Another Brain Teaser.

[wendigo100]

An interesting paradox.

Nothing can travel faster than the speed of light. Imagine a searchlight beaming up at the clouds. Flick the searchlight and the bright circle whizzes across the clouds. It must be possible to either flick the searchlight fast enough, or move the clouds high enough, to make the spot move FTL.

Hold on, the spot isn't the same bunch of photons moving across the clouds, is it. Therefore, I'd have thought there is no light travelling faster than light.

[EternalOptimist]

Hold on, the spot isn't the same bunch of photons moving across the clouds, is it. Therefore, I'd have thought there is no light travelling faster than light.

Well thats one way of looking at it, its information thats travelling FTL not an actual thingy

[threaded]

But doesn't your mass increase the faster you go? ...an unwanted side effect.

This would explain why it gets very hard to pedal past the 35mph mark!

Nah, that's not so fast, guess either it's mainly a mental limit or your gearings not so good, have a look at my race speeds, I hit 48 mph regular on a MTB, and that's single track dodging trees. On my daily commute I'm quicker, but that's road.

[threaded]

Well thats one way of looking at it, its information thats travelling FTL not an actual thingy

That's actually quite funny. If you knew what you were talking about.

[EternalOptimist]

That's actually quite funny. If you knew what you were talking about.

Well I know what I am talking about, but, as usual, I have no idea what you are talking about

[threaded]

Well I know what I am talking about, but, as usual, I have no idea what you are talking about

That spot of light can carry information (i.e. the light is on), but not faster than the speed of light.

HTH

[TheOmegaMan]

Hold on, the spot isn't the same bunch of photons moving across the clouds, is it. Therefore, I'd have thought there is no light travelling faster than light.

There is no paradox. Imagine photons being emitted from the searchlight. They travel at fast but finite speed so that if the searchlight is moved the photons currently emitted from the light do not hit the cloud where the searchlight is currently pointing.

It is rather like the tracer fire from an AA gun. Both bullets and light have finite speed. Only my mind has infinite speed.

[Sysman]

I never quite understood, what with relativity and stuff, how you define which is the traveller and which is the observer anyway.

But the act of observing affects the results.

Or am I taking a quantum leap here?

[threaded]

But the act of observing affects the results.

Or am I taking a quantum leap here?

Or my favourite, ala the double split experiment, the position of the observer and how do them photons know?

[Paddy]

But doesn't your mass increase the faster you go?

I asked Father O'Leary about that and he says mass should be celebrated standing still.