Why time is a separate physical quantity

[ehpc]

Hi!

I have a question about time.

I don't understand why everyone thinks of a time as some coordinate like x,y,z. I don't get it. From my point of view the time as some physical quantity doesn't exist. Because there is only moving matter. And we can talk about time by observing changes in that matter. So we can talk about time only when the hand of a clock moves from one position to another. And time dilation is just a different type of matter movement. And so time travel is impossible because one must change all matter to it's previous position. I really don't understand why we talk about time as some existing entity.

I suppose I have some major flow in my understanding. So can anyone explain to me this issues or point to some books, articles?

Thank you

 

[Pengwuino]

And time dilation is just a different type of matter movement. And so time travel is impossible because one must change all matter to it's previous position.

What does this mean?

 

[ehpc]

What does this mean?

What exactly you don't understand?

 

[Pengwuino]

What do you mean by "time dilation is just another matter movement"?

 

[ehpc]

I don't know if I can say it right. One says that time slows down when an object's velocity is approaching a speed of light. And I don't understand why we are talking about 'time'? Why not particles start to move slowly and because of that we perceive time differently. But my main point is why we are talking about time like any other real quantity like mass or position. What is a base for that assumption? Why one thinks that time actually exists? I can only see that particles/atoms/whatever are changing their positions. And because of that changing we can talk about time. But the time doesn't really exist. I'm not trying to prove my point, I just want to understand where I'm getting wrong. I hope you understand what I am talking about.

 

[Pengwuino]

The particles don't begin to move slowly though.

In classical mechanics, we define some abstract concept called "time" as some parameter that we can have as an invariant quantity. This is invariant because going from different reference frames, we always have this time ticking away at the same rate whereas other quantities change. Kinetic energy typically changes going from one inertial frame to the next. Velocity changes as well. Time doesn't.

However, this doesn't jive well with observations of high speed systems. Enter Relativity and it helps explain everything we know to be true today.

If you're really looking for a concrete example, look at high energy physics. Particles having lifetimes of $$10^-6s$$, a pure "time" quantity. However, when accelerated to near the speed of light, they take far far longer until they decay which allows us to actually do particle collisions and high energy physics. Time being an invariant quantity would not allow this.

 

[FizixFreak]

Hi!



I don't understand why everyone thinks of a time as some coordinate like x,y,z. I don't get it. From my point of view the time as some physical quantity doesn't exist. Because there is only moving matter. And we can talk about time by observing changes in that matter. So we can talk about time only when the hand of a clock moves from one position to another

I suppose I have some major flow in my understanding. So can anyone explain to me this issues or point to some books, articles?

Thank you

time has existence even if there is no significant movement you see time is not some thing that you see on the clock einstine imagined time as a dimension it self
so yes there is a flaw in your understanding .time is the most essential ''ingredient'' for any process to proceed in the universe if there is no time there is no movement time allows movement time is not dependent on the movement of a object for its description its the other way around . what you see on the clock is actually the mathematical evaluation of time the clocks don't create time they are measuing tool of time if there be no clocks time would still have an existence.
PLEASE LET ME KNOW IF YOU FIND THIS HELPFUL

 

[Chronos]

Time keeps everything in the universe from happening all at once. It is inexorably tied to the finite speed of light and clearly has a place as a coordinate system in astrophysics. A universe without a time dimension is irrelevant.

 

[ehpc]

FizixFreak, yes that's exactly what I'm talking about. I know this point of view. But I don't understand it at all. What is the base for such assumptions? Why one thinks that time exists without movement? Is there some experimental data that proves that time is actually another dimension? Or maybe theoretical explanation?

 

[ehpc]

Chronos, why there is a need of such thing as time to keep everything from happening at once? Isn't it sufficient that there is matter (atoms and stuff) that moves at different speed thus creating different states one after another. Because speed is fixed (not infinite), there is no possible way to make all this states at once. They just follow one after another. Where am I wrong. And please consider answering my questions to FizixFreak.

 

[Chronos]

What is 'speed' without time?

 

[ehpc]

What is 'speed' without time?

Ok you made me thinking. We define speed through distance and time. That's odd. But what the time is anyway? I though of it as changings in a matter. So there is no 'time' at all. But FizixFreak says that time exists even if matter is not moving. So it's kind of 4-th dimension. But is there any scientific proof of time existing as separate entity? Had anyone made such effort? Had anyone explained in detail what time is and why it is what it is? Or we just rely on some intuitive understanding of 'time'?

Speed without a time. How about speed is just a movement of matter perceived by other matter (aka observer). So we can talk about speed just because we participate in that movement ourselves. If nobody is watching is there any speed at all? Yes it is messy but I hope you'll get my point.

 

[ehpc]

And I'm hoping there is someone out there who is as confused as I am so he can contribute to my questions...

 

[Dale]

But what the time is anyway? I though of it as changings in a matter.

And what does the matter change with respect to? Do you understand the mathematical concept of a derivative, which encapsulates the idea of changing?

 

[adaptation]

Ok you made me thinking. We define speed through distance and time. That's odd. But what the time is anyway? I though of it as changings in a matter. So there is no 'time' at all. But FizixFreak says that time exists even if matter is not moving. So it's kind of 4-th dimension. But is there any scientific proof of time existing as separate entity? Had anyone made such effort? Had anyone explained in detail what time is and why it is what it is? Or we just rely on some intuitive understanding of 'time'?

Speed without a time. How about speed is just a movement of matter perceived by other matter (aka observer). So we can talk about speed just because we participate in that movement ourselves. If nobody is watching is there any speed at all? Yes it is messy but I hope you'll get my point.

Time is generally not considered separate from space. In fact, they are considered to be a part of the same thing, space-time.

Maybe this will help. Consider the following example:
Particle A is at position (x,y,z). Particle B interacts with particle A. The interaction causes Particle A to move to (x₂,y₂,z₂).

Note that I didn't use any time words. I just used the word "causes." By using this word, you understand that one event happens before the other. If there is no time, how can I know what happened first? Without time, A and B are simply particles moving in space. With time, it seems like B causes A to move.

Time helps us to understand how events happen in sequence. This helps us to understand which events are the results of other events.

We need a certain frame of reference in which to describe events. It turns out that we can describe many events with an arbitrary number of spatial dimensions, but we also need time for these events to make much sense to us.

I don't claim to understand time. We're in the same boat here. These are just my thoughts. I hope I explained them clearly enough.

 

[ehpc]

And what does the matter change with respect to? Do you understand the mathematical concept of a derivative, which encapsulates the idea of changing?

DaleSpam, yes I understand derivatives and I know that v=ds/dt. But my explanation was descriptive not formal.

To make it clear can anyone answer this questions:
1. Is there some experimental data that proves that time is actually another dimension? Or maybe theoretical explanation?
2. Had anyone (i mean scientist) explained in detail what time is and why it is what it is? Or we just rely on some intuitive understanding of 'time'?

I don't think that this questions are so hard to answer if there is an answer to them of course.

 

[ehpc]

adaptation, thank you for your explanation. But than I have another question. Does time actually exist? Or is it just how we perceive things? Is there a 'time' without us? Had any scientist answered such questions?

 

[Tomsk]

This is really a very deep and subtle and complicated question. It hasn't been answered yet. It may in fact be unnecessary to use time to describe the physical phenomena we observe. One thing that's for certain though, time is a very useful concept, it makes theories far easier to write if you use it!

Take at look at Julian Barbour's website: http://www.platonia.com - he has investigated the nature of time, you might find it interesting. Another good place to look is the FQXi site: http://www.fqxi.org/community/essay/winners/2008.1 There are lots of essays about the nature of time there, quite a few say time doesn't exist on a fundamental level.

It's certainly a very interesting question. Whether anyone will find a good answer any time soon is another matter...

 

[ehpc]

Thank you very much, Tomsk. I have suspected that there is something wrong with 'time' in physics. Now I see that it is simply an open question and has no concrete answer yet. I'll definitely check out those essays. Thanks again, your post was very helpful.

I suggest if anyone finds interesting links on that subject he will post them here.

 

[Naty1]

ehpc:

Do you think all masses (say the elements) are related? Why?

Do you think the weak force and the electromagnetic force are related? Why?

Well, it turns out they are related: we think that way because we have some underlying understanding...you could say, for example, all the elements are related because they are different combinations of electrons, protons and neutrons; and the two forces we know are related from electroweak unification (mathematics). It's like being able to tell you and a brother, for example, are related because it's imprinted in your DNA.

It's likely that all those "different" components that appear distinct now are derived from 'spontaneous symmetry breaking' at the the origin of the universe...the evolution of what you observe currently from an incredibly high energy and very unstable initial conditions near the beginning of the universe...so it is assumed gravity, the strong force and electroweak forces, for example, originate from a single entity...likewise, it's quite possible time and space, as well, spring from that "fundamental" entity...but we don't know much about time at all and not nearly enough about space to understand exactly how they are related.

All the above is obscured by the fact that so far the BIG BANG is outside our best theories...it's a singularity we do not know how to model...that's a big reason black holes are of such interest, because they,too, are singularities which we think exist now and it is hoped studying them will provide some clues as to how gravity and space, for example, are linked. Then we'll have to figure out how the big bang singularity at the beginning of the universe is related to black holes at the end of the universe.

Finally, it just might be that the common "element" among everything we observe (space, time, matter, energy, etc) is INFORMATION in disguise...but that is beyond currently accepted and widely held theory.

It may help you to remember most of the statements in your original post are contrary to the best current scientific understanding: for example:

"And time dilation is just a different type of matter movement."

not so; differences in gravitational potential also affect the observed passage of time...For example, time appears to stop at the horizon of a black hole as viewed by a distant stationary external observer...so both velocity and gravitational potential are factors...

This stuff is NOT obvious nor intuitive; if it were, everybody would be a physicst.

 

[Integral]

When you are meeting with someone you must tell them, not only where to meet but when. It is the same in physics, you must be able to describe where and when. It requires 3 coordinates to tell where and 1 to tell when. Therefore it requires 4 numbers to describe an event. The number of coordinates required to define a quantity determine the number of dimensions. For that reason time is a dimension.

OP you are bordering on pushing a personal theory. Please stop. Rather then telling us what you believe to be true, ask questions about the current state of physics. You can then bring you beliefs into line with that. If you do not care to do that or if you deeply believe that you are correct and in possession of greater knowledge, you will be shown the door as we cannot help you.

 

[ehpc]

OP you are bordering on pushing a personal theory. Please stop. Rather then telling us what you believe to be true, ask questions about the current state of physics. You can then bring you beliefs into line with that. If you do not care to do that or if you deeply believe that you are correct and in possession of greater knowledge, you will be shown the door as we cannot help you.

I don't push anything you just misinterpret my words. Actually Tomsk gave all answers I needed. Somehow he understood what I was asking. So your accusations are irrelevant.

 

[ZapperZ]

DaleSpam, yes I understand derivatives and I know that v=ds/dt. But my explanation was descriptive not formal.

To make it clear can anyone answer this questions:
1. Is there some experimental data that proves that time is actually another dimension? Or maybe theoretical explanation?
2. Had anyone (i mean scientist) explained in detail what time is and why it is what it is? Or we just rely on some intuitive understanding of 'time'?

I don't think that this questions are so hard to answer if there is an answer to them of course.

1. Yes. In fact, there are many phenomena that are characterized by the violation of time symmetry. Furthermore, our description of time within Special Relativity WORKS. And in this formulation, time is on equal footing as the other spatial dimension. Now, unless you think you have something new to falsify Special Relativity, you'd be hard-press to come up with physical evidence to prove your case.

2. There are a few who are trying to define and understand time, but these are WAY beyond what you are proposing. Your proposal is more based on a rather incomplete understanding of SR/GR and your lack of knowledge of various phenomena. For example, can you construct the Hamiltonian of a system without invoking any time coordinates? How complete would such a description be?

Please note that at some point, you must go beyond just speculative handwaving arguments, which is not allowed based on the PF Rules that you have agreed to. If you insist on those of us who counter your argument to show solid, valid evidence, then you too must do the same if you want to argue against. So far, as I see it, you are shooting in the dark while insisting that the rest of us show you the evidence.

Zz.

 

[FizixFreak]

FizixFreak, yes that's exactly what I'm talking about. I know this point of view. But I don't understand it at all. What is the base for such assumptions? Why one thinks that time exists without movement? Is there some experimental data that proves that time is actually another dimension? Or maybe theoretical explanation?

that is a good question...
now that is where relativity comes into play all right now i will try to explain with an example hope it works.
let say you have two observers with a glass of water one takes the glass and puts it in a freezer and the other in a boiler in first condition the water would freeze and in the other it will evaporate the water had existence it chooses to behave differently in different situations the very fact that water exists allows it to freeze or boil now we know for sure that the water had absolute existence but what about time?
if time behaves according to the situation it might have existence you may think that time remains same in every condition but it has been experimentally seen that time passes slower for a person in motion compared to a person at rest so what is happening ?
the time is behaving differently in different situations why?
yes because it has existence but these effects are seen at speeds close to light otherwise the effects are negligible.
i am a rookie myself so i may not have explained it the best please let me know if my post helped you can also search TIME DILATION

 

[FizixFreak]

FizixFreak, yes that's exactly what I'm talking about. I know this point of view. But I don't understand it at all. What is the base for such assumptions? Why one thinks that time exists without movement? Is there some experimental data that proves that time is actually another dimension? Or maybe theoretical explanation?

that is a good question...
now that is where relativity comes into play all right now i will try to explain with an example hope it works.
let say you have two observers with a glass of water one takes the glass and puts it in a freezer and the other in a boiler in first condition the water would freeze and in the other it will evaporate the water had existence it chooses to behave differently in different situations the very fact that water exists allows it to freeze or boil now we know for sure that the water had absolute existence but what about time?
if time behaves according to the situation it might have existence you may think that time remains same in every condition but it has been experimentally seen that time passes slower for a person in motion compared to a person at rest so what is happening ?
the time is behaving differently in different situations why?
yes because it has existence but these effects are seen at speeds close to light otherwise the effects are negligible.
i am a rookie myself so i may not have explained it the best please let me know if my post helped you can also search TIME DILATION it would help.

 

[Dale]

DaleSpam, yes I understand derivatives and I know that v=ds/dt. But my explanation was descriptive not formal.

So let's make it a little formal. You cannot have a derivative, dx/dt, without having both a function, x, which is being differentiated and its independent variable, t. In other words, "change" implies the existence both of that which is changing and that which it is changing with respect to.

So tell me, in velocity, what is the position changing with respect to?

Regarding your enumerated questions:
1) As far as experimental data, yes, there are several centuries worth of experimental data validating physical theories that use time.
2) Time is the thing with respect to which things are changing, i.e. the thing referred to by t in all of the d/dt terms in physical theories.

 

[ehpc]

Thank you, DaleSpam. Your explanations regarding derivatives were very helpful. Now I understand why there is a need for such thing as 'time' to describe different processes. Ok, now my mind is a little bit more clear.

I think I got to check out those links by Tomsk now. If I'll have any further questions, I will come back.

Thanks everyone for helping me out, I appreciate that.

(And for those 'pf mentors' - I do not propose or try to push any new theory or whatever, I am not a physicist at all, I'm just trying to understand some topics that bother my mind. So please do not multiply entities beyond necessity.)

 

[ehpc]

Ok, I have read through this forum posts about 'time'. And have another stupid question, this time about clock.

Apparently we measure time with clock. The clock has arrows in it just like in any other measuring device. So we can talk about time changing by looking at indications of that arrows. If they move, we know the time has changed. But I don't get what exactly does this clock measure..

For comparison if we use voltmeter. It is a measuring device too. And it measures electrical potential difference through magnet. So there is an electrical force iteracting with magnet and that's why the arrow moves. So there is an observable participation of some force.
But what with the clock? What drives arrows in the clock? The tension of the spring for example. Or quartz crystal. Or whatever. But not the thing we are measuring. So the time does not actually move the arrows? Or if the time is interconnected with space, than any motion carries a time within itself? So that's why we are talking about time on clock, because when arrow moves, that means there is a movement in time? But then I have a question. Does voltmeter shows time too? It's arrows are moving too, so it should show time shouldn't it?

My confusion arised from reading through posts of russ_watters one of your 'pf mentors' where he is constantly saying about looking at watches: https://www.physicsforums.com/showpost.php?p=1384224&postcount=5 .

 

[adaptation]

Ok, I have read through this forum posts about 'time'. And have another stupid question, this time about clock.

Apparently we measure time with clock. The clock has arrows in it just like in any other measuring device. So we can talk about time changing by looking at indications of that arrows. If they move, we know the time has changed. But I don't get what exactly does this clock measure..

I do not think that this is a stupid question.

Time does not move the arrows. Energy moves the arrows over time. Measuring how much energy is lost let's us know how much time has passed.

I suppose you could use a voltmeter to measure time. (Use a clock instead! It's much easier.) You ought to be able to see the electrical potential of a battery decrease over time. The rate at which the voltage decreases let's you know that time is passing. The time you would measure would likely not be in the standard form we're used to, seconds, minutes, etc. This means it would be a little difficult to talk about your time (the way you define it with the voltmeter) with some one else.

You could use the sun to measure time. You could use the the tides. You could use the change of seasons. You could use the rate of oxidation of your bike to measure time. You could use the increase of entropy in the universe. You could use about a billion different things. The one thing that all of these measuring devices have in common is that they show you a change.

Clocks are more convenient because they help us communicate time intervals more easily with each other.

 

[ehpc]

Thanx, adaptation. Your phrase "Energy moves the arrows over time" made me thinking about space coordinates. Basically we do not measure x,y,z coordinates either, we just move through them and that's how we can tell about them. So there is no proper (aka voltmeter for voltage) measuring device for coordinates too, isn't it? And now I'm wondering what space is.. Am I thinking right? That's why the time is so close to space?

 

[Vanadium 50]

A voltmeter doesn't directly measure voltage either. The voltage is converted to a current, which produces a magnetic field, which causes the meter mechanism to turn and the arrow to move.

As far as a measuring device for coordinates, what's wrong with a ruler?

 

[ehpc]

Vanadium 50, I don't remember saying anything about voltmeter directly measuring voltage, but whatever. The wrong with the ruler is the same as with watches. There is no special space-force that helps to move the ruler. The ruler moves through space. For comparison, magnetic field does help arrow to change it's position. If there is a field, there is movement. Field causes movement. But does space causes you to take a ruler and make a measurement? Or you think there is no difference between space and voltage measurement? Then please explain.

 

[adaptation]

Vanadium 50, I don't remember saying anything about voltmeter directly measuring voltage, but whatever. The wrong with the ruler is the same as with watches. There is no special space-force that helps to move the ruler. The ruler moves through space. For comparison, magnetic field does help arrow to change it's position. If there is a field, there is movement. Field causes movement. But does space causes you to take a ruler and make a measurement? Or you think there is no difference between space and voltage measurement? Then please explain.

I believe Vanadium 50 was just clarifying a point. (A point I didn't get the first time around, so thanks.)

I see what you're saying about space also. It's kind of the same as time. You can measure space with feet, light years, meters, the wingspan of a canary. It doesn't really matter. Generally we choose to use meters because meters are easy to communicate to others.

A ruler should not move when you use it to make a measurement. The ruler needs to be motionless (relative to something) for you to be able to use it in a meaningful way.

Both time and space are relative to the observer. We use common units of space (usually meters) and time (usually seconds). The units we use are less important than the things we are measuring. The units we have created to measure these things are only tools for us to use to describe the world.

Where would things happen if they didn't happen in space? How would things happen if there were no time?

And as a suggestion, maybe you should stop thinking of space and time as separate things. Try to think about space-time as the "arena" of physics. Everything happens in space-time.

 

[ehpc]

Thanx, adaptation. I've just read wikipedia article about space and it says: "Space is one of the few fundamental quantities in physics, meaning that it cannot be defined via other quantities because nothing more fundamental is known at the present.".
Does this mean that there is no actual definition/explanation of what space is, so kind of the space is the space?

 

[adaptation]

Thanx, adaptation. I've just read wikipedia article about space and it says: "Space is one of the few fundamental quantities in physics, meaning that it cannot be defined via other quantities because nothing more fundamental is known at the present.".
Does this mean that there is no actual definition/explanation of what space is, so kind of the space is the space?

You're certainly welcome!

There are many models that describe what space is. The popular idea at the moment is that space-time is a continuum composed of three dimensions of space and one of time. "en.wikipedia.org/wiki/Spacetime"[/URL]

On that page you can read how a space-time interval is defined. Maybe that will also help answer some of your questions.