That's not the one, but it's along similar lines. The site had lots of graphics and was written in layman's terms. I think I first read it around 1999 or 2000

That's not the one, but it's along similar lines. The site had lots of graphics and was written in layman's terms. I think I first read it around 1999 or 2000, and then lost it. I agree with the others that any force above light pressure would appear to violate Newton’s laws. However, I have never seen an analysis or simulation that incorporates the delay in the speed of light. Ring 1 would be limited to light pressure, and be symmetrical, but ring 2 would dissipate one half of the wave by canceling it, so technically only 3/4 of the energy would be emitted if we thought of the whole system as a black box. The other 1/4 would have to go somewhere, probably mostly heating the rings but some of it could go into the box as kinetic energy. I think an easier way to run the experiment might be to set up a square wave with a duty cycle of 25% and a period equal to the time it takes for light to propagate between the rings. Then it would just be a matter of varying the phase on one of the rings and seeing if there’s a net force on the setup. With a spacing of 10 centimeters, there would only be 0.33 nanoseconds to build a magnetic field, and it’s going to fall by the square of the distance between coils, unless we could use the long wire approximation for large coils which falls linearly by distance: https://en.wikipedia.org/wiki/Ampère%27s_force_law#Equation https://en.wikipedia.org/wiki/Ampère%27s_force_law#Equation The forces might be small but they should be measurable, and if they are even a fraction of a percent above light pressure, it’s a really big deal. Maybe the duty cycle should be 33% or 50%, maybe the period should be double or half this, maybe another waveform would be more efficient, but you get the idea. Blah what I wouldn’t give to have the disposable income to work on this and the hundred other half-baked ideas laying around the house. It’s a special kind of hell to toil away one’s life making rent while watching the wondrous breakthroughs of the world spring forth from other people’s minds.