If you're on a spaceship accelerating at 9.8 metres per second per second you will feel the same weight as if standing on Earth. This is the equivalence principle at the heart of general relativity. It would also be a convenient way for Earth humans to travel.

It's also remarkably fast. Assuming you have a power source capable of sustaining this acceleration, after one year of travelling your speed will be 300 million metres per second (670 million miles per hour), almost exactly the speed of light.

This means that just by standing on Earth for one year you have experienced enough acceleration to propel you to light speed.

* Fun Google query
* I've just finished re-reading the excellent Boat of a Million Years by Poul Anderson. Highly recommended.
* I'm ignoring the fact that as you approach light speed your mass increases, so it takes an increasing amount of energy to accelerate you. So you'll never actually reach light speed in practice.
* Image source

This post was originally on LiveJournal.