Why does light travel along a diagonal path in the Michelson-Morley experiment?

[Highwaydude]

Hello, I am newly learning special relativity. I have this particular doubt>

Why is light moving along the hypoteneuse of the triangle while we are moving the apparatus?
(Its not like it has a horizontal component of velocity which is equal to the velocity of the apparatus).

 

[ghwellsjr]

Why do you think you know how light is moving?

If you know, you need to let the rest of us know, because you have information that nobody else has.

 

[Bill_K]

Highwaydude, A light beam aimed vertically in the moving frame will be seen to have a horizontal component in the stationary frame. If if did not, it would fail to hit the mirror.

 

[Highwaydude]

Sorry for replying late.. yes after a bit of thinking I've figured it out, like you said, since the apparatus is moving we are seeing it as if it moves along an angle. :)