Thread: Window spying and Special Relativity

Apologies again if this is an obvious question but that is where I am .....

Anyway after ingesting a few animations , some online lectures and derivations it has occurred to me that a way of directly experiencing the time dilation effect of Special Relativity would be if one was to attempt to eavesdrop on a window pane as I have heard say is the fashion in CIA (et al) circles of late.(you know how they can listen to conversations by sending a laser beam to a window of a building with a conversation going on inside)

So if a laser beam was directed to the window of a passing train or even a subsonic (I suppose) plane would the conversations that were picked up directly( ie in an analogue manner ) sound slowed down to the eavesdropping listener?

Likewise if a telescope on the ground able to directly view the inside of the Space Station in good enough detail (looking in through the window) would the occupants appear to be moving slowly(apart from the fact that they were floating I mean)? If one of them blinked would it be measurably slower than his normal blink.


As I say this may seem obvious but it would be reassuring to me if I knew it was the case as it would make the whole thing seem very "real" .

By the way . for the purposes of Special/General Relativity is the Space Station accelerating wrt the observer who is directly beneath?If it is accelerating then does GR have to be employed in this case?

Not gonna work:

Any speeds we can achieve result in negligible effects: for example the space station Mir has an orbital velocity of about 7700 metres per second = 0.0000257 times the speed of light, yielding a time dilation factor of 1.00000000033.
After a full YEAR the cosmonaut's watch will be 3.8 seconds behind an earthbound timepiece.

thanks for your speedy (ironically) reply.

Yes I had in my head a value for c of +/-180,000 ft/sec and was thinking of posting something to the effect that the speed of light was actually amazingly slow considering the size of the universe (I think that is probably still the case but it is clearly a good bit faster than I thought!)

After checking I see i t is 186,000 miles per second.

I will just have to put a bit more work into the theory!

Anyone who ever writes something in ft or miles should be hanged, drawn and quartered.

All processes in a moving system evolve at a slower rate, so you would indeed observe things like people blinking happening in slower motion.

It's interesting though because in a moving spaceship, events are more advanced at the rear, since light emitted from the center of the ship will strike it first before hitting the front. They both end up back in the center at the same time though because they both make the same round trip. What makes the motion appear slower is that this round trip is a longer one than if the ship were at rest.