What is time? Does time even exist?

[Strange]

That about sums it up michel123456 yes. That motion isn't dependant upon time, it's just motion.

 

Isn't motion just change of position over time?

 

 

To state that more completely, I think the question is. Why didn't GPS work at all when they first established the system until relativity was appled?

 

Do you have a reference for that? I was under the impression that the relativistic corrections were built in from the start.

 

 

Why even with the calculations provided by relativity do they keep needing to fix a drift in the system?

 

All sorts of reasons. All of them well understood.

Several meters? That's not very accurate at all.

That is mainly a technical / cost limitation. Nothing to do with relativity; altough it does allow the receivers to use approximations which are easier to calculate.

 

Differential GPS can be accurate to a few cms. Future extensions to the satellite network will improve the standard accuracy to a similar level.

[Didymus]

Dan, while I appreciate each of your thought experiments.... All three of them only show distance between objects... Has nothing to do with "space" itself existing. Like time, space is a way we describe where matter is... It is not, by itself, any sort of alterable fabric.

 

If you define "one foot" by the size of a ruler.... Then stretch that ruler, you are not stretching space... only the object. Likewise, if we see a clock effected by forces (such as a muon lasting longer than expected), it would be difficult to prove that the muon is inalterably lasting a set amount of time, but that time is shifting from everyone else's perspective. It would be much more logical to state that the muon is simply decaying more slowly by that same extent.

 

My point is that matter and energy is alterable. Space and time are ideas to describe what matter and energy is doing. They can not be altered, dilated, compressed, bent, created or destroyed any more than "Monday" can be. Monday doesn't exist... It's just a way people define when to go back to work and die a little more on the inside.

Edited August 16, 2013 by Didymus

[Daniel Foreman]

Dan, while I appreciate each of your thought experiments.... All three of them only show distance between objects... Has nothing to do with "space" itself existing. Like time, space is a way we describe where matter is... It is not, by itself, any sort of alterable fabric.

 

 

You kinda need space for distance to happen. You can argue this all you like, but some things are simply there no matter how you state it.

 

P.S. they were not thought experiments, go chuck something, and you'll see space happening.

 

 

 

If you define "one foot" by the size of a ruler.... Then stretch that ruler, you are not stretching space... only the object. Likewise, if we see a clock effected by forces (such as a muon lasting longer than expected), it would be difficult to prove that the muon is inalterably lasting a set amount of time, but that time is shifting from everyone else's perspective. It would be much more logical to state that the muon is simply decaying more slowly by that same extent.

 

Stretching a ruler to alter the measurement of a foot is what we call, cheating. lol. The only way a measurement is going to work is if you make a ruler out of an inflexible hard to alter material, then make a few dozen copies of it. You then use the copies of that ruler to calibrate all other foot long measurements, only breaking out the original when you need to make reference copies. This should be done as little as possible to preseve the original measurement. The same thing was done with kilo weight measurements for many ways, though I think they've changed the definition recently.

 

Time is not shifting or changing of being altered in any way shape or form simply because clock misses a few ticks, operates to fast or two slow. Under those circumstances the clocks measurements are just plain wrong.

 

 

 

My point is that matter and energy is alterable. Space and time are ideas to describe what matter and energy is doing. They can not be altered, dilated, compressed, bent, created or destroyed any more than "Monday" can be. Monday doesn't exist... It's just a way people define when to go back to work and die a little more on the inside.

 

No argument here. Space can not be altered it is the framework in which we operate (it is not simply an idea though, space is there. Anyone refuting it might as well try arguing that most human beings don't have a nose in the rough middle of their faces). As time doesn't exist as any force or dimension outside a math book so it also can not be altered. All you can do in the universe is play cosmic pool with atoms.

 

 

 

...unless I've misjudged your illustrations. I agree that matter is separated.... I don't see how your illustrations suggest that the space between two objects is an object itself... Let alone an alterable object able to be created, destroyed, bent or changed.

 

I never said space was an object, I've always called it a framework. If I ever said it was an object, then it was in error.

 

 

 

Isn't motion just change of position over time?

 

Only in mathematics. In mathematics you need to state the position of something using X, Y, Z and Time. But that's only because the purpose of mathematics is to predict the motion of something into the past or into the future using data sets.

 

http://www.youtube.com/watch?v=pyX8kQ-JzHI <<< try watching that, the video is from stanford university on classical mechanics, it deals with time within mathematical systems there.

 

In the real universe, motion is just the act of moving. In the real universe there is no past, or future, there is only the ever moving present.

 

 

 

Do you have a reference for that? I was under the impression that the relativistic corrections were built in from the start.

 

I came across this information while writing an article about the sensors on mobiles phones. But I can't find it anymore. So feel free to disregard this statement until I find the source again.

 

However are you saying that relativity calculations are not required to make the system work? People are always trotting out GPS as some kind of evidence of time.

Edited August 16, 2013 by Daniel Foreman

[swansont]

Several meters? That's not very accurate at all. I'm just under 2 meters tall, so if I want it to pin point a button on my shirt it's pretty rubbish really

Great. Go use a map and compass then. How does that do for finding a button on your shirt? Millions of people find that GPS is accurate enough to use for many purposes.

 

Accuracy and precision are relative, and you are attempting to use them as some absolute, which is a form of equivocation.

 

7 meters of error every minute is actually a lot more than I thought it would be. I mean that's 11.6 cm per second. That is a really noticeable amount. As for 10 K per day, if you want to find your house, then that's pretty far out of your way!

 

So you were wrong about the impact of relativity vs the measurement errors.

 

Great, then we can agree the math doesn't work. It gets "in the ball park" but that's all.

 

Or not. I don't see how you can honestly say the math doesn't work. The positioning error is, as you had referenced, due to several physical factors. Not math. That e.g. the troposphere correction isn't perfect, and that clocks aren't perfect, is not a failure of math. All measurements have error in them.

 

When faced with "stuff moves" and "stuff moves because time allows it too". I'll take the first response.

Another straw-man and false dichotomy. Who is saying that time "allows" things to move?

 

Because yes, I can easily confirm that stuff moves. I can't easily confirm that stuff moves faster or slower because time itself is going faster or slower. I also don't accept that you can throw a crew across the galaxy at near to light speed as possible, only to have them age very slowly, while the earth grows old fast because time has slowed down for them.

Things are not true only if you can personally confirm them. Doesn't work that way. Nature does not check with you to see if it's OK to do things.

 

Now what I can accept, is that as you approach light speed matter within that ship is "dampened down", so it's less easy to move. I don't think it would have anything to do with time itself slowing down, I think it would be a mechanical process. After all you are moving relative to the motion of that ship with that ship. If you did hit light speed it makes absolute sense that while at light speed you wouldn't be able to freely move around within that ship. After all if the ship is moving at light speed, and you try to walk from the back to the front, then you are then breaking the speed of light are you not?

Great: come up with such a mechanism. Test it, and show that experiment agrees with your model. Then you might be in a position to challenge a theory that's got ~100 years worth of experiment backing it up, and upon which technology has been built.

 

Until you do that, scientifically speaking, what you think isn't worth warm spit.

 

I don't think what Einstein was describing was ever a dilation of time or the alteration of a time dimension, but simply a way of describing the behaviour of matter under the most extreme condition.

Have you actually read any of his papers? This indicates that the answer is "no"

 

Do you have a reference for that? I was under the impression that the relativistic corrections were built in from the start.

 

On the first satellite with a clock, the relativistic corrections were initially turned off, because some people weren't convince that relativity was a real effect. After launch, they confirmed that the uncorrected signal was off by the amount that relativity predicted it would be to within a percent or two, and they turned on the adjustment.

 

http://relativity.livingreviews.org/Articles/lrr-2003-1/fulltext.html

Look at Chapter 5, about halfway down

[Daniel Foreman]

 

 

Great. Go use a map and compass then. How does that do for finding a button on your shirt? Millions of people find that GPS is accurate enough to use for many purposes.

 

Accuracy and precision are relative, and you are attempting to use them as some absolute, which is a form of equivocation.

 

But I keep loosing buttons off my shirt, I want to GPS tag them all so I don't keep having to buy them. epically as my new GPS tagged buttons are worth a few thousands a piece. It's a perfectly valid application even if you don't personally want use it. I also plan to GPS track socks.

 

I'm not going to respond to everything else you said, simply because I've covered this multiple times with you in multiple previous posts. At this point I have to consider the words "The definition of a fool is trying the same thing over and over again while expecting a different result." At this point you either get what I'm saying or you don't. Dropping into picky pedantic's with you over GPS certainly isn't going to help. Not when you start answering your own questions in an effort to point score.

 

 

 

Have you actually read any of his papers? This indicates that the answer is "no"

Edited August 16, 2013 by Daniel Foreman

[Ihcisphysicist]

That is why i say that 'perspective' plays the biggest role in the illusion of time and space. So one could say that there is no time from the largest perspective of the universe.

Edited August 23, 2013 by Ihcisphysicist

[pears]

Motion is a relationship between space and time. It describes the change in position of an object in space, with respect to time. You cannot describe motion without reference to time. But the concepts of motion and time do seem to be bound up together. If all motion in the universe ceases then can time really be said to be passing in any meaningful way? If there was no motion, there would be no pendulums, no oscillations in atomic clocks, no biological processes such as aging, or conscious awareness of the passing of time, and no change in the entropy of the universe. So a universe with no motion would be indistinguishable from a universe where time had stopped. Could the flow of time really be said to exist in such a static universe?

 

So it seems that in some way time, or at least the idea of time as a flow does depend on the concept of motion, or at least on the concept of change.

 

But then as time depends on motion for its definition, so does motion depend on time. You cannot discuss the one without discussing the other, as in the Opening Poster's experiments 1 and 3 demonstrate:

 

 

 

Space itself exists that is a self-evident fact, and I can prove it with several experiments.

 

Experiment one.

 

Take one room, place a ball gun at the end of it calibrated to a specific speed. Set a timer to run when the ball is fired. Place a catcher at the other end of it ready to receive a ball. Setup a trigger sensor in the catchers mit that stops the timer.

 

Now separate the machine and catcher across a range of different distances, record the times it's taken the ball to fly from the machine to the catcher.

 

Conclusion: If the ball takes varying amount of time to reach the catcher, and providing that the time taken to travel is shorter at a closer distance than it is at a longer distance. Then we can confirm that the space between the pitcher and catcher exists.

 

Experiment three:

 

Look at your own feet, and drop a hammer from your face, onto your toes.

 

Conclusion: The release of the hammer didn't hurt the millisecond it was let go, therefore time must have passed between the release of the hammer and the breaking of your toes. The hammer must have travelled through something in that time. This is called space.

 

So to a certain extent I do agree with the OP that time (or the apparent flow of time) depends on motions or physical changes, however I think that as time is dependent on motion, so motion is dependent on time to have any possible meaning.

 

 

Time still passes even if there is no motion, in fact, the rate of time passing is greatest when there is no motion. Further, when you are dealing with QM, the concept of motion becomes rather fuzzy, so any tie between time and motion tends to fall apart.

 

But if all motions and changes in the universe ceased, how could you possibly know if time was flowing? Also what do you mean that the rate of time passing is greatest when there is no motion? I am out of my depth with your second sentence (well I am possibly out of my depth in the whole discussion but anyway...). What does it mean for motion to go fuzzy at the QM level? But regardless, I assume some changes are still occurring at the QM level when time is 'flowing', which is I suppose is what Daniel ultimately means when he talks of motion. At least that is what I mean when I think of the flow of time being dependent on motion.

 

 

Time cannot be confused with matter (matter is a physical system with properties such as energy and momentum defined at a given instant in time). If all interactions between matter ceased and all expansion within the universe stopped then time, real time, will continue to flow whereas it is [math]x^0[/math], apparent time, which will be stopped, somehow as stooping a clock with your hands does not mean that you have stopped the flow of time.

 

Can you tell me more about this real or absolute time? I read the wikipedia article but couldn't find much more about it after a quick google (maybe I'm searching for the wrong things) How can its existence be demonstrated?

Edited August 25, 2013 by pears

[ADreamIveDreamt]

Father Time is awesome.

[Myuncle]

Motion is a relationship between space and time. It describes the change in position of an object in space, with respect to time. You cannot describe motion without reference to time. But the concepts of motion and time do seem to be bound up together. If all motion in the universe ceases then can time really be said to be passing in any meaningful way? If there was no motion, there would be no pendulums, no oscillations in atomic clocks, no biological processes such as aging, or conscious awareness of the passing of time, and no change in the entropy of the universe. So a universe with no motion would be indistinguishable from a universe where time had stopped. Could the flow of time really be said to exist in such a static universe?

 

If you consider time as the speed of our clock, then movement does not depend on time, it can only be calculated by time. If you consider time as a separate dimension you have to prove its existence, have you ever seen it, heard it, touched it? Why insisting on a dimension if we have no proof of it?

[swansont]

But if all motions and changes in the universe ceased, how could you possibly know if time was flowing?

You can't. But neither can you know that it wouldn't. What you can do is extrapolate from what we d know, and that is that time does not cease as motion decreases.

 

Also what do you mean that the rate of time passing is greatest when there is no motion? I am out of my depth with your second sentence (well I am possibly out of my depth in the whole discussion but anyway...).

Time dilation is speed dependent, and has no effect at zero speed. Moving clocks run slow. A stationary clock runs as fast as a clock will.

 

 

What does it mean for motion to go fuzzy at the QM level? But regardless, I assume some changes are still occurring at the QM level when time is 'flowing', which is I suppose is what Daniel ultimately means when he talks of motion. At least that is what I mean when I think of the flow of time being dependent on motion.

One cannot simultaneously know the momentum and position of anything with arbitrary precision. So if something were truly at rest, we would know it has no momentum, and we could not know where it is.

 

In terms of QM and clocks, the "motion" of electrons inside the atom is not well defined. It is not classical. You can't equate a state change of an electron with motion.

[pears]

 

If you consider time as the speed of our clock, then movement does not depend on time, it can only be calculated by time. If you consider time as a separate dimension you have to prove its existence, have you ever seen it, heard it, touched it? Why insisting on a dimension if we have no proof of it?

 

Why would you expect to observe time in this way? In what sense would you expect to observe it? The inference of time as a dimension fits in well with our understanding of the universe. Just because it is not directly observable in the way you suggest, (i.e. as if it were a material object) does not mean the model is wrong.

You can't. But neither can you know that it wouldn't. What you can do is extrapolate from what we d know, and that is that time does not cease as motion decreases.

 

Then it is pure speculation either way. In what sense can something that cannot be measured or observed in any way be said to exist - or not?

 

Time dilation is speed dependent, and has no effect at zero speed. Moving clocks run slow. A stationary clock runs as fast as a clock will.

 

Ah I see what you mean. But speed and motion are relative, so there is not absolute value of stationary. It can only be stationary relative to the observer, for whom the clock is running apparently normally. But if the clock ran slowly then so would the internal clock in the observer (i.e their aging process and their internal mechanism for perceiving time). So they would see time running normally, but another observer, with another clock, and biochemical system, would run differently, relative to the first observer. If all processes in the universe stopped, all observers at all points would perceive time running normally at their frozen instant of time (relative to them) but were there a hypothetical outside observer, outside of the universe, observing the frozen universe, they could conclude that time had stopped there.

 

One cannot simultaneously know the momentum and position of anything with arbitrary precision. So if something were truly at rest, we would know it has no momentum, and we could not know where it is.

 

In terms of QM and clocks, the "motion" of electrons inside the atom is not well defined. It is not classical. You can't equate a state change of an electron with motion.

 

 

I see thank you, though presumably when you say 'truly at rest' you mean relative to the observer?

[swansont]

If all processes in the universe stopped, all observers at all points would perceive time running normally at their frozen instant of time (relative to them) but were there a hypothetical outside observer, outside of the universe, observing the frozen universe, they could conclude that time had stopped there.

 

 

There is no observer "outside the universe", by definition.

[pears]

I know that. That's why I used the word hypothetical.

 

It's a thought experiment to demonstrate my point that when there is no relative motion in the universe, then it is quite feasible to conclude that time is not flowing.

Edited August 27, 2013 by pears

[swansont]

 

It's a thought experiment to demonstrate my point that when there is no relative motion in the universe, then it is quite feasible to conclude that time is not flowing.

 

 

But if I have a very cold cloud of atoms (at, say, a microKelvin), time flows just fine, regardless of the small amount of motion they still have. I don't see why making them move incrementally less would stop time.

[pears]

I'm not postulating that. I've only postulated that when there is no motion in the universe as a whole then time could be thought of as not flowing. In your atom cloud, there may be no motion between the atoms but there would be some inside the atoms. I suppose if you stopped all motion in a region of space, including an atomic clock by pressing a magic button, the clock would stop ticking and time would appear to not flow. I guess the question is, what is the nature of the magic button? Is it a motion stopper or a time stopper, or do they amount to the same thing?

 

I hadn't actually contemplated the cease of motion in an isolated region. I fear it may be too much for my brain to handle at this stage.

[swansont]

I'm not postulating that. I've only postulated that when there is no motion in the universe as a whole then time could be thought of as not flowing. In your atom cloud, there may be no motion between the atoms but there would be some inside the atoms. I suppose if you stopped all motion in a region of space, including an atomic clock by pressing a magic button, the clock would stop ticking and time would appear to not flow. I guess the question is, what is the nature of the magic button? Is it a motion stopper or a time stopper, or do they amount to the same thing?

 

But that's the thing — such a situation violates the laws of physics. There's no way to scientifically answer a question that's predicated on the laws not applying. You are free to conclude that time stops, just as I am free to conclude that the invisible infinite unicorn will kick the universe and restart it should this ever happen.

[pears]

Well indeed. But then this whole thread is more of a philosophical discussion than a scientific one. Can a question such as "What is time?" even be answered by science?

[zapatos]

Well indeed. But then this whole thread is more of a philosophical discussion than a scientific one. Can a question such as "What is time?" even be answered by science?

I think that 'science' has answered that question to its own satisfaction (see post #4). If others don't like that answer then they are free to come up with their own answers.

 

To me, my wedding band is jewelry. To my wife it is a symbol. To a jeweler it is piece of merchandise.

 

It is possible for a single thing to have multiple valid descriptions which vary according to a person's perspective.

Edited August 27, 2013 by zapatos

[Myuncle]

 

Why would you expect to observe time in this way? In what sense would you expect to observe it? The inference of time as a dimension fits in well with our understanding of the universe. Just because it is not directly observable in the way you suggest, (i.e. as if it were a material object) does not

mean the model is wrong.

 

I don't expect to observe time as a dimension, since I can't, because I have no proof of its existence. Universe and motion has existed absolutely fine without the need of time as a dimension. The only ones who need time as a dimension, it looks like it's us humans. I am just being realistic, and can observe only matter, the only thing we can do is calculate the speed of matter, by comparing it with the speed of our clock. Time doesn't flow, a river can flow, a clock can flow, but not time.

[michel123456]

I really am amazed with people having problem with time and having no problem with space.

Why don't you ask yourself "what is distance"?

 

 

If you really- but really- very profoundly - think about it, you may realize that it is not obvious at all: what is distance.

 

It is not less mysterious than Time.

Edited August 28, 2013 by michel123456

[Didymus]

Space is nothing but a way to explain where matter is. Time is nothing but a way to describe the order in which events occured. Neither "exist" as a fabric that can be created, destroyed, bent, altered, or manipulated in any way. Because they don't exist beyond a way to describe things that do exist.

[Greg H.]

Space is nothing but a way to explain where matter is. Time is nothing but a way to describe the order in which events occured. Neither "exist" as a fabric that can be created, destroyed, bent, altered, or manipulated in any way. Because they don't exist beyond a way to describe things that do exist.

 

I tend to describe both in terms of separations. Distance is the separation between two discrete sets of physical coordinates. Time is the separation of two discrete events. It's probably not the best description, but it helps.

Edited August 29, 2013 by Greg H.

[Daniel Foreman]

I really am amazed with people having problem with time and having no problem with space.

Why don't you ask yourself "what is distance"?

 

 

If you really- but really- very profoundly - think about it, you may realize that it is not obvious at all: what is distance.

 

It is not less mysterious than Time.

 

That's because space is easy to quantify. I work with spacial co-ordinates all the time. So when I think about space I think in terms of X, Y and Z. Now I know these are mathematical terms just like T. But unlike Time, I can see space around me. In fact I'm designed to judge distances that's why human beings have two eyes, to do just that.

 

I suspect you're thinking in terms of what is space, as in what is it made up of and how does it work?

 

That issue only comes along when you try to equate non-matter elements of the universe into matter based metaphors. Space is space, it is the framework in which matter exists. Just like matter is matter, it is the stuff we are all made up of. I have little patience with people who talk about "the fabric of space" and start equating it to rubber sheets and the like. Because that's just translating something that isn't matter into a metaphor. There has to come a point were you stop doing that and allow it to be classified by what is actually is, that being... well space! We know matter doesn't exist all together at one single point, we know it likes to spread around. And once again, as is common to science, we observe the movement of matter as it exists in space and is affected by various other forces. Matter is the medium by which we translate these aspects of the universe. Which is a fundamental flaw in our approach, but we have nothing else to do it with.

[Strange]

In fact I'm designed to judge distances that's why human beings have two eyes, to do just that.

 

Ah, maybe that is the problem. Some of us also have the ability to judge the time between events as well; it is built into the brain.

 

Those of us with this "miraculous" ability struggle to see why someone would think time doesn't exist.

[Greg H.]

Here's an interesting observation that is (I think) on topic:

 

Imagine the following conversation:

 

Al: How far is it to there from here?

Bob: Oh, bout half an hour by car.

 

I hear this all the time. (I've even said it myself - maybe it's a Southern thing). And we, or at least most of the people I know, accept that as a valid answer even though it's clearly not a response in distance.