I recently was told that we know there’s only one time dimension because otherwise we’d pivot between different dimensions of time, as we are able to do in space. But I still don’t understand, other than paradoxes and causality, why we can’t move backwards in time.
Even on a 1D spatial plane [edit to say yes… a line, not a plane.] we would be able to move forwards and backwards.
But we can’t with time. Why?
In: Physics
Relativity. It’s the laziest way I can say it. You put a dot on a one-dimensional line and it can move forward and backward as much as it wants. As soon as you put a second dot on that line, the second dot can go forward as much as it wants, but can’t go back beyond the first dot.
Our bodies, and everything around us, are constantly changing. You’re unable to reverse these changes by simply moving differently.
We don’t know why things cannot move different directions in time. We only know they do. It could just be a set property of the universe.
But if we could move different directions in time, the universe could probably not exist, at least as we know it, and no kind of life could develop, or even molecules. Everything would just kind of exist in a now, where there are no causes and effects, and everything is at an equilibrium. Anything trying to move forward temporarily, would be countered by moving backwards.
BTW, a plane is 2 dimensions. A line would be 1 dimension.
Mass and energy are the same thing, each can be converted onto the other, so I will just refer to them both as mass.
The universe has a finite amount of mass, it stays the same whatever happens. Travelling back in time would mean that your mass would be added to the mass of the universe. But the mass of the universe is constant so this cannot happen.
You’re not moving AT ALL in time. You’re riding the “present”, like the rest of the universe. You don’t have any organs (like legs) or devices (like cars or rockets) that would allow you to actually MOVE (to the future or to the past) independently of what the universe is doing. It’s not like space, where you CAN move because you have legs / spaceships.
Thank you. It’s just au hard to conceive of non-linear time. This is really helpful. It’s tricky because ducks can reorganize themselves in a row, so I’m imagining rubber duckies now.
There’s also a metaphor here about my chronic fatigue, the mess in my house, and having a friend come in and help clean but in reality the ducks are more helpful.
The increase of entropy (in simple, but slightly incorrect terms, chaos) is what dictates time. In a closed system, the increase of entropy is the only way to “see” time. Entropy can only increase in a closed system like the universe, it takes added energy to decrease entropy. Because we cannot add energy to the universe, like someone else said, entropy cannot be decreased, thus time cannot flow backwards.
If you want to dive WAY beyond “like I’m 5” statistical thermodynamics is what really put it into perspective for me.
> Even on a 1D spatial plane
A 1D “Spatial plane” is a Dot. not a line.
You cannot move forward or backward on a dot.
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