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> Should we ultimately be able to develop relativistic rockets Aren't all rockets relativistic? In the sense that "there's no inherent reason", I take it to me

> Should we ultimately be able to develop relativistic rockets Aren't all rockets relativistic? In the sense that "there's no inherent reason", I take it to mean "near to c", for some value of "near". that is, it's a "relative" term.

somenameforme 3y ago
Contrary to what many people think, the speed of light isn't like a speed limit. Imagine you're on a ship with near infinite fuel. And there's a button that each time you press will generate enough thrust to gain 1km/s of velocity. It's not like the 300,001st time you press that button (with the speed of light being around 300k km/s), it just won't work anymore somehow, nor will it require any more thrust than the 50th press required. No you'll keep accelerating, to no limit. What relativity does is change things in a way relative to who's observing. From your perspective distances would begin to physically contract, time everywhere else would begin to accelerate, and things would probably start looking a bit odd. But you could keep hitting that button to your heart's content, and continue going faster and faster. By contrast for a relatively at rest observer, looking at you, they would see your relativistic mass start to approach infinity as you approached the speed of light. And so they would see you slowing down (as accelerating an infinite mass object would be impossible), and the movement of time for you (relative to them) would begin to slow dramatically, hence why time for them (relative to you) seems to accelerate dramatically. The calculations for relativistic rockets are quite remarkable [1], because it's an exponential system. For instance, here are some times it'd take you to travel to various points in a typical relativistic rocket that continues to accelerate at 1g (you go half way to a target at 1g, and then half way in reverse): - Proxima Centauri - 4.3 light years away - 3.6 "real" years of travel - Vega - 27 light years away - 6.6 "real" years of travel - Center of our galaxy - 30,000 light years away - 20 "real" years of travel - Andromeda Galaxy - 2,000,000 light years away - 28 "real" years of travel With a relativistic rocket, if you wanted to see what the end of the universe looked like in a single human lifetime, you could. It's really really weird. So basically a relativistic rocket is more about creating a rocket that can just keep accelerating for years at a time, rather than reaching any specific speed. They're certainly similar in effect, but framing it in terms of years of acceleration makes it a pretty well defined problem. [1] - https://math.ucr.edu/home/baez/physics/Relativity/SR/Rocket/rocket.html https://math.ucr.edu/home/baez/physics/Relativity/SR/Rocket/...

somenameforme 3y ago

Contrary to what many people think, the speed of light isn't like a speed limit. Imagine you're on a ship with near infinite fuel. And there's a button that each time you press will generate enough thrust to gain 1km/s of velocity. It's not like the 300,001st time you press that button (with the speed of light being around 300k km/s), it just won't work anymore somehow, nor will it require any more thrust than the 50th press required. No you'll keep accelerating, to no limit. What relativity does is change things in a way relative to who's observing. From your perspective distances would begin to physically contract, time everywhere else would begin to accelerate, and things would probably start looking a bit odd. But you could keep hitting that button to your heart's content, and continue going faster and faster. By contrast for a relatively at rest observer, looking at you, they would see your relativistic mass start to approach infinity as you approached the speed of light. And so they would see you slowing down (as accelerating an infinite mass object would be impossible), and the movement of time for you (relative to them) would begin to slow dramatically, hence why time for them (relative to you) seems to accelerate dramatically. The calculations for relativistic rockets are quite remarkable [1], because it's an exponential system. For instance, here are some times it'd take you to travel to various points in a typical relativistic rocket that continues to accelerate at 1g (you go half way to a target at 1g, and then half way in reverse): - Proxima Centauri - 4.3 light years away - 3.6 "real" years of travel - Vega - 27 light years away - 6.6 "real" years of travel - Center of our galaxy - 30,000 light years away - 20 "real" years of travel - Andromeda Galaxy - 2,000,000 light years away - 28 "real" years of travel With a relativistic rocket, if you wanted to see what the end of the universe looked like in a single human lifetime, you could. It's really really weird. So basically a relativistic rocket is more about creating a rocket that can just keep accelerating for years at a time, rather than reaching any specific speed. They're certainly similar in effect, but framing it in terms of years of acceleration makes it a pretty well defined problem. [1] - https://math.ucr.edu/home/baez/physics/Relativity/SR/Rocket/rocket.html https://math.ucr.edu/home/baez/physics/Relativity/SR/Rocket/...