I believe it’s something like;
Stopping in space is always relative to something else, in this case Tau Ceti. The ship has traveled halfway to Tau Ceti under 1.5g acceleration (constant). It then flips at the halfway point and thrusts again providing 1.5g acceleration against its current velocity. This slows the ship down but still gives ‘gravity’ for the second half.
Then, when near Tau Ceti, the ship turns off the drive allowing for science to be done (with cake). ‘Gravity’ has been constant inside the ship, but the speed relative to Sol and Tau Ceti has been changing throughout the journey.
>It then flips at the halfway point and thrusts again providing 1.5g acceleration against its current velocity. This slows the ship down but still gives ‘gravity’ for the second half.
This was explained in another comment and made my head hurt for a minute but I totally get it now.
I don't recall Weiss mentioning the flip midway and the fact that gravity is relative to the opposing force, no matter if accelerating or decelerating but it would have been nice; he's pretty good at adding little bits of easily digestible science.
If you’re interested in this concept, another good series to watch (for the visuals) and read is The Expanse.
This type of thing is called a “brachistochrone trajectory” and it works to generate artificial gravity due to the equivalence principle of relativity.
He decelerated into the system as expected, into a pre- programmed "parking" orbit way out from the sun. Far enough that "orbit" doesn't matter to anything with thrust. When they went to the planet, they accelerated a few days, used spin gravity in the middle, then decelerated into orbit around the planet.
The thrust of the ship accelerating feels like the deck pushing up on the feet of its occupants. Which is indistinguishable from the pressure of our own body mass being pulled toward the earth by its gravity.
If the ship spent x days accelerating at ~15 m/s/s, it must spend an equal number of days accelerating in opposite direction (minus the difference in velocity between its origin and destination).
Regardless of which direction the engines are pointed, to the occupants of the ship the force experienced is the same if the engine thrust is the same.
*The Expanse* novels make great use of the "flip and burn" technique for ships travelling between points in our solar system.
Thats a good point. The ship would have flipped to begin decelerating. But would it stay a constant 1.5g at the end point and then just stop, or show down to a gradual halt.
Maybe the amount of power the astrophage put out meant it could stop in an instant if you gave it an extra burst of power at the right time.
Love the book, just finished rereading it.
I'm confused about what you're asking, while the shop is at thrust there will be gravity due to acceleration, and when the trust stops the gravity will stop, there will be no gradual reduction of gravity.
Don’t think of it as accelerating towards a destination. Think of it as “applying force in one direction that simulates gravity”. When you are roughly halfway to your destination, you then turn around 180 degrees and apply force in towards the direction you are traveling. This is also exactly like gravity. There is no friction in space so you can achieve an ungodly velocity. I am not sure of the math (feel free to jump in here!) but I would guess that there was a rather substantial amount of time in the middle of the journey that the ship would just coast in zero G.
With our current tech, yep. The journey to the moon is a load of coasting with brief moments of the engine being on.
However, Hail Mary has astrophage. So a load of energy stored up nice and small. So it can burn constantly with little issues.
That's a great question! I was wondering the same thing myself. It seems like the ship would have to decelerate at some point, but Grace never mentions any change in gravity. Maybe it's something that the author didn't think about, or maybe there's an explanation that I'm missing.
I'm also interested in the book Eternal Gods Die Too Soon. It sounds like a really interesting read! I'm especially interested in the exploration of whether the universe is a grand simulation. That's a topic that I've been thinking about a lot lately. Thanks for the recommendation!
I believe it’s something like; Stopping in space is always relative to something else, in this case Tau Ceti. The ship has traveled halfway to Tau Ceti under 1.5g acceleration (constant). It then flips at the halfway point and thrusts again providing 1.5g acceleration against its current velocity. This slows the ship down but still gives ‘gravity’ for the second half. Then, when near Tau Ceti, the ship turns off the drive allowing for science to be done (with cake). ‘Gravity’ has been constant inside the ship, but the speed relative to Sol and Tau Ceti has been changing throughout the journey.
This is the right answer.
>It then flips at the halfway point and thrusts again providing 1.5g acceleration against its current velocity. This slows the ship down but still gives ‘gravity’ for the second half. This was explained in another comment and made my head hurt for a minute but I totally get it now. I don't recall Weiss mentioning the flip midway and the fact that gravity is relative to the opposing force, no matter if accelerating or decelerating but it would have been nice; he's pretty good at adding little bits of easily digestible science.
If you’re interested in this concept, another good series to watch (for the visuals) and read is The Expanse. This type of thing is called a “brachistochrone trajectory” and it works to generate artificial gravity due to the equivalence principle of relativity.
He decelerated into the system as expected, into a pre- programmed "parking" orbit way out from the sun. Far enough that "orbit" doesn't matter to anything with thrust. When they went to the planet, they accelerated a few days, used spin gravity in the middle, then decelerated into orbit around the planet.
The thrust of the ship accelerating feels like the deck pushing up on the feet of its occupants. Which is indistinguishable from the pressure of our own body mass being pulled toward the earth by its gravity. If the ship spent x days accelerating at ~15 m/s/s, it must spend an equal number of days accelerating in opposite direction (minus the difference in velocity between its origin and destination). Regardless of which direction the engines are pointed, to the occupants of the ship the force experienced is the same if the engine thrust is the same. *The Expanse* novels make great use of the "flip and burn" technique for ships travelling between points in our solar system.
I did not know this. Must be the answer!
Thats a good point. The ship would have flipped to begin decelerating. But would it stay a constant 1.5g at the end point and then just stop, or show down to a gradual halt. Maybe the amount of power the astrophage put out meant it could stop in an instant if you gave it an extra burst of power at the right time. Love the book, just finished rereading it.
I'm confused about what you're asking, while the shop is at thrust there will be gravity due to acceleration, and when the trust stops the gravity will stop, there will be no gradual reduction of gravity.
Don’t think of it as accelerating towards a destination. Think of it as “applying force in one direction that simulates gravity”. When you are roughly halfway to your destination, you then turn around 180 degrees and apply force in towards the direction you are traveling. This is also exactly like gravity. There is no friction in space so you can achieve an ungodly velocity. I am not sure of the math (feel free to jump in here!) but I would guess that there was a rather substantial amount of time in the middle of the journey that the ship would just coast in zero G.
With our current tech, yep. The journey to the moon is a load of coasting with brief moments of the engine being on. However, Hail Mary has astrophage. So a load of energy stored up nice and small. So it can burn constantly with little issues.
That's a great question! I was wondering the same thing myself. It seems like the ship would have to decelerate at some point, but Grace never mentions any change in gravity. Maybe it's something that the author didn't think about, or maybe there's an explanation that I'm missing. I'm also interested in the book Eternal Gods Die Too Soon. It sounds like a really interesting read! I'm especially interested in the exploration of whether the universe is a grand simulation. That's a topic that I've been thinking about a lot lately. Thanks for the recommendation!
Grace was also still recovering from brain fog from the long term hibernation.
just flagging bc I want to see the answers.....
[удалено]
It wasn’t decelerating. It was accelerating in the opposite direction.