Photon wavelengths and frequencies

[Quarinteen]

Hello guys. I was thinking about solar sails and was wondering if it was possible to instead simply create a sail that is pushed by photons create something that creates an opposite force that pushes off the photons. If you did this in theory would you not be able to double the momentum? An opposite wavelength that won’t cancel out the push but amplified it?

 

[Mister T]

Do a google search for solar sails.

 

[phyzguy]

Hello guys. I was thinking about solar sails and was wondering if it was possible to instead simply create a sail that is pushed by photons create something that creates an opposite force that pushes off the photons. If you did this in theory would you not be able to double the momentum? An opposite wavelength that won’t cancel out the push but amplified it?

I think we call this a mirror.

 

[Dale]

Hello guys. I was thinking about solar sails and was wondering if it was possible to instead simply create a sail that is pushed by photons create something that creates an opposite force that pushes off the photons. If you did this in theory would you not be able to double the momentum? An opposite wavelength that won’t cancel out the push but amplified it?

You could have a solar sail that reflected the light instead of absorbing it. That would passively double the change in momentum compared to one that absorbed. If you wanted to add an active "push" then you could just shine a laser off the back in addition.

 

[Ibix]

The only way you could get more momentum out of a light sail than using a perfect mirror, as phyzguy proposes, is if the sail actually emits something. And that's just making it a photon rocket - probably not a particularly efficient one.

 

[Ibix]

You could have a solar sail that reflected the light instead of absorbing it. That would passively double the change in momentum compared to one that absorbed. If you wanted to add an active "push" then you could just shine a laser off the back in addition.

Great minds think alike, I see.

 

[hmmm27]

You could have a solar sail that reflected the light instead of absorbing it. That would passively double the change in momentum compared to one that absorbed. If you wanted to add an active "push" then you could just shine a laser off the back in addition.

Lasers aren't terribly efficient : what about just a thermal mass of sorts : sub-critical atomic pile at the focal point of a parabolic mirror/sail.

 

[Dale]

Lasers aren't terribly efficient : what about just a thermal mass of sorts : sub-critical atomic pile at the focal point of a parabolic mirror/sail.

That is basically the way the Pioneer anomaly works.