If light has no Mass,. how can a Photonic Thruster be considered for space exploration?

Question

Amplified Light ,. such as high powered lasers do, exhibit physical properties akin to "Mass Particles". hmm how can something that has no mass be a candidate for future space rocket propulsion?.

Answer 1

Photons don't have mass, but they do have momentum. That momentum is calculated by assigning a mass-equivalent value, or relativistic mass, to their energy, according to E=MC^2.

It's this value that figures into the propulsion equations, allowing for conservation of momentum.

Answer 2

It has no mass while it is moving, but it has energy. This energy gives an inertial thrust when light hits something and stops moving. We refer to it as 'light pressure'.

A parallel example would be how magnetism also is a massless force, yet is able to 'move' material things by transferring energy. In fact, at a deep level this happens by an exchange of photons too.

Answer 3

Peter got it correct....Because light has momentum.

The amount is referred to as the Poyting vector.

The amount of momentum, P, is found simply by taking the cross product of the magnetic field intensity, B, and the elecrtric field, E, of the light wave.

P = B X E

So yes, light has momentum, and the emission of light from a spacecraft imparts a back reaction that propells the craft.

Answer 4

Light has momentum but no mass. There is a curious way in which light can be said to contribute mass even though it has no mass.

Answer 5

Here is a link to a site that explains the obstacles that had to be overcome.

Answer 6

no rest mass, but it has energy, which is equivalent to mass