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I have read this in scientific American: According to quantum field theory, all particles spend a little time as combinations of all other particles"

Is this right? How long? And how can they be a combination of all other particles at once? Do they transform?

Answer in laymans terms if possible

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Lee, whether it was you or someone messing with your account that kind of abusive attitude won't be tolerated here. I rolled back the edit since the original question was perfectly fine. To the downvoters: nobody feed the troll. –  Michael Brown May 22 '13 at 12:45
    
Please don't say it happened again, my fb and gmail was hacked and all sorts of abuse sent everywhere. What was said? –  Lee May 22 '13 at 12:55
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@Lee, click on the "edited [x] mins ago" link just above the "Michael Brown" link. –  Alfred Centauri May 22 '13 at 12:59
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The answer is sort of yes, in a technical sort of way, but not really. :) The concept the article is refering to is "virtual particles." If you use that search term you'll find plenty on this site and elsewhere on the web. The question here is closely related, and the article by Matt Strassler is a great exposition for layman. I think he does a good job cutting through some common confusions. –  Michael Brown May 22 '13 at 13:21
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@Lee and you can ask Prof. Strassler questions too, he answers very nicely and patiently. His site is mainly devoted to explain particle physics to laypeople, whereas Physics SE is rather for learning physics at a technical level. –  Dilaton May 22 '13 at 13:25
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1 Answer 1

A particle is just an excitation in some quantum field. These fields permeate all space and are coupled to each other. As one of these excitations evolves in time, it can take any number of paths. The probability amplitude for a particle to be at some location after some amount of time is the sum of all the possible paths the particle could have taken to get there, weighted by a factor which makes out of the way paths less likely.

Because the fields that the particles are made of are coupled to each other, some of these paths "go through" another type of field and thus another type of particle. For example, one possible path for a photon has it split into an electron and a positron that then recombine into a photon. An electron can emit a photon, that photon can become a bunch of quarks, the quarks can recombine into the photon and the photon can then recombine with the electron. In this sense, any particle is made up of all particles as it moves through time.

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