The Naked Scientists

The Naked Scientists Forum

Author Topic: Does Time have a Direction Without Gravity?  (Read 13279 times)

Offline MikeS

  • Neilep Level Member
  • ******
  • Posts: 1044
  • The Devils Advocate
    • View Profile
Does Time have a Direction Without Gravity?
« on: 03/02/2012 11:26:36 »
Does Time have a Direction Without Gravity?

I don't think it does.


 

Offline Soul Surfer

  • Neilep Level Member
  • ******
  • Posts: 3345
  • keep banging the rocks together
    • View Profile
    • ian kimber's web workspace
Re: Does Time have a Direction Without Gravity?
« Reply #1 on: 03/02/2012 19:08:16 »
Yes it does. thermodynamics would still work in the absence of gravity and that also defines the arrow of time.
 

Offline MikeS

  • Neilep Level Member
  • ******
  • Posts: 1044
  • The Devils Advocate
    • View Profile
Re: Does Time have a Direction Without Gravity?
« Reply #2 on: 04/02/2012 07:22:52 »
Yes it does. thermodynamics would still work in the absence of gravity and that also defines the arrow of time.

I believe you are saying that entropy defines the arrow of time and in this I would agree.
When two massive objects combine, time dilates for them.  This is the same as a reduction of useful energy which is the same as an increase in entropy.  (It takes more energy to do anything in a strong gravitational field then in a weak one).  Gravity is an example of entropy (possibly the main example) and as such defines the arrow of time.

quote "thermodynamics would still work in the absence of gravity".
Presumably you mean entropy would still work in the absence of gravity.
Could you give examples please?
Thanks
 

Offline Soul Surfer

  • Neilep Level Member
  • ******
  • Posts: 3345
  • keep banging the rocks together
    • View Profile
    • ian kimber's web workspace
Re: Does Time have a Direction Without Gravity?
« Reply #3 on: 05/02/2012 00:12:05 »
thermodynamics involves more than just entropy which is itself a very complex and mostly misunderstood process. What entropy  is not is a gradual randomisation of things because this only applies to the thermodynamics of non interacting particles. Most particles interact even if it only by gravity and this means that the end result is not an even random distribution.
 

Offline MikeS

  • Neilep Level Member
  • ******
  • Posts: 1044
  • The Devils Advocate
    • View Profile
Re: Does Time have a Direction Without Gravity?
« Reply #4 on: 05/02/2012 10:04:26 »
Thanks but you last post ignored my last question
"Presumably you mean entropy would still work in the absence of gravity.
Could you give examples please?"

I personally don't believe that time has a direction without gravity.
You said "thermodynamics would still work in the absence of gravity".
I assumed this to mean "entropy would still work in the absence of gravity."
If my interpretation of what aspect of thermodynamics you are referring to is wrong then please explain what aspect you are referring to and please give examples as I previously requested.

Any examples you give I would like to follow through to see whether or not they are connected to gravity.  Without examples I can't do it.
 

Offline MikeS

  • Neilep Level Member
  • ******
  • Posts: 1044
  • The Devils Advocate
    • View Profile
Re: Does Time have a Direction Without Gravity?
« Reply #5 on: 05/02/2012 10:12:22 »
My original question was
“Does Time have a Direction Without Gravity?”
Quote Soul Surfer
“Yes it does. thermodynamics would still work in the absence of gravity and that also defines the arrow of time.”

What do the Laws of Thermodynamics have to say?

1   You cannot win (that is, you cannot get something for nothing, because matter and energy are conserved).

This is time independent and gravity independent.  This only works in the sense that nothing is happening. If something were happening then it would happen in time.  We can’t discuss whether that something is affected by gravity because there is no something to discuss.

2   You cannot break even (you cannot return to the same energy state, because there is always an increase in disorder; entropy always increases).

This is the best example of the passage of time and times arrow itself being dependant upon gravity.  I mentioned this in my last post.
“I believe you are saying that entropy defines the arrow of time and in this I would agree.
When two massive objects combine, time dilates for them.  This is the same as a reduction of useful energy which is the same as an increase in entropy.  (It takes more energy to do anything in a strong gravitational field then in a weak one).  Gravity is an example of entropy (possibly the main example) and as such defines the arrow of time.”  In other words both gravity and entropy carry the arrow of time.

There may be other examples of entropy that do not at first sight appear to be gravity dependent but I believe that if investigated in sufficient depth they would ultimately prove to be gravity dependent.  Entropy is a process whereby something happens.  Nothing can happen independent of time and it requires more than just times arrow.  There has to be a passage of time.  For example the infinite gravity at the event horizon of a black hole carries times arrow but there is no passage of time as perceived from a distant observer.

3   You cannot get out of the game (because absolute zero is unattainable).  The Third Law explains this further. It says that all processes cease as temperature approaches absolute zero. This is the temperature at which molecules cease movement, cease producing kinetic energy. In other words, there is no energy.

If absolute zero were attainable then the arrow of time would still point forward but the clock would have stopped.  Again, this is a condition found at the event horizon of a black hole.  To get to this situation this is something that has happened in time and in this example is caused by gravity.  When time ceases to flow, times arrow remains.

Zeroth Law   The so-called Zeroth Law is a bit more fundamental than the other Three Laws. It came into being after the Three. It essentially says that if each of two systems is in equilibrium with a third system, the first two are in equilibrium with one another.

That’s not a process and does not require either time or gravity.



As far as I can see, there is no process in thermodynamics that can work without gravity.
 

Offline Soul Surfer

  • Neilep Level Member
  • ******
  • Posts: 3345
  • keep banging the rocks together
    • View Profile
    • ian kimber's web workspace
Re: Does Time have a Direction Without Gravity?
« Reply #6 on: 05/02/2012 13:21:20 »
hydrogen and oxygen atoms can combine to form water molecules in the complete absence of gravity.  This releases energy and results in an increase in entropy and takes time.  This is an electromagnetic process.
 

Offline JP

  • Neilep Level Member
  • ******
  • Posts: 3366
  • Thanked: 2 times
    • View Profile
Re: Does Time have a Direction Without Gravity?
« Reply #7 on: 05/02/2012 14:20:28 »
Mix a hot gas and a cold gas together in a box in the absence of gravity.  They will mix and won't unmix.  This is an increase in entropy without gravity.
 

Offline syhprum

  • Neilep Level Member
  • ******
  • Posts: 3812
  • Thanked: 19 times
    • View Profile
Re: Does Time have a Direction Without Gravity?
« Reply #8 on: 05/02/2012 21:11:50 »
I believe that SS meant molecules not atoms Hydrogen atoms combine to form molecules with a large release of energy
 

Post by MikeS click to view.

Offline MikeS

  • Neilep Level Member
  • ******
  • Posts: 1044
  • The Devils Advocate
    • View Profile
Re: Does Time have a Direction Without Gravity?
« Reply #9 on: 06/02/2012 13:23:57 »
Shrunk
Geezer
quote
"As this is a new theory thinly disguised as a question, it's moving to "New Theories"."

To the best of my knowledge there is absolutely nothing been mentioned so far that constitutes a "New Theory".
 

Offline MikeS

  • Neilep Level Member
  • ******
  • Posts: 1044
  • The Devils Advocate
    • View Profile
Re: Does Time have a Direction Without Gravity?
« Reply #10 on: 06/02/2012 13:30:23 »
Before responding to the previous replies could I please rephrase, in this post, the original question from

Does Time have a Direction Without Gravity?
to
Can time exist without gravity?
 

Offline imatfaal

  • Neilep Level Member
  • ******
  • Posts: 2787
  • rouge moderator
    • View Profile
Re: Does Time have a Direction Without Gravity?
« Reply #11 on: 06/02/2012 15:26:01 »
Try clarifying again.  If you are asking whether it is necessary to have existence of matter and energy (and thus gravity) for time to be considered then possibly yes.  If you are asking whether we need to consider gravity in any discussion of time then definitely no.
 

Offline MikeS

  • Neilep Level Member
  • ******
  • Posts: 1044
  • The Devils Advocate
    • View Profile
Re: Does Time have a Direction Without Gravity?
« Reply #12 on: 07/02/2012 09:23:19 »
Try clarifying again.  If you are asking whether it is necessary to have existence of matter and energy (and thus gravity) for time to be considered then possibly yes. If you are asking whether we need to consider gravity in any discussion  of time then definitely no.

"If... it is necessary to have existence of matter and energy (and thus gravity) for time to be considered then possibly yes."
If that is true then the following has to be false.   "If you are asking whether we need to consider gravity in any discussion" (on the nature) "of time then definitely no."

We know that a graduated gravitational potential due to mass dilates local time.  How then can you say "If you are asking whether we need to consider gravity in any discussion" (on the nature) "of time then definitely no."

The local gravitational potential quite obviously does affect the local time dilation factor.  Therefore gravity needs to be considered in any discussion on the nature of time.

 

Offline imatfaal

  • Neilep Level Member
  • ******
  • Posts: 2787
  • rouge moderator
    • View Profile
Re: Does Time have a Direction Without Gravity?
« Reply #13 on: 07/02/2012 10:59:56 »
Sorry Mike but you are so obsessed with gravity and time dilation you aren't seeing the wood for the trees.  Nothing dilates local time - you need to get that straight; you can never find your own clock running slow! In your own frame all time is undilated.  When you look at a source in a frame at a different relative velocity or at a different gravitational potential then you get time dilation.

To analyse any reaction you need to choose a frame (ie you cannot mix terms from different FoR) and once you have chosen that frame you know that there can be no time dilation differences within that frame. And that all calculations will still hold true if you make that frame travel at high relative speed (ie by moving yourself and then choosing yourself as the rest frame) and will still hold true if that frame is at a different gravitational potential compared to the frame of the experimenter.  So yes you can ignore time dilation by either doing the experiment within the frame of the interaction or by compensating for frame differences.  The time dilation does not affect the reaction - it affects the observation of it.
 

Offline MikeS

  • Neilep Level Member
  • ******
  • Posts: 1044
  • The Devils Advocate
    • View Profile
Re: Does Time have a Direction Without Gravity?
« Reply #14 on: 07/02/2012 11:56:23 »
Try clarifying again.  If you are asking whether it is necessary to have existence of matter and energy (and thus gravity) for time to be considered then possibly yes. If you are asking whether we need to consider gravity in any discussion  of time then definitely no.

"If... it is necessary to have existence of matter and energy (and thus gravity) for time to be considered then possibly yes."
If that is true then the following has to be false.   "If you are asking whether we need to consider gravity in any discussion" (on the nature) "of time then definitely no."

We know that a graduated gravitational potential due to mass dilates local time as viewed from the reference frame of a distant observer.  How then can you say "If you are asking whether we need to consider gravity in any discussion" (on the nature) "of time then definitely no."

The local gravitational potential quite obviously does affect the local time dilation factor as viewed from the reference frame of a distant observer.  Therefore gravity needs to be considered in any discussion on the nature of time.


There was nothing wrong in what I said.  When referring to local time I should have added "as viewed from the reference frame of a distant observer."  Local time has dilated, that's the whole point.  A local clock does not register that dilation as it is in that time frame.  However, from the time frame of a distant observer then in that 'local' frame, time has dilated.



 So yes you can ignore time dilation by either doing the experiment within the frame of the interaction or by compensating for frame differences. The time dilation does not affect the reaction - it affects the observation of it.
I agree but the local passage of time (time dilation factor) according to a distant observer still depends upon the local gravitational potential or acceleration.  Therefore you cannot divorce gravity from time when considering the nature of time.  You can ignore the effects of gravity in local time to all practical considerations under normal circumstances but you cannot when considering the nature of time as gravity is an integral part. Gravity always plays its part in the passage of time but mostly goes unnoticed.  It is always there and it is always affecting the local time dilation factor according to a distant observer.
 

Offline MikeS

  • Neilep Level Member
  • ******
  • Posts: 1044
  • The Devils Advocate
    • View Profile
Re: Does Time have a Direction Without Gravity?
« Reply #15 on: 07/02/2012 12:18:16 »
So yes you can ignore time dilation by either doing the experiment within the frame of the interaction or by compensating for frame differences.  The time dilation does not affect the reaction - it affects the observation of it.
Thinking about it, I believe you are wrong.  It affects the amount of energy required to do the reaction and results in higher entropy.

The time dilation factor does affect the reaction in as much as entropy increases at a higher rate in a greater time dilation than in a lesser one.  You need more energy to do anything (including any chemical reaction, experiment etc.) in a greater time dilated (higher gravitational) potential than in a lower time dilated (lower gravitational) potential.  This is the answer I was looking for but had as then not found in answer to Soul Surfer  and JP earlier in this thread.
 

Offline imatfaal

  • Neilep Level Member
  • ******
  • Posts: 2787
  • rouge moderator
    • View Profile
Re: Does Time have a Direction Without Gravity?
« Reply #16 on: 07/02/2012 17:53:41 »
So yes you can ignore time dilation by either doing the experiment within the frame of the interaction or by compensating for frame differences.  The time dilation does not affect the reaction - it affects the observation of it.
Thinking about it, I believe you are wrong.  It affects the amount of energy required to do the reaction and results in higher entropy.

The time dilation factor does affect the reaction in as much as entropy increases at a higher rate in a greater time dilation than in a lesser one.  You need more energy to do anything (including any chemical reaction, experiment etc.) in a greater time dilated (higher gravitational) potential than in a lower time dilated (lower gravitational) potential.  This is the answer I was looking for but had as then not found in answer to Soul Surfer  and JP earlier in this thread.

Mike this is getting bizarre. 

Quote
.... in a greater time dilated (higher gravitational) potential than in a lower time dilated (lower gravitational) potential.
  Even ignoring the claim about energy needed this sentence is wrong.  gravitational potential goes up as you leave the gravity well of a massive body - clocks at a high gravitational potential run faster than those at a low gravitational potential.  You are making claims of a subject you really do not understand.

Please at least read the wikipage on this subject http://en.wikipedia.org/wiki/Gravitational_time_dilation
 

Offline yor_on

  • Naked Science Forum GOD!
  • *******
  • Posts: 11978
  • Thanked: 4 times
  • (Ah, yes:) *a table is always good to hide under*
    • View Profile
Re: Does Time have a Direction Without Gravity?
« Reply #17 on: 08/02/2012 11:13:24 »
Time is a really strange subject. Myself I think of it as two 'properties'. 'Time' itself and then a, or more, 'arrows' depending on how you see it.  But as no interactions can exist without a arrow, as far as I see? Time as a concept must exist, with the rest becoming expressions of 'changes' possibly? And if we discuss 'change', then it should be directly related to the SpaceTime geometry you define it from, at least in relativity where 'frames of reference' will define whatever positions in time and 'space' you measure, relative what 'frame' you define it from.
 

Offline imatfaal

  • Neilep Level Member
  • ******
  • Posts: 2787
  • rouge moderator
    • View Profile
Re: Does Time have a Direction Without Gravity?
« Reply #18 on: 08/02/2012 17:41:32 »
It's definitely a head-scratcher YorOn.  Using your two properties:  Interactions without time seem to be impossible, but interactions without an arrow it is difficult to agree.  Barring large numbers of particles where probability/entropy comes into play, I don't believe there are any reactions/interactions that are not time reversible; ie which make just as much sense going in one direction as the other.  We only get the arrow from the complexity/entropy side of things and that only applies in large macro systems
 

Offline yor_on

  • Naked Science Forum GOD!
  • *******
  • Posts: 11978
  • Thanked: 4 times
  • (Ah, yes:) *a table is always good to hide under*
    • View Profile
Re: Does Time have a Direction Without Gravity?
« Reply #19 on: 08/02/2012 18:10:38 »
There are interactions that's not time-reversible (CPT). You state a interesting question when you say "Barring large numbers of particles where probability/entropy comes into play, I don't believe there are any reactions/interactions that are not time reversible." Probability is what QM use to define macroscopic behavior, but from where do they draw/define those probability's? From experience, isn't that so? Why does that invalidate time reversibility?

Time reversibility in its simplest form is like a movie you can play both ways, both making sense, as a Feynman diagram. But that we see that something can be expressed 't' or '-t', is that equivalent to 'times arrow' going backwards?

Not if you trust our experience.
 

Offline imatfaal

  • Neilep Level Member
  • ******
  • Posts: 2787
  • rouge moderator
    • View Profile
Re: Does Time have a Direction Without Gravity?
« Reply #20 on: 09/02/2012 12:48:28 »
Which small scale interactions are non time-reversible?  There are parity violations (electron spin out of decay is always left handed).  The only area where we would immediately know that a reaction has been reversed is with large numbers of particles - this is what I meant by probability/entropy related;  QM is a different matter entirely and I think is all time reversible.

In all experiments barring entropy related we don't know which is t- or t+ - our experience is another matter entirely, and very difficult to link to a physical law outside thermodynamics and entropy.

 

Offline yor_on

  • Naked Science Forum GOD!
  • *******
  • Posts: 11978
  • Thanked: 4 times
  • (Ah, yes:) *a table is always good to hide under*
    • View Profile
Re: Does Time have a Direction Without Gravity?
« Reply #21 on: 10/02/2012 11:56:29 »
We know what times arrow is?

I'm not sure how you think there, everything you do is inside the arrow. If you think of it as a equation, you still will see it unfold inside that arrow in practicality. As for what QM thingies that's not time reversible, there are some easy (weak nuclear force) to find if you use Google, and I've seen some pdf:s discussing it too in more depth. It's been some time since I read about it but I'll see if I can find one on my laptop. Conceptually it seems to be possible that most interactions we see can be played backwards, but as far as I know the ones we measure all act inside the arrow we have.

About Einstein and time reversibility.
 

Offline yor_on

  • Naked Science Forum GOD!
  • *******
  • Posts: 11978
  • Thanked: 4 times
  • (Ah, yes:) *a table is always good to hide under*
    • View Profile
Re: Does Time have a Direction Without Gravity?
« Reply #22 on: 10/02/2012 12:24:34 »
One way to think of it might be to consider all processes unfolding as results of 'emergences'. That we from those unfolding can see linear processes that you might play both ways will then become a result from the 'constants' that we find, defining them.

Well, possibly, I can't be sure of that at all :) but to me it seems as we have a 'hidden game' in where 'times arrow' defines the 'linearity' we experience.
 

Offline imatfaal

  • Neilep Level Member
  • ******
  • Posts: 2787
  • rouge moderator
    • View Profile
Re: Does Time have a Direction Without Gravity?
« Reply #23 on: 13/02/2012 14:34:39 »
Yoron - a few experiments have shown CP violations - but I did not know of any that have show CPT violations.  Weak Nuclear implies a violation of T - but it is more a violation of CP and theoretically the T should follows.

this has a nice explanation
http://www.lbl.gov/abc/wallchart/chapters/05/2.html
 

Offline Phractality

  • Hero Member
  • *****
  • Posts: 523
  • Thanked: 1 times
    • View Profile
Re: Does Time have a Direction Without Gravity?
« Reply #24 on: 14/02/2012 04:23:20 »
I believe, in the proverbial "closed system", radioactive decay must proceed in the direction of increasing entropy. You start with uranium and end up with lead, and that is independent of gravity. You can't go from lead to uranium without a low-entropy input from outside the system.

In my own model, the direction of time is determined by the expansion of space, with alternate scale-wise universes running in alternate directions.
 

The Naked Scientists Forum

Re: Does Time have a Direction Without Gravity?
« Reply #24 on: 14/02/2012 04:23:20 »

 

SMF 2.0.10 | SMF © 2015, Simple Machines
SMFAds for Free Forums