I am really loving teaching the sophomore project lab this semester. Students are designing their own semester long experiment. We are at the grant proposal stage.

It has created so many interesting discussions with the students. One thing that has surprised me is the amount of creative juices it has gotten going with me. I have been asking a lot of what ifs.

Photons can cause force. It is how we use lasers to cool and stop atoms. Light from the sun can be collected with a sail and it can be used to drive a space ship. There is even a wacky idea of using micro-space ships powered by reflecting an Earth-based super laser off of them.

Here is the latest wacky idea I had. What if now and again a space craft dropped a highly reflective mirror and directed a high powered laser off of it. The mirror directs the light to the mirror on the laser forming a pseudo cavity, where the photon bounces back and forth 1000s of times. Both the mirror and the space would be accelerated in opposite directions. Could that generate meaningful thrust to a rocket ship? You definitely would be accelerating the mirror, so you would have to drop a new one now and again. But let’s ignore that.

The answer is no. When you calculate the time it takes to get to Mars, it is still 18 years. (There are faster ways.) But if you could reduce the mass, increase the quality of the cavity, or increase the laser power, it might work sometime.

It’s fun to think out side the box.