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Life, including spaceflight, would be pretty much the same as it is for us. Since the entire solar system would be moving, the relative velocities of the plane

Life, including spaceflight, would be pretty much the same as it is for us. Since the entire solar system would be moving, the relative velocities of the planets and moons would be the same as in any other solar system. The rest of the universe would look quite different, though. Stars "ahead" of the solar system - in the path of its motion - would be noticeably blue-tinted and clumped together. Stars behind the system would be red-shifted. There are some great visualizations at [0]. [0] https://math.ucr.edu/home/baez/physics/Relativity/SR/Spaceship/spaceship.html https://math.ucr.edu/home/baez/physics/Relativity/SR/Spacesh...

swayvil 5y ago
The rest of the universe might age very quickly, relatively speaking. Stars might pass through their lifecycle in a matter of weeks. Constellations might deform over days.
- Semiapies 5y ago
  Not at just half the speed of light.
  - MichaelApproved 5y ago
    Not even at 99.999% the speed of light. You’d need to even faster.
- catillac 5y ago
  There is a bad-but-good hard SF book about this general subject called Tau Zero. You’d definitely need to be going much faster than 0.5c to get anything close to the effects you’re describing, but that book is a fun read if you’re interested in the subject.
  - swayvil 5y ago
    Ya I read it. It's good. But ya, you'd have to be going really #*$&#@ fast.
- EForEndeavour 5y ago
  These numbers are wildly exaggerated, but isn't this also the wrong "direction" of relativistic time dilation? In the frame of the planet orbiting the hypervelocity star, the rest of the universe is moving at 0.5c, so the planet would measure all clocks in the rest of the universe to be running slower by a factor of 1/sqrt(1-0.5^2) = 1.15. Astronomers on this planet would measure stellar lifecycles (and every other physical process) to proceed slower, not faster.
  - deleted 5y ago
    [deleted]
  - dumpsterdiver 5y ago
    > These numbers are wildly exaggerated, but isn't this also the wrong "direction" of relativistic time dilation? In the frame of the planet orbiting the hypervelocity star, the rest of the universe is moving at 0.5c, so the planet would measure all clocks in the rest of the universe to be running slower by a factor of 1/sqrt(1-0.5^2) = 1.15. Astronomers on this planet would measure stellar lifecycles (and every other physical process) to proceed slower, not faster. You have it backwards (easy to do with such a thought experiment!). The direction of time dialation originally stated was correct. Clocks on a body moving at ludicrous speeds will be slower (to the observers present, who are able to look at those clocks) than clocks on a body not moving at ludicrous speeds. Which is to say, if you did a loop around the galaxy at light speed (hypothetical, of course) and came back to Earth and compared your clock with a terrestrial clock, your clock would be waaaay behind, and you would be younger than the people you left behind. This effect is measurable and provable even in the orbit of our own planet (albeit, at a miniscule scale). And so while your time did in fact move more slowly, the overall effect is that you time travelled into the future because everyone else was moving much faster. This of course assumes that you are able to escape intact, which is most unlikely (again, this is just a thought experiment, for argument's sake). In your defense, I know how easy it is to get turned around in such a thought experiment. Theoretically speaking from the perspective of the par-luminal traveller, it's easy to think "my clock moves slower, so am I slower?" In a way, yes, you are! Your reality moves slower relative to theirs, and for those not travelling at light speed time passes more quickly relative to your time. Objectively speaking, a human lifecycle on a very fast moving planet will equate to many, many lifecycles on a slow moving planet, if all other things are equal. And so while you are truly travelling much faster, your time moves slower, relatively speaking. Remember as a kid being told about a hypothetical traveller that enters a black hole, and at one point they become a long spaghetti string and then simply freeze in time? That's because they are moving much faster than us, and from the outside looking in they appear to be frozen. The light emitted from their mass is but an echo. They have moved far beyond the light that we see. From the inside looking out, the universe would move much faster. Again, this is an extreme example used for clarification, but it might not be as extreme as you think. Consider a solar system that gets caught within the grasp of a black hole. Initially the tidal forces tear it apart, but over eons that mass might begin acting like a normal solar system again, and harbor life once more.
- user-the-name 5y ago
  It would not. The universe would actually age slower. However, it would also be much shorter along the axis of motion, and the stars in front of you would be much further along in their evolution than the star behind you. So you would perceive any given star to be evolving more slowly, but you would keep encountering older and older stars as you travel.
  - swayvil 5y ago
    A man goes on a 50 year voyage travelling at near lightspeed. When he returns all of his friends have aged 50 years. But he has only aged 1 year. So you see, his friends were aging 50x faster.
    - user-the-name 5y ago
      If a man goes on a 50 year voyage and returns, he will not have travelled in a straight line, like a planet zooming through space would. He would have to accelerate and change directions, which brings in the effects of general relativity which complicate things. So these two are not equivalent cases.
knodi123 5y ago
what about the relative velocity of the interstellar medium? does diffuse hydrogen pelting your planet at 50%C have any negative side effects?
- NikolaeVarius 5y ago
  Life on earth seems to have done just fine.
  - knodi123 5y ago
    Earth isn't moving at 50%C relative to the interstellar medium.

swayvil 5y ago

The rest of the universe might age very quickly, relatively speaking. Stars might pass through their lifecycle in a matter of weeks. Constellations might deform over days.

Semiapies 5y ago
Not at just half the speed of light.
- MichaelApproved 5y ago
  Not even at 99.999% the speed of light. You’d need to even faster.
catillac 5y ago
There is a bad-but-good hard SF book about this general subject called Tau Zero. You’d definitely need to be going much faster than 0.5c to get anything close to the effects you’re describing, but that book is a fun read if you’re interested in the subject.
- swayvil 5y ago
  Ya I read it. It's good. But ya, you'd have to be going really #*$&#@ fast.
EForEndeavour 5y ago
These numbers are wildly exaggerated, but isn't this also the wrong "direction" of relativistic time dilation? In the frame of the planet orbiting the hypervelocity star, the rest of the universe is moving at 0.5c, so the planet would measure all clocks in the rest of the universe to be running slower by a factor of 1/sqrt(1-0.5^2) = 1.15. Astronomers on this planet would measure stellar lifecycles (and every other physical process) to proceed slower, not faster.
- deleted 5y ago
  [deleted]
- dumpsterdiver 5y ago
  > These numbers are wildly exaggerated, but isn't this also the wrong "direction" of relativistic time dilation? In the frame of the planet orbiting the hypervelocity star, the rest of the universe is moving at 0.5c, so the planet would measure all clocks in the rest of the universe to be running slower by a factor of 1/sqrt(1-0.5^2) = 1.15. Astronomers on this planet would measure stellar lifecycles (and every other physical process) to proceed slower, not faster. You have it backwards (easy to do with such a thought experiment!). The direction of time dialation originally stated was correct. Clocks on a body moving at ludicrous speeds will be slower (to the observers present, who are able to look at those clocks) than clocks on a body not moving at ludicrous speeds. Which is to say, if you did a loop around the galaxy at light speed (hypothetical, of course) and came back to Earth and compared your clock with a terrestrial clock, your clock would be waaaay behind, and you would be younger than the people you left behind. This effect is measurable and provable even in the orbit of our own planet (albeit, at a miniscule scale). And so while your time did in fact move more slowly, the overall effect is that you time travelled into the future because everyone else was moving much faster. This of course assumes that you are able to escape intact, which is most unlikely (again, this is just a thought experiment, for argument's sake). In your defense, I know how easy it is to get turned around in such a thought experiment. Theoretically speaking from the perspective of the par-luminal traveller, it's easy to think "my clock moves slower, so am I slower?" In a way, yes, you are! Your reality moves slower relative to theirs, and for those not travelling at light speed time passes more quickly relative to your time. Objectively speaking, a human lifecycle on a very fast moving planet will equate to many, many lifecycles on a slow moving planet, if all other things are equal. And so while you are truly travelling much faster, your time moves slower, relatively speaking. Remember as a kid being told about a hypothetical traveller that enters a black hole, and at one point they become a long spaghetti string and then simply freeze in time? That's because they are moving much faster than us, and from the outside looking in they appear to be frozen. The light emitted from their mass is but an echo. They have moved far beyond the light that we see. From the inside looking out, the universe would move much faster. Again, this is an extreme example used for clarification, but it might not be as extreme as you think. Consider a solar system that gets caught within the grasp of a black hole. Initially the tidal forces tear it apart, but over eons that mass might begin acting like a normal solar system again, and harbor life once more.
user-the-name 5y ago
It would not. The universe would actually age slower. However, it would also be much shorter along the axis of motion, and the stars in front of you would be much further along in their evolution than the star behind you. So you would perceive any given star to be evolving more slowly, but you would keep encountering older and older stars as you travel.
- swayvil 5y ago
  A man goes on a 50 year voyage travelling at near lightspeed. When he returns all of his friends have aged 50 years. But he has only aged 1 year. So you see, his friends were aging 50x faster.
  - user-the-name 5y ago
    If a man goes on a 50 year voyage and returns, he will not have travelled in a straight line, like a planet zooming through space would. He would have to accelerate and change directions, which brings in the effects of general relativity which complicate things. So these two are not equivalent cases.

knodi123 5y ago

what about the relative velocity of the interstellar medium? does diffuse hydrogen pelting your planet at 50%C have any negative side effects?

NikolaeVarius 5y ago
Life on earth seems to have done just fine.
- knodi123 5y ago
  Earth isn't moving at 50%C relative to the interstellar medium.