4 ms·
> this is absolutely possible by the laws of physics Not with antimatter rockets, it's not. Even though antimatter is extremely energy dense, the rocket equati
by alextingle 2y ago
> this is absolutely possible by the laws of physics
Not with antimatter rockets, it's not. Even though antimatter is extremely energy dense, the rocket equation still applies. You need reaction mass.
If you use laser beams as your rocket exhaust, then you get maximal efficiency (exhaust velocity is C), but very low thrust. That's not going to get you anywhere in days or weeks.
If you use stored matter (hydrogen, say) as your rocket exhaust, then you'd get better thrust, but all sorts of other issues come into play. Radiating all that waste heat. Running out of reaction mass. Again, there's not a practical design that could get you anywhere near a nearby star in "days or weeks", even if you assume "perfect" materials, efficiency, etc.
> If you're on a ship with sufficient fuel, you can keep accelerating forever
Um, no.
- sethev 2y agoYeah, forever is an overstatement since we know there's not sufficient fuel for that. However, my main point was there's not a global speed limit in the sense that a traveler would be prevented from accelerating at some point because they were "near the speed of light". That's pretty mind boggling and quite different from "you can never reach the speed of light therefore you could never travel across the Milky Way in a human lifetime". If you could carry sufficient fuel to accelerate at 9.8 m/s for 12 years you could travel across the Milky Way galaxy (112000 light years). You would be 12 years older but 112000 light years away from where you started. That's amazing to me. It's a given that this is impractical.