EmDrive:
A man named Shawyer has a proposal for a sort of space drive that puts out no exhaust. (https://www.rt.com/usa/177204-nasa-space-drive-emdrive/ as of 2/24, 2016) Of course a garden variety rocket shoots hot gas out the back, and the balance of momentum is maintained by the rocket moving forward. This was true when the Chinese invented the contraption, and so it has been ever since. But I am always interested in the impossible, so I had a look at it. The heart of the drive is a microwave generator that puts the microwaves into a shaped vessel, from which they cannot escape. What’s more, the company that built it was awarded £250,000 by the UK Department of Trade and Industry to pursue the design.
Now you could actually make something like it, only you would have to dump the microwaves out the back of the machine. We all know that E = mc2, mass has an energy equivalent, so as energy shoots out one way, momentum must be conserved by the device going the other. But this device, looking at a picture, does not do that.
A microwave drive, or a visible light drive for that matter, might have some advantages if vast amounts of electrical power could be created by a cheap, light, long lasting device. Had I the task, I would choose to have a nuclear reactor, thorium reactors are much in press although I’m sure I could build something better, and from the heart of this device all manner of heat and light would escape and be directed more or less parallel by an ordinary cone such as a modern rocket uses. But to approach half the speed of light with a one ton vehicle, would require about a half ton of matter to be converted to energy. A lot of the thrust would be used up accelerating the fuel itself, so the amount that would need to be converted would be somewhere between a half a ton and a ton. Then of course, there’s stopping, turning around and coming back. In short, your light drive would face, on a different scale, the kind of problems that any rocket faces.
Absent matter OR energy, or information if you could figure out how to harness it, which I can’t, then there will be no thrust. I just don’t see it. By all means, follow the link and have a look. But don’t sink your money into it.
I’m sorry. If you’ve paid taxes in the UK you’ve already sunk money into it. Had I the smarts, which I don’t, I could figure how to get somebody to fund my own research. I once had someone offer to do as much, but that person seemed to be as much interested in getting money out of me as out of the government. Besides, there was a quarrel, to which I was not party but which made doing further business impossible.
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