Exploring Time at the Quantum Level

[Windseaker]

A question:
Does time slow down at quantum level, does time slow as we get smaller?? ∴∞

 

[Drakkith]

Nope. Time stays the same at all scales as far as we know.

 

[Windseaker]

Drakkith, please excuse me, Is there a quantum mechanics proof or paper on this type of time problem. would you know where to look for more information on quantum time?
Your probable correct.
Thank you

 

[Drakkith]

No mainstream papers, no. None of the current quantum theories deal with time. That's left up to Special and General Relativity.

 

[TumblingDice]

Is this possibly just an ill-formed question? Time is what clocks measure based on whatever units are defined for it. From one aspect, we have precision clocks based on atomic frequencies, covering the very small all the way up to our very large world.

From another aspect, clocks are defined to track particular units of time at a desired rate. So by definition, any proper clock we make will be created to track time according to the rate we expect it to. Creating a 'small' clock doesn't provide any help because we'd just calibrate to the rate we measure time in the rest frame.

 

[TumblingDice]

Is there a quantum mechanics proof or paper on this type of time problem. would you know where to look for more information on quantum time?

Time has been one of my largest interests in physics theory, but a lot of my thoughts are further ahead than my knowledge, so I need to learn more current theory before discussing here at PF.

From what I've learned from Feynman and Susskind lectures, (I think): Time, like most everything else, gets 'fuzzier' the closer you look. For example, I had heard that it's OK for virtual particles to borrow energy from the future as long as they give it back. Since then I've learned what seems to be a more accurate description/explanation, and that is there is a minimum amount of time (Δt) required over any measurement to acquire an accurate energylevel. That's quite an over simplification on my part but, if correct, offers an idea of complications one might run into trying to accurately acquire any meaningful 'clock' to reference at the quantum level.

Way out of my league, but maybe my comments will stir up more discussion. (?)

Edit: Also, regarding the theory that time is an 'emergent' property just as spatial dimensions, I believe that involves time disappearing the closer and closer you look.

 

[bhobba]

Way out of my league, but maybe my comments will stir up more discussion. (?)

The issue with time in QM is its a parameter and position is an observable.

But SR tells us they need to be treated on the same footing. So we either need to promote time to an observable or position to a parameter.

The first solution evidently leads to great mathematical difficulties so was abandoned. The second solution leads to QFT.

What this tells us about time is unclear - except perhaps it may be a bit less 'real' than is generally thought - being something we need in our equations to parameterize it, like coordinates, rather than real like something we observe.

Such would seem to gell with the idea time is simply an emergent thing from entropy.

Thanks
Bill

 

[TumblingDice]

The issue with time in QM is its a parameter and position is an observable. ... What this tells us about time is unclear - except perhaps it may be a bit less 'real' than is generally thought - being something we need in our equations to parameterize it, like coordinates, rather than real like something we observe.

Your mention of coordinates is part of what I recall. I came away with the idea that time degrades to nothing more than a set of coordinates to define sequences at the quantum level - like an ordering of 1, 2, 3... rather than our normal concept of time. Is there anything wrong with that understanding at a learning level?

 

[bhobba]

Is there anything wrong with that understanding at a learning level?

Nothing - except it will not help you understand this one bit better, or less, for that matter, IMHO anyway.

The physics lies in the math and what it implies - not in how you want to interpret basic ideas like what coordinates are.

Relativity implies position and time must be treated the same - but aside from the vague common sense ideas we all have about such things nothing IMHO can really be gained from looking into it deeper. Time is what a clock indicates - position is what conceptual coordinate systems tell us. That is it's a vector - and values assigned by coordinate systems are simply man made things.

These are the mathematical things we build our theories from and conjectures beyond that belong more to philosophy than physics.

I got the following book years and years ago that may help you:
https://www.amazon.com/dp/0486604438/?tag=pfamazon01-20

Personally I got nothing from it - but then again to me, generally, philosophical analysis is more like boring droning statements of the obvious where I end up saying - so?

Thanks
Bill

 

[TumblingDice]

The last thing I want to bring into my understanding of physics is philosophy. What I was trying to communicate between your deeper understanding and my shallower level, was that: Time at the quantum level, that you referred to 'like coordinates', is required to maintain the concept of time in the math, as you said SR requires. So this is all part of me thinking that time 'as coordinates' at the quantum level is more like an arbitrary set of units to facilitate the integration of time into the math. So no philosophizing on my end. Only trying to grab the tiger's tail.

Hope I'm not mis-quoting. too poorly here. Was it Einstein who said something like, "Time is so that everything doesn't happen at once?"

 

[bhobba]

Was it Einstein who said something like, "Time is so that everything doesn't happen at once?"

Yea - but that's like saying - position is so that things don't occupy the same place - not really that illuminating is it?

All I am trying to get across is don't get too caught up in this sort of stuff. Vague commonsense ideas is all you need to start - it will evolve and develop as you progress.

For example, once you understand SR you see that length contraction is best understood as hyperbolic rotation and is analogous to rotating a rod to fit through a door. Its length hasn't changed one whit - but its geometrical relation to other things has. You have gained a deeper understanding of what's going on - but not by a deeper analysis of what length is, but by understanding what the math is saying better.

Thanks
Bill

 

[Mandragonia]

The issue with time in QM is its a parameter and position is an observable.

Radioactive decay of nuclei is a QM process. The decay rate is perfectly observable. This suggests to me that there are dynamic processes going on inside an unstable nucleus which effectively serve as an internal "clock".

 

[Mandragonia]

Your mention of coordinates is part of what I recall. I came away with the idea that time degrades to nothing more than a set of coordinates to define sequences at the quantum level - like an ordering of 1, 2, 3... rather than our normal concept of time. Is there anything wrong with that understanding at a learning level?

Yes! It is a entirely wrong way of looking at things. Time exists! At the cosmological level, at the human level, at the quantum level. Processes may indeed occur sequentially (that is the ordering aspect of time, to which you correctly refer), but they also occur at a certain rate. In quantum mechanics this is no different from classical physics.

Take a look at the Schroedinger equation applied to an atom. The kinetic energy term in the hamiltonian provides information on the average speed of the particle. The potential energy is there because of the Coulomb attraction between the nucleus and the electron. And as we know from classical physics, force leads to acceleration. On the right side you find the derivative with respect to time. This term is there to describe the evolution of the wave function.

You see that all three terms in the Schroedinger equation are in some way related to time. And not in arbitrary units! No, their magnitude is specified by the value of four physical parameters: Planck's constant, electron mass, electric charge of electron and nucleus, dielectric constant of the vacuum. Even in stationary orbitals, which may give the appearance of completely time-independence, there is a well-defined unit of time. It is the amount of time T associated with one revolution of the electron around the nucleus (which of course should not be taken too literally; in QM the electron is not really circling around the nucleus but exists as a cloud-like wave function). This period of time is given by:

T = 4 * epsilon(0)^2 * h^4 / {m * e^4}

 

[bhobba]

Radioactive decay of nuclei is a QM process. The decay rate is perfectly observable. This suggests to me that there are dynamic processes going on inside an unstable nucleus which effectively serve as an internal "clock".

Of course eg Atomic clocks.

But so?

Thanks
Bill

 

[Mandragonia]

Atomic clocks...? Perhaps you can rotate them like a rod and fit them through the doors of perception. Peace man!