this post was submitted on 04 Jun 2024
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I thought it was widely agreed that time was a construct?
It has been a common belief in philosophical circles for centuries, but not among physicists. Both Newton and Einstein thought of time as being one of the fundamental properties of the physical universe.
However, in the past decade or two, some theoretical physicists have now come back around to the idea that space and time could instead be emergent properties of a deeper, underlying reality.
If you really want to go cross-eyed, read up on the holographic principle.
My favorite theory is that time and space are reversed in a black hole which could be at the beginning and the end of the universe.
This is the crux of quantum field theory, no? Where Newtonian and Einsteinian physics are all entirely emergent properties of fields that are governed by quantum principles? I’m in the cross-eyed camp so I’m way out my depth.
"Einsteinian" physics do unfortunately not arise from quantum physical principles, which is the major flaw in our current understanding of the universe. Quantum physics is very applicable to the microcosm, but cannot accurately solve for the macrocosm, while it is the opposite for gravitational theory.
In relativity time is a real dimension like space , but of a different type, and your speed in time depends on your speed in space and on your proximity to big masses, like planets. This kind of physics is necessary to keep the satellites synchronised otherwise their clocks go at a different speed from those on earth, so this is all very real and confirmed.
The way i understand it is that a faster or heavier object has more energy, thus bends spacetime more.
It's far stranger than that.
The problem that shows exactly how tangled the problem is, is this: accelerating is the same as gravity.
Not "they feel the same" or "We can compare them" or " They're similar in many ways" no, I mean literally. They are the same thing. This has been proven.
The force that is making you stick the planet is the same as being in a car and driving constantly faster and faster forever.
If this makes zero sense to you, that's good, it means you're human. But it also means that our vision of the universe is radically different than whatever kind of objective reality is out there, if there is one.
(What gives is time. Time is what's changing when you move through space AND when in a gravitational field. You can also study this field for decades and barely come closer to being able to visualize it. Our brains were not meant.)
But this is consistent with what i said? Not moving and no mass = frozen in spacetime. Which is why it needed big bang as external factor to spread spacetime (i.e. change to unchanging environment). Right?
You're always moving at the speed of light through time. When you accelerate, you are borrowing from your speed through time and converting it to speed through space. The faster you move through space, the slower you move through time. The faster you move through time, the slower you move through space.
What does it mean to move slower through time?
That's another great question that unlocks another incredibly strange point about reality.
You're only moving faster/slower through space/time to an outside observer. Your own rate of time and your own velocity through space will always feel centered on you, and it will always look like the rest of the universe that is slowing or accelerating.
And in fact, another mind-melty point behind relativity is that if you jump out of a 20th story window, there is no action that says you're falling, instead the action is saying that you have changed your velocity (or altered Earth's velocity in respect to your acceleration) and now the rest of the world is passing you very rapidly. It would feel like Earth and the building and everything else is wooshing past you while you stand still. And that's a correct perspective. It is rushing past you, you are sitting still in space. (The problem comes when that wall of asphalt and dirt swings past and doesn't miss you.)
If you fall into a black hole where spacetime is distorted as far as we can imagine, to you nothing will feel different (at first) you will see the whole universe seem to roll into a tight ball behind you and it will look like it's in rapid-motion if you pointed a telescope into it, you would see stars being born and galaxies fading and the entire future of the universe will rush past and you will hit the singularity at the death of the back hole, some billions and billions and of years into the future. If you could magically escape right before you get pulled apart, you would find the entire universe has died outside and all the stars have gone out.
Wow that’s amazing to think about
Time passes more slowly for you than for an outside observer, e.g., if you are moving to some place, for someone on the outside, your journey could take decades, while for yourself only minutes pass.
So moving faster at some point starts to become slower because everything around you has the benefit of having more time to move?
They're talking about time dilation.
Objects with no mass traveling at light speed in a vacuum don't experience time.
A photon, traveling through a vacuum for forty years, from its perspective, leaves the instant it arrives.
Likewise, if you can travel at the speed of light for forty years and came back to earth, your twin would age forty years and you wouldn't age at all.
At a much smaller scale we have to use time dilation to keep clocks in space running at the same time as clocks on Earth. Because in geosynchronous orbit they are traveling faster than objects on the ground.
Ah right, i got it the wrong way around again.
Time is, change isn't. Time is how we measure change.