6 ms·

> If you accelerate at 1g constantly for 1y you travel 0.5 light years Can't we accelerate past 1G constantly? Or do we expend so much energy doing it that we

> If you accelerate at 1g constantly for 1y you travel 0.5 light years Can't we accelerate past 1G constantly? Or do we expend so much energy doing it that we can't realistically do it with today's technology?

mjmas 7d ago
We can't necessarily survive that well when under acceleration greater than 9.81 metres per second per second for extended periods of time.
- lostlogin 7d ago
  Gravity on Earth varies about .7%. Increasing the acceleration a little bit more than that (eg to 1%) would make a difference. https://en.wikipedia.org/wiki/Gravity_of_Earth https://en.wikipedia.org/wiki/Gravity_of_Earth
  - rrr_oh_man 7d ago
    > "Increasing the acceleration a little bit more than that (eg to 1%) would make a difference." Wouldn't that be only a few months on a decades-long journey at 1.01G vs 1G??
    - lostlogin 6d ago
      I was thinking of journeys that are hundreds or thousands of years. If the acceleration was too great but survivable, what happens? I can’t imagine my back, knees or ankles would like it.
wallst07 7d ago
We can easily accelerate past 1g... 1g is just chosen for human comfort, but running any rocket engine continuously for a year requires an impossible amount of fuel.
jdjfbfbdbfnf 7d ago
We need a massive rocket to escape the earths gravity (1g). That takes us minutes and a crap ton of fuel. The issue is to keep doing that with fuel and oxidiser constantly for 1, 2 or 10 or 25 years is a monumental amount of energy, which is a monumental amount of weight, which is a monumental amount of volume... Also you also need the exact same amount of fuel to stop again.... So yeah ... We don't got it yet
TheOtherHobbes 7d ago
We can't do it with any rocket-like propulsive technology. By the time you get anywhere close to c the front of your spacecraft is being abraded into nothing by interstellar gas, larger particles of dust will kill you, and colliding with anything bigger creates an explosion that can be seen for light years. You need to be flying a large asteroid to even think about surviving it - you still won't for long, but you will have time to think about it - and the energy requirements are wildly impractical. Magic warp bubble tech is the bare minimum, and we're nowhere close to inventing that.
myrmidon 7d ago
Sadly there is no realistic approach to get there (even assuming fantasy-levels of technology). Chemical rockets are currently the only thing that allow sustaining such accelerations briefly for human-size payloads, but the low exhaust velocity and exponential reaction mass requirement make sustaining it for days/months/years completely impossible. You'd have to supply the energy externally (i.e. some sort of beam propulsion), but getting any significant fraction of g out of such a system (with human-sized payloads) seems unlikely within the next centuries, especially as the distance increases.
- consp 7d ago
  > You'd have to supply the energy externally (i.e. some sort of beam propulsion), but getting any significant fraction of g out of such a system (with human-sized payloads) seems unlikely within the next centuries, especially as the distance increases. Or some form of ram scope, plenty of H everywhere, but those also have the issue of you collecting things while going at relativistic speeds.
  - 21asdffdsa12 7d ago
    You need ablative ships cruising ahead of you..
40four 7d ago
Not with current technology. That was kind of the physics “trick” in the book ‘Project Hail Mary’, where the astrophage provided enough energy and propulsion to be able to sustain 1G of acceleration.
- Enginerrrd 6d ago
  The astrophage was pumped around the ship to act as shielding for cosmic rays too.
SideburnsOfDoom 6d ago
> Can't we accelerate past 1G constantly? It's hard to accelerate at or beyond 1G for very long with current technology. Roughly speaking, the rocket runs out of fuel soon. Packing more fuel makes the rocket heavier, meaning diminishing returns when using the fuel. The mass required grows exponentially. See "The tyranny of the rocket equation"

mjmas 7d ago

We can't necessarily survive that well when under acceleration greater than 9.81 metres per second per second for extended periods of time.

lostlogin 7d ago
Gravity on Earth varies about .7%. Increasing the acceleration a little bit more than that (eg to 1%) would make a difference. https://en.wikipedia.org/wiki/Gravity_of_Earth https://en.wikipedia.org/wiki/Gravity_of_Earth
- rrr_oh_man 7d ago
  > "Increasing the acceleration a little bit more than that (eg to 1%) would make a difference." Wouldn't that be only a few months on a decades-long journey at 1.01G vs 1G??
  - lostlogin 6d ago
    I was thinking of journeys that are hundreds or thousands of years. If the acceleration was too great but survivable, what happens? I can’t imagine my back, knees or ankles would like it.

wallst07 7d ago

We can easily accelerate past 1g... 1g is just chosen for human comfort, but running any rocket engine continuously for a year requires an impossible amount of fuel.

jdjfbfbdbfnf 7d ago

We need a massive rocket to escape the earths gravity (1g). That takes us minutes and a crap ton of fuel. The issue is to keep doing that with fuel and oxidiser constantly for 1, 2 or 10 or 25 years is a monumental amount of energy, which is a monumental amount of weight, which is a monumental amount of volume... Also you also need the exact same amount of fuel to stop again.... So yeah ... We don't got it yet

TheOtherHobbes 7d ago

We can't do it with any rocket-like propulsive technology. By the time you get anywhere close to c the front of your spacecraft is being abraded into nothing by interstellar gas, larger particles of dust will kill you, and colliding with anything bigger creates an explosion that can be seen for light years. You need to be flying a large asteroid to even think about surviving it - you still won't for long, but you will have time to think about it - and the energy requirements are wildly impractical. Magic warp bubble tech is the bare minimum, and we're nowhere close to inventing that.

myrmidon 7d ago

Sadly there is no realistic approach to get there (even assuming fantasy-levels of technology). Chemical rockets are currently the only thing that allow sustaining such accelerations briefly for human-size payloads, but the low exhaust velocity and exponential reaction mass requirement make sustaining it for days/months/years completely impossible. You'd have to supply the energy externally (i.e. some sort of beam propulsion), but getting any significant fraction of g out of such a system (with human-sized payloads) seems unlikely within the next centuries, especially as the distance increases.

consp 7d ago
> You'd have to supply the energy externally (i.e. some sort of beam propulsion), but getting any significant fraction of g out of such a system (with human-sized payloads) seems unlikely within the next centuries, especially as the distance increases. Or some form of ram scope, plenty of H everywhere, but those also have the issue of you collecting things while going at relativistic speeds.
- 21asdffdsa12 7d ago
  You need ablative ships cruising ahead of you..

40four 7d ago

Not with current technology. That was kind of the physics “trick” in the book ‘Project Hail Mary’, where the astrophage provided enough energy and propulsion to be able to sustain 1G of acceleration.

Enginerrrd 6d ago
The astrophage was pumped around the ship to act as shielding for cosmic rays too.

SideburnsOfDoom 6d ago

> Can't we accelerate past 1G constantly? It's hard to accelerate at or beyond 1G for very long with current technology. Roughly speaking, the rocket runs out of fuel soon. Packing more fuel makes the rocket heavier, meaning diminishing returns when using the fuel. The mass required grows exponentially. See "The tyranny of the rocket equation"