Evolving Time's Arrow

The human brain has evolved a frontal lobe which is what allows us to care about the future. Most other life only reacts to the stimulus in the present moment. I would like to see a physicist or philosophers take on entropy/fitness.

I don't think Callander "rejects special relativity's conclusions", only the "block universe" interpretation of them, quite rightly too in my opinion. It is possible to formulate a relativistic spacetime model which evolves. Two notable attempts are George Ellis's "Evolving Block Universe" (which I think is a misnomer and a mistake to use the word "block", perhaps a better word might be "hypersurface"?) and Joy Christian's "Relative Becoming" model. These have the nice advantage of allowing free will also!

"If you are considering a closed system then you could expend energy to decrease the system's entropy, however, the universe would still have a net gain of entropy increase."

The point is though, that the reversal of entropy does not mean a reversal of "time" and the example of the apple is a reversal in the *order* of physical processes not of "time", as we could just as well calibrate our clocks by regular processes where gravity is repulsive for instance.

Your statement I think refers to the "Maxwell's Demon" principle where the energy expended to decrease entropy (or it's information content), must be accounted for as additional entropy and that is right. I don't think that applies in the case of gravity however if you consider the "closed system" to be the universe. Gravitational fields are considered to contain negative energy, hence the cosmic energy equation of state E = 0. When gravity acts to form a star I view that *cosmically* as a lower entropy macrostate. (Which contains the most useful energy that can "do work", the star or the hydrogen gas cloud that formed it?). The energy required to increase the entropy or restore the cosmic entropy number is stored in the star and is slowly radiated back out and eventually fully returned by supernova for example.

I guess it depends on your definition of information and how you quantify the energy content of gravitational fields. Black holes are a whole other case!!

"If physics can explain how a causal arrow of time emerges, then biology will do the rest, says Callender."

If the flow of time is viewed (correctly, in my opinion) as being nothing more and nothing less than the evolution of the physical universe (an evolution which is governed by rules that we strive to understand and which we refer to as the laws of physics), then there is no way for "a causal arrow of time" *not* to emerge!

jcns

The fallacy is indeed not very obvious. As a schoolboy I was cheated by the teacher who explained Galilei's flawless principle of relativity and attributed it to Einstein. Most textbooks derive the Lorentz transformation from postulated equivalence of all inertial reference frames. Actually, Poincaré's LT predates what Einstein in 1905 on p. 891 called "principle of relativity".

Seemingly a shift in time must not matter. So called laws of physics remain apparently unchanged. I came to the insight that this invariance only holds on the level of abstracted and extrapolated time scale. This usual notion of time must not be confused with the already elapsed time of reality. The latter has peculiarities: It cannot at all be shifted at will, and it only excludes the past. The usual notion of time is in this respect unphysical, and Poincarè's round-trip synchronization includes something that does not yet exist at the moment of consideration.

Hence the first premise is untenable. Yes, if Callender is honest then he has to hint at the false premise.

By the way, mathematicians also considered Cantor's naive set theory rigorously deduced, and Hilbert fought for this belief in a paradise by replacing it with the method of axioms which were ambiguously enough designed as to hide Cantor's mistake and avoid obvious paradoxes.

Eckard

time arrow has no physical existence, time does not point anywhere, time is a numerical order of change

There is a bit of confusion apparent. There are a number of ways of looking at this. Group theory is a good way of looking at this. Relativity is given by the group SO(3,1), which is a set of transformations that can be thought of as rotations. The group SO(3) describes the set of rotations in three dimensional space. The group SO(3,1) has this indefinite metric, where the one separated by a comma reflects the pseudo-Euclidean metric. This group can be decomposed into SU(2)xSU(1,1). SU(2) is related to SO(3) by a double cover, and is a set of elliptical rotations. SU(1,1) is a hyperbolic variant of SU(2). SU(2) contains 3 rotational matrices (often represented by Pauli matrices) and these are pure spatial rotations. SU(1,1) has 3 elements which correspond to Lorenz boosts.

If we think of pushing a spatial manifold in time this can be thought of changing elements that transform under group SU(2) according to elements which construct time and the hyperbolic SU(1,1). We may similarly think of trying to transform a manifold with two spatial dimensions and one of time according to the SU(2) elements. This will result in a noncommutative algebra. This is then equivalent to saying that pushing a slice of space through time is different from pushing a 3-dimensional spacetime through a spatial distance.

Cheers LC

Eckard Blumschein wrote: "Yes, if Callender is honest then he has to hint at the false premise."

Impossible. George Orwell calls this "crimestop":

http://www.liferesearchuniversal.com/1984-17

George Orwell: "Crimestop means the faculty of stopping short, as though by instinct, at the threshold of any dangerous thought. It includes the power of not grasping analogies, of failing to perceive logical errors, of misunderstanding the simplest arguments if they are inimical to Ingsoc, and of being bored or repelled by any train of thought which is capable of leading in a heretical direction. Crimestop, in short, means protective stupidity."

Pentcho Valev pvalev@yahoo.com

Dear Roy,

Can a reform of SR and spacetime overcome all paradoxes? To me, the wording Evolving Block Universe by George Ellis illustrates the calamity. It sounds to me like a cruciader in his burka or like communist free market economy. Did Joy Cristian's attempt resolve the problems? Will Lee Smolin achieve the impossible?

I would rather prefer a honest clarification on the fundamental level, no matter what hurting implications are to be expected. When Hilbert defended Cantor's paradise against Brouwer, he also warned of a huge heap of rubble. This was exaggerated.

Regards,

Eckard

The question as to why the 'arrow of time' is one directional is very easy to answer, if one understands what reality and 'time' actually is, which I would suggest is a very good start point.

Since light travels at a speed that does not vary from one wave to the next, then each state of any given entity, can only be seen (by human and non-human)in the sequence of change in which it occurred. Otherwise you would see flowers blooming before the buds had formed, etc. This statement works for any medium that coneys experiential information to our senses. It also works if the speed of light has changed historically (that just makes calculation of the original state manifested in the observation a lot more difficult). Our sense of 'time' is actually a perception of real change. And yes we have instigated a man-made measuring system called time, but don't let that confuse the underlying issue, which is about change in reality.

Paul Reed

LC and Tom,

Would it be possible for either (or both) of you to express your ideas about space and time in non-mathematical terms? How do your ideas relate to the human experience of time and space?

In a post in another FQXi blog (Breaking the Universe's Speed Limit) LC wrote: "A[s] for block time being contrary to human experience or intution, those do not really count for much. The non-block time is just a system of spatial geometries which are related to each other by a diffeomorphism group. The notion of time is actually somewhat lost in this picture."

To which I replied: "Regarding whether human experience and intuition count for much, I simultaneously agree with you and disagree with you. Certainly, everyone must agree that human experience and intuition have proven to be extremely fallible. This fact is perfectly illustrated by the pre-Copernican belief that the sun revolves around the Earth.

On the other hand, however, human experience and intuition must count for something, because our empirical observations comprise the very bedrock foundation of science! If we dismiss empirical observations as unimportant (not really counting for much), then what are we left with as the basis for doing science?"

So how do your views of time and space relate to empirical observations which we humans might make, fallible though such observations might be? Which is simply another way of asking, how can we test your concepts experimentally? Are they falsifiable? If so, how?

Thank you.

jcns

Dear Pentcho,

It took centuries for the Vatican to rehabilitate Galileo Galilei who had to recant relativity. I hope the community of physicists will able to eventually admit the correctness of his following insights:

- Salviati: The relations smaller, equal to, and larger do not hold for entities of infinite quantities.

In other words, infinity is a property, not an exhaustible quantity.

Accordingly we may distinguish between potentially infinite and actually uncountable, but Cantor's cardinality has no logical basis. Already aleph_2 has proven nonsense without any application.

- Galileo Galilei made a careful study of the laws of falling objects. He realized that the velocity of any object relates to a chosen point of reference. Galilei as well as Newton, who was born in the year 1642 when Galilei died, assumed the space unchanging and the universe like a big clock. The belonging addition of velocities and ubiquitous synchronism of remote processes are foundational in technology.

So called relativism has been based on the not always appropriate suggestion to synchronize remote clocks A and B by means of a round-trip measurement. This works well as long as there is no motion between clock A and clock B because in this case the measurement is subject to the Doppler effect to be considered. Poincarè's round-trip method averages the past and the future (with respect to the moment of reflection) time of flight. As a first resulting paradox, the Lorentz transformation is independent of the sign of velocity.

I see stupidity behind the reasoning of those who were misled to ignore Galilei. Many mathematician from Dedekind and Cantor to Cohen agreed on that there must be more real than rational numbers because the latter are a subset of the reals. Most physicists were not ready to accept that the Michelson-Morley did not confirm the existence of an ether.

Regards,

Eckard

jcns,

I'll try, though I don't think (and I expect Lawrence will agree) that one can fully appreciate spacetime dynamics without understanding the mathematics. As Lawrence notes, there is more than one way to write the equations that lead to the same physics. We choose our models for their ability to explain current phenomena and to make additional novel predictions.

Classical physics is the domain of human experience. Even our quantum mechanical experiments are designed within classical parameters. What we've learned over the past three centuries or so, though, is that not even classical results are intutive. For example, one cannot intutively connect the falling of an apple from a tree with the falling of the moon toward the Earth without Newtonian mechanics. Even Galilean physics (as I discovered to my surprise recently, by the varied responses to a simple projectile problem) is not immediately intuitive even among people who should know better.

What all classical physics has in common is the mathematics of continuous functions. In other words, Newton's apple does not stop falling at the Earth's surface, but continues falling in principle -- just as the moon's orbit is continuous. Continuous functions are evident to the limit of classical physics, i.e., relativity.

Most of what we know of physics, objectively, is counterintuitive. Lawrence is quite correct that human experience and intuition play an insignificant role.

Quantum mechanical functions are algebraic, i.e., discrete. The basis is the analysis of probabilistic quantum events in a Hilbert space, which means a complex model -- because quantum mechanics does not allow space collapsed to a point (singularity), and the complex plane is fundamentally two-dimensional.

So far as experimental results go, and remembering that all are designed within classical parameters -- I offered a quasi-classical model in my FQXi 2008 essay ("Time counts") in which I constructed a complex analog to Kepler's second law. Because it is based on the (non) conservation of angular momentum using escape velocities between gravitating classical bodies, if each point of spacetime is characterized by a unique escape velocity (it is), the principle is already experimentally verified. What the mathematics shows is a very slight loss of information among bodies.

Point is, to get to these models where Lawrence among others can speak of group theory and noncommutative algebra to model physical phenomena, we have to go through what we know about the classical and quantum worlds and then follow the path where it leads without contradicting previous results. Intuition isn't much help.

Tom

Tom,

Quick reply to thank you for your reply to my question and to let you know I'm pondering what you wrote. More later, assuming I can think of anything resembling cogent to add.

jcns

Time is an epiphenomenon of change

Change is the fundamental property of material world. Time that we measure with clocks is the numerical order of change, i.e. motion in space. In physical world time exists as the numerical order of change in space. In physics time is a mathematical dimension used for description of change in material world. It is an utter misunderstanding to think time is part of space and change run in time. On the contrary: time is an epiphenomena of change, time we measure with clocks is the numerical order of change.

Amrit

Correct, just about.

Love the word epiphenomenon, the best I could come up with was conceptualisation.

Paul Reed

Tom and LC,

Without claiming that what follows resembles cogent, I'd like to keep this constructive discussion going. If you've read any of my other posts in this or other FQXi blogs you must know that my approach to physics is naive, primitive, and visceral, but I hope not unscientific, in the best sense of that word. I exist in a universe which, statistically, is mostly not hospitable to fragile life forms such as myself. Understanding physics, therefore, is, for me, a matter of survival as well as a matter of great intellectual curiosity and fascination.

The universe in which I find myself is extremely dynamical. There are lots of things in motion, cars, clouds, airplanes, planets, galaxies, occasionally (and frighteningly, during earthquakes and tornados) even pieces of buildings, trees, etc. If some of these objects were to collide with me it could be fatal at worst and uncomfortable at best. Again, understanding how this all works (i.e., understanding the laws of physics which appear to govern it all) on a visceral, intuitive level is essential to survival.

Tom, you wrote "Point is, to get to these models where Lawrence among others can speak of group theory and noncommutative algebra to model physical phenomena, we have to go through what we know about the classical and quantum worlds and then follow the path where it leads without contradicting previous results. Intuition isn't much help." My reply is that unless these models are taken to be purely academic, mathematical exercises they ultimately must tell us something of practical value about the universe in which we exist. It is this "something" which I'm trying to tease out of our discussion. How will these models ultimately allow me to improve my chances of survival?

Without a doubt, mathematical models play an important role in physics. At some point, however, mathematical models must somehow come into contact with empirical observations if they are to be of any real value, in my opinion. Granted, human experience and intuition are known to be extremely fallible, but that not withstanding they are still our only real basis for doing science (as opposed to pure mathematics).

Mathematicians presumably could develop a model of the Ptolemaic picture of the universe as readily as they could develop a model of the post-Copernican picture. We then could talk about these two models in purely mathematical terms ad nauseam, but it is also satisfying to be able to talk also about the fact that one model has the sun revolving around the Earth whereas the other model has the Earth revolving around the sun while simultaneously rotating on its axis. One model ultimately is more useful than the other, despite the fact that human intuition accepted the less useful model as being "obviously" true for centuries.

As repeatedly noted elsewhere in these blogs, I'm a huge advocate of zeroing in on better and better paradigms. And I've long been concerned that the mainstream, prevailing paradigm for the fundamental nature of time is lacking. Not "wrong" perhaps, but lacking, or incomplete. Inasmuch as "time" plays such a central and crucial role in physics I believe it's worthwhile being certain that we have this paradigm nailed down as correct as possible.

Unless I'm mistaken (please correct me if I am), the prevailing paradigm for the nature of time may be summarized by the so-called "operational" definition, i.e., "time is that which is measured by clocks." Clocks are then typically defined in some sort of slippery way as being devices which measure time by way of some sort of "regular motion," but it is never made perfectly clear how one would know whether motion was "regular" or not without resorting to the use of a clock. I'm not saying that this is "wrong" per se, but only that it seems, at best, incomplete. This view of time apparently leads logically to concepts such as block time.

In some of my essays such as 'Time: Illusion and Reality,' I've tried to suggest another paradigm, another way of looking at the nature of time, which, unfortunately, is also, in and of itself, incomplete I fear. In this way of looking at time our dynamical universe is the clock. Different physical configurations of the universe define, and are identically equivalent to, different particular times. This view does not allow for block time, and it makes a "causal arrow of time" an inevitability. It further rules out time travel (at least of the variety portrayed in science fiction literature).

Lawrence actually appeared to key in on this view in one of his posts to the article on 'Breaking the Universe's Speed Limit' when he wrote, "A[s] for block time being contrary to human experience or intution, those do not really count for much. The non-block time is just a system of spatial geometries which are related to each other by a diffeomorphism group. The notion of time is actually somewhat lost in this picture." Yes, in my view non-block time is indeed a system of spatial geometries! Exactly! But as he points out, the conventional notion of time is somewhat lost in this picture. And this may be where this paradigm is incomplete.

I can't help thinking that if some very clever person could somehow meld these two views of time the resulting paradigm might offer a more useful way of looking at the universe than any previously proposed. Unfortunately, I do not know how to accomplish this melding, but I sense that it would not be easy.

Apologies for rattling on for so long.

Regards,

jcns

JCNS,

You wrote, "If you've read any of my other posts in this or other FQXi blogs you must know that my approach to physics is naive, primitive, and visceral, but I hope not unscientific, in the best sense of that word."

Sure.

"I exist in a universe which, statistically, is mostly not hospitable to fragile life forms such as myself. Understanding physics, therefore, is, for me, a matter of survival as well as a matter of great intellectual curiosity and fascination."

I agree. I touched on this in my 2010 FQXi essay. "When one calculates

outcomes from a field of infinite parameters, the great majority lead an organism to extinction. Yet conscious creatures play with loaded dice; 'good' and 'bad' choices, assuming that all strategies are rational, i.e., survival-based, depend on having at least one good choice independent of all environmental influences considered as a continuum. E.g., if a one-celled creature needs light to survive, it either has the motive ability to seek

a light source in order to 'be,' or it ceases to be when the light goes away."

We're fragile only when we don't have options. More consciousness creates more survival options and more robust life. We're all complex systems of cooperating cells.

"The universe in which I find myself is extremely dynamical. There are lots of things in motion, cars, clouds, airplanes, planets, galaxies, occasionally (and frighteningly, during earthquakes and tornados) even pieces of buildings, trees, etc. If some of these objects were to collide with me it could be fatal at worst and uncomfortable at best. Again, understanding how this all works (i.e., understanding the laws of physics which appear to govern it all) on a visceral, intuitive level is essential to survival."

Absolutely.

"Tom, you wrote 'Point is, to get to these models where Lawrence among others can speak of group theory and noncommutative algebra to model physical phenomena, we have to go through what we know about the classical and quantum worlds and then follow the path where it leads without contradicting previous results. Intuition isn't much help.' My reply is that unless these models are taken to be purely academic, mathematical exercises they ultimately must tell us something of practical value about the universe in which we exist. It is this 'something' which I'm trying to tease out of our discussion. How will these models ultimately allow me to improve my chances of survival?"

Does electrical power improve your chances of survival? There's a story, maybe apocryphal but surely instructive, that a matron upon being introduced to Michael Faraday, asked of what use are his discoveries. Faraday supposedly replied, "Madame, of what use is a newborn baby?"

"Without a doubt, mathematical models play an important role in physics. At some point, however, mathematical models must somehow come into contact with empirical observations if they are to be of any real value, in my opinion. Granted, human experience and intuition are known to be extremely fallible, but that not withstanding they are still our only real basis for doing science (as opposed to pure mathematics)."

Actually, experience and intuition are of little use in doing science. Most of what we know, objectively, is counterintuitive. As Einsten said, "Imagination is more important than knowledge."

"Mathematicians presumably could develop a model of the Ptolemaic picture of the universe as readily as they could develop a model of the post-Copernican picture."

True.

"We then could talk about these two models in purely mathematical terms ad nauseam, but it is also satisfying to be able to talk also about the fact that one model has the sun revolving around the Earth whereas the other model has the Earth revolving around the sun while simultaneously rotating on its axis. One model ultimately is more useful than the other, despite the fact that human intuition accepted the less useful model as being "obviously" true for centuries."

They accepted it because of their quasi-religious philosophy that the circle represents perfection. A perfect universe, therefore, had to incorporate perfectly circular orbits (and they almost are, in fact). We should be wary of trying to impose religion or philosophy on science.

"As repeatedly noted elsewhere in these blogs, I'm a huge advocate of zeroing in on better and better paradigms. And I've long been concerned that the mainstream, prevailing paradigm for the fundamental nature of time is lacking. Not 'wrong' perhaps, but lacking, or incomplete. Inasmuch as 'time' plays such a central and crucial role in physics I believe it's worthwhile being certain that we have this paradigm nailed down as correct as possible."

How certain can we be of anything?

"Unless I'm mistaken (please correct me if I am), the prevailing paradigm for the nature of time may be summarized by the so-called 'operational' definition, i.e., 'time is that which is measured by clocks.' Clocks are then typically defined in some sort of slippery way as being devices which measure time by way of some sort of 'regular motion,' but it is never made perfectly clear how one would know whether motion was 'regular' or not without resorting to the use of a clock. I'm not saying that this is 'wrong' per se, but only that it seems, at best, incomplete. This view of time apparently leads logically to concepts such as block time."

Not regular motion -- regular physical processes. Motion is measured change in relative position among mass points. A physical process, however, need not involve classical motion. I won't get into a long discussion of the nature of time, about which I've written extensively. If you are interested, you can find my views here .

"In some of my essays such as 'Time: Illusion and Reality,' I've tried to suggest another paradigm, another way of looking at the nature of time, which, unfortunately, is also, in and of itself, incomplete I fear. In this way of looking at time our dynamical universe is the clock. Different physical configurations of the universe define, and are identically equivalent to, different particular times. This view does not allow for block time, and it makes a 'causal arrow of time' an inevitability. It further rules out time travel (at least of the variety portrayed in science fiction literature)."

Interesting. I'd say go for it, and build a mathematical model to accompany.

"Lawrence actually appeared to key in on this view in one of his posts to the article on 'Breaking the Universe's Speed Limit' when he wrote, "A[s] for block time being contrary to human experience or intution, those do not really count for much. The non-block time is just a system of spatial geometries which are related to each other by a diffeomorphism group. The notion of time is actually somewhat lost in this picture." Yes, in my view non-block time is indeed a system of spatial geometries! Exactly! But as he points out, the conventional notion of time is somewhat lost in this picture. And this may be where this paradigm is incomplete.

I can't help thinking that if some very clever person could somehow meld these two views of time the resulting paradigm might offer a more useful way of looking at the universe than any previously proposed. Unfortunately, I do not know how to accomplish this melding, but I sense that it would not be easy."

Easy or not, it's worthwhile. Google for Gerard 't Hooft's advice on how to be a theoretical physcist. Good list of prerequisites to study.

"Apologies for rattling on for so long."

Rattling makes music, too. :-)

Tom

How about:

Physical causality only operates in one temporal direction: crack the egg, mix it up with a bit of milk, cook it, eat it.

It can NEVER go the other way.

Wait for an eternity - the eggs won't unscramble.

Thus, the direction of physical causality defines the temporal order.

End of story.

Robert L. Oldershaw

...//www3.amherst.edu/~rloldershaw

Discrete Scale Relativity; Fractal Cosmology