4 ms·
If you emit a particle (a photon) and then catch it the net effect will be 0.
by henryfjordan 7y ago
If you emit a particle (a photon) and then catch it the net effect will be 0.
- moopling 7y agoExactly, it is much like using a fan on a boat to blow a sail.
- redorb 7y agomythbusters were able to show a weird effect where the fan on a boat thing worked - I think they chalked it up to some blown wind from the fan drawing in more than from around the fan.. https://youtu.be/uKXMTzMQWjo?t=75 https://youtu.be/uKXMTzMQWjo?t=75
- walrus01 7y agoFrom a physics point of view it's not like they created an infinite motion machine, the stored energy in the liquid petroleum is being burned, heat from the internal combustion engine radiated into the atmosphere, etc. It's just converting stored energy (some amount of kJ or kWh in a fuel tank, or battery) into an aerodynamically weird highly inefficient thrust method.
- umvi 7y agoNet effect is not zero if the photon bounces off of the sail
- comboy 7y agoWhy use sail then? You can just shoot your photon the opposite way.
- seiferteric 7y agoThat would be a "photon rocket" which is an existing idea, but requires a lot of energy, whereas this uses free energy from the sun.
- gitgud 7y agoIf it bounces off in the opposite direction then the net effect would be actually be negative.
- deleted 7y ago[deleted]
- simplicio 7y agoBut if your emitter emits in every direction (like a lightbulb) and you only catch the ones going in one direction in the sail, you'd propel yourself in that direction. So having a directional lightsource fire into the sail wouldn't work, but having one that emits light in every direction on one side of the sail would.
- bsmith0 7y agoSo just use a directional light source pointing away from the craft...