Rocket scientists agree that we have about reached the limit of our ability to travel in space using chemical rockets. To achieve anything near the speed of light we will need a new energy source and a new propellant. Nuclear fission is not an option.

Of all the failed technologies that litter the onward march of science - steam carriages zeppelins armoured trains - none has been so catastrophic to prosperity as the last century's attempt to generate electricity from nuclear fission.