Comment by ExoticPearTree
9 hours ago
> 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?
9 hours ago
> 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?
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.
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.
> 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.
You need ablative ships cruising ahead of you..
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.
The astrophage was pumped around the ship to act as shielding for cosmic rays too.
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.
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
We can't necessarily survive that well when under acceleration greater than 9.81 metres per second per second for extended periods of time.
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
> "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??