The argument is that light has no rest mass but
has mass by virtue of its motion.

But its motion isn't relative. If its mass comes

The argument is that light has no rest mass but
has mass by virtue of its motion.

The argument is that light has no rest mass but
has mass by virtue of its motion.

The argument is that light has no rest mass but
has mass by virtue of its motion.

But its motion isn't relative. If its mass comes
from its kinetic energy or speed then all light
particles would have the same mass.
Not a valid argument you see.
If you are to argue light's relativistic mass
then you must argue it comes from its wave and
would be quantified/measured by its wavelength.

The relativity of the energy of a light wave
though is directional. The Doppler shift on
light can make the wavelength grow(lower energy)
if you are moving away from the light source; or
it can make the wavelength shrink (higher energy)
by moving toward it.

This is only energy. It's not mass.

It is interesting to note that for accelerated
matter relativistic mass goes up regardless of
direction of motion. It is only relative to
speed not direction.

So you can see relativistic mass for light is
a totally different beast than relativistic mass
for matter in motion!

How can the mass of light depend upon direction?
Its nonsense

Light is massless.

The argument is that light has no rest mass but
has mass by virtue of its motion.

The argument is that light has no rest mass but
has mass by virtue of its motion.

But its motion isn't relative.

If its mass comes
from its kinetic energy or speed then all light
particles would have the same mass.

Not a valid argument you see.