Universe : Can time move backward (New theory special)

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Discussion Overview

The discussion revolves around the concept of time and its potential to move backward, challenging traditional views that associate time with entropy and thermodynamics. Participants explore a new theory suggesting that gravity may play a central role in controlling time, supported by computer simulations of Newtonian physics that demonstrate opposing arrows of time in different universes.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • Some participants reference a video and sources claiming that entropy and thermodynamics do not explain time, proposing instead that gravity controls time.
  • One participant argues that if gravity were to control time, it would complicate existing theories in physics.
  • Another participant states that cause and effect define the arrow of time.
  • A participant shares an arXiv paper discussing a time-symmetric law that could model a dynamically closed universe, suggesting that typical solutions divide into two distinct futures from a single past.
  • Some participants express confusion regarding the technical details of the arXiv paper and its implications for the understanding of time.
  • There is a notion that time may not exist as an independent entity but is rather an abstraction arising from changes in the universe.

Areas of Agreement / Disagreement

Participants express differing views on the nature of time, with some supporting the idea that gravity controls time while others maintain that cause and effect are fundamental to understanding the arrow of time. The discussion remains unresolved with multiple competing perspectives presented.

Contextual Notes

The discussion includes references to complex theoretical concepts and models that may not be fully understood by all participants, indicating a reliance on specific definitions and assumptions that are not universally agreed upon.

CaptCoonoor
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So, Hey Guys,
I was watching DNews and Suddenly I came across this video. Also I found two sources of 'theory'
Source A ;
Source B;
Seems like they are saying Entropy isn't the factor Explaining time, They even said that Thermodynamics (and it's second law) isn't what explains the time, They believe that "GRAVITY" controls time...
They tested out using computer simulation which created 2 Universes (of Newtonian physics) and the arrow of time was opposite in both the universe!
But time is relative right? that means that to them its foward right?
I'll argue that they are incorrect because it will make physics even more complex, I mean some theory's can't be explained by this... (hope i make sense there :P)

Comment down your opinion guys!
 
Physics news on Phys.org
Cause and effect are the arrow of time.
 
Here's the arXiv version: http://arxiv.org/abs/1409.0917

Julian Barbour, Tim Koslowski, Flavio Mercati

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 non-trivial 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.
 
Lord Crc said:
Here's the arXiv version: http://arxiv.org/abs/1409.0917

Julian Barbour, Tim Koslowski, Flavio Mercati
I really didn't get this... :(
 
CaptCoonoor said:
I really didn't get this... :(

See. #2 Cause and effect are the arrow of time.
Look at figure 6. time-independent (autonomous) Hamiltonian [6]: http://arxiv.org/abs/1409.0917

... it is very natural to identify an arrow of time with the direction in which structure, measured in our case by CS, grows. We then have a dynamically-enforced scenario with one past (the minimum of CS, which occurs near τ = 0) and two futures.The growth-of-complexity arrow always points away from the unique past. In the atypical solutions that terminate with Icm = 0 (footnote 3) there is one past and only one future.

"time is an abstraction at which we arrive through the changes of things.” Thus, time as such does not exist but only change. Much of my research has been devoted to the implications of this insight. I have shown how, alongside the relativity of motion, the notion of time as change can be built into the foundations of dynamics. In fact, this idea is contained in a hidden form within general relativity. Its potential consequences for the yet to be found quantum mechanics of the universe are profound. The quantum universe is likely to be static. Motion and the apparent passage of time may be nothing but very well founded illusions."
 

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