Re: Laser as Reactionless Propulsion

Spike Jones (spike66@ibm.net)
Tue, 20 Apr 1999 21:00:21 -0700 

--------------1E1C782F6026B8CE45D1FCBC
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit

Ross A. Finlayson wrote: Does shooting a laser from a laser generator not generate opposite force of the beam output?

It does.

> Do photons from a laser upon impact of a reflective surface cause an > inertial reaction, no matter how infinitesimal?

They do. 

> If lasers have no "kick" upon firing, and photons from a coherent laser
> do cause an inertial reaction, then lasers could be used as reactionless
> propulsion.

Im not sure I understand the question, but lasers (or any light source, coherent
or otherwise) can be used as a propulsion device, altho not an energy efficient
one. All you need to know is that momentum is conserved in such as system, just as in a traditional propulsion system, and that the momentum of a photon
is hn/c and the energy of that photon is hn where h is Planck's constant and n is the frequency of the photon. With just that information you can show that it is possible to push a mirror with photons, but it takes a lot of energy to make just a small amount of delta V.

If we had nanotech, we could create extraordinarily thin mirrors in the form of a lightsail, which could reflect sunlight (or laser light) for propulsion.
As for your copyright, sorry Ross. You and I are at least a century too young to be the first to think of these things. {8^D spike 

--------------1E1C782F6026B8CE45D1FCBC
Content-Type: text/html; charset=us-ascii
Content-Transfer-Encoding: 7bit

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
Ross A. Finlayson wrote:  Does shooting a laser from a laser generator not generate opposite force of the beam output?

It does.

Do photons from a laser upon impact of a reflective surface cause an
inertial reaction, no matter how infinitesimal?
They do.
If lasers have no "kick" upon firing, and photons from a coherent laser
do cause an inertial reaction, then lasers could be used as reactionless propulsion.
Im not sure I understand the question, but lasers (or any light source, coherent
or otherwise) can be used as a propulsion device, altho not an energy efficient
one.  All you need to know is that momentum is conserved in such as system,
just as in a traditional propulsion system, and that the momentum of a photon
is hn/c and the energy of that photon is hn where h is Planck's constant
and n  is the frequency of the photon.  With just that information you can
show that it is possible to push a mirror with photons, but it takes a lot
of energy to make just a small amount of delta V.

If we had nanotech, we could create extraordinarily thin mirrors in the
form of a lightsail, which could reflect sunlight (or laser light) for propulsion.
As for your copyright, sorry Ross.  You and I are at least a century too
young to be the first to think of these things.  {8^D  spike --------------1E1C782F6026B8CE45D1FCBC--