4 ms·

I think it's technically possible to explore our own galaxy in a human lifetime by accelerating to an appreciable fraction of c, just need to develop fusion roc

I think it's technically possible to explore our own galaxy in a human lifetime by accelerating to an appreciable fraction of c, just need to develop fusion rockets.

rbanffy 6y ago
Fusion rockets are not nearly enough for that. You'd still need to carry an impossible amount of propellant, deal with friction and live through the months-long acceleration/deceleration cycles, most of which at non-relativistic speeds. If you got a ramscoop engine, maybe you'd be able to grab enough propellant to push you at 1g for years at a time while cleaning your path of particles that'd impact your shielding.
close04 6y ago
Even at the speed of light, taking into account acceleration and deceleration you could cover ~50 light years in a lifetime. The Milky Way is ~150000 light years across. In day to day terms it's like walking 10km relative to exploring the whole Earth.
- phonypc 6y ago
  I'm sure someone better informed could weigh in with more details, but IIRC, taking time dilation into account, you could explore infinitely if you could somehow travel at the speed of light. Some large fraction of c would be sufficient to cross the galaxy in a lifetime, relative to you the traveller.
  - perl4ever 6y ago
    Yes, but taking into account any drive that uses mass you couldn't carry enough to accelerate for very long. There's been a lot of speculation about scooping up hydrogen from the interstellar medium as fuel, but I think it's mainly wishful thinking. https://en.wikipedia.org/wiki/Bussard_ramjet https://en.wikipedia.org/wiki/Bussard_ramjet https://en.wikipedia.org/wiki/Tau_Zero https://en.wikipedia.org/wiki/Tau_Zero
  - close04 6y ago
    In 50 years experienced by the explorer inside the ship, at a more "realistic" speed of 0.9c the ship would travel ~115 light years, and at 0.99c it would do ~350 light years (excluding gravitational time dilation). Anything higher than that would probably be a bit incomprehensible for the human mind. At 0.99999c the ship would travel ~11000 light years, all of which would be fully experienced by the people at home. That's for the dash, the exploration itself comes on top of that. And while at the speed of light time passes infinitely slow for you, it passes infinitely fast for the universe, which would very abruptly end your exploration. We will not be exploring any significant portion of our galaxy without rewriting our current theory, inventing a game changing technology, or maybe discovering some phenomena.

I think it's technically possible to explore our own galaxy in a human lifetime by accelerating to an appreciable fraction of c, just need to develop fusion rockets.

rbanffy 6y ago

Fusion rockets are not nearly enough for that. You'd still need to carry an impossible amount of propellant, deal with friction and live through the months-long acceleration/deceleration cycles, most of which at non-relativistic speeds. If you got a ramscoop engine, maybe you'd be able to grab enough propellant to push you at 1g for years at a time while cleaning your path of particles that'd impact your shielding.

close04 6y ago

Even at the speed of light, taking into account acceleration and deceleration you could cover ~50 light years in a lifetime. The Milky Way is ~150000 light years across. In day to day terms it's like walking 10km relative to exploring the whole Earth.

phonypc 6y ago
I'm sure someone better informed could weigh in with more details, but IIRC, taking time dilation into account, you could explore infinitely if you could somehow travel at the speed of light. Some large fraction of c would be sufficient to cross the galaxy in a lifetime, relative to you the traveller.
- perl4ever 6y ago
  Yes, but taking into account any drive that uses mass you couldn't carry enough to accelerate for very long. There's been a lot of speculation about scooping up hydrogen from the interstellar medium as fuel, but I think it's mainly wishful thinking. https://en.wikipedia.org/wiki/Bussard_ramjet https://en.wikipedia.org/wiki/Bussard_ramjet https://en.wikipedia.org/wiki/Tau_Zero https://en.wikipedia.org/wiki/Tau_Zero
- close04 6y ago
  In 50 years experienced by the explorer inside the ship, at a more "realistic" speed of 0.9c the ship would travel ~115 light years, and at 0.99c it would do ~350 light years (excluding gravitational time dilation). Anything higher than that would probably be a bit incomprehensible for the human mind. At 0.99999c the ship would travel ~11000 light years, all of which would be fully experienced by the people at home. That's for the dash, the exploration itself comes on top of that. And while at the speed of light time passes infinitely slow for you, it passes infinitely fast for the universe, which would very abruptly end your exploration. We will not be exploring any significant portion of our galaxy without rewriting our current theory, inventing a game changing technology, or maybe discovering some phenomena.