Also, if time does exist, doesn’t there have to be a definable beginning or end? Otherwise it’s just infinity which to me suggests the absense of time.
I partially read “The Discoverers” by Daniel Boorstin several years ago and he discussed how different societies conceptualized of time and how they kept time. And it has had me wondering ever since. Then I started exploring Zen Buddhism which emphasizes the present moment as the only tangible reality, along with the illusion of the ego, which only furthered my questioning.
EDIT – I am aware that the concept of time is based on the revolution of the Earth and it’s moon. However, that is just how humans conceive of time. That’s not proof of time itself.
EDIT 2 – The explanation of timespace and relativity is the best from an objective point of view. No matter how much I read or watch, it was always a bit hard to grasp but it makes sense in terms of change or entropy. The reality of time being flexible vs the human perception of time being linear and unchangeable gets closer to what I am asking.
EDIT 3 – “Exist” is a tricky word.
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Time exists, because it happens whether we want it to or not. While some of the time units like the hour and the second are pretty arbitrary, the day, the lunar month and the year are tied directly to things that everyone all over the Earth can see and experience for themselves.
Take a banana and put it on a table. The banana will ripen and then decay without any action on your part. Likewise all mammals age and ultimately die. So you can call the way we measure time arbitrary or invented, but duration happens whether you like it or not.
Time exists, and it is flowing in a one way direction. This is called the arrow of time. It has a beginning – the Big Bang – and a hypothesized end – the Big Chill. You experience the existence of time every single day.
It is *also* true that time is perceived subjectively, which is what Mr. Boorstin might be alluding to. Our subjective perception of time is influenced by language, psychological state, hormones, drugs, and more. We also know that other animals might perceive time differently.
This is not in conflict with the existence of time.
Yes, time exists.
The way we measure it is fairly arbitrary. It’s formally defined as 9,192,631,770 vibrations of a particular cesium isotope. That number was arrived at later; originally time started being measured in easily divisible segments based on the earth’s rotation, and the formal measurement is just however many vibrations it takes to count out one of the seconds that were already in use.
But time does pass, regardless of whether you call it a second, or a minute, or X vibrations of an atom, or anything else. You can see this in the decay of subatomic particles; when we produce them, they last for a certain interval and then decay. We can slap different labels on this interval, but it’s an interval of *something* and that something is time.
Time can also be bent and twisted. You mentioned relativity in one of your comments; that describes how gravity modifies time. When you’re moving very fast or are in a very high gravitational field, time appears to speed up for everything that isn’t you (from your perspective), and you age very slowly for anyone looking at you from outside (their perspective). It’s called “relativity” because the way things work is directly relative to your frame of reference (meaning, where you are and how fast you’re going, among other things). We can prove this, too; when we make those particles and get them moving really fast, the amount of time they last before they decay is increased in a way that’s directly related to their original lifespan and the speed they’re going at.
With all of that said, it’s also accurate to say that the present moment is the only tangible reality. You can’t reach back in time to change things; you can’t reach forward in time to change things there, either. All you can do is whatever is available to you in any given moment. But that’s more of a spiritual and mental-health thing than a physics thing.
You probably have to define to yourself what you mean by real and tangible.
Given that people recently won a Nobel prize for, ELI5 showing that things don’t have to exist when we’re not looking at them, it’s hard to argue that anything is.
You’re right to distinguish between the measurement of time, and time itself. Seconds, minutes, and years are arbitrary, but time is not. Aristotle considers time to be a measure of movement which seems counter intuitive until you think about it. Time is how we sensibly describe things as occurring before or after other things. As long as you can discuss the world in those terms, you’re presupposing the existence of time…regardless of how it is measured, or if it’s even measured at all.
Since we have the theory of general relativity I would say that time only exists in the measurement the humans give it. Which is relative to humans and not the universe as the universe itself does not need to track time, but we do.
This question is a matter of perspective and is the same as asking if there’s nobody in the forest and a tree falls does it make a noise if there’s nobody to track time does that mean that there is still time?
Time exists but not as anything per se. So you can’t pick time out of the universe and examine it as though it were a thing. Also at the same time (no pun intended), time does not exist. This is because the past isn’t hidden somewhere and the future doesn’t exist, so now is all there is.
The universe is paradoxical and contradictory. This makes reality interesting.
It exists, but not as an independent thing. The fact that we treat it as a distinct thing is a quirk/limitation with our perception of it. Time and space are actually the same thing which is why we refer to it as spacetime.
The reason that we don’t interpret it “correctly” is because it’s hard to because you only start to notice contradictory evidence to our daily experience at extreme scales. For example, the “easiest” way to demonstrate that time isn’t how we generally perceive it requires having super accurate clocks as well as the ability to put such clocks into high earth orbit. When you do this you find that the clocks in high earth orbit run more slowly than clocks on the earth’s surface. It turns out that this is because they’re experiencing less gravity.
Gravity warps spacetime which is why it affects both object travelling through space as well as the passing of time because space and time are not two things but the same thing. Time is more like a vector of 4th spacetime. Similar to how up, down, forwards and backwards are vectors of three dimensional space.
There is a very big problem in physics related to time and the existence of time arrow. All strict laws of physics allow time inversion without any drastic consequences, the only area that prevents it is thermodynamics, but it’s not much of a strict discipline, and there’s no mathematical proofs that time cannot be inverted. In order for time arrow to exist, time should be non-reversible according to at least one law, but we really don’t have anything solid on that except out experience. It’s an opened problem.
At its most basic time is just a unit of measure like distance.
Distance is the measure between 2 coordinates, and time is the measure between 2 events.
Beyond that it just becomes arbitrarily agreed upon units of measure.
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