# Time

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Is the concept of time somewhat biological or human perception type construct then as put forth in physics?

I have a somewhat gut level idea that maybe time as we study it is a product of animation, such as a chemical reaction takes x amount of time to occur. Last example of what I am trying to get at is this, is time a product of natural phenomena or is time its own thing.

If time is its own entity how do we know?

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Time is it's own thing because of geometry.

We can look at the world around us and see various geometrical regularities. Lines, angles, etc.

We can construct a mathematical model about it (called - Geometry). We can then examine these models and ask various questions: What is a Dimension? What is the shortest line between 2 points (on a flat or curved surface)? And so on.

We look at light and see how it behaves.

We start to look at the way light behaves in certain circumstances (near gravitating objects like stars and such).

Looking this way we can see light behaves in a very specific way in a gravitational field. This behaviour can be geometrically represented and this turns out to requires area around a gravitational object to have space curved through 4 dimensions.

Now we know of the 3 spatial dimensions (Up/Down, Left/Right and Forwards/Backwards). But what is this 4th one?

When we look at the effects of rotation on space we can use this to look for an effect associated with the gravitational field that matches the extra dimension of the rotation.

This effect turns out to be a distortion of time. That is, time seems to run slower in a gravitational field and the stronger the field the slower time runs.

So from this, we can conclude that Time is a dimension as real as the Spatial dimensions, but the way the universe is constructed, it appears that the 3D space is like a membrane moving along this 4th dimension.

Is the concept of time somewhat biological or human perception type construct then as put forth in physics?

So what is time? Time is a Dimension necessitated by geometry demonstrated by how the movement of objects (not just light) are observed in our universe. It is the 4th dimension.

Human perception of time is different. We think we see a constant "movement" through time, but in reality our perception of "now" is blurred.

Our perception of Time is analogous to our visual perception. We tend to think of our eyes and visual system recording the world around us like a video camera does.

However, our eyes are not really like that.

If you hold out your hand at arms length, and look at you little finger's nail. That is roughly the amount of area that our eyes can make out any detail. But we can "see" far more area than that with detail.

The reason this occurs is that our eyes are constantly moving around, they will look at one point, then move onto another point. Our brain compiles this mosaic into what we think is our field of view, and not all of these mosaics are up to date.

Our brain's perception of "Now" is like this. WE don't actually perceive a Now, like how the "now" of a frame of a movie is stored, or a photo. It is more like a long exposure photo, the scene blurred out over a period of time and not all points within that time period receive the same attention.

This blurring can extend over longer periods too. Ever heard the saying that "a watched pot never boils". What occurs is that when we are watching that pot, because more attention is put into those moment, we perceive that as being longer. However, if you later think back to that time, it might seem like it was quite short. Also, if we are in a situation like a car accident, it can seem like the whole thing lasted for several minute, but it might have been over in a matter of a couple of seconds.

This "Human Perception" of time does not actually reflect the reality of time. Our brains have evolved to pay attention to what is important and ignore what isn't.

In this sense, that is our human perception of time, is an illusions created by our brains. However, certain physical phenomena are regular (the swinging of a pendulum, the decays of certain particles etc), are regular and can be predicted accurately and are independent of our "perceptions". We can therefore use these to be a measure of time that does not rely on our own messy perceptions.

It is through the "Physics" of these phenomena that we can mark out points in time (much like a ruler can make out point in space). This "thing" that can be measured by these phenomena and that we can detect the curvature of, is what Time really is. And that is the 4th dimension.

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If time is its own entity how do we know?

Edtharan has done a good job already, but maybe you should look up Hermann Minkowski, who developed Minkowski space, which extends from three dimensions to a four dimensional manifold, i.e time as the added dimension. So time isn't a seperate entity, but can be considered a factor of space geometry.

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Foodchain: No, time isn't an entity. You cannot "move" through time, time has no length, it doesn't flow, you cannot see it, and you cannot hold it in your hand. There is no real geometry to it - Minkowski's fourth dimension is a mathematical artifice. Time is a measure of change compared to other change. Since it's a measure it's a dimension, but it really isn't like the Dimensions of space. It's rather like heat, a derived effect of motion. As such it exists, but it isn't fundamental. Amazingly this rational view, which is the one Einstein held from circa 1949, is deemed speculative by crackpots who entertain notions of time machines. So please search the internet for "TIME EXPLAINED v2.1"

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Foodchain: No, time isn't an entity. You cannot "move" through time, time has no length, it doesn't flow, you cannot see it, and you cannot hold it in your hand. There is no real geometry to it - Minkowski's fourth dimension is a mathematical artifice. Time is a measure of change compared to other change. Since it's a measure it's a dimension, but it really isn't like the Dimensions of space. It's rather like heat, a derived effect of motion. As such it exists, but it isn't fundamental. Amazingly this rational view, which is the one Einstein held from circa 1949, is deemed speculative by crackpots who entertain notions of time machines. So please search the internet for "TIME EXPLAINED v2.1"

I am moving through time at the moment. What is a second if not a length?

I cannot hold a meter in my had, does that mean it does not exist?

Igore time explained, it's random speculation.

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Farsight, please stop using speculations as fact. The rest of us admit that we're not sure about time's nature, but you don't seem to. The same goes for other places where you interject with a speculation rather than a real theory.

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Is the concept of time somewhat biological or human perception type construct then as put forth in physics?

I have a somewhat gut level idea that maybe time as we study it is a product of animation, such as a chemical reaction takes x amount of time to occur. Last example of what I am trying to get at is this, is time a product of natural phenomena or is time its own thing.

If time is its own entity how do we know?

I don't quite understand the meaning of your last question but FWIW, I would say that time can be thought of as an internal parametrization of changes. Ie. you parametrize the evolution of the system, by a small subsystem (a clock device).

So what you are measureing is how the system as a whole evolves, relative to the evolution of this clock device.

The problem is to find the proper measure of "evolution", when doing this comparasion. The whole point with time that makes it sensible is that it is a kind of event ordering.

One nice way of thinking of it, that nicely merges with both general relativity and QM, is that the system diffuses into the future. At each point there are typically always different possible ways, but nature always chooses the easiest path. And time can be thought to be a parametrization of this path, at least in a differential sense. The toplogy of the finite time might in general be complex, like in general relativity.

One choice or measure of evolution is based on generalized entropy principles. IMO one of the most beautiful parts of classical physics is statistical mechanics. And this can be extended, to deal with more abstract models. And in such a model time can be defined as a parametrization of the system diffusion into the future so to speak.

This thinking means the only measure you need is a measure of distinguishability or change. Then the measures of space and time dimesions (meters and seconds) can simply be thought of as constructs based on this more fundamental measure, in a relational way.

/Fredrik

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In classical mechanics, there is only one path.

In QM, there are many "virtual paths", so it begs the question how to parametrized a bunch of competing parts. The resolution is to consider the stated of information, and instead parametrize the state of information. Then we get only one path, and the parametrization can go on.

/Fredrik

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I don't quite understand the meaning of your last question but FWIW, I would say that time can be thought of as an internal parametrization of changes. Ie. you parametrize the evolution of the system, by a small subsystem (a clock device).

So what you are measureing is how the system as a whole evolves, relative to the evolution of this clock device.

The problem is to find the proper measure of "evolution", when doing this comparasion. The whole point with time that makes it sensible is that it is a kind of event ordering.

One nice way of thinking of it, that nicely merges with both general relativity and QM, is that the system diffuses into the future. At each point there are typically always different possible ways, but nature always chooses the easiest path. And time can be thought to be a parametrization of this path, at least in a differential sense. The toplogy of the finite time might in general be complex, like in general relativity.

One choice or measure of evolution is based on generalized entropy principles. IMO one of the most beautiful parts of classical physics is statistical mechanics. And this can be extended, to deal with more abstract models. And in such a model time can be defined as a parametrization of the system diffusion into the future so to speak.

This thinking means the only measure you need is a measure of distinguishability or change. Then the measures of space and time dimesions (meters and seconds) can simply be thought of as constructs based on this more fundamental measure, in a relational way.

/Fredrik

Basically we have energy and matter. Such is physical, I was wondering if time gets that same label and where does it fit in, or if time is a product of energy and matter interacting.

Either way I was looking for peoples thoughts on the matter, or facts, whichever is fine.

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Basically we have energy and matter. Such is physical, I was wondering if time gets that same label and where does it fit in, or if time is a product of energy and matter interacting.

Yes I was trying provide another point of view.

What is "physical" and what is not never occured to me as an important question, but that's just me. To me "physical" certainly isn't the same as "real". The question is more what's observable and what's not.

If you'd ask me if energy and matter is "physical", I think it can be debated, or considered a matter of definition, in either case I don't find it a fundamental question. My point is that even whatever we consider to be physical, still needs to be communicated so to speak, which brings us to the information concepts. Interaction = communication.

But to play along, I would say that energy, mass and energy and entangled up with each other in a relational way. They are not independent things. Traditionally in QM, time is related to energy approximately like space is related to momentum. They can be thought of as different point of views of a similar thing. Mass is something like constrained energy, as opposed to free energy (like radiation).

/Fredrik

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Yes I was trying provide another point of view.

What is "physical" and what is not never occured to me as an important question, but that's just me. To me "physical" certainly isn't the same as "real". The question is more what's observable and what's not.

If you'd ask me if energy and matter is "physical", I think it can be debated, or considered a matter of definition, in either case I don't find it a fundamental question. My point is that even whatever we consider to be physical, still needs to be communicated so to speak, which brings us to the information concepts. Interaction = communication.

But to play along, I would say that energy, mass and energy and entangled up with each other in a relational way. They are not independent things. Traditionally in QM, time is related to energy approximately like space is related to momentum. They can be thought of as different point of views of a similar thing. Mass is something like constrained energy, as opposed to free energy (like radiation).

/Fredrik

I sort of understand. I have not spent a lot of time studying physics per say, but I am now so I will not be as educated in it as I would like for the sake of communication.

Ok, an atom is real, its physical. The name if you will could change, or the human thought about the atom can be changed, but the atom itself is simply just that, its a physical reality or it exists. I think the same could be said of energy, like a photon, human thought about what it is could indeed change, but the photon itself, for its physical reality is simply just that, whatever the absolute fact of either matter or energy is aside, they are existing physically.

So is time the same?

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Why are you relating time to things like energy? why not things like forwards, or up or down? (i.e. space)

And fredrik when most scientists say "physical" they mean things that obay our known physical laws, not stuff you can poke.

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Why are you relating time to things like energy? why not things like forwards, or up or down? (i.e. space)

I am not trying per say to attempt to say time is something, I am more or less asking a question and attempting to at this point learn even how to ask the question:D

I can understand time I think as used as nothing more then a measurement, but a measurement of what exactly? So for a completely controlled chemical reaction, it will take x time for the reaction to take place, though I don’t know if time for the reaction is absolute down to say a billionth of a second every time around, but the reaction occurs over a certain period of "time" in general. So conservation laws aside as I don’t know how to apply them really to what I am asking about, is time merely a measurement of physical activity then, such as a meter or a second, or how many seconds a slug takes to move a meter in distance for instance, or is time again some tangible entity, like an atom or a photon?

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I know foodchain, my wording was quite poor.

My favourite and simplest method of thinking about time, is direction, what are you measureing when you measure length?

Just because you are not very good at measuring time (although in most modern experiments we like to measure time because we're very good at it).

Time is a dimension. Not a thing.

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Ok, an atom is real, its physical. The name if you will could change, or the human thought about the atom can be changed, but the atom itself is simply just that, its a physical reality or it exists. I think the same could be said of energy, like a photon, human thought about what it is could indeed change, but the photon itself, for its physical reality is simply just that, whatever the absolute fact of either matter or energy is aside, they are existing physically.

So is time the same?

I still don't quite understand the "obsession" of classification of physical and non-physical.

Suppose we say that "time is physical", what implications would you pull from that?

The question wether the physical reality is independent of the human brains, isn't that an easy question IMO. If you take that view to it's extreme, it's to say that things exists wether they could ever be observed or not, which IMO is a akward position, which doesn't make much sense.I think our brains tend to simplify things, and reality is really more complex than common sense suggests at times.

"Measuring time" would mean, making measurements on a clock device in parallell to the rest of your system, and then perform some calculations to arrive at the "progress parameter" we call time.

If you wonder if time is a degree of freedom, like space. It could also be a matter of definition. But generally I would say time is not a degree of freedom like space dimensions is usually considered to be. My preferred view is rather than time is a parametrization of configurational changes.

But since these things are all relational, there can be many apparently different alternative views which effectively represent the same underlying representation. Therefore the important things is to understand the relation, and see that the representation is not unique.

/Fredrik

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I can understand time I think as used as nothing more then a measurement, but a measurement of what exactly? So for a completely controlled chemical reaction, it will take x time for the reaction to take place, though I don’t know if time for the reaction is absolute down to say a billionth of a second every time around, but the reaction occurs over a certain period of "time" in general. So conservation laws aside as I don’t know how to apply them really to what I am asking about, is time merely a measurement of physical activity then, such as a meter or a second, or how many seconds a slug takes to move a meter in distance for instance, or is time again some tangible entity, like an atom or a photon?

In the case of the chemical reaction you actually make two measurements in parallell. You make a measurement on the concentrations of products and reactants, and you make measurements of your clock device. The reading of the clock device have no observer invariant meaning. It is only a relative pace keeper of your chemical reaction. Of course in the construction it is assumed that you are able to distinguish the clock device from your chemical reaction, not to mix the readings up

Like I tried to explain, I think the best view is to think of time as relative change. So a certain number of seconds means that if you bring your standardised clock device with you during your observations, time is simply a measure of how much the clock change relative to your overall change.

So how come different things happen at different rates as compared to your clock device? It can be interpreted intuitively as that the probability of a specific changes in the clock device is large or small compare to the probability of your overall change.

A simplistic analogy...

If you are sort of like in empty space and don't see anything (ie nothing happens) the only thing that happens is your clock is ticking. (let's ignore the human biology for simplicity) That's about as exiting as it gets. So the change that so to speak "peaks" the probability of possible futures is that your clock will proceed with another "tick".

However if you are with your clock in a much more active environment, the most probable change is no longer a plain clock tick. Many another things are more likely to happens at a higher rate.

I'm sorry if this is unreadable but IMO this is a intuitive view of time in terms of probabilistic reasoning that I find to be very simple yet powerful.

/Fredrik

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I am moving through time at the moment. What is a second if not a length? I cannot hold a meter in my head, does that mean it does not exist? Ignore time explained, it's random speculation.

No, you are not moving through time. That's a fantasy. A second is not a length. That's a fantasy too. You can hold up your arms a metre apart. The distance between them is a length. You can step sideways by one metre, so you can move through space. But you simply can't do that with time. You are kidding yourself that you can.

A second is a unit measure of change as compared to other change. If nothing changes, you have no time. And you cannot move through a measure of change.

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Farsight, please stop using speculations as fact. The rest of us admit that we're not sure about time's nature, but you don't seem to. The same goes for other places where you interject with a speculation rather than a real theory.

Noted.

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No, you are not moving through time. That's a fantasy. A second is not a length. That's a fantasy too. You can hold up your arms a metre apart. The distance between them is a length. You can step sideways by one metre, so you can move through space. But you simply can't do that with time. You are kidding yourself that you can.

A second is a unit measure of change as compared to other change. If nothing changes, you have no time. And you cannot move through a measure of change.

Says you.

(childish I know but some people know why)

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farsight, then explain how i can hold up my arms 10 seconds apart.

anyone can do it. put your left hand up then down, count off 10 seconds and then repeat with your other arm.

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and Dont try this at Home Kiddies!

although the experiment is perfectly armless, you could end up Committed!

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Farsight, then explain how I can hold up my arms 10 seconds apart. Anyone can do it. Put your left hand up then down, count off 10 seconds and then repeat with your other arm.

You've got two events here - two motions, two changes. When you say "apart" you're assigning a notional "distance" between them based on other events, starting with the seconds as indicated by your watch. These are calibrated against an atomic clock, such that:

Under the International System of Units, the second is currently defined as the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium-133 atom. This definition refers to a caesium atom at rest at a temperature of 0K…

So one second is circa nine billion little atomic events, and the word "radiation" tells you these events are associated with light. If these events didn't happen, and nothing changed, you'd have nothing to count, and there would be no time. The only distance associated with these event is the distance travelled by something electromagnetic within the caesium atom during the event interval. It's a spatial distance, not a time distance. Hence a light year is a spatial distance, not a time distance. When you realise this you realise that

The metre is the length of the path travelled by light in vacuum during a time interval of 1/299792458 of a second.

..is circular. Both seconds and metres are defined using the distance travelled by light, which is why we always measure c to be the same value. When you say "apart" there's no actual time distance in there. It's just what you grew up with, and it's difficult to think any other way. Really, really difficult.

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So one second is circa nine billion little atomic events, and the word "radiation" tells you these events are associated with light. If these events didn't happen, and nothing changed, you'd have nothing to count, and there would be no time. The only distance associated with these event is the distance travelled by something electromagnetic within the caesium atom during the event interval. It's a spatial distance, not a time distance. Hence a light year is a spatial distance, not a time distance. When you realise this you realise that

That's how we define time. That's not necessarily the representation of what time actually is.

Without a meterstick, we'd still have spatial dimensions. They exist regardless of how we measure them. You cannot argue the nonexistence of a time dimension based on the ways it is measured.

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I still don't quite understand the "obsession" of classification of physical and non-physical.

Suppose we say that "time is physical", what implications would you pull from that?

The question wether the physical reality is independent of the human brains, isn't that an easy question IMO. If you take that view to it's extreme, it's to say that things exists wether they could ever be observed or not, which IMO is a akward position, which doesn't make much sense.I think our brains tend to simplify things, and reality is really more complex than common sense suggests at times.

"Measuring time" would mean, making measurements on a clock device in parallell to the rest of your system, and then perform some calculations to arrive at the "progress parameter" we call time.

If you wonder if time is a degree of freedom, like space. It could also be a matter of definition. But generally I would say time is not a degree of freedom like space dimensions is usually considered to be. My preferred view is rather than time is a parametrization of configurational changes.

But since these things are all relational, there can be many apparently different alternative views which effectively represent the same underlying representation. Therefore the important things is to understand the relation, and see that the representation is not unique.

/Fredrik

I know but I think you have me confused. I am not saying time is this or that, I am trying to ask a question on what time is, and I guess from what you are saying that its general relative to whom you are asking. I think its important that we can correctly define the physical world around us also.

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especialy since the human vocabulary is quite limited in such areas at the moment.

arguments based upon semantics are bound to arise, so its important to see the Meaning of the sentiment as opposed to the Letters used.

it`s all to easy to slip away from Scientist to English Teacher else!

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