[ExI] Electromagnetic launcher efficiency

[Anders Sandberg]

On 2012-08-13 18:01, spike wrote:
> Anders, I don’t know where I last saw the equations on that, but it is an interesting question.

In a sense it goes back to the question what the entropy cost of moving 
something from A to B is. But here we also have the "real world" 
constraint that it has to be done using electromagnetic fields.

>  estimate half the waste energy goes into the track and half goes into the rollercoaster and the air

This is what has me worried. If a lot of heat goes into the launched 
object it will melt. Even a fairly modest railgun (kilometers per 
second) has more than enough energy to vaporise the object. The fact 
that naval raiguns doesn't launch puffs of metal is a good sign, but I 
would like to be sure this holds to really high velocities.


-- 
Anders Sandberg
Future of Humanity Institute
Oxford University