2007-12-12 04:04:28 · 5 answers · asked by Narok 1 in Science & Mathematics ➔ Physics
Classically, no. However, people have long speculated about whether or not photons have a very minscule mass. You can look up the Proca paper and references to it for more details. The current upper limit for the mass (it has to weigh less than this if it has mass) is about 10^(-60) grams.
2007-12-12 04:08:19 · answer #1 · answered by eri 7 · 0⤊ 2⤋
Maybe not in the classical standard model sense, but it certainly has energy E = hf = hc/L; where h is Planck's constant, f is light frequency, c is light speed and L is wavelength and Lf = c. And where there is energy, there is momentum = p; in fact pc = hf = E. Thus, p = hf/c and in the classical sense p = mc = hf/c; so that m = hf/c^2, which is a sort of virtual mass for a photon.
This is a virtual mass because from m = m0/sqrt(1 - (v/c)^2) we have p =[m0/sqrt(1 - (v/c)^2)]c so if this were a real mass m would be infinite when v = c. And, clearly, the mass of a photon is not infinite; so it is not a real so-called inertial mass that would approach infinity at light speed.
Bottom line, light has momenta, which requires a mass in the classical model, but the mass is virtual because it can and does reach light speed without expanding to infinity.
2007-12-12 04:44:07 · answer #2 · answered by oldprof 7 · 0⤊ 0⤋
The answer is that photons DO have momentum (they also have angular momentum), but they do NOT have mass.
As stated in another answer, physicists and theorists are speculating whether photons may have an extremely small mass, but this is still conjecture at this point.
How can a photon have momentum but no mass - since we are taught that momentum equals mass times velocity? Well that's just the way photons seem to be. You might as well as why a photon can appear as both a wave and a particle. It does, and it is, but that we struggle to grasp the idea.
It is one of the features of physics, and the universe: our earth-born intuition and experience does not help us much in having a "feel" for how things at ultra high velocities or ultra small sizes operate.
2007-12-12 04:34:13 · answer #3 · answered by Anonymous · 0⤊ 0⤋
The official answer is no; however, photons, which light is made of, are particles... so maybe there is some mass there, but definitely not much.
2007-12-12 04:12:27 · answer #4 · answered by tuberk768 5 · 0⤊ 1⤋
i think, since light travels at a speed, light is made up of packets of somthin i forgot
2007-12-12 04:07:20 · answer #5 · answered by Anonymous · 1⤊ 4⤋