Does light continue to travel through space after its source is removed?

[k9b4]

Does light continue to travel through space after its source is removed?

 

[jedishrfu]

yes it does.

 

[Drakkith]

Yep. Electromagnetic radiation is the "far-field" part of the field of a transmitter and continues to propagate even if the transmitter is turned off.

http://en.wikipedia.org/wiki/Electromagnetic_radiation#Near_and_far_fields

 

[Nugatory]

Here's an easy but pretty good analogy: I throw a stone into a quiet pond. The ripples spread out in a circle, and they will keep on propagating long after the stone has sunk to the bottom and is no longer disturbing the surface of the water.

 

[NascentOxygen]

Does light continue to travel through space after its source is removed?

Fortunately for astronomers, it does.

 

[sophiecentaur]

It never looks back.

 

[NascentOxygen]

Yet it does reflect.

 

[sophiecentaur]

Yet it does reflect.

And it gives a wave as it goes past.
:D

 

[NascentOxygen]

and if not going past, it gives a standing wave.

 

[Sharath K Menon]

Yes it does!
so probably, when you are observing a star thousands of lightyears away, you see how it looked thousands of years ago.

That start could be fizzled up, and dead, and you don't even know

 

[thetexan]

In fact you can actually watch this in action. Believe it or not they created a camera that can film pulses of light.

http://www.ted.com/talks/ramesh_ras...es_one_trillion_frames_per_second?language=en

tex

 

[Drakkith]

In fact you can actually watch this in action. Believe it or not they created a camera that can film pulses of light.

http://www.ted.com/talks/ramesh_ras...es_one_trillion_frames_per_second?language=en

tex

Just so there's no confusion, each frame is imaging a separate pulse of light, not the same one.

 

[sophiecentaur]

. . . . the same as the familiar sampling scope technique, which uses picosecond sample pulses to plot the voltage variation in a repeated waveform. Even more than that, he seems to be saying that the process is repeated many times, to achieve a sufficient exposure at each position of the pulse. because the actual energy admitted in a single fs sample is so incredibly low. Fair dooz. It's still pretty clever and produces an interesting insight into the progress of the light through (and also back through) that bottle.