Has the stability problem of changing entropy and time been resolved?

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Discussion Overview

The discussion centers around the concept of changing entropy and its implications for the direction of time, particularly whether negative changes in entropy could allow for time to move backwards. Participants explore theoretical frameworks, potential models, and the challenges associated with these ideas.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification
  • Theoretical speculation

Main Points Raised

  • One participant suggests that a negative change in entropy (##\Delta S <0##) could imply a reversal of time, referencing a paper on the topic.
  • Another participant argues that the direction of time is defined by the increase of entropy, linking it to memory and causation.
  • A different viewpoint questions the feasibility of isolating a system where entropy decreases while another system's entropy increases, raising concerns about interactions between systems.
  • One participant speculates that negative temperatures in quantum mechanics might provide insights into the possibility of reversing entropy.
  • Further questions are raised about the conditions under which two systems could exhibit opposing entropy changes and the implications for causation and interaction.
  • Some participants mention theoretical models involving black holes as potential avenues for exploring these concepts.

Areas of Agreement / Disagreement

Participants express a range of views on the relationship between entropy and time, with no consensus on the feasibility of reversing entropy or the implications of such a reversal. The discussion remains unresolved regarding the practical implementation of these ideas.

Contextual Notes

Participants acknowledge various assumptions about the definitions of time and entropy, as well as the complexities of system interactions, without reaching a definitive conclusion on these matters.

MathematicalPhysicist
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My question is, if somehow it were possible to change the change of entropy such that it were negative, i.e. ##\Delta S <0## wouldn't we go backwards in time, from the future to the past?

I have this paper:
https://arxiv.org/abs/gr-qc/0503077

I wonder if the stability problem was ever resolved.
I haven't yet read this paper (even if it's a little bit outdated).
 
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I think change in entropy defines the "direction" of time (past versus future) along the arbitrary parameter T.

By definition, going towards "-T" or "+T" is not what defines "backward" or "forward" in time. I.e. "Forward" in time will be that direction along T for which the total entropy increases... in a sense, in order for events to cause effects on your senses which cause effects on your brain and which cause your memories to form (generally speaking storage of information), and enable you to recall the past... defines it.

The past is thus also defined by the direction in T in which you are capable (because of the way entropy, information, causation, and memory work) of remembering.
 
"T" is time, right? (in thermodynamics it's temperature).

I am not concerned about my brain functioning of past or future but that if you can possibly change the enviornement but not you, s.t the enviornemnt will have a decrease in entropy while your brain will still have an increase in entropy, so to speak to isolate myself from the enviornment.

I think it's possible, the problem is how to implement it, toughy.
.
 
Why do you think it is "possible"?
 
It's a hunch from the fact that quantum mechanically you can have negative temperatures (I must admit that I haven't delved into this anomaly of negative tmperatures yet, but I am planning of doing it eventaully).
 
Are you assuming you can define a system in a region A and a second system in separate (in space) region B such that according to a "time" defined for both systems, changes in entropy are positive in A but are negative in B?

Is there ANY interaction allowed between A and B while one system is reversing in time? If there IS, what is the change in entropy of the total system? Why? What is relationship of causation between A and B?

If there is no interaction (as long as they have change in entropy in opposite directions of time) what could cause one or other system to "flip" its direction of entropy? Could a system cause its own flip? How?
 
That's the trillion dollars question, how to implement this?

There are many papers that argue that it maybe possible through some interaction with black holes, I heard a conversation of Seth Lloyd in which he talks about such a model he has.

I don't know how to implement this but I am willing to keep on learning...
 
MathematicalPhysicist said:
That's the trillion dollars question, how to implement this?
Reverse time travel?, yes that's hard no matter how much dollars you throw at at.
 

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