this post was submitted on 20 Aug 2024
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Space-time itself is curved, therefore there is no such thing as a straight line.
Not true, as when space bends, it bends the rulers and compasses too. We experience no spatial distortion.
A person traveling near the speed of light doesn't feel like time is slower for them (but it is and we can measure it)
The principle is equivalent.
That said, it's not a straight line in any topology standard I am aware of.
Sure you could CREATE a topology framework where this would be considered a straight line, but there is no real world model that could come even close without so much mass being concentrated in static relative areas, and EVEN THEN it would only be straight for a predetermined instant before the mass deforming spacetime began interacting with each other.
That's the problem with spacetime deformations, almost no layman takes into account the ridiculous amounts of static mass to make those strange topologies.
Space-time itself is curved, therefore everything is moving in a straight line, it only appears to be curved to the outside observer
We have geodesics for that.
If anyone wants to grasp the basics: here is some fun reading (leading on to some beautiful math). Changing the idea of parallelity leads to hyperbolic geometry and other fun stuff. :)
Please correct my layman understanding if I'm wring here. But isn't everything traveling in a straight line until an external force is applied. For example the earth orbiting the sun is traveling in a straight line in a curved apacetime. Also if you jump, the moment you leave the ground until you touch it again coming back down you were traveling in a straight line.
I dunno lol
relative to the body of earth, including its rotation it would be an arc path, and including it's tilt it would be 3d, if we also include the travel around the sun in orbit, that elongates it around the orbit, so uh.
In my understanding, since gravity is acting on us, an external force is applied when we jump. That's why a jump is a parabola. "Gravity's Rainbow"
What they are getting at is that gravity is not a force so much as your mass trying to travel in a straight line through curved spacetime. The weight you feel is because the surface of the earth is in your way.
Get into low earth orbit and that straight path has you going in apparent circles around the planet. You are very much within the earth’s gravity but you don’t feel “weight” because the surface of the earth is no longer blocking your path. You still have mass and inertia and all that, of course.
Yes, that's exactly what I meant :D