this post was submitted on 14 Apr 2024
1295 points (95.6% liked)

Science Memes

10340 readers
1097 users here now

Welcome to c/science_memes @ Mander.xyz!

A place for majestic STEMLORD peacocking, as well as memes about the realities of working in a lab.

Rules

  1. Don't throw mud. Behave like an intellectual and remember the human.
  2. Keep it rooted (on topic).
  3. No spam.
  4. Infographics welcome, get schooled.

Research Committee

Other Mander Communities

Science and Research

Biology and Life Sciences

Physical Sciences

Humanities and Social Sciences

Practical and Applied Sciences

Memes

Miscellaneous

founded 2 years ago
MODERATORS
[email protected]
[email protected]
[email protected]
1295
we live in an explosion (mander.xyz)
submitted 5 months ago* (last edited 5 months ago) by [email protected] to c/[email protected]
168 comments fedilink hide all child comments
 
you are viewing a single comment's thread
view the rest of the comments
[–] [email protected] 1 points 5 months ago (1 children)

Why would it only work on earth? How do you think we took close up pictures of pluto?

[–] [email protected] 1 points 5 months ago (1 children)

It would only work on earth because we've only given the time/space machine information about the rotation of the earth.

But my question is more about science theory than fiction. Does observing gravity give any information about how fast that mass is rotating?

[–] [email protected] 1 points 5 months ago (1 children)

"It would only work on earth because we’ve only given the time/space machine information about the rotation of the earth."

So you're the one that only wants it to work on earth then.

And no. "Observing" Gravity does not give any information of how fast an object is spinning around it's own axis.

[–] [email protected] 1 points 5 months ago (1 children)

So you're the one that only wants it to work on earth then.

No. Are you suggesting we supply this machine with the rotational velocity of all planets in the known universe? Or some other solution?

How could we jump to a planet on the other side of the galaxy?

[–] [email protected] 2 points 5 months ago (1 children)

Is this a time machine or a star-trek space ship? This thing keeps changing

[–] [email protected] 2 points 5 months ago (1 children)

What? This whole thread is discussing how a time only device is useless.

[–] [email protected] 1 points 5 months ago (1 children)

No, some are talking about how it needs to detect gravitation from other planets.

That has nothing to do with a time machine working on earth.

[–] [email protected] 1 points 5 months ago (1 children)

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?

[–] [email protected] 1 points 5 months ago (1 children)

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.

[–] [email protected] 1 points 5 months ago (1 children)

We know the rotational speed, but this time machine wouldn't.

[–] [email protected] 2 points 5 months ago (1 children)

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?

[–] [email protected] 1 points 5 months ago (1 children)

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?

[–] [email protected] 1 points 5 months ago (1 children)

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

[–] [email protected] 1 points 5 months ago (1 children)

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.

[–] [email protected] 1 points 5 months ago (1 children)

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.

[–] [email protected] 2 points 5 months ago (1 children)

I don't even know what this conversation is about anymore.

It's about how a theoretical time/space machine would navigate obeying current physics knowledge.

You wanna go inside a gas giant now?

I'd like the option. I'd certainly like to land on planets with liquid cores.

How about this. When you develop timetravel through space in all dimensions to "jump" anywhere at any time. Let us know.

Nah. Let's design the solution now so it's ready to be used when needed.

[–] [email protected] 1 points 5 months ago (1 children)

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

[–] [email protected] 1 points 5 months ago (2 children)

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.

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.

I have a magical spell that already does everything you want. It's called "goannoyium-someoneelsium-fuckwad". I already solved your little problem

No. You didn't.

[–] [email protected] 2 points 4 months ago (1 children)

Didn't we recently discover the core is solid?

[–] [email protected] 1 points 4 months ago (1 children)

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.

[–] [email protected] 1 points 4 months ago (1 children)

Well there's magma under the crust but the core is solid.

[–] [email protected] 1 points 4 months ago

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.

[–] [email protected] 1 points 5 months ago (1 children)

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.

[–] [email protected] 1 points 4 months ago

Dunno. How does the spell work? How can we be sure it works 100% of the time?