Physicists investigate how time moves forward

Sep 05, 2008 By Lisa Zyga feature

As humans, we have a very intuitive concept of time, and of the differences between the past, present, and future. But, as scientists Edward Feng of the University of California, Berkeley, and Gavin Crooks of the Lawrence Berkeley National Laboratory point out, science does not provide a clear definition of time.

“In our everyday lives we have the sense that time flows inexorably from the past into the future; water flows downhill; mountains erode; we are born, grow old, and die; we anticipate the future but remember the past,” the scientists write in a recent study in Physical Review Letters. “Yet almost all of the fundamental theories of physics – classical mechanics, electrodynamics, quantum mechanics, general relativity, and so on – are symmetric with respect to time reversal.

“The only fundamental theory that picks out a preferred direction of time is the second law of thermodynamics, which asserts that the entropy of the Universe increases as time flows toward the future. This provides an orientation, or arrow of time, and it is generally believed that all other time asymmetries, such as our sense that future and past are different, are a direct consequence of this thermodynamic arrow.”

In their study, Feng and Crooks have developed a method to accurately measure “time asymmetry” (which refers to our intuitive concept of time, that the past differs from the future, in contrast with time symmetry, where there is no distinction between past and future). They began by investigating the increase in energy dissipation, or entropy, in various arrangements.

The scientists’ method of measuring time asymmetry is best explained in the context of an experiment. In the macroscopic world, where glasses of milk are spilled, time asymmetry is obvious. But on the microscopic scale, because the amount of energy involved is so small, it’s more difficult to tell that entropy is increasing, and that time is moving forward and not backward. In fact, during some intervals, entropy might actually decrease. So even though overall entropy is still increasing on average, in accordance with the second law, the direction of time is not obvious at every moment in the experiment. Further, the scientists show that even an average entropy increase does not necessarily ensure time asymmetry, but can arise in an arrangement that appears time-symmetric.

Feng and Crooks wanted their new measurement method to explain how time can move forward even at points when entropy is decreasing. To do this, they analyzed the folding and unfolding of a single RNA molecule attached to two tiny beads. By controlling the distance between one bead and an adjacent optical laser trap, the scientists could stretch and compress the RNA molecule. Initially, the RNA starts in thermal equilibrium, but, as it’s alternately stretched and compressed, the total entropy of the RNA and the surrounding bath increases on average.

“We use an ensemble, or large number, of RNA trajectories to measure the time asymmetry,” Feng explained to PhysOrg.com. “Using work measurements for both forward and reverse experiments, we simply plug these measurements into an expression for A, or time asymmetry, in the paper. Assuming we know the free energy change, this gives the square of the length of time's arrow.”

To measure time asymmetry in this arrangement, an observer watching the RNA’s trajectory of unfolding and folding should be able to tell if the trajectory was generated by stretching or compressing. The scientists quantify this observation in terms of the “Jensen-Shannon divergence,” a probability which gives a “0” if stretching and compressing are identical, a “1” if they are distinguishable at every moment, and some fraction of one if they overlap occasionally.

This probability, Feng and Crooks explain, can more accurately describe time asymmetry than a simple measurement of average entropy, since the average entropy is sensitive to unusual events. For example, if the RNA becomes tangled, it resists being unfolded when the beads expand. Because the tangled RNA is pulled apart very slowly, the process is essentially time-symmetric. The scientists show that a model of this process has large average dissipation, or entropy increase, but small time asymmetry, as one intuitively expects due to the slow pulling.

“The Jensen-Shannon divergence is better than the average dissipation due to its mathematical form,” Feng said. “This accounts for the rare events in a different way, which we show with the RNA molecule that can get stuck.”

Besides the theoretical interest, this research could have other applications, such as for estimating free energy differences in non-equilibrium experiments. The scientists explain that understanding the relation between time asymmetry and entropy could also be important for studying molecular motors and other kinds of biological machinery.

“While time blatantly moves forward in the macroscopic world, the direction of time becomes confusing on the scale of a single molecule,” Feng summarized. “Our definition employing the Jensen-Shannon divergence highlights this distinction. We hope this will have an impact as scientists study biological molecules and continue to perform single-molecule experiments.”

More information: Feng, Edward H. and Crooks, Gavin E. “Length of Time’s Arrow.” Physical Review Letters 101, 090602 (2008).

Copyright 2008 PhysOrg.com.
All rights reserved. This material may not be published, broadcast, rewritten or redistributed in whole or part without the express written permission of PhysOrg.com.

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Velanarris
4 / 5 (6) Sep 05, 2008
"Science does not provide a clear definition of time", ... because time is an a-prior mode of understanding, an inherent mental ordering of phenomenon,.. not a 'thing', that is intrinsic in reality itself.

We regard the reality in which we have mental access to, subjective phenomenal reality, as opposed to noumenal reality, ... this reality is forever entangled with, and tainted by mental constructs and modes of understanding, the result of which are conceptual artifacts like 'time'.
Hey look, the holographic theory of self applied to science.

I somewhat agree with you and in other manners I disagree. Time does appear to be relative but there are processes that define time and are defined by time such as gravitation and the bonding of time with space in regard to velocity and acceleration.

I do understand where you're comming from though and you could be completely correct, I'm just not so sure it's that clear cut.
ShadowRam
4.5 / 5 (4) Sep 05, 2008
"Science does not provide a clear definition of time", ... because time is an a-prior mode of understanding, an inherent mental ordering of phenomenon,.. not a 'thing', that is intrinsic in reality itself.

We regard the reality in which we have mental access to, subjective phenomenal reality, as opposed to noumenal reality, ... this reality is forever entangled with, and tainted by mental constructs and modes of understanding, the result of which are conceptual artifacts like 'time'.


Exactly.. Time is a conception we made up as we observe Systems moving energy from one high state to another. (Such as a clock 'unwinding')

I bet if we re-wrote time as a concept of energy flow instead of its own entity, a lot of equations will solve and fall into our lap.
mattytheory
3.3 / 5 (3) Sep 05, 2008
Posted by Noumenon:
"Science does not provide a clear definition of time", ... because time is an a-prior mode of understanding, an inherent mental ordering of phenomenon,.. not a 'thing', that is intrinsic in reality itself.

We regard the reality in which we have mental access to, subjective phenomenal reality, as opposed to noumenal reality, ... this reality is forever entangled with, and tainted by mental constructs and modes of understanding, the result of which are conceptual artifacts like 'time'.


Very well worded. I believe you are correct in your assessment that time, as we experience it on a day-to-day basis, is probably an artefact defined completely by our limited understanding of the reality which underlies our world. However, I would be curious in regards to your thoughts about extra dimensions of time, as some theoretical explanations of our universe are purported to require.
E_L_Earnhardt
3.3 / 5 (3) Sep 05, 2008
"Time" is "cause and effect". It therefore varies
enslaved by "cause and effect". We choose some basic cause and effect and compare others. "Rate"
of a chosen cause and effect is compared to others. "Time" stops with the chosen standard.
Velanarris
3.7 / 5 (3) Sep 05, 2008
Velanarris,

I don't know what you mean by 'holographic theory of self', ..really its more a matter of epistemology. Reality, [i]as it is[/i], ...noumenal reality, ...cannot be reproduced within the confines of a bio-mechanical mind; ...to 'fit', it must conform to conditions inherent within mind, given minds operating nature,.. in other words, understood within a-priori conceptual paradigms, time, etc.

To have knowledge of reality, implies that the mind has encapsulated it within the scope of its pre-existing intellectual forms and logical relations (space, causality, time, etc). None of these are discoverable in themselves apart from their mental application.


The holographic theory of self is a very complex ideology but the basic tennants are that reality exists as it does because we perceive it to be so. In reality, there are no physical laws that aren't imposed upon us by our observational awareness.

It sounds kinda loopy from a scientific perspective but it has some correlation with the so called "odd" behavior of quantum mechanics.
Noumenon
3.4 / 5 (7) Sep 05, 2008
Velanarris, mattytheory,

... there are processes that define time and are defined by time such as gravitation and the bonding of time with space in regard to velocity and acceleration.


We can't get out of our own intellectual way, ...so it appears that these things have infused in themselves a 'real' component of time, but we are the ones doing the defining, the ones obtaining the knowledge of these processes, ... the form of this knowledge is predetermined given the minds 'design'.

Noumenon
1.7 / 5 (3) Sep 05, 2008

Velanarris,

I don't know what you mean by 'holographic theory of self', ..really its more a matter of epistemology. Reality, [i]as it is[/i], ...noumenal reality, ...cannot be reproduced within the confines of a bio-mechanical mind; ...to 'fit', it must conform to conditions inherent within mind, given minds operating nature,.. in other words, understood within a-priori conceptual paradigms, time, etc.

To have knowledge of reality, implies that the mind has encapsulated it within the scope of its pre-existing intellectual forms and logical relations (space, causality, time, etc). None of these are discoverable in themselves apart from their mental application.


The holographic theory of self is a very complex ideology but the basic tennants are that reality exists as it does because we perceive it to be so. In reality, there are no physical laws that aren't imposed upon us by our observational awareness.

It sounds kinda loopy from a scientific perspective but it has some correlation with the so called "odd" behavior of quantum mechanics.


Ok, I wasn't aware of that. From my perspective I would reference Kant's Critique, I believe he discovered something, though entirely useless as it doesn't change anything, except that phenomenal reality (reality as it theoretically could be subjectively understood), might not be all there is.

Yes, the 'odd' behavior of QM, i'm sure reality is not odd to itself,.. only to us in trying to obtain knowledge of it in terms necessary for a macroscopically evolved mind. For example, 'there is no' wave function collapse as an entity in itself, ...reality is whatever it is, until it is made to conform to conditions of understanding, the 'observation' is an odd shaped box.
Yes
5 / 5 (1) Sep 05, 2008
I am working on an experiment where I try to investigate what will happen when from the macroscopic world with macroscopic times I stimulate a microscopic oscillating system like a microspring with its resonance frequency. If the time on microcopic scale is QM odd then how will that macroscopic timed event couple to the microscopic spring resonance frequency.
earls
1 / 5 (1) Sep 05, 2008
Yes, it seems to me you're implying you will be attempting to observe something at its specific wavelength of light?
SentientMarine
3 / 5 (2) Sep 06, 2008
Brilliant. Perhaps the most assumed and least tested of all the fundamentals time may be of equal or greater significance to any other phenomena even gravity.
RealPhysicist
1.7 / 5 (3) Sep 06, 2008
Time is very easy to define... If E=MC^2, then time is simply the flow of/and/or distribution of energy wihtin space-time over a given period. Not only that all time is instantaneous and is happening in parralel, when we mean the "arrow of time" we really mean the direction, distribution and flow of energy.

In my opinion the universe is strange kind of circuit, I've been studying some interesting ideas of William James Sidis - The animate and inanimate, and he conceived the concept of the "reverse universe", and I thought, hey that sounds like an electronic circuit.

If we interpreted many phenomena in the universe in similar terms of electronic and their components (i.e. black holes, etc), I bet we'd be doing a lot better. Nature appears to be a self-repeating fractally recursive structure.
superhuman
4 / 5 (3) Sep 06, 2008
"Science does not provide a clear definition of time", ... because time is an a-prior mode of understanding, an inherent mental ordering of phenomenon,.. not a 'thing', that is intrinsic in reality itself.

We regard the reality in which we have mental access to, subjective phenomenal reality, as opposed to noumenal reality, ... this reality is forever entangled with, and tainted by mental constructs and modes of understanding, the result of which are conceptual artifacts like 'time'.


On the contrary, time is very intrinsic in the objective reality itself (the one accessible by way of experiments - the only one science is interested in), 2nd law of thermodynamics is pretty damn solid and in the macro world there is absolutely no ambiguity as to which way the time is going and no room for it to be tainted by our mental constructs.

And if you want to argue on the more counterproductive philosophical level where objective reality is inaccessible - to know that something is an artifact of our mental constructs you would have to have access to the objective reality itself, which you don't.

You could argue that everything is such an artifact, but then the statement loses all its descriptive power.
Noumenon
3 / 5 (3) Sep 06, 2008
The only reality science is interested in is the phenomenal world, and yes in this world time is very intrinsic as you state, you are quite correct,... but realize that by definition, the 'phenmenal world' is that scope of reality which has been conformed to human modes of understanding, in other words, modeled using relations and elements of thought. Although we can define it however, we are not going to discover the tic-toc particle of time because it's not a thing in itself, it's a mental ordering of phenomenon.
Noumenon
3 / 5 (3) Sep 06, 2008
"Science does not provide a clear definition of time", ... because time is an a-prior mode of understanding, an inherent mental ordering of phenomenon,.. not a 'thing', that is intrinsic in reality itself.

We regard the reality in which we have mental access to, subjective phenomenal reality, as opposed to noumenal reality, ... this reality is forever entangled with, and tainted by mental constructs and modes of understanding, the result of which are conceptual artifacts like 'time'.


On the contrary, time is very intrinsic in the objective reality itself (the one accessible by way of experiments - the only one science is interested in), 2nd law of thermodynamics is pretty damn solid and in the macro world there is absolutely no ambiguity as to which way the time is going and no room for it to be tainted by our mental constructs.


Entropy is a concept which requires a mass of elements, gas particles, whatever,.. but time is lost somehow in this system if you expect to find it, rather than apply it. Examine a single element of this system alone and as the point of the article, it becomes a problem.
Velanarris
5 / 5 (1) Sep 06, 2008
"Science does not provide a clear definition of time", ... because time is an a-prior mode of understanding, an inherent mental ordering of phenomenon,.. not a 'thing', that is intrinsic in reality itself.

We regard the reality in which we have mental access to, subjective phenomenal reality, as opposed to noumenal reality, ... this reality is forever entangled with, and tainted by mental constructs and modes of understanding, the result of which are conceptual artifacts like 'time'.


On the contrary, time is very intrinsic in the objective reality itself (the one accessible by way of experiments - the only one science is interested in), 2nd law of thermodynamics is pretty damn solid and in the macro world there is absolutely no ambiguity as to which way the time is going and no room for it to be tainted by our mental constructs.

And if you want to argue on the more counterproductive philosophical level where objective reality is inaccessible - to know that something is an artifact of our mental constructs you would have to have access to the objective reality itself, which you don't.

You could argue that everything is such an artifact, but then the statement loses all its descriptive power.


But, in order for the second law of thermodynamics to be correct it relies on time being held as an inviolate constant, which there is no scientific basis for outside of the second law of thermodynamics.

Alizee
Sep 06, 2008
This comment has been removed by a moderator.
superhuman
3.5 / 5 (4) Sep 06, 2008
The only reality science is interested in is the phenomenal world, and yes in this world time is very intrinsic as you state, you are quite correct,... but realize that by definition, the 'phenmenal world' is that scope of reality which has been conformed to human modes of understanding, in other words, modeled using relations and elements of thought. Although we can define it however, we are not going to discover the tic-toc particle of time because it's not a thing in itself, it's a mental ordering of phenomenon.


Its not a "mental ordering of phenomenon" cause that ordering is constantly being preserved in the reality itself most importantly in its spatial relations.

Turn on a camera and it will record events, their spatial relations on film prove that this ordering is a part of reality and not a product of human mind.
superhuman
4 / 5 (2) Sep 06, 2008
But, in order for the second law of thermodynamics to be correct it relies on time being held as an inviolate constant, which there is no scientific basis for outside of the second law of thermodynamics.


It does not rely on time being held as an inviolate constant, time can change freely, what matters is that at the later point in time the total entropy of a closed system (and Universe as a whole) will be higher so by calculating entropy we can find out the time order of macroscopic events.
Velanarris
4 / 5 (2) Sep 06, 2008
It does not rely on time being held as an inviolate constant, time can change freely, what matters is that at the later point in time the total entropy of a closed system (and Universe as a whole) will be higher so by calculating entropy we can find out the time order of macroscopic events.


But right there you used "time" to define the law. It's a required entitiy for the second law to work.
mattytheory
4 / 5 (2) Sep 06, 2008
The only reality science is interested in is the phenomenal world, and yes in this world time is very intrinsic as you state, you are quite correct,... but realize that by definition, the 'phenmenal world' is that scope of reality which has been conformed to human modes of understanding, in other words, modeled using relations and elements of thought. Although we can define it however, we are not going to discover the tic-toc particle of time because it's not a thing in itself, it's a mental ordering of phenomenon.


Its not a "mental ordering of phenomenon" cause that ordering is constantly being preserved in the reality itself most importantly in its spatial relations.

Turn on a camera and it will record events, their spatial relations on film prove that this ordering is a part of reality and not a product of human mind.


Here's a thought experiment for you: Imagine a universe where there was exactly ONE object. It would thereby be impossible to experience time because time is essentially a spatial rate of change and there would be nothing to measure against. Does time still exist, or does the effect only exist as it is observed, in order to explain the spatial changes themselves?
superhuman
4 / 5 (2) Sep 06, 2008
It does not rely on time being held as an inviolate constant, time can change freely, what matters is that at the later point in time the total entropy of a closed system (and Universe as a whole) will be higher so by calculating entropy we can find out the time order of macroscopic events.


But right there you used "time" to define the law. It's a required entitiy for the second law to work.


Yes, but it doesn't have to be constant also the law only defines the direction of time flow - time arrow, not what time is.
superhuman
4 / 5 (3) Sep 06, 2008
Here's a thought experiment for you: Imagine a universe where there was exactly ONE object. It would thereby be impossible to experience time because time is essentially a spatial rate of change and there would be nothing to measure against. Does time still exist, or does the effect only exist as it is observed, in order to explain the spatial changes themselves?


Universe is a 4d spacetime (or at least thats our best model to date) so time would still be there if I tried to imagine a universe just as there would be space, even if said universe were to be completely empty.

If anything is an artifact of human mind its the fact that we only see one instance of time dimension and therefore can only define time as a "measure of change", but that doesn't make time any less real or a product of human mind.
Velanarris
5 / 5 (1) Sep 06, 2008
Here's a thought experiment for you: Imagine a universe where there was exactly ONE object. It would thereby be impossible to experience time because time is essentially a spatial rate of change and there would be nothing to measure against. Does time still exist, or does the effect only exist as it is observed, in order to explain the spatial changes themselves?


Universe is a 4d spacetime (or at least thats our best model to date) so time would still be there if I tried to imagine a universe just as there would be space, even if said universe were to be completely empty.

If anything is an artifact of human mind its the fact that we only see one instance of time dimension and therefore can only define time as a "measure of change", but that doesn't make time any less real or a product of human mind.


Agreed. That scenario is much like Newton's problem of ether. If you were in the universe with nothing else and you were set to spin.

How would you know you were spinning? Would your perceptions know you're spinning but ignore it due to your frame of reference? Do you spin at all since there is nothing for you to be "spinning" in reference to.
Alizee
Sep 07, 2008
This comment has been removed by a moderator.
Jenson
5 / 5 (2) Sep 07, 2008
Noumonen is correct suggesting that time is a product of the human psychi. Time of itself doesn't exist, we perceive it (time) the way we do because our brains generally only see in terms of black and white, movements and non-movement etc, if we were able to see the world the way it really is you would see that time doesn't exist and all there really is in the universe is devolution *or* evolution.
The perception of the speed at which all this takes place can seem different though, if you remember back to your days as very young children when a day lasted forever, the mind was young and open to many more perceptions than a mature 'mind'.
One other thing to think about is that speed at which everything appears to take place differs depending on ones place in the universe, i.e the day of a human seems short compared to the day of the earth itself which could be millions of years. The day for a single bacteria seems very short compared to our day.
With this in mind think about how the earth would appear for a second of its time. The path its on through its 3D space and the amount of activity that would take place on the surface over that period. In the blink of an earthy eye a human would live a life time.
mattytheory
5 / 5 (2) Sep 07, 2008
How would you know you were spinning? Would your perceptions know you're spinning but ignore it due to your frame of reference? Do you spin at all since there is nothing for you to be "spinning" in reference to.


Of course you would be spinning. The fact that you can't prove it to yourself does not detract from the fact that you are. In other words, you would not be able to perceive it, but it would still be happening. In addition, establishing a frame of reference under these circumstances is impossible because there is nothing relative to yourself upon which you could base it.
Alizee
Sep 07, 2008
This comment has been removed by a moderator.
WDGhrist
5 / 5 (2) Sep 07, 2008
I think that one of the things that causes confusion is to talk about time "flowing." Time does not flow; time is the dimension in which "flow" occurs. It seem to me that a definition of time is that it is a linear ordering of observable states of the universe, similarly to the way in which "direction" (spatial dimension) is a linear ordering of locations. If an object moves right and left we do not say that the "direction" (right-left) is moving; we say that the object is moving in that direction.

What "flows" with respect to time is the coming into existence of more and more observable states of the universe. The past consists of all states that have come into existence. For time to "reverse" would mean that more and more past states would cease to have ever existed, which to me seems a logical contradiction. What makes time different from spatial dimensions is that all locations of the spatial dimension exist together, whereas only past points of time have actual existence.

For events to violate the second law of thermodynamics would not be a reversal of time, it would simply mean that new states would be coming into existence where the change from one state to the next would be different than what is allowed by the second law. Suppose an egg is cracked open and fried, and the egg "unfries" and reassembles itself. That sequence of events, if observed, would not be a reversal of time, it would be a repetition of events in forward and then reverse order, not a reversal of time itself. For time to reverse would mean that the fried state of the egg would cease to have ever existed and ever to have been observed. When I watch a movie that depicts something of this sort, I do not have a sense that the "arrow of time" has turned backwards, I simply have a sense that something is being depicted that is the reverse of what is normal or even possible.

The reason that we can say that most "fundamental theories of physics" are time reversible is that we can conceptually lay out a time line of events that is not dependent upon the events actually having occurred, rather is only dependent upon the possibility that they could occur.

It does occur to me that if it were logically possible for time to actually reverse (i.e., for past states to cease to have existed), then the one "fundamental theory of physics" that would come into play would be the indeterminacy of quantum theory. What would happen if time truly reversed and then turned forward again is that the new sequence of states that would come into existence would not exactly duplicate the previous sequence whose existence had been erased.
Yes
5 / 5 (1) Sep 07, 2008
I think that what this article is about, is that at nanoscale time seems to be perceived differently. That applied, we will have to think about perception of time, not only by a mind like ours or the mind of a bacteria if exists, but also time perceived by an object.
Imagine an oscillator of a macro sized spring and a mass as we know it from lab. With Hooke's law and some math, we can find an expression for the first eigen frequency of the system. Now imagine that we go smaller and smaller. Imagine that when arriving at nanoscale the system starts perceiving time differently.
Maybe because internal molecular vibrations of the system becomes obvious for the system itself. As a result time starts to contract depending on the energy present in the system. The energy continuously changes as a result of interaction with neighboring particles, so the time perception of the nanosystem as a function of our time conception becomes a chaotic mess. Maybe while you were observing the behavior of the nanosystem, years have gone by for that system or while you were watching the system for a year, the system perceived only a ms.
Odd behaviour of the nano system like frequency responses can give clues about this:)
SmartK8
5 / 5 (2) Sep 08, 2008
I think we shouldn't anthropomorphise objects (in this case systems) which are not self-aware that is the main problem with time (and human antropomorphism). This is what we do. We are examining the physical systems without examining how we percieve them first. Our mind presents a certain subjective filter to the reality (even to the results of detection machines). We were and still are sometimes amazed when molecular clocks in animals and/or human are being discovered. This is the nature telling us there is no global time (sorry Newton). But we're still perceiving time because of our self-awareness thus we create such expressions as 'how hypotetical unanimated object will perceive the time'. It won't. There won't be any time existing in such system (neither semantical nor physical). I think when we strip away our subjectivness what we'll get is: There is no timespace only space changing in present moment (i.e. state machine).
seanpu
5 / 5 (1) Sep 08, 2008
hmm, that said SmartK8, time is purely a product of our mind's ability to perceive the universe. if time doesn't exist, only space changing, we, as humans, will call this change "time". but thats just semantics. if by "time" we mean "energy changing/moving/rate of" or E.Delta then that makes little differences to any equations we right. Energy still moved from here to there at a rate and we can quantify against our E.Delta-meters (clocks). all our scientific measurements are relative to the clock speed (atomic, biological or otherwise). so whatever "time" is we probably cannot conceptualize it (instinctively) as anything else.
SmartK8
5 / 5 (1) Sep 08, 2008
seanpu: Yeah probably, but thinking out loud. My opinion (not originally I guess) is that the brain with higher cognitive functions merges all the parallel energy changes into a single mind-concept called (by us) time. If for example a chemical reaction is accelerated by a catalyzator we know exactly why it is faster. But overall it took "less time" than in chemical reaction without a catalyzator. Isn't it possible that the motion somehow influences (accelerates) the "reaction" on the physical level rather than the dimensional platform. I agree that difference between no time dimension and the concept of time as a dimension is basically a semantical one (except for the science fiction fans and people who lost someone - time travel/no time travel) because we're nowhere near to exploit the options. What I'm worried about is that we might be simplifying things (even though they're not) too much and miss some points which could be easily (by my standards) pin-pointed.
amsv
5 / 5 (1) Sep 08, 2008
I think that time is a very usefull tool, but really don't exist.
Someone here has given the blind bats example, as for them space would be like time to us. I completely disagree: Even blind bats can "see" objects and space using it's sonar. They have an acoustic vision, very similar to our light vision.
Anyway, I'm pretty much convinced that the key to understand our universe it's motion.
If you give that some serious thought, everything in our universe (including us) moves at near light speeds.
Therefore, I think that all fundamental forces of nature (nuclear strong; nuclear weak; gravity and electromagnetism) have their origin in some kind of motion.
Alizee
Sep 08, 2008
This comment has been removed by a moderator.
Alizee
Sep 08, 2008
This comment has been removed by a moderator.
adam81
5 / 5 (1) Sep 08, 2008


It does occur to me that if it were logically possible for time to actually reverse (i.e., for past states to cease to have existed), then the one "fundamental theory of physics" that would come into play would be the indeterminacy of quantum theory. What would happen if time truly reversed and then turned forward again is that the new sequence of states that would come into existence would not exactly duplicate the previous sequence whose existence had been erased.


But for time to reverse, wouldn't the original sequence of events have to have taken place, otherwise where would it be reversing from?

Wouldn't it make more sense to say that if one reversed time, the point at which we emerged would be the start of a new timeline and by default a new universe to contain it, since that original timeline would still need to exist, but logically not in the same 'place' as the new one?
Jenson
1 / 5 (1) Sep 08, 2008
Nope, everything, what the bats can perceive directly are the time intervals between its ultrasound signal and its echoes.


No, the bat is sensing changes in its flow of consciousness. When the bat is not flying he is not sending out waves and he senses a certain flow of consciousness then he produces a sound and the wave is returned from the wall and it's detected, then the normal flow of consciousness continues until another wave is returned. So it is not time the bat is sensing it is changes in the flow of his consciousness (whatever that is for a bat).
Koen
5 / 5 (1) Sep 08, 2008
With respect to the arrow of time: we don't even know if time is running forward while we 'walk forward', or if time is running backward while we 'walk backward'. Maybe the arrow of time switches a zillion times "per second" while we do not even notice this. Now comes the beauty of the science of physics: if we cannot distinguish between this forward and back time arrow by means of an experiment, then it is not worth to spend time thinking about it.
Alizee
Sep 08, 2008
This comment has been removed by a moderator.
tgoldman
not rated yet Sep 08, 2008
This article is WRONG: "The only fundamental theory that picks out a preferred direction of time is the second law of thermodynamics" is not true -- the Standard Model of particle physics has a time reversal violating term which picks a direction in time. The effect has been observed experimentally.
Traveler
1 / 5 (2) Sep 08, 2008
Every physicist worth his or her PhD should know by now that time is not a variable. It cannot change by definition. So any talk of time moving forward or backward is crackpottery. We are moving neither toward the future nor the past. There is only the changing present. Nothing can move in spacetime for this very reason.

Of course, the impossibility of movement in spacetime is not something that one hears too often because it makes a lot of famous people look rather foolish. However it is the reason that Sir Karl Popper wrote in his Conjectures and Refutations that spacetime is Einstein's block universe in which nothing happens. It is also the reason that relativist Dr. Robert Geroch wrote in Relativity from A to B, "There is no dynamics within space-time itself: nothing ever moves therein; nothing happens; nothing changes. [...] In particular, one does not think of particles as "moving through" space-time, or as "following along" their world-lines. Click on the link below for more on this topic:

Nasty Little Truth About Spacetime Physics
http://www.rebels...ious.htm

Alizee
Sep 09, 2008
This comment has been removed by a moderator.
Traveler
1 / 5 (1) Sep 10, 2008
Can you propose some alternative for explanation of experimentally verified changes of pion decay rates during motion of high speed? No?

Yes. There is only one time definition used in relativity. It's the same one used by Newton. Time is that which is measured by a clock, as per Einstein. As far as so-called "time dilation" is concerned, clocks slow down (or speed up) for the same reason that every physical phenomenon occurs: conservation of energy. Besides, it's not as if relativity explains why clocks slow down. They just observe it and put the moronic "time dilation" on it. Time cannot change, by definition. Change exists and time (temporal interval) is abstractly derived from it. Deny at your own detriment.

All the time travel nonsense we hear from famous physcists like Stephen Hawking, Kip Thorne and others is pure crackpottery. It tells me they don't understand the very theory they are supposed to be experts in, among other things. The result is that I have very little respect for spacetime physicists.
superhuman
5 / 5 (1) Sep 11, 2008
Every physicist worth his or her PhD should know by now that time is not a variable. It cannot change by definition. So any talk of time moving forward or backward is crackpottery. We are moving neither toward the future nor the past. There is only the changing present. Nothing can move in spacetime for this very reason.

Of course, the impossibility of movement in spacetime is not something that one hears too often because it makes a lot of famous people look rather foolish. However it is the reason that Sir Karl Popper wrote in his Conjectures and Refutations that spacetime is Einstein's block universe in which nothing happens. It is also the reason that relativist Dr. Robert Geroch wrote in Relativity from A to B, "There is no dynamics within space-time itself: nothing ever moves therein; nothing happens; nothing changes. [...] In particular, one does not think of particles as "moving through" space-time, or as "following along" their world-lines. Click on the link below for more on this topic:


You fail to understand some very basic things about science (though maybe not so obvious):

1. All definitions used by science are created by science and science can change them when such change is warranted.

2. Science is interested in finding the simplest and most useful explanation, not the one which best agrees with our common sense or the one that agrees with our present definitions - the one which has the most predictive power and least assumptions.

Heres an example of what it means:
Suppose we have a giant model of reality which correctly explains 60 000/100 000 physical phenomena. We try to develop it to explain more.
After some work we find out that by changing the concept of time (throwing out an absolute time) we can improve our model so that it will predict another 20 000 phenomena correctly.

We will happily make such change, even if the new definition of time is far less intuitive and harder to understand.
We will make it cause if it explains more phenomena it means it is closer to the way Nature really operates and understanding Nature is the ultimate goal of science.
We will also make it cause it has superior predictive power which will allow us to both make farther progress in science and to develop new technology.

General relativity is an example of just such situation, to gain more insight into reality the concept of time has been redefined and the spacetime was born.

Thats why arguing that time is not a variable and cannot change cause that is its definition is a misunderstanding on your side - science does not use your definition, science treats time as a dimension (either whole dimension or as a single point in it depending on context), something very similar to space dimensions. Scientific time is relative and flows with different rates in different situations.

You are of course free to use your own definition of time but attacking science based on it is rather silly.
SongDog
not rated yet Sep 11, 2008
Occam suggests you're all spouting words. Get a simple concept.
Alizee
Sep 14, 2008
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Alizee
Sep 14, 2008
This comment has been removed by a moderator.
war
not rated yet Sep 16, 2008
Time: This is a condition of space resulting from the constant flip flop between universe
and anti-universe.
Our universe is in a constant flux at a set frequency. That frequency is about
137,036,000,000 oscillations per second. which is related to the Fine Structure Constant. Time
Stress is a term used when talking about the percent of potential difference of total time present
in a field force. Its like talking about the potential difference in a electric circuit. Total time =
100% of the forward and 100% of the backward cycle. Each side is represented as a whole
100%. Most of the universe operates on a stress of 3% or less. That is 3% of total time and is
true on both sides of the cycle. (Figure 3) That 3% includes most electron interaction at shell
distance from the nucleus. All chemical bonding. Normal gravity (Anything that won't crush you) and sex.
Due to the design of the universe and ourselves, we are only aware of time passing in
universe, and we call this arrow, forward time. There is no bias for forward time, time and anti-
time are of equal overall duration.
Filter Mechanics theory
David C Beach



brant
not rated yet Sep 16, 2008
Time is the result of matter. If you did not have a universe would you need time?
So claiming that you are finding out about time by measuring it with matter is sort an oxymoron..
Now that is not to say that you cannot slow process down as evidenced by slow light. You might even be able to time travel because everything exists at one moment in time.
If you have the "ability" you can see all events at once..

Soounds crazy, doesnt it?
stargate
not rated yet Sep 28, 2008
"Time" - Is the consideration, observation and experience of energy particles in matter changing position within space whose constant rate of agreed upon change can be measured by instruments we can then call 'time.' It is the action of energy in space and the duration of an object or particle in co-action. The 'action' of time is the relative change of particle in space.
stargate
not rated yet Sep 28, 2008
"Space" - viewpoint of dimension, it doesn't exist without a point of view or a point to view from. It is the forming of agreements of points in which one can state dimensions and thus allow objects within in the form of energy and particles. Thus energy, particles, matter and time require space for their existence.
stargate
not rated yet Sep 28, 2008
"Viewpoint" - a point of awareness from which one can perceive. The awareness or awareness unit who can view dimension, and objects, and have agreements to which he can agree.
stargate
not rated yet Sep 28, 2008
"Understanding" - in all forms, whether mathematics, scientific, psychological, etc., breakdown into: agreement, reality and communication. One of the fundamental laws of agreement in this universe is that all forms, all energies, all particles must endue or persist in order to have a reality with it and thus conveyed via senses of the viewpoint as uniform communication, we agree upon this rate of change of particle and have our common understanding.

Thus one viewpoint to another will always have their own view as their position of observation is normally not in the same space as another (another law of this universe - two objects can not occupy the same space, unless you become identified as that object. Not true of spirits, ghosts or life-force whose physical universe laws don't apply.)
velvetpink
1 / 5 (1) Nov 09, 2008
Time is not moving forward. You should well know that by now. So its again a blind investigation.

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