why does the mass of light not increase when it travells at a speed of light in vaccum,as accor. to einstein?

Answer 1

The relativity laws to which you refer only apply to objects that have "rest mass". These objects can be slowed and their intrinsic mass measured. Anything that travels at c (such as a photon) will ALWAYS travel at c and hence can never be "at rest" with respect to any frame of reference, therefore it can have no rest mass, and relativistic mass increase does not apply.

Answer 2

Were all things consistent, it would appear that your question should be valid. It is possible for electromagnetic energy to form into mass, and it is thought that as a mass increases its speed it increases its mass, so why should it seem unusual for a person to think that electromagnetic energy should be only of a single value? 1. It isn't. as the energy of electromagnetic energy changes frequency, its potential mass value also changes. 2. A mistake was made in thinking that moving mass gained greater mass - it does not. The overall frequency of the mass converts toward becoming a single frequency at the expense of energy (hf) at right angles to direction of travel.

There is a easy to read paper, "The Problem and Repair of Relativity" found at http://360.yahoo.com/noddarc. clock on "blog" then on "list view" and scroll down.

Answer 3

Because light has no mass, as far as anyone knows. All known massless particles travel at the speed of light. All known massive particles travel more slowly

Answer 4

Einstein equation was for particles, and holds good for particle theory.

Light is considered as wave theory and is massless