Quote Originally Posted by Eric View Post
http://www.dailymail.co.uk/sciencete...e-planets.html says there is a promising star system 39 light years away. It then says the following:


How close will we be able to get to light speed as our technology improves?
There's no theoretical limit.

Practically, we use jets (of matter) to create thrust. That means we are limited by how much fuel we start with and the specific performance of the engine, which has to impart kinetic energy to the fuel. The current method is to bring a fuel and imparts this energy to itself with a bit of provocation... it burns, releasing energy from chemical bonds. The engine's job is mostly to keep pumping fuel into the right spot so that it can be accelerated such that the equal and opposite acceleration happens to the engine, and therefore the ship it's attached to.

Project Orion was a plan to explode nukes behind a ship to ride the shock waves to accelerate. That is not impractical in design, only in getting it off the ground w/o massively polluting the Earth. That would be capable of much higher speeds, due to the ludicrously more energy held in atomic bonds compared to molecular bonds.