3 ms·

This gets really interesting, and weird, if we're ever able to start making ships capable of approaching relativistic rates. You could arrive at the destination

This gets really interesting, and weird, if we're ever able to start making ships capable of approaching relativistic rates. You could arrive at the destination after 500 years, only to discover that humans colonized it 50,000 years ago. For those who may not know, the speed of light isn't really a speed limit per se. If you have a button that gives you an acceleration of 1km/s, nothing stops you from hitting it 300,000 times in a row (with the speed of light being ~300,000km/s), or even a billion. Instead the entire universe begins to distort with distances becoming literally physically closer, and with rate of time itself also changing (length contraction + time dilation are the terms). It has the interesting implication that if we could ever create a ship that "just" accelerates at 1g, you could travel essentially anywhere in the universe, even if it's billions of light years away, in a single human lifespan! [1] So for instance the distance to the closest galaxy, Canis Major, is about 25,000 light years. You could get there in our 1g ship in less than 20 years. Of course, 25,000 years would genuinely have passed in the interim, so you get all sorts of fun paradoxes and oddities. And the oddities are exponential, so you could travel a billion light years in 40 years. And this isn't just hypothetical or whatever. Time dilation plays a major role in many things, like particle accelerators. Unstable emergent particles end up 'living' for far longer than they should thanks to the fact they're moving at near light speed relative to us, which means that time is [relatively] passing for it more slowly than for us. [1] - http://convertalot.com/relativistic_star_ship_calculator.html http://convertalot.com/relativistic_star_ship_calculator.htm...

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atrus 2y ago
> would genuinely have passed I think the whole point of this whole relativity thing is that there are no genuine years :P
ngcc_hk 2y ago
You are wrong in the sense time dilation happen in different observer … it is nothing to do with one object. Your time remained as your length to you. Light speed is the limit. You cannot exceed it and you reach it time stop to you … but still you move on in the speed of light. Another issue you have thought of is the real space “dilution” or that bloody constant Einstein mistake originally. The so called dark energy describe it. We are not sure as it depends upon the model. But it is very unlikely you can reach everywhere you like unless the universe loop around itself (so like on a Sphere you can cover the whole surface of the sphere if you travel with unlimited time … except it expand as we think it is and you cannot). One possibility though is the universe contract. Then no need to travel la. The whole universe collapse on you. What happen when we reach the point our laws of physics as we know it no longer held … no human knows. May be … Let there be light. As God in bible does not make this world out of nothing it seems. Or if you not God person then the empty vacuum field has possible enough to produce the universe (and destroyed it in 10^-32 second. Anyway all amazing stuff. Just as a hacker really really want an emulator and look around this human artifice that is our gift to the universe. (Just hope the tv serial of hitter in Germany olpymic does not hurt our images).
kosmozaut 2y ago
"Pushing Ice" by Alastair Reynolds is a great sci-fi novel that explores some of these ideas, if anyone's interested. Highly recommended!
- jcul 2y ago
  Thanks, going to check it out. Sounds like my kind of thing.
ornornor 2y ago
> And this isn't just hypothetical or whatever. I always find it fascinating to think that this manifests in GPS that everyone casually uses: the timings have to account for the fact that time on the constellation’s satellites passes a little bit faster than on earth and corrected to get accurate positioning on earth.

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atrus 2y ago

> would genuinely have passed I think the whole point of this whole relativity thing is that there are no genuine years :P

ngcc_hk 2y ago

You are wrong in the sense time dilation happen in different observer … it is nothing to do with one object. Your time remained as your length to you. Light speed is the limit. You cannot exceed it and you reach it time stop to you … but still you move on in the speed of light. Another issue you have thought of is the real space “dilution” or that bloody constant Einstein mistake originally. The so called dark energy describe it. We are not sure as it depends upon the model. But it is very unlikely you can reach everywhere you like unless the universe loop around itself (so like on a Sphere you can cover the whole surface of the sphere if you travel with unlimited time … except it expand as we think it is and you cannot). One possibility though is the universe contract. Then no need to travel la. The whole universe collapse on you. What happen when we reach the point our laws of physics as we know it no longer held … no human knows. May be … Let there be light. As God in bible does not make this world out of nothing it seems. Or if you not God person then the empty vacuum field has possible enough to produce the universe (and destroyed it in 10^-32 second. Anyway all amazing stuff. Just as a hacker really really want an emulator and look around this human artifice that is our gift to the universe. (Just hope the tv serial of hitter in Germany olpymic does not hurt our images).

kosmozaut 2y ago

"Pushing Ice" by Alastair Reynolds is a great sci-fi novel that explores some of these ideas, if anyone's interested. Highly recommended!

jcul 2y ago
Thanks, going to check it out. Sounds like my kind of thing.

ornornor 2y ago

> And this isn't just hypothetical or whatever. I always find it fascinating to think that this manifests in GPS that everyone casually uses: the timings have to account for the fact that time on the constellation’s satellites passes a little bit faster than on earth and corrected to get accurate positioning on earth.