How can gravity bend light when light has no mass???

Question

Thanks for detailed answer...Tom Science 4

Answer 1

Gravity curves spacetime, and light travels in straight lines through space. If space is curved, light will appear to curve as it travels through it.

Answer 2

All of the answers to date are wrong.

The answer is not that light has some mysterious mass, but that your assumption about gravity is wrong. Gravity affects EVERYTHING. Mass, energy, zero rest mass particles - the lot.

It was this realisation that led Einstein to formulate the principle of equivalence (that gravity is indistinguishable from acceleration) and hence general relativity. And the principle of equivalence leads to a description in terms of curved coordinates - which is not quite the same as saying gravity curves space time.

It was a thought experiment that led Einstein to his conclusions. Imagine a tower with equipment at top and bottom that can turn mass into photons and back. You turn some mass into photons at the bottom and shine them to the top, then turn them back to mass. Now if light is not affected by gravity you just got the mass to the top of the tower without doing any work - you gained mgh of energy - and bingo perpetual motion. This is clearly not correct.

Answer 3

Light is traveling the straightest path possible through a distorted space.
Gravity distorts and warps the space around an object - it only indirectly "bends" the light because it is actually the space which is "bent."

Note: You are correct in the fact that light has no "conventional" mass - but don't forget that mass and energy are equivalent - light does indeed have rest mass. Einstein's E=MC2 equation can also be written as C2=E/M, hence the "mass" of light is merely all converted to energy. Photons are said to be "massless" and carry no electric field.

Answer 4

Techically light does have mass, it is both a wave and a particle, depending on how you choose to look at it. As a discrete particle it has infinitessimal mass, thus it would be subject to gravity as a stone thrown into a lake. Light takes a bit of getting used to when thinking about it, but it is well worth the time.

Answer 5

Quantum theory offers us the model that light can be particles, called photons. They travel at the speed of light, but have the property of energy, related to their wavelength. Since they have speed and energy, they can be said to have mass. Thus, they can be deflected by gravity. Photons make sense when you ask how it is that light kicks electrons of photo-emissive surfaces. We have accepted the photon model since Einstein and friends. Now, if you accept all this, is it possible to see what is behind a fat man? Could you line up fat men to make a telescope? The answer is yes, if you could figure out their focal length so you would know where to put them. Scientists love this sort of thing for mid-term exams.

Answer 6

According to the Dual Nature Theory, any particle has some wave character & any wave has some particle character. So, light also has some particle character, although its wave character is much more predominant, just like an elephant would have some wave character, although negligible. That is why, light has some mass, because any particle must have mass associated with it for its existence. That is why gravity can bend light.

Answer 7

A photon is just a single (part particle) wave of magnetic and electric force , No mass there .
Gravity can not bend light by it self .
Space is not a complete vacuum , It contains a small amount of gasses .
The space gasses are thicker near large bodies of mass .
This is why gravity seems to bend light .

(Its that simple no relative space warping particles )

Answer 8

this is a bogus question ' cause light does have some mass