Science Forums 2

[hefner]

...So I like to look at it this way: yes, it would require an ever more disproportionate expenditure of fuel to add speed, as you approach the limit c, but not because you are getting heavier! Light moves at about one foot per nanosecond, or 12 IPN. Let's say you accelerate from Earth until you're moving away at 10 IPN. You can then apply your rocket engine thrusters according to the normal Newtonian calculations, and easily achieve an additional 1.0 IPN. But because of clock and ruler distortions, that additional 1 IPN in your frame, constitutes only an additional 0.28 IPN as far as Earthbound folks are concerned. See? the steep climb has nothing to do with mass change.