What proof do we have that TIME exists?

[sahmgeek]

Define "raw, unfiltered reality".

exactly. Ask Chalnoth; he/she proposed it.

 

[sahmgeek]

Events occur in a particular order because of the second law of thermodynamics - that is, entropy will always increase. Like Chalnoth said, time doesn't flow, as relativity treats it as a fourth dimension that we move through, not it flowing by us.

I did not suggest that time, itself, flows. I think i said that we experience time as flowing (i.e. arrow of time). HUGE difference. so, on this point, we agree.

 

[Drakkith]

exactly. Ask Chalnoth; he/she proposed it.

Ah, I see now. The way we experience the universe is dependant on our senses.

 

[petm1]

It seems more and more likely that time is discrete - that is, divided into moments. The length of such a moment would the Planck Time, which is the amount of time that is takes light to travel one Planck length. The Planck Length is for all purposes the smallest you can get, as it corresponds to Planck's Constant, a figure which represents the size of the smallest unit of energy, a quantum.

Think of Planck's time, we use a photon to measure it but is time the photon? Is time the length of the photons motion in one dimension? I liken time to the duration of the photon's motion not as one dimensional like the photon but as a dilating three dimensional sphere with the photon used as the radius, making time the dilating area that gives the photon's its direction in space.

It seems more and more likely that time is discrete - that is, divided into moments. The length of such a moment would the Planck Time, which is the amount of time that is takes light to travel one Planck length. The Planck Length is for all purposes the smallest you can get, as it corresponds to Planck's Constant, a figure which represents the size of the smallest unit of energy, a quantum.

Matter is discrete and if you think of time as a three sphere then to me matter appears as one moment of time filled with energy a four dimensional object that we can use as a clock. Billions of clocks all started at the same relative time, from the same Planck length, and still relative to each of us today.

 

[Drakkith]

Think of Planck's time, we use a photon to measure it but is time the photon? Is time the length of the photons motion in one dimension? I liken time to the duration of the photon's motion not as one dimensional like the photon but as a dilating three dimensional sphere with the photon used as the radius, making time the dilating area that gives the photon's its direction in space.

What? The distance the photon travels is used to measure the time, the photon is not time itself. I can't follow the rest of your post as it doesn't make any sense to me. My personal view is simply that time is a measurement just like distance is.

 

[Chalnoth]

true, but the implications of this raise a huge question concerning whether we will ever be able to understand raw, unfiltered reality (if there is such a thing...i think there is).

Understanding the true nature of reality is what science is for.

 

[Chalnoth]

Ah, I see now. The way we experience the universe is dependant on our senses.

Yes, precisely. And more than that the way our brains behave. This is why science is so important: it allows us to move past the biases imposed by our limited senses and cognitive biases.

 

[sahmgeek]

Yes, precisely. And more than that the way our brains behave. This is why science is so important: it allows us to move past the biases imposed by our limited senses and cognitive biases.

how is that at all possible? how are we getting beyond the limits of our senses? science is LIMITED TO our senses, is it not?

 

[Chalnoth]

how is that at all possible? how are we getting beyond the limits of our senses? science is LIMITED TO our senses, is it not?

Not at all!

To take a trivial example, we can only see electromagnetic radiation within a narrow range of wavelengths, from about 390nm to 750nm. But with the right instruments we can detect any form of electromagnetic radiation, from radiation with wavelengths of many meters (or more) to radiation with wavelengths as small as a proton (sometimes even smaller).

 

[sahmgeek]

Not at all!

To take a trivial example, we can only see electromagnetic radiation within a narrow range of wavelengths, from about 390nm to 750nm. But with the right instruments we can detect any form of electromagnetic radiation, from radiation with wavelengths of many meters (or more) to radiation with wavelengths as small as a proton (sometimes even smaller).

Instruments are an extension of our senses. Our senses magnified.

 

[Chalnoth]

Instruments are an extension of our senses. Our senses magnified.

Which is one way which science allows us to push past our limitations.

The other major way is cognitive: by requiring independent verification of results, and by using explicit models of the universe which provide precisely predictions, we can move past our cognitive biases.

Any attempt to access the fundamental behavior of reality which only relies on personal experience is doomed to fail because our cognitive biases are basically guaranteed to muck things up. So we need to correct for them. And that is what science is good at.

 

[alt]

Super weird indeed. Moreover, if time exists, & it passes linearly, it should have an infinite speed, since it passes continuously..Time is weirder than existence itself

The above and your further comments in a later post about time having infinite speed.

I'm not sure what you're getting at. I just walked past my desk - it has an infinite number of points on it, yet I walked past them in about one second - not t infinite speed.

 

[alt]

Which is one way which science allows us to push past our limitations.

The other major way is cognitive: by requiring independent verification of results, and by using explicit models of the universe which provide precisely predictions, we can move past our cognitive biases.

Any attempt to access the fundamental behavior of reality which only relies on personal experience is doomed to fail because our cognitive biases are basically guaranteed to muck things up. So we need to correct for them. And that is what science is good at.

I certainly respect what you're saying here. Nevertheless, it s still a matter of personal experience on the part of scientists.

Chalnoth, I want to ask you - what is your personal experience of the present moment. What time (or any other) value do you place on it ?

 

[Homesick345]

The above and your further comments in a later post about time having infinite speed.

I'm not sure what you're getting at. I just walked past my desk - it has an infinite number of points on it, yet I walked past them in about one second - not t infinite speed.

I'm not sure what I'm getting at neither. I always felt that time goes through a "contimuum", a flow, while matter is discrete. Since early childhood, I felt time goes at vertiginous speeds (of course what is that speed & what I'm getting at; may well be nonsense - sorry!)

 

[Chalnoth]

I certainly respect what you're saying here. Nevertheless, it s still a matter of personal experience on the part of scientists.

Not at all!

The main point here is that we don't trust our perceptions, or even our thought process. We check them against others. Others are unlikely to fall for the same errors in the same way, and even when they are due to various cognitive biases, there are generally many different ways to test a given scientific model, and those different ways of testing the same model are highly unlikely to be susceptible to our cognitive biases in the same way.

To say it another way, science is a way of answering the question, "How can we learn what's true without being able to trust ourselves?" Independent verification provides that.

Chalnoth, I want to ask you - what is your personal experience of the present moment. What time (or any other) value do you place on it ?

I don't go by personal experience. I go by evidence.

The evidence to date is that the best description we currently have for the description of time lies in General Relativity. And GR has a number of interesting features which upset our typical colloquial notions of time. One of the most critical is that there is no such thing as a global "now" in General Relativity. That is to say, different observers will generally disagree as to which far-away events occur simultaneously.

While it may seem weird or trivial, this is a truly profound insight. The lack of a global now means, necessarily, that the past and future have the exact same existence as the present. And that is profoundly strange, given our colloquial notions. We are not a set of beings traveling in time, for example: we exist at all times. If we were able to somehow step outside of our space-time and observe the whole of our space-time from the outside, we would see both our past and future selves.

The only thing that gives the illusion of the flow of time is our cognitive processes. Specifically, our brains process information about our surroundings in a time-ordered fashion, and store memories in a time-ordered fashion. So that when we perceive the world, everything appears strongly time-ordered, when in reality this ordering is simply a feature of our cognitive processes, which in turn have a strict time ordering due to the nature of entropy (which tends to increase with time).

 

[petm1]

What? The distance the photon travels is used to measure the time, the photon is not time itself. I can't follow the rest of your post as it doesn't make any sense to me. My personal view is simply that time is a measurement just like distance is.

Does a photon stand outside of time? You do not think it is a part of time? After all a photon is the smallest part of my present as far as I can see.

 

[Drakkith]

Does a photon stand outside of time? You do not think it is a part of time? After all a photon is the smallest part of my present as far as I can see.

I have no idea what you are trying to say.

 

[TheTechNoir]

As I said, this speaks more about us than it does about the reality of time. We don't experience the real world raw and unfiltered. We experience the world through the lens of our senses and the processing that goes on in our brains.

I am inclined to agree with this.

As for what Chalnoth was saying about a finite number of instances, you should read about quantization and consider that concept.

 

[Homesick345]

I am inclined to agree with this.

As for what Chalnoth was saying about a finite number of instances, you should read about quantization and consider that concept.

Brilliant I would never have hoped to get such depth and insight from all the guys thanks people!

 

[TheTechNoir]

I found myself wondering the same thing long before I took an interest in reading about/learning about physics as well. The idea of length or time occurring in discreet packets never really crossed my mind as a solution but when I started learning about physics and learned of this concept it appealed to me because it put the pieces together in my head and resolved my puzzlement.

I later found out that the question was long ago posed (albeit in a more thought out and encompassing manner) as a paradox, or series of paradox' called Zeno's Paradox. You may find some of this article relates to what you were asking http://en.wikipedia.org/wiki/Zeno's_paradoxes (note: you may find some of the philosophical talk to be rubbish)EDIT: I should probably be careful here not to derail this into the realm of philosophy - that isn't my intention. The scientific answers are being/have been provided in this thread. I am just as an afterthought thinking/wondering if this concept is what you had in mind as what was puzzling you.

 

[Homesick345]

I found myself wondering the same thing long before I took an interest in reading about/learning about physics as well. The idea of length or time occurring in discreet packets never really crossed my mind as a solution but when I started learning about physics and learned of this concept it appealed to me because it put the pieces together in my head and resolved my puzzlement.

I later found out that the question was long ago posed (albeit in a more thought out and encompassing manner) as a paradox, or series of paradox' called Zeno's Paradox. You may find some of this article relates to what you were asking http://en.wikipedia.org/wiki/Zeno's_paradoxes (note: you may find some of the philosophical talk to be rubbish)

I was just looking the Zeno paradoxes yesterday! Of course it's the same line of thinking. ...in all humility, I see time a more complex and puzzling thing than matter. I know about the famous Einstein quote, time is what you measure with a clock...to a trained brilliant physicist, of course this would be easy to grasp , time as an experimental concept. All in all it is such an elusive and dizzying concept, this time thing...

 

[alt]

Not at all!

The main point here is that we don't trust our perceptions, or even our thought process. We check them against others. Others are unlikely to fall for the same errors in the same way, and even when they are due to various cognitive biases, there are generally many different ways to test a given scientific model, and those different ways of testing the same model are highly unlikely to be susceptible to our cognitive biases in the same way.

To say it another way, science is a way of answering the question, "How can we learn what's true without being able to trust ourselves?" Independent verification provides that.

I wasn't really arguing against this.

I don't go by personal experience. I go by evidence.

I was asking you for your personal view on what the present momnet is - it's duration, how you conceive it, etc. But if you have none, or care not to render one, that's OK

The evidence to date is that the best description we currently have for the description of time lies in General Relativity. And GR has a number of interesting features which upset our typical colloquial notions of time. One of the most critical is that there is no such thing as a global "now" in General Relativity. That is to say, different observers will generally disagree as to which far-away events occur simultaneously.

While it may seem weird or trivial, this is a truly profound insight. The lack of a global now means, necessarily, that the past and future have the exact same existence as the present. And that is profoundly strange, given our colloquial notions. We are not a set of beings traveling in time, for example: we exist at all times. If we were able to somehow step outside of our space-time and observe the whole of our space-time from the outside, we would see both our past and future selves.

There is nothing terribly new in these concepts though. Many ancient texts have considered them. Even Augustine, in his 'Confesssions' struggled very deeply with them. And may I add, said 'Confessions' (absent of all the "If it please thee Lord", etc), is as as excellent a treatise of the concept of time, as I have come across.

The only thing that gives the illusion of the flow of time is our cognitive processes. Specifically, our brains process information about our surroundings in a time-ordered fashion, and store memories in a time-ordered fashion. So that when we perceive the world, everything appears strongly time-ordered, when in reality this ordering is simply a feature of our cognitive processes, which in turn have a strict time ordering due to the nature of entropy (which tends to increase with time).

So if this ordering is simply a feature of our cognitive processes, is it suggested that the reality is that of one, eternal now ? In truth, I'm not sure what you are saying .. what your conclusion is, in this above paragraph.

 

[Chalnoth]

I later found out that the question was long ago posed (albeit in a more thought out and encompassing manner) as a paradox, or series of paradox' called Zeno's Paradox. You may find some of this article relates to what you were asking http://en.wikipedia.org/wiki/Zeno's_paradoxes (note: you may find some of the philosophical talk to be rubbish)

Zeno's paradox doesn't really have anything to do with the nature of time. It has to do with the fact that when you use the wrong coordinate system for a given application, you get strange results. The problem arises in Zeno's paradox because you've created an artificial infinity at distance=1 (or time=0, depending on the paradox). The infinity has nothing to do with reality, it's just due to the numbers we are using to describe reality.

These sorts of situations are very common in General Relativity. In fact, for most space-times, it is impossible to describe the entire space-time with only one coordinate system and still have things well-behaved everywhere. A simple example is the surface of a sphere, like the Earth. With the Earth, we usually like to use a simple coordinate system containing longitude and latitude. But the longitude/latitude coordinates have a problem: at the north and south poles, many different longitudes correspond to the exact same point (the pole). The fact that many points in our coordinate system map onto just one point on in the real world causes infinities for some calculations, leading to nonsensical results (you might conclude, for example, that the gravitational attraction at the poles was infinite!).

So Zeno's paradox is an artificial paradox: it only exists because we've used a particular set of numbers to describe the real world, and then tried to use those numbers beyond infinity. That is a nonsensical thing to do.

 

[sahmgeek]

The only thing that gives the illusion of the flow of time is our cognitive processes. Specifically, our brains process information about our surroundings in a time-ordered fashion, and store memories in a time-ordered fashion. So that when we perceive the world, everything appears strongly time-ordered, when in reality this ordering is simply a feature of our cognitive processes, which in turn have a strict time ordering due to the nature of entropy (which tends to increase with time).

I would also be interested in hearing further clarification on this perspective.

Let me change your language a bit and see what happens:
Specifically, our brains process information about our surroundings at input (i.e. when observation takes place) and that input occurs at EVERY present moment. Is that time-ordered processing?

Also, are you suggesting that the "perceived world" is not orderly independent of observation?

What I'm hinting at here is the combined use of "time" and "ordered" could be misleading. For instance, the world may be orderly independent of observation, but "flow of time" could still just be a function of cognitive processes. does that make sense? it is not my intention to confuse or complicate, but just to get at the heart of the matter.

sidenote: whether or not memories are stored in a time-ordered fashion is debatable, i think. i would have to dig, but recall research suggesting that memory can be unreliable b/c, with time, they can become "entangled", shall we say ;).

 

[sahmgeek]

Also, are you suggesting that the "perceived world" is not orderly independent of observation?

If I understand QM correctly (which i may not!), this is kind of what it says, right? I was just wondering if that was your contention as well?

 

[Chalnoth]

I would also be interested in hearing further clarification on this perspective.

Let me change your language a bit and see what happens:
Specifically, our brains process information about our surroundings at input (i.e. when observation takes place) and that input occurs at EVERY present moment. Is that time-ordered processing?

Well, the time ordering comes in due to the nature of entropy. Entropy fixes a set arrow of time, makes it so that things in the future depend upon things in the past. The appearance of time ordering that we interpret is a feature of this effect occurring within our brains, of this inexorable rise of entropy. It isn't the only thing that does this, however.

Also, are you suggesting that the "perceived world" is not orderly independent of observation?

No, not at all. What I am saying is that by virtue of how our brains work, we observe the world from a fixed perspective. That perspective is not, however, the only way to describe the behavior of the universe that surrounds us. We are starting to obtain inklings of just how different the universe can appear from different perspectives with our studies of General Relativity and Quantum Mechanics.

Holography in particular is a fascinating subject, where the physical behavior of one system in, for example, two dimensions is mathematically identical to the physical behavior of a different system in three dimensions. This means that for this system, whether we think of it as a two-dimensional system or a three-dimensional system depends entirely upon our perspective. And that is mindbogglingly weird.

sidenote: whether or not memories are stored in a time-ordered fashion is debatable, i think. i would have to dig, but recall research suggesting that memory can be unreliable b/c, with time, they can become "entangled", shall we say ;).

What I mean is that the order in which they are stored is ordered by time. Memories are, of course, distributed all across the brain, are not accessed in anything remotely related to time ordering, and are modified every time they are accessed. I was merely referring to the way in which they are originally stored.

 

[Mark M]

Think of Planck's time, we use a photon to measure it but is time the photon? Is time the length of the photons motion in one dimension? I liken time to the duration of the photon's motion not as one dimensional like the photon but as a dilating three dimensional sphere with the photon used as the radius, making time the dilating area that gives the photon's its direction in space.

It really isn't that trivial - time can be defined as $T=\frac{D}{S}$. At times less than the Planck Time, no distance is traveled by anything. Hence, T=0. No time has passed. So, we can quantize time into units of Planck Time.

 

[sahmgeek]

Holography in particular is a fascinating subject, where the physical behavior of one system in, for example, two dimensions is mathematically identical to the physical behavior of a different system in three dimensions. This means that for this system, whether we think of it as a two-dimensional system or a three-dimensional system depends entirely upon our perspective. And that is mindbogglingly weird.

Indeed, it is all fascinating and mindbogglingly weird! I suppose that is why I find myself here discussing it (in an orderly fashion, at ever present moments...)

 

[sahmgeek]

btw Homesick, if you don't already have it, Scientific American's "A Matter of Time" special edition had some really thought-provoking articles. http://www.scientificamerican.com/special/toc.cfm?issueid=40&sc=singletopic

 

[Tanelorn]

Is time not a physical characteristic of our Universe and our reality?
Time is also a relative measurement separating two events.

 

[petm1]

It really isn't that trivial - time can be defined as T=DS. At times less than the Planck Time, no distance is traveled by anything. Hence, T=0. No time has passed. So, we can quantize time into units of Planck Time.

Time is how we count existence; a clock can only count its own existence as a clock. A photon may not change in time as it moves in space, other than red shift, but its duration of existence always matches the length in space that it has traveled. Motion may not be measured at Planck's time but we should still have existence at that scale. Time is the smallest and largest common denominator of existence, everything that exists does so as its own part of our temporal universe, otherwise we would not be able to describe the anything as a four dimensional object.

 

[sahmgeek]

Is time not a physical characteristic of our Universe and our reality?

Can you flesh that out a little more?

 

[SHISHKABOB]

The above and your further comments in a later post about time having infinite speed.

I'm not sure what you're getting at. I just walked past my desk - it has an infinite number of points on it, yet I walked past them in about one second - not t infinite speed.

I've only taken a class called contemporary physics that touched on quantum mechanics for just a portion of the quarter, but my understanding of it drew me to the conclusion that space was quantized. Or at least that's what I got out of the class. The idea that space is not infinitely divisible.

Therefore, unless this conception is erroneous, then walking past your desk *in reality* is not a matter of walking past something with an infinite set of points on it, but rather walking past something with a finite number of points.

If you take a line, and consider each and every single one of the infinite points on it as you move along it, wouldn't you never get anywhere?

 

[Drakkith]

I've only taken a class called contemporary physics that touched on quantum mechanics for just a portion of the quarter, but my understanding of it drew me to the conclusion that space was quantized. Or at least that's what I got out of the class. The idea that space is not infinitely divisible.

Therefore, unless this conception is erroneous, then walking past your desk *in reality* is not a matter of walking past something with an infinite set of points on it, but rather walking past something with a finite number of points.

If you take a line, and consider each and every single one of the infinite points on it as you move along it, wouldn't you never get anywhere?

Sure you would, as each point would be visited for an infinitely short amount of time. Or something like that.

 

[SHISHKABOB]

Sure you would, as each point would be visited for an infinitely short amount of time. Or something like that.

but... if it's infinite... then, each one gets an infinitely short amount of time but then what is 1/∞ times infinity and... ouch there goes my brain

I don't think 1/∞ makes sense anyways