Arrow of time

[swansont]

Why? if you expect zero momentum, then the reverse explosion would never occur. What would be the cause of the separation of the 3 particles? Certainly not a zero state.

An excess of energy is needed, but the momentum can still be zero. A beta decay, for example, from the parent nucleus at rest, but any explosion will do.

[Greg Boyles]

Yes, the amount of entropy is statistical, but the probability of interaction that give rise to the statistics show an asymmetry. The asymmetry tends to show up as soon as you have three particles and/or internal states.

 

e.g. It's physically possible for three particles to come together, stick to each other and be at rest, in the reversal of a simple explosion. But it's more likely that they don't. If we run a number of trials we would see that it does happen — in, say, one case out of a million, the particles would do that, and entropy would decrease. But the probability shows the asymmetry.

 

 

If you can't remember his name, how do I know you accurately remembered what he said? This is your thread — you have some responsibility here.

 

Give me friggin break swansont!

 

I remembered the statement because it flew in the face of common sense from my non physics point of view. But I am not that great with retaining names at the best of times.

 

I seriously doubt that he is the only phycist that has and does postulate such a scenario and I don't think anyone in here, including you, would contend that it is the flight of fancy of a crackpot within the physics community.

 

So I really don't think that watching the video all over again so I can post his name in here is going to add anything significant to the discussion.

 

Antiparticles have a negative vacuum energy and would be a particle moving backwards in time. But we don't see these effects so it is unlikely you can model proper particles moving backwards or even forwards in time. They might even be allowed to move at superluminal speeds and still not oscillate in time; they might even have a negative energy (though this actually is a frame-dependant assertion).

 

 

 

No, you arguing that an arrow of time exists from entropy. There is no such thing, as I have explained, past, present and future coexist side-by-side because we can discern a past and a present and a future to allow events to be recorded as though it were moving in some forward directionality.

 

What about causality?

 

Consider throwing a stone into a pond such that ripples eminated out from the entry point of the stone into the water.

 

If there is no arrow of time then causality goes out the window. Theoretically ripples could eminate out from a point before the stone enters the water.

 

Surely causality demands that there is an arrow of time despite the possibility that the past, present and future exist simultanously some where in space time.

 

Einteins theory dictates that you can only travel forward in time, i.e. when your time slows down due to light speed.

 

That indicates an arrow of time surely?

[Mystery111]

Give me friggin break swansont!

 

I remembered the statement because it flew in the face of common sense from my non physics point of view. But I am not that great with retaining names at the best of times.

 

I seriously doubt that he is the only phycist that has and does postulate such a scenario and I don't think anyone in here, including you, would contend that it is the flight of fancy of a crackpot within the physics community.

 

So I really don't think that watching the video all over again so I can post his name in here is going to add anything significant to the discussion.

 

 

 

What about causality?

 

Consider throwing a stone into a pond such that ripples eminated out from the entry point of the stone into the water.

 

If there is no arrow of time then causality goes out the window. Theoretically ripples could eminate out from a point before the stone enters the water.

 

Surely causality demands that there is an arrow of time despite the possibility that the past, present and future exist simultanously some where in space time.

 

Einteins theory dictates that you can only travel forward in time, i.e. when your time slows down due to light speed.

 

That indicates an arrow of time surely?

 

No I don't believe it does. There is no arrow.

[Greg Boyles]

No I don't believe it does. There is no arrow.

Can you suggest a link for further reading?

 

I am trying to comprehend how it can be that there is no arrow of time but failing.

[swansont]

Give me friggin break swansont!

 

I remembered the statement because it flew in the face of common sense from my non physics point of view. But I am not that great with retaining names at the best of times.

 

I seriously doubt that he is the only phycist that has and does postulate such a scenario and I don't think anyone in here, including you, would contend that it is the flight of fancy of a crackpot within the physics community.

 

So I really don't think that watching the video all over again so I can post his name in here is going to add anything significant to the discussion.

 

Right, it would add nothing. Because the physicist has only made this comment in that one video, and has been silent on it otherwise, so knowing the name and being able to search for things s/he wrote to put the comments in context would be completely useless.

 

No, I'm not inclined to give you break. You've taken too many of them in other threads. You need some rigor in your diet.

[Mystery111]

Can you suggest a link for further reading?

 

I am trying to comprehend how it can be that there is no arrow of time but failing.

 

http://www.motionmountain.net/download.html

 

"Time is a concept introduced specially to describe the flow of events around us; it does not itself flow, it describes flow. Time does not advance. Time is neither linear nor cyclic. The idea that time flows is as hindering to understanding nature as is the idea that mirrors Page 71 exchange right and left. The misleading use of the expression ‘flow of time’, propagated first by some flawed Ref. 36 Greek thinkers and then again by Newton, continues. Aristotle (384/3–322 bce), careful to think logically, pointed out its misconception, and many did so after him. Nevertheless, expressions such as ‘time reversal’, the ‘irreversibility of time’, and the much-abused ‘time’s arrow’ are still common. Just read a popular science magazine chosen at random.''

[DrRocket]

Yes, the second law of thermodynamics gives a forward arrow of time -- but it is a statistical law. It applies only to a large number of things. When we look at the behavior of a small number of particles, they show time symmetry. No arrow of time is revealed.

 

There are a large number of particles in this system that we call the universe.

[michel123456]

There are a large number of particles in this system that we call the universe.

That's why i like this Forum so much...

 

Why are they a so large number of particles? Does our model work with less particles?

[Greg Boyles]

http://www.motionmou...t/download.html

 

"Time is a concept introduced specially to describe the flow of events around us; it does not itself flow, it describes flow. Time does not advance. Time is neither linear nor cyclic. The idea that time flows is as hindering to understanding nature as is the idea that mirrors Page 71 exchange right and left. The misleading use of the expression 'flow of time', propagated first by some flawed Ref. 36 Greek thinkers and then again by Newton, continues. Aristotle (384/3–322 bce), careful to think logically, pointed out its misconception, and many did so after him. Nevertheless, expressions such as 'time reversal', the 'irreversibility of time', and the much-abused 'time's arrow' are still common. Just read a popular science magazine chosen at random.''

 

 

This is great so far - thankyou very much.

OK then.

 

So time might be viewed as a ruler where the intervals are fixed. Events, objects and human perceptiom move along the ruler rather than the ruler moving underneath them.

 

Would that be correct so far?

 

Assumung it is, how does this get us any further in this debate?

 

If your car travels at 60km/h and hits another car, then the results will be indentical to if the other car travels at 60km an hour and hits your car.

 

So instances travelling along the stationary ruler of time still results in the same net effect. You can't reverse the flow of instances and travel back in time, an egg can't be unbroken........

 

It would be equally valid to say that the ruler of time does indeed move under the events, objects and human perception.

Edited November 6, 2011 by Greg Boyles

[michel123456]

This is great so far - thankyou very much.

OK then.

 

So time might be viewed as a ruler where the intervals are fixed. Events, objects and human perceptiom move along the ruler rather than the ruler moving underneath them.

 

Would that be correct so far?

 

Assumung it is, how does this get us any further in this debate?

(...)

 

Wonderful.

Now that you have accepted that you are moving along a ruler, the work is almost done.

The next step to make is the most difficult: if you are moving along time, it means that when you leave a time coordinate A and move into another time coordinate B, the A coordinate gets empty.

Right?

 

And now the definitive step: put something else in coordinate A.

A new Universe is born.

Edited November 6, 2011 by michel123456

[Greg Boyles]

Wonderful.

Now that you have accepted that you are moving along a ruler, the work is almost done.

The next step to make is the most difficult: if you are moving along time, it means that when you leave a time coordinate A and move into another time coordinate B, the A coordinate gets empty.

Right?

 

And now the definitive step: put something else in coordinate A.

A new Universe is born.

 

OK coordinate A is empty - accepted.

 

Apart from the lasing evidence of coordinate A in our memories, fossil and geological record etc.

 

OK.

 

So it might be more valid to say that there is an arrow of events rather than an arrow of time.

 

 

But please note in my previous post that I said that it is equally valid to say that the ruler is moving under us as it is to say we are moving along the ruler.

 

 

In which case an arrow of events and an arrow of time amount to the same net result.

 

 

 

New universe.......since puting something else in coordinate A will change the results in coordinate B........understood.

 

But that is sort of irrelevant with respect to arrows.

Edited November 7, 2011 by Greg Boyles

[michel123456]

OK coordinate A is empty - accepted.

Thank you.

 

Apart from the lasing evidence of coordinate A in our memories, fossil and geological record etc.

 

OK.

 

So it might be more valid to say that there is an arrow of events rather than an arrow of time.

 

 

But please note in my previous post that I said that it is equally valid to say that the ruler is moving under us as it is to say we are moving along the ruler.

 

 

In which case an arrow of events and an arrow of time amount to the same net result.

 

 

 

New universe.......since puting something else in coordinate A will change the results in coordinate B........understood.(...)

Emphasis mine.

I hope you understand the implications.

Especially after noticing that this "something else in coordinate A" is not observable by us.

[Greg Boyles]

Thank you.

 

 

Emphasis mine.

I hope you understand the implications.

Especially after noticing that this "something else in coordinate A" is not observable by us.

 

Modified coordinate A not observable by us - understood and accepted. We would only be able to observe the evidence of coordinate A as we and our present reality experienced it.

 

But I still don't see how this precludes an arrow of time/events - interchangeable as far as I can see.

Edited November 8, 2011 by Greg Boyles

[michel123456]

Modified coordinate A not observable by us - understood and accepted. We would only be able to observe the evidence of coordinate A as we and our present reality experienced it.

 

But I still don't see how this precludes an arrow of time/events - interchangeable as far as I can see.

 

Thanks.

The idea that moving through time corresponds to a change in coordinates seems so evident to me that I am still surprised that the current view on time is not like that at all.

The common concept is that we are not translating, but extending somehow like a rubber band. Common view states that we never leave a time coordinate: once we occupied it once we continue to stay there "forever". Under this POV, a time traveler going back to a previous time coordinate will find his past.

Under my conception, he will find nothing but an empty coordinate, or at most a coordinate occupied with something completely different, something that belongs to our universe but that we cannot observe.

 

As for the rest.

I am afraid to find the arrow of time you will have to step (and sink) into the deep waters of speculations.

 

For example, since you accepted that we are moving through time, ask yourself "what is the direction of this movement through time?"

 

My answer is the following: the direction exists and is pointed from the past to the future.

The past is outside, we observe it in the form of stars & galaxies.

The present is yourself, the observator.

The future we don't know but it must be inside.

 

So the direction is from the outside (the past) to the inside (the future)

I will stop here.

 

I am sorry: if it is too hard to swallow please move this post in speculations, not the entire thread. Thank you.

Edited November 8, 2011 by michel123456

[Iggy]

This is great so far - thankyou very much.

OK then.

 

So time might be viewed as a ruler where the intervals are fixed. Events, objects and human perceptiom move along the ruler rather than the ruler moving underneath them.

 

Would that be correct so far?

Thanks.

The idea that moving through time corresponds to a change in coordinates seems so evident to me that I am still surprised that the current view on time is not like that at all.

The common concept is that we are not translating, but extending somehow like a rubber band. Common view states that we never leave a time coordinate: once we occupied it once we continue to stay there "forever".

I highlighted several words above. They mean different things. I don't know what "we" means.

 

An event is, by definition, a specific place at a certain time. Neil Armstrong setting foot on the moon is an event. No one would think that an event moves with respect to time. That would be nonsensical.

 

An object is not so easily defined. A clock is a good idea of an object. It is different today than it was yesterday. It changes with time or "over" time. Specifically, certain parts of the object move with respect to other parts over time.

 

Human perception is like an object... it is, after all, the workings of the human body and brain.

 

 

Logically then, does an object move through time so that if an object is here today then it must be gone yesterday? No. Today the clock is here today and yesterday the clock was here yesterday. That's the end of the story. You don't get to say "today the clock is gone yesterday" because that is a nonsensical thing to say.

[michel123456]

Ha.

"we" means "the observators". We are the one observing.

 

Logically then, does an object move through time so that if an object is here today then it must be gone yesterday? No. Today the clock is here today and yesterday the clock was here yesterday. That's the end of the story. You don't get to say "today the clock is gone yesterday" because that is a nonsensical thing to say.

 

I will try.

We live in a 3d world + time = 4d world.

Now try to reduce 3d into 1d: it is a line representing space (as in a spacetime diagram)

Perpendicular to this line, put the line of time. You get a spacetime plane.

Say your table top is representing this plane.

Now put a ping-pong ball on it and make it roll over from here to there. The ball changed coordinates in spacetime: it moved. The ball does not continue to "exist" at each coordinate it passed through.

You can call an "event" the concept of recording the coordinates the ball went through, but there is only one ping-pong ball. The ball did not duplicate.

[Iggy]

We are the one observing.

But who watches the watchmen?

 

 

Perpendicular to this line, put the line of time. You get a spacetime plane.

So, the vertical dimension represents time. Got it.

 

Now put a ping-pong ball on it and make it roll over from here to there. The ball changed coordinates in spacetime: it moved.

So, the movement of the ball represents time. Got it.

 

Oh, wait... you've ended up with two dimensions of time. That's probably not going to fly.

[michel123456]

I knew it was difficult to explain motion.

 

I'll try otherwise.

In four dimensions an object A at spacetime coordinates 1,1,1,1

Changes coordinates and translates to 1,1,1,2

 

Where is the object A?

_ at coordinates 1,1,1,1?

_ at coordinates 1,1,1,2?

_ or at both?

Edited November 8, 2011 by michel123456

[Iggy]

You actually explained it fantastically well, and I agree -- if you want to say "today the clock is gone yesterday" then you NEED two dimensions of time. It doesn't otherwise make sense.

 

What you started to do was to take an object and represent its movement in the universe with a tabletop (the tabletop being a space time diagram). That's a fantastic idea.

 

What I could then do is to take your "ball rolling on the tabletop" and diagram it myself. It would require three dimensions: one of space and two of time. You've ended up with two different time dimensions, but... why? I only know of the one.

 

EDIT:

 

I'll try otherwise.

In four dimensions an object A at spacetime coordinates 1,1,1,1

Changes coordinates and translates to 1,1,1,2

 

Where is the object A?

_ at coordinates 1,1,1,1?

_ at coordinates 1,1,1,2?

_ or at both?

Again, you've described it perfectly. You want to say "first the object is at 1,1,1,1 then it is at 1,1,1,2" so you obviously need another number: 1,1,1,1,1... 2,1,1,1,2" which means "first and second" in this case. You've ended up with 5 numbers... that's three dimensions of space and two of time.

Edited November 8, 2011 by Iggy

[michel123456]

O.K. i may be wrong.

but you must admit that current POV states that both coordinates contain object A.

 

--------------

edit.

No I am not wrong.

Edited November 8, 2011 by michel123456

[Iggy]

O.K. i may be wrong...

 

--------------

edit.

No I am not wrong.

If there are two dimensions of time... you could be both

 

but you must admit that current POV states that both coordinates contain object A.

You actually asked 3 questions:

 

Where is the object A?

_ at coordinates 1,1,1,1?

_ at coordinates 1,1,1,2?

_ or at both?

 

Is object A at 1,1,1,1? The answer is yes. You said it was.

Is object A at 1,1,1,2? The answer is yes. You said it was.

Is object A at 1,1,1,1 and 1,1,1,2. The answer is yes. See the above two answers.

[michel123456]

So you are stating that

1,1,1,1

and

1,1,1,2

are occupied by the same object

 

If I asked you are coordinates

1,1,1,1

and

2,1,1,1

occupied by the same object?

What would you think? (speaking about point & massive object)

Edited November 9, 2011 by michel123456

[Iggy]

So you are stating that

1,1,1,1

and

1,1,1,2

are occupied by the same object

Well, you said that. I was working off your premise, but it's a good premise. I agree. Your car keys are the same yesterday as today... same keys. Ok.

 

If I asked you are coordinates

1,1,1,1

and

2,1,1,1

occupied by the same object?

Now you have the same car keys on the kitchen table and the coffee table at the same time. In my everyday experience, that doesn't happen.

[Greg Boyles]

Well, you said that. I was working off your premise, but it's a good premise. I agree. Your car keys are the same yesterday as today... same keys. Ok.

 

 

Now you have the same car keys on the kitchen table and the coffee table at the same time. In my everyday experience, that doesn't happen.

 

Where does this get us as far as the arrow of time/events?

 

If we assume that time is like a ruler under us and that we move along the ruler, is it not fair to say that this is entirely equivalent to the ruler moving beaneath us?

 

If I am in space and I move x kilometers right then is it not effectively equivalent to the universe moving x kilometers to my left? Where I was is not to my left or in my past in the case of time.

[Iggy]

Where does this get us as far as the arrow of time/events?

nowhere.

 

If we assume that time is like a ruler under us and that we move along the ruler...

You already lost me. If I defined "move" I would maybe say "a change of position over time" or, perhaps better put "a change of position between two times". That definition, however, doesn't work if you say "moving through time".

 

With my definition of "move", if you say "moving through time" you are literally saying "a change of position between two times through time". I can't make any sense of that so I don't know what "move through time" means.

 

This does all seem rather off topic.