Why do we Experience a 'Flow' of Time?

[timmdeeg]

Yes,

All objects move in space-time hence all motions can be desrcibed as velocity. We define time using the motion. Thats what I am thinking at least.

If we talk about the flow of proper time how can you "model" it using motion? Proper time is invariant but motion isn't.

 

[Arman777]

If we talk about the flow of proper time how can you "model" it using motion? Proper time is invariant but motion isn't.

For a light clock it can be defined as $\frac {2d}{c}$ where the $d$ is distance between two mirrors.

Here again there's $c$ which is motion of a light.

I don't think its possible to measure/define time using motion.

Time and motion are linked together. We can't define motion without time but also vice versa

 

[PeroK]

For a light clock it can be defined as $\frac {2d}{c}$ where the $d$ is distance between two mirrors.

Here again there's $c$ which is motion of a light.

I don't think its possible to measure/define time using motion.

Time and motion are linked together. We can't define motion without time but also vice versa

What about studying, say, the posts on PF? The number of posts per hour, average, maximum etc. There you clearly have the concept of time, but no immediate concept of motion through space.

Or, it would seem artificial to consider the concept of carbon dating, say, in the context of four dimensional spacetime.

 

[Stavros Kiri]

why do we experience a flow of time? Why is everything in the 'now' flowing toward the future, and not the past? Also, why do we all experience this flow the exact same way?

From the practical standpoint, the flow and arrow of time is connected to motion, processes and the 2nd law of thermodynamics. Especially irreversible processes "leave their mark" and they cannot but be (potentially) observed, especially since we also take part. I think that explains (partially [?]) of what we feel etc. ...

 

[Arman777]

What about studying, say, the posts on PF? The number of posts per hour, average, maximum etc. There you clearly have the concept of time, but no immediate concept of motion through space.

Or, it would seem artificial to consider the concept of carbon dating, say, in the context of four dimensional spacetime.

To post something you need to write something that's motion. Also making a clock using PF posts per hour is not a great idea. Anyway I don't think this example is a proper example ??

For carbon dating well, for decay we have also some motions that we can describe for atoms etc.

 

[Dale]

the fact that we remember the past and not the future has to do with entropy. And this is what gives us a sense of "flow" of time.

I think this actually answers the title question. Our mental experience of time is based on this.

It has always struck me that we walk through time backwards, “looking” at where we have been and unable to “see” what is right in front of us.

 

[Stavros Kiri]

I think this actually answers the title question. Our mental experience of time is based on this.

It has always struck me that we walk through time backwards, “looking” at where we have been and unable to “see” what is right in front of us.

Cf.
https://www.physicsforums.com/threads/why-do-we-experience-a-flow-of-time.941255/page-4#post-5954695

 

[Dale]

For carbon dating well, for decay we have also some motions that we can describe for atoms etc.

Radioactive decay, and other state transitions (like the hyperfine transition) do not appear to require thermal motion. In fact, it is a confounder that we try to eliminate or compensate.

 

[Arman777]

Radioactive decay, and other state transitions (like the hyperfine transition) do not appear to require thermal motion. In fact, it is a confounder that we try to eliminate or compensate.

"Carbon-14 dating, also called radiocarbon dating, the method of age determination that depends upon the decay of the nitrogen of radiocarbon (carbon-14). Carbon-14 is continually formed in nature by the interaction of neutrons with nitrogen-14 in the Earth’s atmosphere; the neutrons required for this reaction are produced by cosmic rays interacting with the atmosphere."

https://www.britannica.com/science/carbon-14-dating

I mean this a type of motion. Carbon 14 just don't produce by itself and also to understand the decay part, again we need the motion. "Decay" itself is the motion.

 

[jbriggs444]

"Decay" itself is the motion.

Decay is not a "motion" in any relevant sense.

 

[Arman777]

Decay is not a "motion" in any relevant sense.

The process of decay is motion. In decay, it emits an electron and an electron antineutrino. So there's "motion".

I mean really any of you think that we can measure time without using "motion" or in other sense "velocity". Is this really how universe works or you guys just want to think that way?

Even when you measure the time you are measuring the cycles of a motion of a thing.

I am asking this seriously without motion how can you even define time? If I am wrong tell me a way to measure time without motion in any sense.

If any of you can prove this with math, I ll stop arguing. Otherwise I can assume that I am right and you guys are wrong.

And I ll be really happy If I am wrong because I want to see a way that its possible.

 

[Sorcerer]

What about studying, say, the posts on PF? The number of posts per hour, average, maximum etc. There you clearly have the concept of time, but no immediate concept of motion through space.

Or, it would seem artificial to consider the concept of carbon dating, say, in the context of four dimensional spacetime.

But wouldn’t someone in motion with respect to Earth measure those same coordinates as mixed between space and time as described by the Lorentz transformation?

 

[rede96]

I am asking this seriously without motion how can you even define time? If I am wrong tell me a way to measure time without motion in any sense.

Imagine a universe where you are the only thing that exits. You are floating in space, you have no sight, hearing, touch, taste or smell. Only your thoughts. It is impossible for you to define ‘motion’ in the way you have used the term ‘motion’ in your posts. Yet you can still count the seconds in your mind.

 

[Arman777]

Imagine a universe where you are the only thing that exits. You are floating in space, you have no sight, hearing, touch, taste or smell. Only your thoughts.

A problematic description. First thing is how can you define only yourself in the entire space and nothing else?

Yet you can still count the seconds in your mind.

I don't see any math in your description. I don't think this argument will be valid.
How you defined time? by just counting seconds in your mind? Whats seconds for you ? just counting numbers? Even you count numbers there's "speed" (motion). I can count 10 number faster than you.
In this sense there's also speed of how fast you count.

In any case I don't think this is valid

 

[jbriggs444]

A problematic description. First thing is how can you define only yourself in the entire space and nothing else?

I don't see any math in your description. I don't think this argument will be valid.
How you defined time? by just counting seconds in your mind? Whats seconds for you ? just counting numbers? Even you count numbers there's "speed" (motion). I can count 10 number faster than you.
In this sense there's also speed of how fast you count.

In any case I don't think this is valid

None of those objections are substantive.

 

[Arman777]

None of those objections are substantive.

What about his objection. Do you think its valid?

Is it solves my question? I don't think so

I still didn't get any mathematical answer to my question rather then I get 1 philosophical answer. Which doesn't make any sense at all

 

[stevendaryl]

I don't see any math in your description. I don't think this argument will be valid.
How you defined time? by just counting seconds in your mind? Whats seconds for you ? just counting numbers? Even you count numbers there's "speed" (motion). I can count 10 number faster than you.

Well, you're now at the point of defining any change between moments of time to be motion. Obviously, the phrase "between moments of time" makes it circular if you're using "motion" to define "time". If you eliminate "between moments of time" in your definition of motion, then it no longer has to do with time. The change in temperature between the North Pole and the equator doesn't imply time or motion, unless you assume that there is an observer who observed the temperature at one place at one time and observed the temperature of the other place at another time.

So, that might be the key to the notion of time: When two different objects with different properties are described as the same object at different times. There's one object, which is me as a baby. There's another object, which is me as an old man. Time connects the two and allows us to think of them as two different states of the same human being.

 

[PeroK]

But wouldn’t someone in motion with respect to Earth measure those same coordinates as mixed between space and time as described by the Lorentz transformation?

I don't really see the relevance of that. In fact, information technology in general is a human endeavour which has a time parameter, but no recognisable map to spacetime.

For example, a computer program, is not a physical object, has no spacetime coordinates - the physical location of the program is largely irrelevant - but it does have a history. Both as a logical object, it has a version history, and as a run time object it has a usage history, say.

Time, but not space, is very much a factor in IT systems. Especially in any sort of logical rather than physical view of a system.

 

[kent davidge]

Time connects the two and allows us to think of them as two different states of the same human being

And with that being noticed, a better explanation is that time happens when there's change of state of a system, not necessarly of motion. (This always has been my thought about time, good to see that someone else also thinks so.)

 

[kent davidge]

So I think @Arman777's point is valid, the only thing is that change of state is not always change of position --it's only one possible case.

 

[Arman777]

So I think @Arman777's point is valid, the only thing is that change of state is not always change of position --it's only one possible case.

Thanks. But for example what kind of state of changes ?

In the baby and old man case. I can say that there's change in the molecular level in the body of the person. That molecular changes causes the to be person to be old. It doesn't happen by suddenly. And those molecular change can be expressed as motion. By motion, I don't consider only the change in the time dimension but also in the space. For example, when the body gets old there are molecular motions in our body, Like chemical things. We can understand that the two different states. But for change in that state again, we need a molecular motion.

Or without any motion (in atomic level or in general ) how can we understand the change in the state?

Or again in other words, change of state doesn't happen by motion?

 

[stevendaryl]

Thanks. But for example what kind of state of changes ?

In the baby and old man case. I can say that there's change in the molecular level in the body of the person. That molecular changes causes the to be person to be old. It doesn't happen by suddenly. And those molecular change can be expressed as motion. By motion, I don't consider only the change in the time dimension but also in the space. For example, when the body gets old there are molecular motions in our body, Like chemical things. We can understand that the two different states. But for change in that state again, we need a molecular motion.

Or without any motion (in atomic level or in general ) how can we understand the change in the state?

Or again in other words, change of state doesn't happen by motion?

There is certainly no necessary reason for changes of state to be associated with motion. For example, in particle physics, the neutral kaon, $K^0$ oscillates with time to change into its own anti-particle, $\bar{K^0}$.

 

[kent davidge]

for example what kind of state of changes ?

We have to be carefull about the use of the term "state". For your question I would use the situation given by @rede96. In that case there is change of state, because the very act of thinking about something involves brain activity, which changes the state of the brain from "before thinking about something" to "after thinking about something" --and this something may be the simplest of all the thoughts.

But, yet, the inteligent being may not be moving at all in space (we could not say that he/she is or is not moving in time, because we are actually trying to define time.)

 

[PeroK]

Thanks. But for example what kind of state of changes ?

In the baby and old man case. I can say that there's change in the molecular level in the body of the person. That molecular changes causes the to be person to be old. It doesn't happen by suddenly. And those molecular change can be expressed as motion. By motion, I don't consider only the change in the time dimension but also in the space. For example, when the body gets old there are molecular motions in our body, Like chemical things. We can understand that the two different states. But for change in that state again, we need a molecular motion.

Or without any motion (in atomic level or in general ) how can we understand the change in the state?

Or again in other words, change of state doesn't happen by motion?

I don't find this argument satisfactory, because age is not defined by motion. If you count my grey hairs, for example. That must be due to a difference in my body's processes from when I was younger. Okay, things must have "moved" somewhere along the line as part of that change, but it's stretching a point to say that the biological processes that produce grey rather than dark hairs are defined by that motion.

 

[Sean Nelson]

A problematic description. First thing is how can you define only yourself in the entire space and nothing else?

I don't see any math in your description. I don't think this argument will be valid.
How you defined time? by just counting seconds in your mind? Whats seconds for you ? just counting numbers? Even you count numbers there's "speed" (motion). I can count 10 number faster than you.
In this sense there's also speed of how fast you count.

In any case I don't think this is valid

I agree. To say that using this description, also leaves question to an inability to know if you are static or in motion. Without a point of reference with your description of your solidarity in space. How do you know if you are not traveling. What is your frame of reference to show you are not traveling 25,000 km per hour. This said you have removed your question of time.

 

[jbriggs444]

also leaves question to an inability to know if you are static or in motion.

That is precisely the point. That the notion of "motion", a variation of "position" in some (three dimensional?) space is not essential to the notion of time.

 

[PeroK]

Additionally, if we take a quantum system, then the conventional concept of motion.of a particle breaks down and it's actually the state (vector) that is changing.

In a harmonic oscillator, for example, it's not that the particle has moved from A to B, but that the state has changed, leading to the change in the expected value of a position measurement from A to B.

And, if we consider the spin state of a particle, then that and the expected value of spin measurements can change, with time, independent of the motion of the particle. Or any motion.

 

[Arman777]

That is precisely the point. That the notion of "motion", a variation of "position" in some (three dimensional?) space is not essential to the notion of time.

Then I am asking again how can you define time without using the notion of motion ?

 

[PeroK]

Then I am asking again how can you define time without using the notion of motion ?

As in post #97, you could, theoretically, use spin precession of an electron in a uniform magnetic field to measure time.

In general, the state of a quantum system changes with time.

 

[Dale]

Even you count numbers there's "speed" (motion).

. "Decay" itself is the motion.

I disagree with those descriptions. That is just redefining “motion” so that it loses all meaning and therefore can be used to justify your (now meaningless) claim.

The process of decay is motion. In decay, it emits an electron and an electron antineutrino. So there's "motion".

None of that is motion. After the decay then the decay products move, but the decay itself is not motion.

The usual hyperfine transition used in standard atomic clocks is not motion, and in fact must be corrected for any motion that does occur.

 

[Sorcerer]

I don't really see the relevance of that. In fact, information technology in general is a human endeavour which has a time parameter, but no recognisable map to spacetime.

For example, a computer program, is not a physical object, has no spacetime coordinates - the physical location of the program is largely irrelevant - but it does have a history. Both as a logical object, it has a version history, and as a run time object it has a usage history, say.

Time, but not space, is very much a factor in IT systems. Especially in any sort of logical rather than physical view of a system.

Yeah but computers only work because electric signals move around inside them, right?

 

[Arman777]

As in post #97, you could, theoretically, use spin precession of an electron in a uniform magnetic field to measure time.

In general, the state of a quantum system changes with time.

Okay then can you show mathematically for us how you do that ? Build a clock for us.

 

[Arman777]

therefore can be used to justify your (now meaningless) claim.

I don't see how can you do that ?

None of that is motion. After the decay then the decay products move, but the decay itself is not motion.

The usual hyperfine transition used in standard atomic clocks is not motion, and in fact must be corrected for any motion that does occur.

If, after decay particles don't move, then how can you possibly understand that decay "happened". I am really curious about that.

I am not sure you guys understand me. Motion happens at any level in the universe. Theres has to be change in the system so we can understand the change but the change happens also in the space. Becasue that's where we live in and it can be count as motion.

The usual hyperfine transition used in standard atomic clocks is not motion, and in fact must be corrected for any motion that does occur.

So the atoms in the clock don't move at all (also the electrons) and we can perfectly know their position and nothing happens to them or etc right ? They are not excited or we don't measure things. Well Of course not there's no such thing as not moving particle. Your definiton doesn't make sense at all actually.

Motion is everywhere. Everything is in motion respect to something at any level. And to measure the time you need motion.

 

[PeterDonis]

as soon as you start to do physics it's the time derivatives (of spatial coordinates among other things) that appear

Careful. We're in the relativity forum here, where there is no such thing as a "time derivative" in any coordinate-independent sense. There are only "spacetime derivatives". This is a "B" level thread so it's hard to get too technical about this, but I don't think it's useful to focus on just time coordinate derivatives in a relativistic context.

 

[PeterDonis]

What I was trying to say was along the lines that change, as in the evolution of the system is absolute. Something either changes or it doesn’t. So in that sense evolution is one directional.

Sorry, you're contradicting yourself again. If you had left out the last sentence I would probably have let it pass; but if you insist on using the word "directional" you can't get away from the fact that there are two "time" directions, past and future. More generally, any time you have an ordered set--and the proper times along any worldline are an ordered set--there are always two "directions" to the ordering.

As it’s impossible for a system not to change

This is wrong. A system in an energy eigenstate does not change. The fact that it does not have a definite value for all observables does not make that false. If you measure an observable of the system that does not commute with energy, then you change the state of the system so it's no longer in an energy eigenstate; yes, at that point you can say the system will "change", but that's because you changed the state when you measured it, not because it was changing before you measured it.

all systems are constantly evolving forward. Which is how I understood that the flow of time was always forward.

"Forward" is not an inherent property of time, it's a choice we make; we label one of the two directions of time the "forward" direction because that's the direction we can only predict, not remember. Ultimately this is because of the second law of thermodynamics and the fact that our universe started out in a very low entropy state. The underlying laws of physics are time symmetric; they don't pick out either direction of time as "forward"--both directions are the same as far as the underlying laws are concerned. The fact that our universe started out in a very low entropy state is a contingent fact about the particular solution of the laws that we live in, not about the laws themselves.