The forum discussion centers on the concept of time as the fourth dimension in physics, with participants debating its existence and definition. CrystalStudios proposes that time is a dimension correlated with space, suggesting that compression or expansion of space affects time. Other contributors argue against this notion, asserting that time is an illusion and that causality does not require time. The conversation highlights the complexities of defining time, with references to entropy and thermodynamic principles, ultimately revealing a divide between those who view time as a measurable entity and those who consider it a conceptual construct.
PREREQUISITESPhysicists, philosophers, and students of science interested in the fundamental nature of time, causality, and the relationship between time and space.
Within the framework of quantum field theory secondary quantization implies that motion doesn't exist, i.e. time is defined as transition of a physical system with one set of observable values (say, A1-state) to another set of observable values (say, A2-state). If A1-state differs from A2-state by generalized coordinates, then it seems to us that we observe motion, nothing else.Originally posted by jcsd
Motion does exist, if you don't think it does your using a far too stringent definition of exists that rules out even easily observed phenomena.
Originally posted by Antiproton
I would go so far as to say time is axiomatic. You couldn't prove the non-existence of time any more than you could disprove the communtivity of the integers under addition. It's there, and we have to deal with it. Instead, we should be discuss the nature of time, i.e. is it discrete or continuous and so on.
Originally posted by Anton A. Ermolenko
Within the framework of quantum field theory secondary quantization implies that motion doesn't exist, i.e. time is defined as transition of a physical system with one set of observable values (say, A1-state) to another set of observable values (say, A2-state). If A1-state differs from A2-state by generalized coordinates, then it seems to us that we observe motion, nothing else.
Originally posted by Antiproton
I would go so far as to say time is axiomatic. You couldn't prove the non-existence of time any more than you could disprove the communtivity of the integers under addition.
Originally posted by jcsd
Yes indeed; I was going to post, pretty much the same thing: the existence of time is just as axiomatic as the existence of the x, y and z directions.
If we agree with time definition within the framework of quantum field theory, then time is exactly discrete.Originally posted by Antiproton
It's there, and we have to deal with it. Instead, we should be discuss the nature of time, i.e. is it discrete or continuous and so on.
Not exactly that way. Even if A1-state differs from A2-state by generalized coordinates and linear component of four-momentum is not equal to zero (of course it isn't) you can't observe motion, because you can't observe trajectory. You can localize it with a relative exactitude, nothing else.Originally posted by jcsd
But surely if you have time and a spatial axis then you have dx/dt.
Ditto.Originally posted by jcsd
Yes indeed; I was going to post, pretty much the same thing: the existence of time is just as axiomatic as the existence of the x, y and z directions.
Originally posted by Anton A. Ermolenko
Not exactly that way. The system of axioms (of a specific physical theory) may content time as axiom, and may not... time can be only a theorem (e.g. there are axioms of three-dimensional linear space and four-dimensional invariant, such as four-dimensional interval in the Minkowski space-time).
If we agree with time definition within the framework of quantum field theory, then time is exactly discrete.
Not exactly that way. Even if A1-state differs from A2-state by generalized coordinates and linear component of four-momentum is not equal to zero (of course it isn't) you can't observe motion, because you can't observe trajectory. You can localize it with a relative exactitude, nothing else.
Russ
No, we use the motion of something to MEASURE time.
Antiproton
First, time is not measured relative to motion... motion is measured relative to time. v=dx/dt.
Originally posted by Anton A. Ermolenko
Not exactly that way. Even if A1-state differs from A2-state by generalized coordinates and linear component of four-momentum is not equal to zero (of course it isn't) you can't observe motion, because you can't observe trajectory. You can localize it with a relative exactitude, nothing else.
Actually you take one quantization of continuous time for discrete nature of time. Within the framework of QFT the time is discrete. The secondary quantization concept allow to sustitude the time with indexes, because the main difference A1-state from A2-state is the index. We need the time only for synchronization of different physical systems. But it really is discrete.Originally posted by jcsd
Most physical theories DO have the existence of time as an axiom, infact I'm struggling to think of theory in which time is an emergant property (though I'm not saying there isn't one, I remeber years ago reading a book by Paul Davies in which he suggests time may of been an emergant property from the properties of the initla conditons in the universe).
Also, I will not claim to be an expert on QFT but I've yet to hear of a widely accepted physical theory which quantizes time.
Of course not. Transaction from A1-state to A2-state not always implies a modification of localization in three-dimensional space, e.g. A1-state may differs from A2-state by number of virtual photons. And where is motion?Originally posted by maumer
Hello Ermolenko,
are you talking about the evanescent behaviour of particles? If yes, i agree with you that we can't see motion. But you see time in the transaction betweem two states. The transaction, at the end, is a result of a sort of a motion. Something has moved and you define time with a transaction; a sort of motion.
You took my quote out of context. You can do both depending on the type of events/motion being observed.Originally posted by maumer
Decide what you are doing!
Originally posted by Anton A. Ermolenko
We need the time only for synchronization of different physical systems.
Bingo! If we agree with the concept of secondary quantization within the framework of QFT, then of course yes - the (local) time is only difference between two nearest states of the same physical system.Originally posted by maumer
So time is the difference between two states?
Mr. Bingo, could you assert time is axiomatic, too? A human mean?Originally posted by Anton A. Ermolenko
Bingo! If we agree with the concept of secondary quantization within the framework of QFT, then of course yes - the (local) time is only difference between two nearest states of the same physical system.