Mass of a particle , discussion

Dec 2015
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Earth
Can a particle have infinitesimal mass ?
Can a particle be infinitesimally small ?
 

romsek

Math Team
Sep 2015
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We can't know anything about anything on a scale smaller than the Planck length, or Planck energy.

So while what you ask may be possible we can't possibly ever know.
 

topsquark

Math Team
May 2013
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Can a particle have infinitesimal mass ?
Can a particle be infinitesimally small ?
I'm not sure what you mean by an "infinitesimal mass". An electron neutrino has the smallest mass of any particle I know, excepting, of course, massless particles. The electron neutrino has a mass of at most 0.3 eV.

-Dan
 

topsquark

Math Team
May 2013
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1,051
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Is it possible to have m=0 ?
Yes. According to theory neutrinos, photons, and gravitons all have 0 mass. (Of these neutrinos may have a very small mass... No neutrino mass has actually been measured yet. Gravitons haven't yet been observed but the theory of them predicts that they don't.) There is no problem with having a particle with no mass. Sometimes we even approximate an electron to have no mass to simplify the Math when using high energy scales where the electron mass is essentially negligible.

-Dan
 
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mathman

Forum Staff
May 2007
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neutrinos have small (non-zero) rest mass. photons and gravitons have zero rest mass (but they never stop!).
 
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