Is there any real experimental proof that radiation is massless?

Question

Since photon was identified as massless only by a relativistic mass Einsteinian formula, but what about a real test determination?Was the asumption of massless light a speudoscience?

Answer 1

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LOG ON TO :-

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Linked PDF (experimental)

Phys.Lett. B365 (1996) 178-184

http://arxiv.org/abs/hep-ph/9509415

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A classical field theory is a non-quantum theory in which some physical phenomenom is quantified by a smooth scalar, vector, or tensor field. Classical field theories can be characterized in several ways:

Lorentz covariance: those which are not Lorentz covariant are pretty much ruled out from the beginning, since only Lorentz covariant theories are compatible with str. In particular, Newton's theory of gravitostatics is governed by the Poisson equation
Lap phi = d^2 phi/dx^2 + d^2 phi/dy^2 + d^2 phi/dz^2 = 4 pi rho

(where phi is the gravitational potential, and rho is the density of matter in ``absolute space''), rather than the D'Alembert equation
Box phi = -d^2 phi/dt^2 + d^2 phi/dx^2 + d^2 phi/dy^2 + d^2 phi/dz^2 = 4 pi rho

The Poisson equation is not Lorentz covariant: in Newton's theory, changes in the distribution of matter (rho) in location A result in instantaneous "updates" of the gravitational potential (phi) everywhere in the universe--- something Newton himself recognized to be an unsatisfactory aspect of his theory. The D'Alembert equation on the other hand is Lorentz covariant: changes at location A in rho result in changes in the potential phi which propagate outward at the speed of light.
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(Note: in the convenient and standard relativistic units we will use on this page, G = c = 1.)