I was watching the episode of Carl Sagan’s Cosmos where he explains the hyper-cube and how we can’t see the fourth dimension, but we can a see projection from the 4th dimension into three dimensional space.
This got me thinking about what time actually was, considering Sagan was referring to a spatial dimension and not time. I then searched and found a Straight Dopes on the matter.
In the article “Dex” states:
This got me wondering whether or not time had multiple dimensions, but unfortunately there was no definitive information on the subject to be found anywhere.
I then reflected on one of my previous posts where I dismissed the idea that sending information faster than the speed of light would be tantamount to sending information back in time.
I started to wonder what time was and how something like time could be compressed. I know that I exist in space time, which is the point where my space meets my time, similar to how two planes converge at a single vector.
It makes me think about scrubbing through video. I can open a video and move the slider watching as each frame of video is rendered. Would it make sense to make such a comparison?
Does time itself have any attributes like velocity? Is that why gravity is able to impede its flow, and is that why travelling faster makes time slow down? If this is the case why is it we always seem to travel along with time and never against it? I ask this question because if you think about relative speed on a highway, the traffic moving in the same direction as you always appears slower than the traffic you moving in the opposite direction. Why is it time always slows down as speed increases, what would you need to do to get the opposite effect?
If time does have something like velocity, would we even notice if that velocity changed? Is it possible that this velocity is slowing down or speeding up, and could it reverse? Maybe time is like a pendulum, it goes forward slowing down as it hits its apex and then swings in reverse. But also like a pendulum, if time is affected by gravity does that mean it’s doomed to reach an inevitable stop?
Here is a recent thread that asks a very closely related question, and the discussion generally addresses this question.
Bottom line is that nobody knows what time really is. Some scientists think that the perception of the forward flow of time is an artifact of the human mind, hence the title of the following thread.
For the parts of your question dealing with relativity, it might help to look at speed as a rotation. For starters, consider a stick. Hold that stick in some random orientation in a coordinate system, and you can find the “height” of the stick (the z coordinate of the top of the stick minus the z coordinate of the bottom), and the “length” of the stick (the x coordinate of one end minus the x coordinate of the other), and the “width” (the difference in y coordinates). Now, if you use a different coordinate system, or hold the stick in a different orientation, then all of these measurements will change. But that’s nothing weird, it doesn’t reflect anything about the stick itself changing, it’s just a matter of the coordinates you use. But in any coordinate system you use, you can take (height)^2 + (length)^2 + (width)^2, and you’ll always get the same answer, and that does tell you something about the stick itself.
Well, now let’s extend this to spacetime. If I take two points in spacetime, and look at them in different coordinates, I can get different values for the length, or width, or height, or even different values for the separation in time between two points. But if I take (length)^2 + (width)^2 + (height)^2 - (separation in time)^2, I always get the same value. That’s what’s inherently real, and the changing things are just artifacts of the coordinate system I happen to be using.
Likewise, every object is always moving at speed 1 (otherwise known as c) through spacetime. That motion is a combination of motion through space and motion through time, but exactly what combination depends on your coordinate system. If you’re using a coordinate system where you’re at rest, then all of your motion through time, so you’re moving through time at a rate of 1 second per second. If you’re using a coordinate system where something is moving through space, then its motion through time must correspondingly be different, to keep the total speed at 1.
I think it’s only the agency that sorts causes before effects, and it seems to us to flow because we do our thinking with our brains, whose only evolved function is to manipulate effects through causes.