Naked Universe of Ana
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Worldline and Geodesic in General Relativity
🕑 Added 2025-08-29 15:05:10 +0000 UTCOh yes, I have prepared a little surprise and expanded the topic. Actually I realized that geodesics are not the whole story I wanted to tell.
I dug up my old favorite book on GR and remembered that there are also worldlines.
So. Every object leaves a trace in spacetime. This trace is called a worldline. A planet, a satellite, you right now. Everyone has their own line that shows where and when they were. You are literally reading my post and your body is already leaving a worldline on the graph.
But there are special lines. If an object is not pushed or forced by anything except gravity, it moves along the straightest possible path in curved spacetime. That path is called a geodesic (now it feels like I finally explained exactly what I wanted).
So a geodesic is just a worldline without the extra kicks and bullshit, on pure chill.
A satellite on orbit flies along a geodesic. But a person in a rocket with engines on still has a worldline, only it is no longer a geodesic.
And now the thing I teased yesterday.
The three types of geodesics.
Timelike
These are trajectories for everything that has mass. An apple falling from a tree or an astronaut floating weightless are both just following such lines, as long as the rope doesn’t snap…
Lightlike
These are the routes for photons. They have no mass. Their own clocks don’t tick, but they still go straight. When light passes near a black hole its line bends together with spacetime.
Spacelike
These are purely mathematical trajectories. No physical object can move along them, because that would mean going faster than light. But they are exactly what cosmologists(losers who should get laid instead and do not create crazy ideas) need to measure distances and describe the geometry of the Universe.
So?
How do you feel rn about your prediction?:)
P.s. I added my best pics here😌😌
Comments
Andy pitman
Oh wow love to have more lessons from you beautiful and see more of that amazing mind and goddess body❤
Bags
And to think I was going to spend £8 on a physics book
Ana
LoL
Brian
haha yeah all my cosmologist friends are super losers
