15 ms·

I agree but the nearest star is (only?) 4 light years away. If we only managed to travel close to the speed of light, we surely live long enough today. Time dil

by dreen 6y ago

I agree but the nearest star is (only?) 4 light years away. If we only managed to travel close to the speed of light, we surely live long enough today. Time dilation will cause our friends to be older by a few years than they should be, but not by that much right?

koolba 6y ago
> Time dilation will cause our friends to be older by a few years than they should be, but not by that much right? Technically they wouldn’t be older, you’d be younger.
- dangirsh 6y ago
  "relativity"
tobmlt 6y ago
The trip becomes quicker (to you) the faster you go. If you could ride a beam of light, you’d be there instantaneously, thanks to length contraction. Meanwhile 4 years would pass on earth in some sense. (To an observer watching from earth with a hypothetical telescope, you are seen to arrive only after eight years total. Of course you could just ride the light back and tell him about it all, ha.)
maxerickson 6y ago
With FTL you could wish yourself a good trip before you left.
speeder 6y ago
There is a cool calculator of what happen if you travel around with constant 1G acceleration. Long story short: to travel to Alpha Centauri it would take for the traveller still about 4 years, and when back at home, people would have aged only some months more than the astronauts. Crazy things happen if you decide to go on galaxy-wide trips though, to the astronauts because space contraction they perceive their own trip as happening still rather quick, a 100 000 ly trip (the size of our galaxy, for reference) takes 22 years for someone inside a spaceship with 1g acceleration, perfectly doable. But people outside still see it taking 100 000 years... (meaning they will be 100 000 years "older" from the point of view of the astronauts) After I found all this out, I concluded space travel isn't THAT hard, assuming you have a way to accelerate constantly at 1g for 22 years (that is the hardest part actually), you can get anywhere in the galaxy in a human lifetime, no need for generation ships, cryogenics or other crazy tech. In fact even going to other galaxies is easy, a trip to Andromeda takes 28 years! Mind you, all those calculations were done assuming you will burn at 1g until half the distance, and then burn at 1g to brake, if you don't brake you can get even faster to places (although that wouldn't be very useful I guess). According to google the universe is 93 billion ly wide. If you accelerate (and decelerate later) at constant 1g, this trip takes 49 years for the astronaut!
- SketchySeaBeast 6y ago
  I think you're forgetting that there's a hard upper limit on velocity. Edit: Ah, wasn't aware of length contraction. https://courses.lumenlearning.com/physics/chapter/28-3-length-contraction/ https://courses.lumenlearning.com/physics/chapter/28-3-lengt...
  - akvadrako 6y ago
    Not on subjective velocity. As you approach the speed of light from an outsider's perspective from the insider's perspective the universe appears to shrink.
    - SketchySeaBeast 6y ago
      But if you experience 22 years to make 10,000 ly's of distance, you've subjectively gone much much faster than the speed of light, haven't you? I thought that was a constant in all frames of reference.
      - akvadrako 6y ago
        From your own perspective you are always stationary, it's just the universe that is moving (and shrinking).
        SketchySeaBeast 6y ago
        Quote from the original claim: > After I found all this out, I concluded space travel isn't THAT hard, assuming you have a way to accelerate constantly at 1g for 22 years (that is the hardest part actually), you can get anywhere in the galaxy in a human lifetime, no need for generation ships, cryogenics or other crazy tech. They are saying add a constant 1g acceleration and you can get anywhere relatively quickly, no warp bubble required. That's what I'm taking exception to. If we add a warp bubble, sure, but a constant 1g acceleration shouldn't ever see you having an experience of moving faster than the speed of light, and that 10,000 ly trip should still take > 10,000 ly.

by dreen 6y ago

koolba 6y ago

> Time dilation will cause our friends to be older by a few years than they should be, but not by that much right? Technically they wouldn’t be older, you’d be younger.

dangirsh 6y ago
"relativity"

tobmlt 6y ago

The trip becomes quicker (to you) the faster you go. If you could ride a beam of light, you’d be there instantaneously, thanks to length contraction. Meanwhile 4 years would pass on earth in some sense. (To an observer watching from earth with a hypothetical telescope, you are seen to arrive only after eight years total. Of course you could just ride the light back and tell him about it all, ha.)

maxerickson 6y ago

With FTL you could wish yourself a good trip before you left.

speeder 6y ago

There is a cool calculator of what happen if you travel around with constant 1G acceleration. Long story short: to travel to Alpha Centauri it would take for the traveller still about 4 years, and when back at home, people would have aged only some months more than the astronauts. Crazy things happen if you decide to go on galaxy-wide trips though, to the astronauts because space contraction they perceive their own trip as happening still rather quick, a 100 000 ly trip (the size of our galaxy, for reference) takes 22 years for someone inside a spaceship with 1g acceleration, perfectly doable. But people outside still see it taking 100 000 years... (meaning they will be 100 000 years "older" from the point of view of the astronauts) After I found all this out, I concluded space travel isn't THAT hard, assuming you have a way to accelerate constantly at 1g for 22 years (that is the hardest part actually), you can get anywhere in the galaxy in a human lifetime, no need for generation ships, cryogenics or other crazy tech. In fact even going to other galaxies is easy, a trip to Andromeda takes 28 years! Mind you, all those calculations were done assuming you will burn at 1g until half the distance, and then burn at 1g to brake, if you don't brake you can get even faster to places (although that wouldn't be very useful I guess). According to google the universe is 93 billion ly wide. If you accelerate (and decelerate later) at constant 1g, this trip takes 49 years for the astronaut!

SketchySeaBeast 6y ago
I think you're forgetting that there's a hard upper limit on velocity. Edit: Ah, wasn't aware of length contraction. https://courses.lumenlearning.com/physics/chapter/28-3-length-contraction/ https://courses.lumenlearning.com/physics/chapter/28-3-lengt...
- akvadrako 6y ago
  Not on subjective velocity. As you approach the speed of light from an outsider's perspective from the insider's perspective the universe appears to shrink.
  - SketchySeaBeast 6y ago
    But if you experience 22 years to make 10,000 ly's of distance, you've subjectively gone much much faster than the speed of light, haven't you? I thought that was a constant in all frames of reference.
    - akvadrako 6y ago
      From your own perspective you are always stationary, it's just the universe that is moving (and shrinking).
      - SketchySeaBeast 6y ago
        Quote from the original claim: > After I found all this out, I concluded space travel isn't THAT hard, assuming you have a way to accelerate constantly at 1g for 22 years (that is the hardest part actually), you can get anywhere in the galaxy in a human lifetime, no need for generation ships, cryogenics or other crazy tech. They are saying add a constant 1g acceleration and you can get anywhere relatively quickly, no warp bubble required. That's what I'm taking exception to. If we add a warp bubble, sure, but a constant 1g acceleration shouldn't ever see you having an experience of moving faster than the speed of light, and that 10,000 ly trip should still take > 10,000 ly.