at school we had a small device in a glass dome it had 4 plates every plate was blackened on one side and silver colored on the other side. when the sun did shine on one side of it, it would start to spin because the air at the black side would heat up and expand more than the air at the normal metal color side. however this device used sun power and is rather simple and straight foreward in function. however since somehow many people use reflective surfaces when trying to convert laser light into movement,I wondered what kind of effect and difference you have between light reflection and light absorption in relation to turning light into movement.
is that reflection stuff just to make it work in space, or is there a logical reason to on earth in the earth atmosphere use reflection instead of absorption (to generate heat and make the air expand) to turn light into movement?
since most likely things like thermal conductivity and wavelength also play a role in this for this fictive scenario there is a IR led as light source. and the materials to add force to are aluminum, aluminum coated black in wood fire or with carbon powder, black paper and optionally some other materials which might have more interesting physics effects behind them.