What is “Time” and how exactly does it work?
In: Physics
“Time” is a measurement of change. In 3D space, you can measure distance and find the position of something. How do you then describe the period between measuring an object at different points? “Time” is the measurement that describes the period between two events.
“Time” is not fixed, it depends on a rate of change. Basically, the clock of “time” can run faster or slower. What changes how fast time flows is “mass.” A more massive object slows “time” as it “flows” past the object. The exact “why” is unknown, but this means that “time” slows down when near massive objects.
So what is it? It’s a measurement of change that can be affected by mass. Why mass slows “time,” we don’t fully know. The best way to understand is a river analogy. “Time” is some part of our universe that keeps flowing like a river. And like a river, they both slow down near the riverbank or “mass.” We use that flow to measure, we can see how the flow changes near mass, but we don’t know *exactly* what it is.
Most of these responses seem to be attempts at physics based explanations so here is a philosophical perspective: Aristotle defined time as the measurement of motion with respect to the before and after. In this sense time is a numerical value that describes how far apart the beginning and end of a motion (or more generally any change) are. As distance is the measurement of a given length, so time is a measurement of a motion across that length not counting the length itself. 🙂
I think Einstein was wrong that time is relative to motion. There must be a single & central present moment of NOW that applies equally to everywhere and everything that currently IS, no matter it’s relative motion or positioning in “spacetime”. In relativity, no such frame of reference (one NOW) exists. That’s absurd, isn’t it?
It’s the stretching of the glue that was holding the fabric of reality together that was blown apart by the big bang.
Time does not exist in the way we think. It’s not a line; that’s an oversimplification. Throw away any concept of linear time you have and try to see the world you navigate in as millions of small atoms. The movement, decaying and transformation of those atoms (and all other particles) is what we can call time, but it’s not bound to a global ‘timeline’. It all happens locally.
It seems this process seems to go slower when close to heavy objects (like Earth).
So in general when we zoom out, all across the earth the decaying / transformation process is about the same rate to our perception (although we do need to correct this on a low level sometimes in machines).
Its analogous to potential energy plus kinetic energy trade off of a ball on a hill. If the ball is at the top of the hill it has no kinetic energy but lots of potential energy, once the ball rolls down to the bottom and is moving fast it has no potential energy but lots of kinetic energy. Apparently time and space distance have a similar inverse relationship. While sitting still you have lots of time and no space distance, while moving really fast, like close to the speed of light, you have lots of space distance but hardly any time. Thats why time slows down when you go faster.
Asking two different physicists what time is and how it works is like asking a Hindu priest and a Presbyterian minister what “God” is and how god works. Both have probably spent a lifetime studying and thinking about that very question. They have very thought-through ideas about it that many many others believe as well. They may really believe that they have the one true answer. But the truth is that no one knows for sure. That’s not a very satisfying answer, but that’s how it is.
Here are the two most popular ideas:
Imagine an ant on the floor of an elevator. The ant can move left, right, forward, backward–any direction it wants, but only on the floor. To the ant, the floor is the only thing that exists. The elevator is moving up at a constant speed, and has been moving in that direction and at that speed for the ant’s entire existence, so the movement isn’t something it feels or notices. The two main ideas say that
1. the elevator floor is rigid and flat. The rocks and loose change on the floor just sit on top of the tiles. If the ant moves 1 tile left as fast as it can, the elevator has gone the same fixed distance up as when the ant moves its fastest a tile forward, back, etc.
2. the elevator floor is spandex with tiles printed right on the fabric. The rocks and loose change on the floor stretch it out where they’re sitting. Because the tiles aren’t all the same size and shape when they’re being stretched, if the ant moves its fastest one tile left, the elevator won’t have gone the same distance up as if the ant had gone one tile right. How much the elevator has gone up while the ant moves across a single tile depends on if/how stretched that tile is.
Time is the elevator shaft.
Edit: Thanks for the award!
Time is a gift, precious and rare, that helps you have the time you need to have the time of your life.
I like the Twilight Zone concept of time – it’s a train of dioramas. To travel through time, you hop off the train and walk (run?) to the car (time) you want. Like, the time stamp of my life 20 minutes ago (20 cars back) has me getting coffee. But fast forward 20 cars from now and you would see me brushing my teeth. Alternate timelines would be different trains.
This is similar to thinking of time as the 4th dimension. 1st dimension is a line – a collection of points. 2nd dimension is a plane – a collection of lines. 3rd dimension is our reality – a collection of planes. 4th dimension is time- a collection of momentary realities.
The problem with this image is that time is continuous – we don’t actually have a way to chop it into pieces. Yet? We say this second or this minute, but our starting point is kinda arbitrary. We have been able to coordinate with other people on our definition of time units by using natural phenomenon, but there is no time particle that we can count.
In my physics of space and time class (decades ago), there was a delightful image of time as a straight line going in one direction, until it reaches now – time zero. From there, it becomes a cone of possibility- do I continue sitting on the couch? Do I get up and brush my teeth? Do I hop in the car and go to the airport and board a flight to China? There is no option for me to suddenly be in China next – that event falls outside of the cone of possible events, into the area known as elsewhen.
I CAN be in China, later, but I can’t jump outside the cone to be in China now. I CAN go to Mars, but I’m gonna have to track the edge of that cone for a long time.
Not sure that answers the question, but it seemed relevant. If my professor couldn’t really give the answer to that question (and he was the editor of the Journal of Theoretical Physics, and at some point in the class smirked a bit and said, “This is MY contribution,” so I’m pretty sure he knew what he was on about), I’m not sure the answer is out there.
🤔⚡☀️”Time” is a measure of magnitudes. The magnitudes change depending-on: position and observation. Ken Wheeler speaks to this concept on His Youtube: “Theoria Apophasis”. Many ‘Theories’ view “Time” as an object, removing the Observer as prime measuring Aspect.
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