Physicists propose identification of a gravitational arrow of time

Physicists propose identification of a gravitational arrow of time
Configuration of masses evolving under Newtonian gravity. Barbour et al. show that nearly all such systems have a moment of “lowest complexity,” which they identify as a unique “past” from which two “futures” emerge.
(Phys.org) —A trio of physicists is proposing a new direction for understanding the concept of time. In their paper published in the journal Physical Review Letters, Julian Barbour, of College Farm in the U.K., Tim Koslowski of the University of New Brunswick in Canada and Flavio Mercati of the Perimeter Institute for Theoretical Physics also in Canada, describe their new ideas beginning with the suggestion that initial conditions don't necessarily need to be imposed on time-symmetric law when attempting to describe solutions to behaviors that define an "arrow of time."

For all the advances made in understanding the world around us, there are still two very basic fundamental concepts that have defied explanation: and gravity. Though we have progressed greatly in measuring both and using both to understand other concepts, we still today are no closer to understanding either than we were when we first conceptualized them. Such an acknowledgment suggests that we likely have a major flaw in our understanding of the universe. In considering such a possibility, the three physicists with this new effort suggest we might look at time in a completely new way—by dividing a dynamically closed universe (ala the Newtonian N-body problem) into two halves with shape complexity growing from a single point—each solution to the problem can then be considered as having one past but two distinctly futures. In such a scenario, an observer would of necessity have to exist on one side or the other, and thus would only ever have that perspective. Critical to this idea is that the all of the energy and angular momentum in such a system would have to be zero.

In essence, the team has removed time from mathematical functions that describe the energy of the universe—that's what allows for splitting the equations that have been created to describe the evolution of the universe into two parts, with both having initial low complexity moving to higher complexity (similar in some respects to theories of time based on entropy).

The proposal by the trio though phrased in a way as to suggest it's a solution to the arrow of time problem, is not likely to be addressed as such by the physics community—it's more likely to be considered as yet another theory that works mathematically, yet still can't answer the basic question of what is time.


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More information: Identification of a Gravitational Arrow of Time, Phys. Rev. Lett. 113, 181101 – Published 29 October 2014 http://dx.doi.org/10.1103/PhysRevLett.113.181101 (free PDF)

ABSTRACT
It is widely believed that special initial conditions must be imposed on any time-symmetric law if its solutions are to exhibit behavior of any kind that defines an "arrow of time." We show that this is not so. The simplest nontrivial time-symmetric law that can be used to model a dynamically closed universe is the Newtonian N-body problem with vanishing total energy and angular momentum. Because of special properties of this system (likely to be shared by any law of the Universe), its typical solutions all divide at a uniquely defined point into two halves. In each, a well-defined measure of shape complexity fluctuates but grows irreversibly between rising bounds from that point. Structures that store dynamical information are created as the complexity grows and act as "records." Each solution can be viewed as having a single past and two distinct futures emerging from it. Any internal observer must be in one half of the solution and will only be aware of the records of one branch and deduce a unique past and future direction from inspection of the available records.

Journal information: Physical Review Letters

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Citation: Physicists propose identification of a gravitational arrow of time (2014, November 3) retrieved 25 June 2019 from https://phys.org/news/2014-11-physicists-identification-gravitational-arrow.html
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Nov 03, 2014
"Now if we take this and use it for anything found in our universe it works. Say the speed of light verse time: If you are traveling at .25 the speed of light you would move through time at twice the speed then if you were moving at .5 the speed of light. Unfortunately your white hole would exist on the other side of zero so you wont ever get to see it. "
https://answers.y...8AA6lL6n
Under J, from 5 years ago.
Multi-verse, mirror universe, 2D, 1D, and nothing. All of it is true. All of it touches.

The fact that 5 years ago this type of thought was plain stupid and today it's given real consideration - well let's just say it's a good feeling. I personally think this is the right direction.

Nov 03, 2014
And yet it seems, once again, that the plane of evolution of subject states that would be offered as an explanation of a time domain, is itself time-like.

Much like those propositions that "time is the metric of rate of change"; the proponents don't seem to grasp that the problem is merely restated by their putative 'solution' - it's still dependent upon a more fundamental time-like dimension that preceding states evolve into. What is this substrate these ever-branching bifurcations are spread upon?

"yet another theory that works mathematically, yet still can't answer the basic question of what is time


Precisely...

Nov 03, 2014
Of course, this is all hogwash since a time dimension makes motion impossible. Nothing can move in a time dimension because a changing time coordinate is self-referential. Why? Because motion in time assumes a velocity in time which would have to be given as v = dt / dt, which is nonsense. It's that simple, folks. This is why Karl Popper called spacetime "Einstein's block universe in which nothing happens." Spacetime physics is not really physics because spacetime is not physical. Talking about an arrow of time is thus nonsense.

Barbour, Koslowski and Mercati are setting themselves up to be the three stooges of physics.

Nov 04, 2014
what a nonsense this paper about 2 futures ......we show recently time has only a mathematical existence in a paper published on FOOP http://link.sprin...4-9840-y

Nov 04, 2014
OPEN LETTER TO EDITORS OF
"Physical Review Letters"

Dear Editors

recent article on time "Identification of Gravitational arrow of Time"
http://phys.org/n...row.html
published in your journal has wrong conclusions because time we
measure with clocks has only a mathematical existence. In the universe
there is no such a thing as "arrow of time" which exists only as a
mathematical direction of numerical order of change which run in
quantum vacuum, see our paper published in
FOOP http://link.sprin...4-9840-y

More than that: gravity is immediate, that's why in Newton formalism
for gravity there is no symbol t and in GR time t is only a parameter
of stress-energy tensor.
From this point of view relating time with gravity is pure mistake.
Yours Sincerely Amrit Srecko Sorli, Foundations of Physics Institute www.fopi.info

Nov 04, 2014
OPEN LETTER TO EDITORS OF
"Physical Review Letters"

Dear Editors

recent article on time "Identification of Gravitational arrow of Time"
http://phys.org/n...row.html


Dear Skippy,

don't forget to leave your silly looking pointy cap at the door so the next couyon doesn't have to do without his hard earned privilege of wearing one.

And P.S. for you Ami-Skippy. You don't need to seen us anymore letters telling us the conclusions are wrong no. We use professional scientist-Skippys to check that and don't need any help from the amateurs no. And don't forget about the silly looking pointy cap.

Nov 04, 2014
I have already solved "Time". Time is caused by the motion of a body (object) through space. Everything is moving through space, however if you Move through space faster such as in a rocket ship the result is less "Time" but if you were to slow down, then more "Time" would occur. Moving faster is simple but moving slower is not since all objects are always in motion within space. To move faster it requires an outside force such as the rocket ship and conversely moving slower also requires and outside force of which there is only one "Gravity" that we can use.

Remember though that Einsteins law E=MC2 in that time is always relative to the observer hence the appearance of the arrow of time where time for one observer moves faster and the other it moves slower. This means that if I am on the rocket ship watching you on the Earth I will see your time passing quickly and you will see my time passing slowly; if in fact we are in a position to observe each others time. (see part 2)

Nov 04, 2014
(part 2)

The equation of "Time" or how time is measure is done in respect to the speed of light. In that speed of light is the universal constant; we measure our speed through space as it appears to the observer. Move faster through space ie catch up with light and the result is less time, conversely move slower than your present speed say by coming to close to a black hole and your observed "Time" will accelerate.

Thus "Time" can be considered as a body's motion through space in respect to the speed of light.

Nov 04, 2014
"Time" does not depend on gravity - it depends on entropy.
Entropy cannot decrease with time - it can only increase.
Computer simulations are Cartesian (deterministic) systems, and have zero entropy.
The Second Law of Thermodynamics does not apply to closed, deterministic systems.
The 'researchers' are using the wrong tools.

Nov 04, 2014
SR&GR created a conundrum for Einstein that he tried to resolve unsuccessfully in to one grand unified field theory. While the speed of light is constant that's not true for gravitation. Einstein focused to much on the speed of light and not enough on the "holes" all around him. That's where the gravitation is. That "electromagnetism is in spacetime A" let's call that space-time "{EM} space-time", and this is what Einstein's "On the Electrodynamics of Moving Bodies" [1] described which reconciles Maxwell's equations for EM with the laws of mechanics, introducing major changes to mechanics close to the speed of light. This later became known as Einstein's special theory of relativity (SR). [2][3] That "gravitation is in spacetime B" let's call that space-time "{G}space-time" and this is what Einstein's General relativity (GR) describes. According to general relativity,the observed gravitational attraction between masses results from the "warping of space and time by those masses". [4]

Nov 04, 2014
When I write about this "manifold of events in spacetime are a "substance" which exists independently of the matter within it" this "manifold of events in spacetime" is this property that makes Time; as we measure it; the emergent {positive arrow of time}. Therefore time is a vector which direction depends on your position in our universe which is created by a change of energy states between gravitation to electromagnetism; and visa versa.
[1]EINSTEIN, A. Zur Elektrodynamik bewegter Korper. Annalen der Physik 17: 891-921, 1905.
[2]EINSTEIN, A.; GROSSMANN, M. Entwurf einer verallgemeinerten Relativitatstheorie und einer Theorie der Gravitation. Zeitschrift fur Mathematik und Physik 62: 225-261, 1913.
[3]EINSTEIN, A. Die Grundlage der allgemeinen Relativitatstheorie. Annalen der Physik, 49, 1916.
[4] HILBERT, D., Die Grundlagen der Physik. Mathematische Annalen, 92, 1924.

Nov 04, 2014
"Time" does not depend on gravity - it depends on entropy.
Actually, gravity is curvature of spacetime. Clocks that feel the acceleration of gravity (or any acceleration) experience time at a different rate than clocks in inertial frames of reference. This is a brute fact, measured by satellites, not a theory.

Entropy cannot decrease with time - it can only increase.
This is incorrect. Laser experiments have verified that over a small enough number of particles, and a short enough time, the particles can be made to behave so as to decrease their entropy. See also Bose-Einstein Condensates. The 2LOT does not apply to quantum systems. See also the Fluctuation Theorem.

Computer simulations are Cartesian (deterministic) systems, and have zero entropy.
Non sequitur. Prove they have zero entropy. That they are deterministic makes no difference; so is classical mechanics, which has non-zero entropy.

Nov 04, 2014
The Second Law of Thermodynamics does not apply to closed, deterministic systems.
The 'researchers' are using the wrong tools.
Another non sequitur. In addition, I'm not sure I agree with the first statement, either; do you have a reference?

Nov 04, 2014
While the speed of light is constant that's not true for gravitation.
Errrr, I don't think you've understood GRT. Not to mention the fact that we can predict how fast gravitational changes propagate through space, and then measure it by watching various phenomena among other stars in our galaxy, and even in other galaxies, and compare it with the speed at which the influence of the light spreads, and even check that against our distance measurements to those objects and their consequent real and apparent sizes.

This hasn't been done in the lab, but we've checked it by observation both in our galaxy and in other galaxies. In fact, we've done it very precisely by observing Jupiter, and the results are that if it's not the same speed of light, it's very close. The first such measurement was made a decade ago: http://www.nrao.e...gravity/

Nov 04, 2014
@Tadchem
Entropy cannot decrease with time - it can only increase.

Entropy can also decrease locally....

Nov 04, 2014


Mechanical time is often confused with actual time among celebrity scientist: Einsteins general relativity applies to mechanical time: not being able to measure a particles position, or relative to the observer says nothing about actual time. Perception of time or mechanical clocks may be relative. but "Time itself" the thing that keep everything from happening at once is not relative!

Nov 04, 2014
There is no absolute time, krydan. One observer sees two events as simultaneous; another sees one first then the other, and yet another observer sees them in the opposite order. This can be replicated for three inertial observers and two inertial events; just a matter of having them in the right positions going the right speeds relative to one another. If any of the events or observers is in an accelerated frame of reference, then it's even easier (though the calculations are more complicated).

Nov 04, 2014
Is interesting. I'm always thinking that gravity and anti-gravity is related when it creates a positive mass and we know we are part of this matter. And loss of antimatter in the Showtime expansion going forward and escapes on stage at the moment (anti-gravity gravity is in stage 0 m / s² or -0 m / s²) of negative gravitational mass created. Reproduce the Big Bang scale will escape the collision of anti-gravity.

Nov 04, 2014
This comment has been removed by a moderator.

Nov 04, 2014
The AWT is
denied since 1887.

See "Michelson-Morley Experiment."

Nov 04, 2014
This comment has been removed by a moderator.

Nov 04, 2014
The AWT is based on dense aether model, which
is not considered debunked and falsified to an incredibly high degree of accuracy with the following study: http://exphy.uni-...2009.pdf

continuing to post about aw/daw is simply promoting pseudoscience and trying to con decent people who might be scientifically illiterate into believing a falsified and debunked conjecture
You apparently missed the history of physics
and you, apparently, have missed out on hundreds of experiments which falsified and debunked your faith/religion/debunked pseudoscience
http://arxiv.org/...1284.pdf

given your complete inability to provide ANY reputable science supporting your conjecture or even supporting the possibility of feasibility of your conjecture, you should consider seeking medical/psychiatric attention

troll elsewhere

Nov 04, 2014
This comment has been removed by a moderator.

Nov 07, 2014
Awful, uncritical reporting. The massive flaw in this paper is that the authors deny the cause of the middle image comes from their initial conditions when obviously it does! They setup a random *spherical* distribution of N-body objects. This isn't justified as a model of our universe, which has no center, and is responsible for the high density picture in the middle.

Nov 10, 2014
The problem starts when you impute "reality" to a mere metric such as time. It is just a mapping system for describing relative positions, initially due to quantum interactions.

Nov 10, 2014
The problem starts whem you impute "reality" to a mere metric. Time is just a mapping system of relative positions and interactions due initially to inherent quantum motions.

It appears The Multiverse, Our Universe and our Human Fabric of reality has more than one arrow of time. I believe there might be 1 to 3 extra dimensions of time and just one in our perceived 4-d space time geometry continuum. . Just a hunch but it appears there is a lot more to learn about String theory, Our Universe, and the extra hidden dimensions. Seems like Time & Gravity are in the ultimate perfect relationship and are essential for human existence on Earth.

Nov 10, 2014
This may add some juice to the debate on what time actually is.
https://www.faceb...?fref=nf

Nov 10, 2014
The problem starts whem you impute "reality" to a mere metric. Time is just a mapping system of relative positions and interactions due initially to inherent quantum motions.
This doesn't make sense. There can be no motion without time, quantum or otherwise.

Nov 11, 2014
Another nonsensical physical abstract theory. Gravity, however is and has been well defined and predictable.

What is it?

The paper reminds me of a theory in the book "Stalking the Wild Pendulum".

Nov 17, 2014
I think there are many people study advanced stuff but , they do not get the answers complete only mechanism something it is missing.

I think there are a lot questions without answer, we do not have a complete definition of time, every time I ask what it is your definition of time on your theory people do not have to answer.

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