Welcome to
Science a GoGo's
Discussion Forums
Please keep your postings on-topic or they will be moved to a galaxy far, far away.
Your use of this forum indicates your agreement to our terms of use.
So that we remain spam-free, please note that all posts by new users are moderated.


The Forums
General Science Talk        Not-Quite-Science        Climate Change Discussion        Physics Forum        Science Fiction

Who's Online Now
0 members (), 95 guests, and 0 robots.
Key: Admin, Global Mod, Mod
Latest Posts
Top Posters(30 Days)
Previous Thread
Next Thread
Print Thread
Page 3 of 4 1 2 3 4
Joined: Aug 2010
Posts: 3,570
B
Megastar
Offline
Megastar
B
Joined: Aug 2010
Posts: 3,570
I would like to return to the earlier consideration of Planck's time, about which I have a thought.


Peter Lynds, Time and Classical and Quantum Mechanics: Indeterminacy vs. Discontinuity (Obtainable from the CERN document server). Makes the point that there can be no static instant of time, during which change could be considered as having paused. He reasons that if there were such an instant, then all change, all motion, would come to a permanent standstill at that point. Presumably, if we consider time as being static, in its entirety, then we have to regard any motion through time as being a smooth, continuous motion that cannot be frozen at any particular instant.

If Plancks time is defined as the smallest interval of time that has any meaning, beyond which it is not possible to further sub-divide time, then, surely, we must regard this as the quantum of time.

Plancks time has a duration, albeit unthinkably small. That being the case, it must be possible to attribute a degree of change, during that period, to any object in relative motion; otherwise, as Lynds points out, that object would be stationary.

There is something more than a little familiar about this line of reasoning. In the same way that light has to be regarded as a wave for some purposes, and as a particle in other situations, could something similar be true of time?

The discussion about whether time is continuous or quantised is ongoing, but it may be no more meaningful than trying to resurrect the argument about whether light is a wave or a particle. Time could be particulate or continuous depending on what question you are asking about it.


There never was nothing.
.
Joined: Dec 2010
Posts: 1,858
B
Megastar
Offline
Megastar
B
Joined: Dec 2010
Posts: 1,858
Bill S.
Can you provide a link to the CERN document server? I found the server, but couldn't find the document you referenced. I searched under both the title and the author, and couldn't find it.

Bill Gill


C is not the speed of light in a vacuum.
C is the universal speed limit.
Joined: Aug 2010
Posts: 3,570
B
Megastar
Offline
Megastar
B
Joined: Aug 2010
Posts: 3,570
Bill.
You should find it at http://arxiv.org/pdf/physics/0310055 or you could Google "Time and Classical and Quantum Mechanics: Indeterminacy vs. Discontinuity". Its about 3 yrs since I originally found it and the link seems to have changed, but this one should get you there.


There never was nothing.
Joined: Dec 2010
Posts: 1,858
B
Megastar
Offline
Megastar
B
Joined: Dec 2010
Posts: 1,858
Thanks I found it. I don't have any more comments right now. I am currently printing it out. That way I can sit down and try to read it and make out what he is saying. I sat here and read about half of it and didn't make much sense of it. On paper it will be better. Maybe tomorrow I will be ready to comment.

And I thought I had spoken to you about making me think. I told you I don't like to think, you are going to have to do better in the future.

Bill Gill


C is not the speed of light in a vacuum.
C is the universal speed limit.
Joined: Dec 2010
Posts: 1,858
B
Megastar
Offline
Megastar
B
Joined: Dec 2010
Posts: 1,858
Well, I'm not sure that I am any more informed than I was before I read it. However, I will try a few comments. Just remember that my comments are strictly my thoughts, and may not have any relevance to the subject.

I can kind of see that if you look at any changing quantity at a single instant in time there will be no change in the quantity, since there is no time for the change to occur. I can see this, it is like looking at one frame of a motion picture. His idea seems to be that since there is no change in that instant there is no way for the quantity to change so that it can move to another instant, so if there is a quantum of time, as there is of energy, then there can be no change and the universe would be static and unchanging. I hope I have that right. Frankly the concepts he is talking about are not really easy to understand, which he admits in the last paragraph of Section 1.

Now to my thoughts on this, keeping in mind that I am not really qualified to do a deep analysis of the paper. An undergraduate degree in physics doesn't get you far enough to really qualify a person to get this deep.

Having made my disclaimer:

It seems to me that one of the problems with his idea is that he speaks of a single instant of time. I'm not sure that any of the hypotheses of quantum time really talk about an instant of time. They mostly assume that the quantum of time is closely related to the Plank Time, which has a definite "duration" if you can call it that. Basically this is just as short an interval as can be determined within the bounds of Quantum Theory (QT).

Another possible problem is that he isn't taking into consideration is the way QT handles state transitions. For example; take a hydrogen atom and consider the electron in the ground state. If a photon having sufficient energy strikes the atom the electron will immediately transition to the first (or higher) excited state. As far as I know there is no mention of time in this transition. If I am correct about this then there is a quantity that changes within an instant of time. So now the universe isn't static, it can move from one instant of time to another.

Of course there is always the view that there is no such thing as time. Scientific American had an article on it last year. I can't tell you what issue, I have already passed it on to my daughter. But here is a link Forget time to an essay about that.

Bill Gill


C is not the speed of light in a vacuum.
C is the universal speed limit.
Joined: Aug 2010
Posts: 3,570
B
Megastar
Offline
Megastar
B
Joined: Aug 2010
Posts: 3,570
Bill.
Thanks for the comments and the link, I know it's going to make me struggle, but I shall try to get something out of it.

Any thoughts about the possibility that time could be particulate or continuous depending on what question you are asking about it.


There never was nothing.
Joined: Dec 2010
Posts: 1,858
B
Megastar
Offline
Megastar
B
Joined: Dec 2010
Posts: 1,858
Originally Posted By: Bill S.
Any thoughts about the possibility that time could be particulate or continuous depending on what question you are asking about it.


I don't have any real thoughts about it, but my thinking about a granular structure to both time and space is that I am willing to accept the idea. This is based on the fact that QT has pretty convincingly shown that energy, in its many manifestations, is granular. Since 1 of the 3 major constituents of the universe works that way I am quite ready to accept it for the other 2. QT has also convincingly show the particle/wave duality exists. Based on that I would certainly not want to throw out the idea of a "particle/wave" duality for time and space, at least not without some pretty convincing evidence. I am not sure just what such a duality would look like, I will have to wait for some theorist to come up with that. I will bet that it wouldn't look anything like what I might expect.

Bill Gill


C is not the speed of light in a vacuum.
C is the universal speed limit.
Joined: May 2010
Posts: 118
K
Senior Member
OP Offline
Senior Member
K
Joined: May 2010
Posts: 118
If Plancks time is defined as the smallest interval of time that has any meaning, beyond which it is not possible to further sub-divide time, then, surely, we must regard this as the quantum of time.

Plancks time has a duration, albeit unthinkably small. That being the case, it must be possible to attribute a degree of change, during that period, to any object in relative motion; otherwise, as Lynds points out, that object would be stationary.


Im glad that everyone is considering the possible equivalence (function) of Planck limits and quanta.

I would like to introduce a concept:

We are aware of time solely due to change. Since the change of particle positions occur in discrete quantities (herky-jerky motions), it is easy to believe that time is moving the same way. There may be a difference between observed time change and the actual nature of time. Once again, let me resort to an analogy:

You are in a supermarket and you notice a large cube of perfectly stacked boxes. You single out one box located at the bottom corner. With a quick horizontal motion, you snatch away the corner stone. What happens next is that you observe the change of box positions. a single stacked column drops by one box height. The amount of time that it takes to complete the transition is how we mark time.

Now think about this: Does it really matter if the corner box is snatched away at 48 kpm (like you did) or at a million kph? All we observe is the motion of the stack which seems to take the same amount of time to change its position.

Time does not have to be quantized for the universe to behave the way that it does. Dont get me wronga quanta of time is perfectly compatible with the scheme and it very well may be true. I wanted to point out that it is not a requirement. With 2 out of 3 constituents quantized; the third does not need to be.

I need to clarify something here. There is a bit of a semantics problem and Ive been changing some terminology to suit the relationships that you setup: I think that time is only the change markera phenomenon of sortsnot a real stand-alone physical entity. The agent of change is kinetic energyhes the guy that doesnt have to be quantized.

There seems to be another conceptual problem that arises from the compatibility of static positions and being stuck. There are two important aspects to this. The first is potential energy (tensor fields).

Lets revisit the stacked boxes. This time, while you are snatching away the corner box; someone snaps a picture of it with a decent camera set to a high shutter speed at just the right time. When you both look at the photo you see a perfectly stacked cube of boxes with the bottom corner missing. The picture taker offers this as proof that the boxes are in a static position and doomed to remain that way. You of course know differently. Potential energy guarantees that the change will take place.

The second aspect is simultaneity. If we observe the cantilever of a mechanical clock (Thats the part that falls in between the teeth of a gear, braking it), we see that it spends most of its time in a static position but it is not stuck. The main reason is that motion is occurring elsewhere inside this closed system. Likewise, I propose that the universe is never motionless or static everywhere at the same time.

Joined: Aug 2010
Posts: 3,570
B
Megastar
Offline
Megastar
B
Joined: Aug 2010
Posts: 3,570
Originally Posted By: Bill
If a photon having sufficient energy strikes the atom the electron will immediately transition to the first (or higher) excited state. As far as I know there is no mention of time in this transition.


My understanding is that you are absolutely right.

This is probably a red herring, but it is prompted by the mention of individual frames of a film. We are all familiar with the situation in which a wheel on film appears to be rotating backwards. Has anyone else wondered why we see the same effect in real life? Watching an accelerating wheel, we see it pass through a particular speed where it "goes backwards". Does this mean that our vision is "quantised"?


There never was nothing.
Joined: Dec 2010
Posts: 1,858
B
Megastar
Offline
Megastar
B
Joined: Dec 2010
Posts: 1,858
Bill S.

I'm not sure that I have ever seen that effect that isn't in a moving picture of some sort, or created by a stroboscopic light source. However, I think that under certain conditions you might see something like that if you were looking at something with the light coming from something like a flourescent lamp, which can have a sort of a 60 Hz (50 Hz many places) blink to it. I do seem to recall that you used to be able to buy a gadget to check the speed of the turntable on your record player. It came with a little disk that you slipped over the spindle of the turntable. The disk had radial lines engraved on it. You also got a special little lamp that used something like neon. The gas would be energized at a 120 Hz (or a 100 Hz rate in may countries) rate (once for each half of the power line frequency). If your turntable was turning at the correct speed the lines on the disk stood still, otherwise they rotated one way or the other. You may have been seeing something like that.

Bill Gill


C is not the speed of light in a vacuum.
C is the universal speed limit.
Joined: Aug 2010
Posts: 3,570
B
Megastar
Offline
Megastar
B
Joined: Aug 2010
Posts: 3,570
Bill.

I first noticed the odd effect with an accelerating wheel over 60 years ago when watching the flywheel on a then quite elderly tractor that was starting up. In spite of having known about it for so long, it is only recently that I started wondering why it happened. The only explanation I can think of is that although our vision seems smoothly continuous, it is in fact like a series of snapshots. From there I got to wondering if our perception of time could be the same. If you get the speed right you can see the effect at any time, especially if the wheel has spokes.


There never was nothing.
Joined: Aug 2010
Posts: 3,570
B
Megastar
Offline
Megastar
B
Joined: Aug 2010
Posts: 3,570
Originally Posted By: Kirby
I think that time is only the change markera phenomenon of sortsnot a real stand-alone physical entity.


Does this place you in the ranks of those who believe that time does not exist?


There never was nothing.
Joined: Aug 2010
Posts: 3,570
B
Megastar
Offline
Megastar
B
Joined: Aug 2010
Posts: 3,570
Originally Posted By: Kirby
Time does not have to be quantized for the universe to behave the way that it does.


In fact time does not have to exist for the universe to behave the way that it does.

The fact that relativity involves time dilation, and makes a strong link between time and space, certainly suggests that time is a real entity, but if we substituted "change" for "time" I suspect the equations would work out just as well.


There never was nothing.
Joined: May 2010
Posts: 118
K
Senior Member
OP Offline
Senior Member
K
Joined: May 2010
Posts: 118
Quote:
Does this place you in the ranks of those who believe that time does not exist?


Unfortunately time is such a handy word. Time is a characteristic of realism so its hard to say that it doesnt exist. I think that its all in the definition or description. Time is more of a characteristic of change like distance. To me, its not a fundamental constituent of the universe i.e. matter/ space/ energy. When energy acts; matter changes its position in space. It moves a certain distance and takes a certain amount of time. I cant discard the reality of time any more than the reality of distance nor their cousins rate and speed.

I just have my doubts about time as a stand-alone physical entitya fabric. In this manner, it doesnt exist. Theres really no problem with this notion. As I have said before, the attachment is based upon the theory of space/time.

Quote:
In fact time does not have to exist for the universe to behave the way that it does.

The fact that relativity involves time dilation, and makes a strong link between time and space, certainly suggests that time is a real entity, but if we substituted "change" for "time" I suspect the equations would work out just as well.


I think that this statement hits its mark like a Zen arrow. I cant add or subtract anything.

Time is difficult to talk about because of semantics. Its real it exists its how it exists. Kind of like differentiating between the distance of dimension and the distance of travel. Time only exists in dynamics not statics.

Just my humble opinion.


Good atmosphere and good conversation...that's the best.
Joined: Aug 2010
Posts: 3,570
B
Megastar
Offline
Megastar
B
Joined: Aug 2010
Posts: 3,570
Kirby, it seems as though we may both be with St. Augustine on this one: "What then is time? If no one asks me, I know; if I wish to explain it to someone who asks, I know not".


There never was nothing.
Joined: Aug 2010
Posts: 3,570
B
Megastar
Offline
Megastar
B
Joined: Aug 2010
Posts: 3,570
Originally Posted By: Kirby
Im glad that everyone is considering the possible equivalence (function) of Planck limits and quanta.


On the subject of quanta; does anyone consider the chronon as a possible quantum of time these days, or has it been relegated to the "recycle bin"?


There never was nothing.
Joined: May 2010
Posts: 118
K
Senior Member
OP Offline
Senior Member
K
Joined: May 2010
Posts: 118
Originally Posted By: Bill S.
Kirby, it seems as though we may both be with St. Augustine on this one: "What then is time? If no one asks me, I know; if I wish to explain it to someone who asks, I know not".


Im not really with St. Augustine. To me, thats the old philosophical issue of non-perceived existence: (If a tree falls in the forest and no one is around to hear; does it make a sound?). I think that it does. Those trees in Russia were knocked down by sound as far as Im concerned. The scientific definition of sound is just a technicality. Deep down inside everyone knows that it made a soundwe can even hear it. smile


Good atmosphere and good conversation...that's the best.
Joined: Aug 2010
Posts: 3,570
B
Megastar
Offline
Megastar
B
Joined: Aug 2010
Posts: 3,570
Surely, sound waves are just vibrations, until an auditory organ converts them into sound. No ears, no sound.


There never was nothing.
Joined: Dec 2006
Posts: 962
Superstar
Offline
Superstar
Joined: Dec 2006
Posts: 962
Sounds like it depends on your definition of "sound". If you define it as vibrations in the air made by a moving object, then yes, there is sound. If you define sound in terms of a receptor/interpreter of those airwaves, then no, no sound is made. I happen to prefer the first definition myself, but that is just my opinion, fwiw.


If you don't care for reality, just wait a while; another will be along shortly. --A Rose

Joined: May 2010
Posts: 118
K
Senior Member
OP Offline
Senior Member
K
Joined: May 2010
Posts: 118
Originally Posted By: Bill S.
Surely, sound waves are just vibrations, until an auditory organ converts them into sound. No ears, no sound.


At either rate, I think that all change (and time along with it), adheres to a discrete registration scheme. It is these functional limits that should be the Planck Limits. If there is some form of change that turns out to be smaller or shorter than the existing values then; its these values that need to be adjusted to reflect reality. Of course, all of this would have to be corroborated by quantum mechanics. And it would have to be both the discrete nature as well as the final values. Besides, what good is a grid of quantum foam with out a functional purpose?

BTW, what is a chronon? I must have missed that one.


Good atmosphere and good conversation...that's the best.
Page 3 of 4 1 2 3 4

Link Copied to Clipboard
Newest Members
debbieevans, bkhj, jackk, Johnmattison, RacerGT
865 Registered Users
Sponsor

Science a GoGo's Home Page | Terms of Use | Privacy Policy | Contact UsokW
Features | News | Books | Physics | Space | Climate Change | Health | Technology | Natural World

Copyright © 1998 - 2016 Science a GoGo and its licensors. All rights reserved.

Powered by UBB.threads™ PHP Forum Software 7.7.5