u/Opening_Ad9824

A lot of talk here about how time runs at different speeds depending on forces applied or speeds traveled.

People really seem to believe it, like it’s taken as gospel that clocks tic at different rates at different locations. GPS offset examples etc etc.

But is this even accurate? Are you not just describing the Doppler effect or redshifting of the observation of time, rather than time itself?

Meaning if we launched in a UFO and flew away from earth at high speed, a clock on earth would appear to be ticking slowly. “Appear” to tic slowly. Because the light or the signal from earth would be arriving in a stretched or delayed manner to our moving UFO.

But if we suddenly banged a u-turn and headed towards earth at high speed, wouldn’t we start receiving those signals in a compressed fashion? So “time” would “tic” “faster” from our perspective?

But once we made it back home to earth, the outgoing and returning time dilations would cancel out, and our watches would still be synchronized to earth time?

So by this understanding time doesn’t dilate at all, it’s just the viewing of information which stretches and compresses? Is that correct?

If so why do we talk about bent spacetime like it’s a real thing out there somewhere past the moon?

I am just wondering if the assembly line is still building vehicles in spring/summer of 2026. I believe they were building the f150 lightning electric pickups there, but I heard that program was canceled in 2025. Are you able to actually see action on the tour? Thanks

Got another ELI5 gravity question for y’all. Been trying to visualize this one in my head.

So if gravity is accelerating me “down” at -9.7ms2 on the surface of earth… and you guys previously said that as a 🚀 leaves the surface of 🌍, the gravitational pull rapidly drops off so you “weigh less”. And you get super nerdy and say the spacetime is warped less the farther you go from earth per Einstein, GR, etc. Ok great got it.

But now for my thought experiment, we dig a tunnel straight down into the earth. Jules Verne style. Let’s say my tunnel goes 50% of the way from the surface to the center of the 🌎. Is the gravitational pull and my weight higher or lower than on the surface? In my head - it’s actually lower. Maybe it’s 25% lower. My rationale is that as I get underground to that point, now 25% of the mass of the earth is pulling away from the center of the earth, forces canceling each other out, so there’s less mass “under” me and therefore less gravitational pull. Maybe it’s even more than 25% lower, because net net there’s less mass “under” me, so that’s another effect.

If I continued to the exact center point of the 🌏, now I would float weightless, as the earth’s mass is all around me 360 degrees, all force vectors canceling each other out. Maybe I would feel some weight from the pull of the ☀️ and 🌙, but I would basically be weightless?

Okay so now let’s talk about spacetime bending. Do we have a scenario where the earth bends spacetime, but then inside the earth, spacetime inverts? How would we explain my weightlessness in terms of GR at the center of the planet?

PS - I also don’t understand how the core of the earth then keeps itself together, if there’s zero g in there, it should all fall apart right? Yet I seem to remember the geologists say the core is the densest part.

Both “forces” originate in “matter”, both have the inverse squared relationship with distance, both at least at first glance appear to pull matter closer together at a distance.

Why do physicists feel so strongly they have zero relationship and are completely disconnected from each other? Do they just feel they cannot question Einstein?

This time dilation theory of gravity doesn’t sit well with me.