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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 t

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.
        simiones 6y ago
        No, you're misunderstanding. From your frame of reference, the universe is much flatter in the direction of travel, and getting flatter and flatter the more time you spend. The distance between Earth and the edge of the galaxy will get smaller and smaller in your direction of travel.
        SketchySeaBeast 6y ago
        Thanks - yeah, I realize now that the length actually shortens.
        6y ago
- speeder 6y ago
  You never reach that limit if you are accelerating with a normal engine at 1g. You will get closer and closer to it, but never reach it. If you somehow DO achieve lightspeed, time stops for you, completely, so from your point of view you are teleporting, but since time is stopped no machine or chemical reaction can happen, thus why we believe lightspeed machinery is impossible. By the way, achieving near lightspeed with 1g acceleration is in a way, hard, for example the trip to alpha centauri at 1g results in you achieving "only" 94% of light speed... to do that same trip peaking at 99.0% of light speed it would take 3g of acceleration, and it would result in the trip being roughly 1/3 shorter (taking 1.7 years more or less, instead of 5)
  - SketchySeaBeast 6y ago
    > 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) But from your frame of reference wouldn't you be moving much faster than the speed of light? If you're taking 22 years to travel 10,000 ly, that means you're moving faster than light in your perception, doesn't it? Isn't that forbidden in any frame of reference?
    - simiones 6y ago
      From your frame of reference, the universe is much smaller in the direction of travel. You'd still see light zoom past you at 1c, though.
    - zaarn 6y ago
      From your perspective, the entire length of the milky way is squished into 22 light years (roughly), so not really violating anything. From the outside frame of reference you still take 10000 years (plus) to cross that distance, from your perspective, the distance gets shorter.
jamesdmiller 6y ago
I think because of the expansion of the universe, you don't have to decelerate as much if you travel to far away galaxies.
simiones 6y ago
> 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. Unfortunately, there is also a kind of rocket equation for constant 1g acceleration, and if I remember correctly it's not really doable for any realistic amount of time, even with matter/antimatter reaction drives.
MaysonL 6y ago
See the novel Tau Zero by Poul Anderson. https://en.wikipedia.org/wiki/Tau_Zero https://en.wikipedia.org/wiki/Tau_Zero

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.
      - simiones 6y ago
        No, you're misunderstanding. From your frame of reference, the universe is much flatter in the direction of travel, and getting flatter and flatter the more time you spend. The distance between Earth and the edge of the galaxy will get smaller and smaller in your direction of travel.
        SketchySeaBeast 6y ago
        Thanks - yeah, I realize now that the length actually shortens.
      - 6y ago
speeder 6y ago
You never reach that limit if you are accelerating with a normal engine at 1g. You will get closer and closer to it, but never reach it. If you somehow DO achieve lightspeed, time stops for you, completely, so from your point of view you are teleporting, but since time is stopped no machine or chemical reaction can happen, thus why we believe lightspeed machinery is impossible. By the way, achieving near lightspeed with 1g acceleration is in a way, hard, for example the trip to alpha centauri at 1g results in you achieving "only" 94% of light speed... to do that same trip peaking at 99.0% of light speed it would take 3g of acceleration, and it would result in the trip being roughly 1/3 shorter (taking 1.7 years more or less, instead of 5)
- SketchySeaBeast 6y ago
  > 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) But from your frame of reference wouldn't you be moving much faster than the speed of light? If you're taking 22 years to travel 10,000 ly, that means you're moving faster than light in your perception, doesn't it? Isn't that forbidden in any frame of reference?
  - simiones 6y ago
    From your frame of reference, the universe is much smaller in the direction of travel. You'd still see light zoom past you at 1c, though.
  - zaarn 6y ago
    From your perspective, the entire length of the milky way is squished into 22 light years (roughly), so not really violating anything. From the outside frame of reference you still take 10000 years (plus) to cross that distance, from your perspective, the distance gets shorter.

jamesdmiller 6y ago

I think because of the expansion of the universe, you don't have to decelerate as much if you travel to far away galaxies.

simiones 6y ago

> 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. Unfortunately, there is also a kind of rocket equation for constant 1g acceleration, and if I remember correctly it's not really doable for any realistic amount of time, even with matter/antimatter reaction drives.

MaysonL 6y ago

See the novel Tau Zero by Poul Anderson. https://en.wikipedia.org/wiki/Tau_Zero https://en.wikipedia.org/wiki/Tau_Zero