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Can someone explain this to me (science question)
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Atticus Fynch
#1 - 2011-12-27 22:56:44 UTC
I'm watching a TV prog on Solar Sails used as a means of propulsion for spacecraft. Basically, light is pushing a huge sail through space.

My question is, if photons have no mass, how can they push anything?

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Indahmawar Fazmarai
#2 - 2011-12-27 23:18:59 UTC
Atticus Fynch wrote:
I'm watching a TV prog on Solar Sails used as a means of propulsion for spacecraft. Basically, light is pushing a huge sail through space.

My question is, if photons have no mass, how can they push anything?


Photons don't have mass, but their energy is a kind of mass (m=e/c^2) and so it haves momentum. The effect of that momentum on matter is called "radiation pressure".

Now the funny thing with solar sails, is that they can move a ship both away from the sun or towards the sun.
Selinate
#3 - 2011-12-27 23:27:10 UTC
When in doubt, try wikipedia.

Photons

Scroll down to physical properties. The only incorrect part of that page that I can find from what I'm looking at is that photons *can* spontaneously "decay" to a positron and electron, but they have to be somewhat high energy photons and I guess I'm not sure if "decay" is the right word for that reaction.

Ah well.
Surfin's PlunderBunny
Sebiestor Tribe
Minmatar Republic
#4 - 2011-12-28 03:36:41 UTC
Solar wind! Big smile

"Little ginger moron" ~David Hasselhoff 

Want to see what Surf is training or how little isk Surf has?  http://eveboard.com/pilot/Surfin%27s_PlunderBunny
Alara IonStorm
#5 - 2011-12-28 03:41:02 UTC
Surfin's PlunderBunny wrote:
Solar wind! Big smile

Don't forget to bring your Solar Scarf and Solar Sweater.

It is Chilly out there.
Brujo Loco
Brujeria Teologica
#6 - 2011-12-28 03:44:44 UTC
Surfin's PlunderBunny
Sebiestor Tribe
Minmatar Republic
#7 - 2011-12-28 03:50:28 UTC
Space weather!

"Little ginger moron" ~David Hasselhoff 

Want to see what Surf is training or how little isk Surf has?  http://eveboard.com/pilot/Surfin%27s_PlunderBunny
Brujo Loco
Brujeria Teologica
#8 - 2011-12-28 04:23:55 UTC