this post was submitted on 14 Apr 2024
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The time machine would use gravity so it can arrive at the same relative position in a different time. But that only gets you on the planet, not the same position on the planet.
How would rotational movement be accounted for in a generic way?
I don't know how it would be accounted for in your imagine time-machine. Because they don't exist.
What I do know. Is that you don't need gravity to "detect" earths rotational speed. Because we already know what it is.
We know the rotational speed, but this time machine wouldn't.
And is there a reason you couldn't program that data into the machine?
Doesn't that sound like something you'd need? Along with a mathematical model of how earth orbits the sun?
If the machine has the ability to jump in time and space (needed to land in the same spot) then it would be a real waste to use it only on earth.
So we would need a mathematical model of the entire universe that is accurate to the metre over all time. This N body is much harder than the 3 body problem.
Or we use gravity and other methods to track relative stationary position.
So, what other methods can be used to determine rotation?
Jesus fucking Christ. We can still calculate the rotation of a body like we normally do.
You observe it. Wait 1 seconds. Observe it again. And the delta in position is your rotational speed per second.
That is the method. The only one
So all travels to new planets require 2 jumps. One to get near and measure the rotation, and one to actually land. I'd prefer something more efficient.
Also there is the assumption that the surface rotational velocity is constant over time. This is only true for solid planets without gas or liquid centers. Insides can spin at different speeds than the surface.
I don't even know what this conversation is about anymore. You wanna go inside a gas giant now?
How about this. When you develop timetravel through space in all dimensions to "jump" anywhere at any time. Let us know.
It's about how a theoretical time/space machine would navigate obeying current physics knowledge.
I'd like the option. I'd certainly like to land on planets with liquid cores.
Nah. Let's design the solution now so it's ready to be used when needed.
When developing. You solve one problem a time. So you don't spend time trying to calculate rotation from gravity.
The beauty of a time machine on earth. Is that we can imagine most of it, and add the time travel part with our imagination to make it "plausible"
You want to add instant teleportation to any point in space at any time, while knowing everything about every planet and star including their location. Instantly.
I have a magical spell that already does everything you want. It's called "goannoyium-someoneelsium-fuckwad".
I already solved your little problem
Teleportation is not being added by me. It's the topic of this entire thread. Even calculating the rotation of just the earth at other points in time is not trivial because Earth has an unobservable liquid core.
No. You didn't.
Didn't we recently discover the core is solid?
Did we? The inner core maybe, but there's definitely some liquid somewhere, cos of volcanoes.
It's not something that is currently predictable though. We don't have decent models for the magnetic field.
Well there's magma under the crust but the core is solid.
The inner core is solid. The outer core is 2000km of liquid.
But the main point is that both of these layers could vary their spin, making long term predictions about the rotation of the crust inaccurate.
I did. The spell puts anyone anywhere at anytime. And it works by whatever exact imaginative solution that doesn't exist you want. Pretty cool huh.
Dunno. How does the spell work? How can we be sure it works 100% of the time?