4 ms·

At 35,000mph would take 402,000 years. Inter-stellar travel is not for the feint-hearted. It's probably possible to accelerate a space-craft to around 10x this

by retube 16y ago

At 35,000mph would take 402,000 years. Inter-stellar travel is not for the feint-hearted. It's probably possible to accelerate a space-craft to around 10x this speed using current motor technology. Even so, that's still 40,000 years - and 21 light years is like a nano-meter away on a galactic or cosmological scale. Really, if you want to cross inter-stellar space in any kind of reasonable time - O(human lifetime) - you need to go faster. Possible solutions are: solar sail or new kinds of ion thruster. Both of these impart a very small force (and hence acceleration) for an exceedingly long time, resulting in very high velocities. Your target speed is about 10% of c. In the case of the solar sail it receives momentum from sun for ~ 50% of distance (assuming similar-sized star to our sun), and then is braked by the momentum from the target star for the rest of the journey. Problem with solar sail is it needs to be GIGANTIC, and composed of materials stronger and lighter than those available today. Additionally force from sunlight is proportional to 1/r^2 so your acceleration decreases with distance. So, nuclear powered ion thruster is probably the answer. But, obviously, this kind of project is expensive. And either way, you need living quarters for an entire society to live and reproduce.

khafra 16y ago
Or you can just keep dropping nuclear bombs out the back of your spaceship and blowing them up.
- Rhapso 16y ago
  I want to see some math on how fast we could go if we disarmed our militaries and used our nukes as rocket fuel.
  - retube 16y ago
    back in the 50s there was Project Orion, studying how conventional, explosive nuclear bombs could be used to power inter-stellar spacecraft: http://en.wikipedia.org/wiki/Project_Orion_%28nuclear_propulsion%29 http://en.wikipedia.org/wiki/Project_Orion_%28nuclear_propul...
avar 16y ago
Why do you limit a reasonable amount of time to a human lifetime? If we're going to colonize interstellar space with anything like our current technology we're probably going to have to ditch that requirement. There's no reason you can't have a multi-generational ship that takes a thousand years to arrive. You don't have to send thousands of people either, it's enough to send a hundred or so, have them populate on the way, and maybe send some frozen sperm & eggs with them to increase genetic diversity. Another possibility that'll probably become viable within 50-200 years is to not send any humans at all, but to only send a fast & small ship with human sperm & eggs that can start hatching humans once it gets there. Raising the infants could be done with robots and other infrastructure manufactured once we get there.
- retube 16y ago
  A thousand years, yes fine (this is ~ 10 x human lifetime) But to get anywhere in that time you're still going to have to get to some non-infinitesimal fraction of light-speed. Anything less than this you're looking at 10k, 100k, a million years to get to even the closest stars. I could imagine the feasibility of a multi-generational ship lasting 100 - 1000 years, but not longer. Just think of mechanical and materials fatigue. I doubt anything could be built which would last any longer (if that long).
  - prawn 16y ago
    The length of time is almost beside the point. If one (long-term) goal is to put our eggs (so to speak) in a basket other than that of our sun, then there aren't a lot of alternatives. Other stars are simply very far away. Ideally we'd be trying a mixture of probes and generational ships, while also experimenting with Moon and Mars bases.
  - avar 16y ago
    > Just think of mechanical and materials fatigue. If you're able to bring machines that can construct and repair other machines from raw materials the limitation becomes how much material and energy you can bring with you, not the amount of time you're out there.
- 16y ago
scotty79 16y ago
> If you want to cross inter-stellar space in any kind of reasonable time - O(human lifetime) - you need to go faster. Or you can just make people stop dying after this unreasonable short 80 years.

by retube 16y ago

khafra 16y ago

Or you can just keep dropping nuclear bombs out the back of your spaceship and blowing them up.

Rhapso 16y ago
I want to see some math on how fast we could go if we disarmed our militaries and used our nukes as rocket fuel.
- retube 16y ago
  back in the 50s there was Project Orion, studying how conventional, explosive nuclear bombs could be used to power inter-stellar spacecraft: http://en.wikipedia.org/wiki/Project_Orion_%28nuclear_propulsion%29 http://en.wikipedia.org/wiki/Project_Orion_%28nuclear_propul...

avar 16y ago

Why do you limit a reasonable amount of time to a human lifetime? If we're going to colonize interstellar space with anything like our current technology we're probably going to have to ditch that requirement. There's no reason you can't have a multi-generational ship that takes a thousand years to arrive. You don't have to send thousands of people either, it's enough to send a hundred or so, have them populate on the way, and maybe send some frozen sperm & eggs with them to increase genetic diversity. Another possibility that'll probably become viable within 50-200 years is to not send any humans at all, but to only send a fast & small ship with human sperm & eggs that can start hatching humans once it gets there. Raising the infants could be done with robots and other infrastructure manufactured once we get there.

retube 16y ago
A thousand years, yes fine (this is ~ 10 x human lifetime) But to get anywhere in that time you're still going to have to get to some non-infinitesimal fraction of light-speed. Anything less than this you're looking at 10k, 100k, a million years to get to even the closest stars. I could imagine the feasibility of a multi-generational ship lasting 100 - 1000 years, but not longer. Just think of mechanical and materials fatigue. I doubt anything could be built which would last any longer (if that long).
- prawn 16y ago
  The length of time is almost beside the point. If one (long-term) goal is to put our eggs (so to speak) in a basket other than that of our sun, then there aren't a lot of alternatives. Other stars are simply very far away. Ideally we'd be trying a mixture of probes and generational ships, while also experimenting with Moon and Mars bases.
- avar 16y ago
  > Just think of mechanical and materials fatigue. If you're able to bring machines that can construct and repair other machines from raw materials the limitation becomes how much material and energy you can bring with you, not the amount of time you're out there.
16y ago

scotty79 16y ago

> If you want to cross inter-stellar space in any kind of reasonable time - O(human lifetime) - you need to go faster. Or you can just make people stop dying after this unreasonable short 80 years.