Can light be used to propel something in space?

Question

Here's the setup I visualize:

- light emission source;
- chamber that is as close to perfectly reflective (both with regard to light and heat) as possible;
- a tiny outlet hole at the end opposite the light emission source.

It seems that such a thing would produce at least a miniscule amount of thrust, though we lack the materials to make such a chamber. But if we could do it, would it work? Light can push against things and alter their trajectories, so I would assume it has to have -some- thrust capability.

Just curious. :-)

Answer 1

Sure. Photons carry momentum p.

p = h/lambda where h is Planck's const. &

lambda is the wavelength of light. Force or thrust is equal to dp/dt or the time derivative of momentum. For a fixed wavelength photon, this is equal to p * rate of photon emission. Or,

Thrust = (h/lambda)*(# of photons per second)

Answer 2

nurses your math must be off, because if we could reach proxima centauri (4.2 light years away) in 17 months we would be moving faster than light, and i don't think a solar sail could do this, sorry.

a solar sail could propel people through the solar system though and if it picks up enough speed the momentum could carry them to other stars, it would take a long time though.

your apparatus sounds interesting but ultimately fails.

it sounds like the light source it carried along, this would be like using a fan to move a sailboat. might work in theory but actually it doesn't. emitting the light would actually push back against the ship, making it go nowhere.

a solar sail using the sun's radiation for propulsion would be a much more powerful source of thrust.

Answer 3

Yes, a photon drive would work, but take a long time because the momentum of a photon is quite small.
E = pc so p = E/c and E = hf are you into the math??

so p = h/lambda lambda = wavelength of the light.

Problem is this small p must push a spaceship with a big mass, so we need lots of photons (a very bright light)

but it is possible. I thought NASA was working on it.

Answer 4

small capsule self contained for a person, square mile of aluminum foil used as a sail. You could reach Proxima Centauri in a year and 5 months (I have the math) mainly because yould have continuous thrusts rather than point the ship in the right direction and let it coast as our spaceships do now.

Answer 5

Im no scientist, but I think your set up would work, but I think the amount of thrust the light would give the object is very minuscule..

Answer 6

You might want to check these links out.

http://www.space.com/businesstechnology/technology/laser_craft_001103-1.html

http://www.space.com/businesstechnology/technology/laser_propulsion_000705.html

http://www.lightcrafttechnologies.com/

I don't see why you couldn't also do this in space