I understand the concept of spacetime being warped (I’ve seen the rubber sheet analogy a thousand times), but does that mean that everything is *technically* always traveling in a straight—albeit warped—line?
In: 2
If you can answer the title question, bravo, it isn’t straightforward.
The second question is easier – no, things don’t normally move in straight lines (on earthly scales) because we usually have other forces exerted, often friction in some way. Pretty much all human-derived motion is “unnatural” from a gravitational point of view – cars go up hills, trains go huge distances without slowing down, and elevators are frankly just mocking the universe.
On a grander, cosmic scale yeah, everything goes in close to straight lines (technically geodesics because you’re not in flat geometry any more). The exceptions are really high energy electromagnetic stuff like accretion disks for black holes which are just maelstroms of energy of all kinds, plus pulsars, magnetars, that kind of oddness. Basically if you look at an object and have to start calculating precisely which way your spaceship hull will melt, you probably shouldn’t trust things will move along local geodesics.
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