Larry Niven near-light-speed story - spaceship on course to hit the Earth. Would like to know more about it.
I am always concerned with the energy of rocket flight because it seems most space enthusiasts underestimate the needs for various space propulsion systems.
I once considered travelling at 1/4 light-speed since that seems about the maximum that could be reached without too exotic means. It is also the speed needed for travelling to Alfa Centauri and back within a human life time.
The Lorentz factor for this speed gives only 3.3 % deviation from non-relativistic mechanics so its influence is minor. But the energy needed to reach it is already enormous.
Some imagine a community of 10,000 people and therefore a huge spaceship would be needed to make such a long trip successful. But I considered the absolute minimum of a single interstellar traveler with a standard body weight of 75 kg. It turns out that at 1/4 light-speed his kinetic energy is even slightly more than the energy released in the largest human created energetic event : the TSAR BOMBA !
That was the 50 Megaton hydrogen bomb which the Soviet Union exploded in 1962. When his body would be put overboard and hit the Earth a similar explosion would result !
It seems Larry Niven also realized the enormous energy involved at near light-speed and years ago I read he wrote a story about it but I never found it. So anybody knows more, a title would be nice ?