, if you want to put it that way. But our views on virtual particles are grounded on Feynman's interaction model. And remember, he put the theory together "just because it works", but once he had done so, physicists determined that if there really were these clouds of virtual particles around carrying forces, then they should have measurable effects of some kind. It is indeed possible to work out some of the expected effects, and when experiments were done to look for them, they agreed very well with predictions.
So that's pretty much standard scientific process. Someone comes up with a theory that models some process, possibly suggesting the existence of something as yet unobserved, and then experiments are done which confirm or deny (confirm in this case) the predictions, lending support that the theory correctly describes the situation.
Order of Kilopi
Virtual particles can't be seen, but they have measurable effects.
But I thought subatomic particles in general, even those that aren't virtual, could only be "seen" indirectly, too. What am I missing? #-o
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A real particle can tear through a cloud chamber, leaving a visible trail. Or hit a phosphor screen and light up a spot briefly. Or hang around indefinitely, perhaps as one of the particles in an atom. A virtual particle can't leave such a direct trace of itself. I suppose in a certain sense those are still indirect methods, but in that sense, doesn't all observation become indirect?
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I got a question, could quantum fluctuations/virtal particles still happen when the universe is in its heat death state?
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I guess I was just nitpicking the use of the term "see". I can see a star in the sky. I can't see an electron, only its effects. But virtual particles produce effects, too...
From what you say, it seems that the distinction betwen real and virtual comes down to the kind of effects that can be produced by each type of particle.
Order of Kilopi
I believe so. "Heat death" just means that everything in the universe has reached thermodynamic equilibrium, so nothing exciting is happening anymore, but that doesn't mean that the laws of physics should suddenly change dramatically.
As to your earlier question, if they could suddenly become real particles under such circumstances, the answer is no, not any more so than they could now. To create a real particle you need to provide energy, so you can't just have one appear out of nowhere.
Order of Kilopi
On second thoughts, those sound like pretty visual signatures, although they are indirect...
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