radio waves

[claymore]

When a radio signal is sent to a space probe bound for the outer planets of the solar system, that signal leaves Earth at the speed of light until it reaches its destination. My question is.....does this signal have any force that it imparts to the probe? however minute it might be. You would think that something arriving on your doorstep at the speed of light would have some kind of impact.

[4candles]

No, it's an electromagnetic wave, possessing no force or mass.

[claymore]

What does an electromagnetic wave consist of 4c, massless particles?

[fo3nix]

Yes, it does have some force. However, it's small enough to neglect in the vast majority of situation.

Electromagnetic waves consist of particles called photons. They're massless.

[4candles]

Yes, cm, like light, heat, or any other wavelength of electromagnetic radiation, radio waves comprise massless particles.

[jake-the-peg]

Sorry 4c you're stuck in the 19th Century there.

Despite being massless Photons carry momentum and can exert a force.

http://dev.physicslab.org/Document.aspx?doctyp e=3&filename=AtomicNuclear_ComptonEffect.xml

This is the principle behind a solar sail
http://en.wikipedia.org/wiki/Light_sail

[4candles]

I stand corrected Jake - thanks for the enlightenment. But that's the joy of AB - you don't 'alf learn a lot!

<Goes into corner with pointy hat marked 'D'>

[mibn2cweus]

Crookes Radiometer