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**Physics, Astronomy & Cosmology / What path do photons follow inside a moving box?**

« **on:**29/09/2014 19:05:11 »

I understand that throwing matter from wall to wall inside a moving box, perpendicular to the boxes motion vector, would be exactly the same as throwing matter from wall to wall inside a stationary box (stationary relative to what, anyway??) because all the matter inside would have [whatever velocity it has]+ velocity of the box. But light/photons, if launched from wall to wall, perpendicularly to the motion vector of the box .. hmm?

I started thinking about this and realized I know nothing when thinking about time dilation and how photons are usually animated to take a longer path trough space between, say, two plates moving trough space, making triangles, but, as the photon has a constant velocity and cannot change(in vacuum, of course, sorry), everything else must bend around that fact and thus time dilation is born. Well, at least, that's how it is usually illustrated. Pop-science, eh?

From what I understand, there are two scenarios:

1) the photons "fall" or, at least, bend towards to the bottom of the moving box, if the box is moving fast enough

2) a very, very fast spaceship moving with v=0.9(9)c , starting 1 light year away in x axis and 1 ly away in y axis (sqrt(2) ly in total) shooting a laser pointer perpendicularly to the ground where an observer is standing on (assume the ground is not a planet and is not rotating and is in such a way that it will always be perpendicular) - since the laser pointer is aimed perpendicularly down to the ground, after roughly 1 year the spaceship with its laser pointer will be right above the observer, 0 distance on the x axis, and the observer will see the laser pointers 1 year (roughly) old light for the first time, but it would appear to come from the current position of the spacecraft, not the original 1 ly (x axis) away. (?) But that is not what supposedly happens, is it? In actuality the laser light would be detected one more year later, when the spaceship is (roughly) 1ly past.

I know nothing.

I started thinking about this and realized I know nothing when thinking about time dilation and how photons are usually animated to take a longer path trough space between, say, two plates moving trough space, making triangles, but, as the photon has a constant velocity and cannot change(in vacuum, of course, sorry), everything else must bend around that fact and thus time dilation is born. Well, at least, that's how it is usually illustrated. Pop-science, eh?

From what I understand, there are two scenarios:

1) the photons "fall" or, at least, bend towards to the bottom of the moving box, if the box is moving fast enough

2) a very, very fast spaceship moving with v=0.9(9)c , starting 1 light year away in x axis and 1 ly away in y axis (sqrt(2) ly in total) shooting a laser pointer perpendicularly to the ground where an observer is standing on (assume the ground is not a planet and is not rotating and is in such a way that it will always be perpendicular) - since the laser pointer is aimed perpendicularly down to the ground, after roughly 1 year the spaceship with its laser pointer will be right above the observer, 0 distance on the x axis, and the observer will see the laser pointers 1 year (roughly) old light for the first time, but it would appear to come from the current position of the spacecraft, not the original 1 ly (x axis) away. (?) But that is not what supposedly happens, is it? In actuality the laser light would be detected one more year later, when the spaceship is (roughly) 1ly past.

I know nothing.