Comment by Sohcahtoa82

Yeah, once you reach a certain speed, even colliding with a fleck of dust can obliterate a ship.

Colliding with a single 0.3 mg grain of salt at 20% of the speed of light creates an impact with 560 MJ of energy, equivalent to 130 kg of TNT, over 8 times the nuclear bomb dropped on Hiroshima.

Even a tiny speck of dust, half a microgram, is equivalent to a hand grenade when hit at 20% the speed of light.

You wouldn't be able to even escape the solar system before your shields were devoured. If you accelerated at 1G constantly, you'd be going 3.5% of the speed of light by the time you reached Pluto's orbit. Space dust particles are already hitting you like nuclear bombs at that speed.