4 ms·

The faster you go, the shorter you have to travel due to length contraction. So travelling really far distances is still possible, for example, by constant acce

The faster you go, the shorter you have to travel due to length contraction. So travelling really far distances is still possible, for example, by constant acceleration [1]. It's just that everyone you left behind will have been dead for billions of years by the time you arrive. [1] https://en.wikipedia.org/wiki/Space_travel_under_constant_acceleration https://en.wikipedia.org/wiki/Space_travel_under_constant_ac...

nomel 3y ago
> for example, by constant acceleration Yes, this is why it won't happen, with our current understanding of physics, and the practical limitation that implies, with the resources we have. ;)
bitwize 3y ago
> It's just that everyone you left behind will have been dead for billions of years by the time you arrive. sad piano plinks https://www.youtube.com/watch?v=kEVZ3NIoEAE https://www.youtube.com/watch?v=kEVZ3NIoEAE
rsaesha 3y ago
To illustrate the problem of accelerating any relevant piece of mass at relativistic speeds, observe how the kinetic energy increases towards infinity as the object approaches the light speed: https://files.mtstatic.com/site_4539/12414/0/webview?Expires=1687505577&Signature=Jw4j2-DfQmrUDa~PJuJGc-usjqfinvXPFzGXvGrsf4rc4MFPpBL4qv2Boi3XGAMg-zcIG4YXlussVBl3QtDS4mhu3OsTIK3ecCjUbmripEcctZqXX7CO5nL7YM5-Y3EcXFIl7rtYupc3UHQNE2a-gUPZgsKH8XEJ78BRT3AgOSg_&Key-Pair-Id=APKAJ5Y6AV4GI7A555NA https://files.mtstatic.com/site_4539/12414/0/webview?Expires... This means it's required infinite energy to reach c speed for any mass. And c speed is quite slow for space travel. Just for the fun of it, let's imagine humanity has assembled, in space, an aircraft-carrier sized vessel, fully equipped to function and nurture the little humans living inside of it. Weight: 100 ktons. Power is infinite ok, because badly rewarded nerds discovered new physics. Good for them they are now immortals of human history. With Lorentz kinetic energy equation, one can estimate the kinect energy this vessel would have while traveling at say, 1% of the speed of light. Energy: 4.5*10^20 J. This is about two thirds of the total energy Earth receives from the sun in one hour. Or close enough to the energy the world consumed in 2017. Now we have humans inside a vessel hurdling through space at 0.01 c, in addition to the pre-existing humans in a planet swirling through space. But there is a problem! It would take 424 years to reach the nearest star system. So we need to go faster and maybe break things. Hopefully not the hull, though. F*** it let's go 0.5 c and reach Andromeda in about 9 years - long enough to write a book. Energy: 1.4*10^24 J. That's 3x the energy released by the Chicxulub meteor impact. Or 30+ times the 2003 world's total fossil fuel reserves. Which raises the question what is the fuel being used? Doesn't matter ok because new physics, we are transforming mass literally in energy no constraints 100% efficiency lol. By e=mc^2 that fuel would weight - at least - 14.9 ktons. There is margin for error, since the vessel would be shedding mass, and getting lighter. That would allow engineering to run the global process at 80% efficiency, which is a very realistic metric and maybe miss a turn or two on the way to the neighboring star. Returns not included.
dumdumchan 3y ago
5 minutes after you takeoff you hit a pebble that obliterates your entire ship because you're covering billions of cubic meters of volume every second (in your time).

nomel 3y ago

> for example, by constant acceleration Yes, this is why it won't happen, with our current understanding of physics, and the practical limitation that implies, with the resources we have. ;)

bitwize 3y ago

> It's just that everyone you left behind will have been dead for billions of years by the time you arrive. sad piano plinks https://www.youtube.com/watch?v=kEVZ3NIoEAE https://www.youtube.com/watch?v=kEVZ3NIoEAE

rsaesha 3y ago

To illustrate the problem of accelerating any relevant piece of mass at relativistic speeds, observe how the kinetic energy increases towards infinity as the object approaches the light speed: https://files.mtstatic.com/site_4539/12414/0/webview?Expires=1687505577&Signature=Jw4j2-DfQmrUDa~PJuJGc-usjqfinvXPFzGXvGrsf4rc4MFPpBL4qv2Boi3XGAMg-zcIG4YXlussVBl3QtDS4mhu3OsTIK3ecCjUbmripEcctZqXX7CO5nL7YM5-Y3EcXFIl7rtYupc3UHQNE2a-gUPZgsKH8XEJ78BRT3AgOSg_&Key-Pair-Id=APKAJ5Y6AV4GI7A555NA https://files.mtstatic.com/site_4539/12414/0/webview?Expires... This means it's required infinite energy to reach c speed for any mass. And c speed is quite slow for space travel. Just for the fun of it, let's imagine humanity has assembled, in space, an aircraft-carrier sized vessel, fully equipped to function and nurture the little humans living inside of it. Weight: 100 ktons. Power is infinite ok, because badly rewarded nerds discovered new physics. Good for them they are now immortals of human history. With Lorentz kinetic energy equation, one can estimate the kinect energy this vessel would have while traveling at say, 1% of the speed of light. Energy: 4.5*10^20 J. This is about two thirds of the total energy Earth receives from the sun in one hour. Or close enough to the energy the world consumed in 2017. Now we have humans inside a vessel hurdling through space at 0.01 c, in addition to the pre-existing humans in a planet swirling through space. But there is a problem! It would take 424 years to reach the nearest star system. So we need to go faster and maybe break things. Hopefully not the hull, though. F*** it let's go 0.5 c and reach Andromeda in about 9 years - long enough to write a book. Energy: 1.4*10^24 J. That's 3x the energy released by the Chicxulub meteor impact. Or 30+ times the 2003 world's total fossil fuel reserves. Which raises the question what is the fuel being used? Doesn't matter ok because new physics, we are transforming mass literally in energy no constraints 100% efficiency lol. By e=mc^2 that fuel would weight - at least - 14.9 ktons. There is margin for error, since the vessel would be shedding mass, and getting lighter. That would allow engineering to run the global process at 80% efficiency, which is a very realistic metric and maybe miss a turn or two on the way to the neighboring star. Returns not included.

dumdumchan 3y ago

5 minutes after you takeoff you hit a pebble that obliterates your entire ship because you're covering billions of cubic meters of volume every second (in your time).