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byron178
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Don't virtual particles time travel backwards?
Why would they?byron178 said:Don't virtual particles time travel backwards?
Well first of all Isaac Asimov certainly was not a "heavy-weight" of physics, he wasn't even a physicist.
maverick_starstrider said:Virtual particles are a calculational tool, not reality, they're a way we can mathematically get the answer we want to arbitrary accuracy, they're not new physics.
byron178 said:Don't virtual particles time travel backwards?
maverick_starstrider said:Well first of all Isaac Asimov certainly was not a "heavy-weight" of physics, he wasn't even a physicist. He was a bio-chemist and a science fiction writer. Also, virtual particles are not needed to explain the Casimir effect. Essentially the issue is something like this. ...
...Virtual particles are a calculational tool, not reality, they're a way we can mathematically get the answer we want to arbitrary accuracy, they're not new physics.
Lapidus said:Wilczek, t'Hooft, Randall, Kane certainly are.
danR said:Yes, my point was that Randall hardly differed from Asimov in the surface form of her popularized argument. I know very well Asimov was a popularizer. In his day most would not have called him a scientist, even a biochemical scientist.
I have the feeling that the above experts would know a thing or two about the 'math-artifact' arguments, and would be able to counter them. If they have countered them in print, then some research is in order by critics to pull some of that print into physics forums and disassemble them.
tiny-tim said:virtual particles are talked about only in perturbation theory
"a particle that does not obey E2 - p2.c2 = m2.c4 for a time allowed by the energy-time uncertainty relation" is just science fiction writing, much like "a spaceship that goes faster than light", or "Heisenberg compensators" … you can't just string words together, you need to be able to insert the idea into a theory
tiny-tim said:hi byron178!
i think you're thinking of anti-matter …
eg an electron going forward in time behaves exactly the same as a positron going backward in time, both in Feynman diagrams and in the equations
(and a creation operator for an electron behaves like an annihilation operator for a positron, and vice versa)
byron178 said:Does that mean they really travel backwards?i was asking if they can travel backwards in time because they can travel faster than light,they become space-like.
byron178 said:Does that mean they really travel backwards?i was asking if they can travel backwards in time because they can travel faster than light,they become space-like.
byron178 said:Does that mean they really travel backwards?i was asking if they can travel backwards in time because they can travel faster than light,they become space-like.
tiny-tim said:no, anti-matter travels slower than light, just like matter (but, as i said, it behaves like matter at the same speed but going backwards in time)
also, motion faster than light (in other words, space-like motion) would not involve going backward in time …
this is a science fiction error, caused by saying that since time dilation of √(1 - (v/c)2) goes from 1 to 0 as v approaches c, that means it must become negative if v > c … and that obviously isn't true!
tiny-tim said:no, anti-matter travels slower than light, just like matter (but, as i said, it behaves like matter at the same speed but going backwards in time)
also, motion faster than light (in other words, space-like motion) would not involve going backward in time …
this is a science fiction error, caused by saying that since time dilation of √(1 - (v/c)2) goes from 1 to 0 as v approaches c, that means it must become negative if v > c … and that obviously isn't true!
byron178 said:there is this article i found that say's they do time travel backwards in time. http://www.desy.de/user/projects/Physics/Quantum/virtual_particles.html
byron178 said:there is this article i found that say's they do time travel backwards in time. http://www.desy.de/user/projects/Physics/Quantum/virtual_particles.html
Lapidus said:Check out science fiction by Leonard Susskind, starting around min 43 till around min 74.
Lapidus said:I think, he is very clear that it is an interpretational issue.
tiny-tim said:but that has nothing to do with moving faster than light …
it's just the example i mentioned earlier, of an anti-particle behaving like a particle going backward in time (in this case, a photon, which of course is its own anti-particle)
byron178 said:but they don't really travel backwards in time,right?
tiny-tim said:right!
byron178 said:are you guys arguing as to if virtual particles exist? i keep reading different respones and have read different articles one by gordon kane where he claims they are real. http://www.scientificamerican.com/article.cfm?id=are-virtual-particles-rea
tiny-tim said:so that an energetic enough photon can knock the W out, leaving the neutron, and someone asks him (around 1:03) whether that means the W was already there, and he replies
"your mental picture that whatever comes out of a system was in there beforehand is a little bit defective!"
tiny-tim said:the only unequivocal thing he says is (at the very start) that "virtual particles are mathematical constructs"
maxverywell said:But it means that before you knock out the W, there was "something" and that "something" somehow become a real W boson. This "something" is actually what we call virtual W and it's a matter of how you define things in physics.
I think he means that virtual particles are described by mathematics (at the way they are described in perturbation theory).
maxverywell said:But it means that before you knock out the W, there was "something" and that "something" somehow become a real W boson. This "something" is actually what we call virtual W and it's a matter of how you define things in physics.
Polyrhythmic said:That's not what he said. At first he states that it is a mathematical construct. Later he goes on to explain that even if it was really there, it wouldn't be detectable because we couldn't distinguish the detection from the creation of an actual virtual particle.
byron178 said:So even if they were real we would not be able to detect them?
maverick_starstrider said:By definition. However, I'm afraid we've high-jacked the thread from you. You'll never really be able to get a handle on what the issue we're discussing is without actually knowing physics. SciAm and science popularizer books essentially throw out damn near everything important to relate things in an "intuitive" analogy with the real world.
As for the rest of you guys, I'd re-iterate that feynman diagrams (and thus a virtual particle picture of QFT) MISS certain physics. I don't see how this doesn't seal the issue. We have an integral, we want to perform a functional integration on it. We can't, so we move to a perturbation approach, from this comes the calculational TOOL of virtual particles. Because we're working perturbatively we miss certain things (which essentially means such things are unexplainable via virtual particles). From this we conclude that virtual particles are real physics?! Where do we go next? When we don't know the ground state of the system so we try a trial wave-function parameterized by some variable lambda (i.e. a variational approach) and we minimize with respect to lambda and call the lowest state the ground-state. We then find out that our ground-state wasn't of the form we guessed but we were kind of close. From this you're saying we conclude that our variational lambda is a REAL degree of freedom of the system? If I have 3 apples do I really have 6 apples plus 3 negative-apples?
maverick_starstrider said:BTW, If you want to talk about heavy-hitters and there opinions here's a lecture I was just watching by Anthony Zee (of "Quantum Field Theory in a Nutshell" fame)
http://v.youku.com/v_show/id_XMTE0OTI4Nzg0.html
Check around the 45 minute mark. He goes on to talk about how the concept of Feynman Diagrams (i.e. virtual particles) "shackled" the study of QFT for quite some time. it wasn't until people like t'Hooft pointed out that there exist phenomena (such as magnetic monopoles) that CANNOT be described through the perturbative framework that virtual particles represent, that QFT began to free itself from the "shackles of Feynman Diagrams". Putting words in his mouth a bit he's basically saying that not only are these perturbation not real things but for a 30 year stretch or so they were blinding people to the real physics by taking these things too seriously.
byron178 said:that's ok,what i want to know is when something travels faster than light will it start traveling backwards in time?will it travel for example today to yesterday?
byron178 said:does quantum entanglement allow information to travel faster than light? http://en.wikipedia.org/wiki/Faster-than-light scroll down to quantum mechanics
maverick_starstrider said:As for the rest of you guys, I'd re-iterate that feynman diagrams (and thus a virtual particle picture of QFT) MISS certain physics. I don't see how this doesn't seal the issue. We have an integral, we want to perform a functional integration on it. We can't, so we move to a perturbation approach, from this comes the calculational TOOL of virtual particles. Because we're working perturbatively we miss certain things (which essentially means such things are unexplainable via virtual particles). From this we conclude that virtual particles are real physics?! Where do we go next? When we don't know the ground state of the system so we try a trial wave-function parameterized by some variable lambda (i.e. a variational approach) and we minimize with respect to lambda and call the lowest state the ground-state. We then find out that our ground-state wasn't of the form we guessed but we were kind of close. From this you're saying we conclude that our variational lambda is a REAL degree of freedom of the system? If I have 3 apples do I really have 6 apples plus 3 negative-apples?
Born2bwire said:No, it does not.
byron178 said:ive been reading on this forum that virtual particles flat out don't exist?then why is it said they exist for a certain amount of time?