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Is there a change in the universe that cannot be reduced to movement? One counter-example should be enough. :)

Heat is a type of change that was once thought to be qualitative, but is now realized to be quantitative, the movement of particles. So perhaps that's true for all change, then?

Excluding the hypothetical change from non-existence to existence of the universe (assuming time has a beginning).

Entanglement might be one example of change without movement? But someone would have to confirm. Wave function collapse perhaps another.

Perhaps this is just another formulation of "is time movement"?

Feel free to suggest better tag(s).

Edit: Posted here also, in case this one closes: https://www.reddit.com/r/AskPhysics/comments/146rc15/is_all_change_movement/?

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    $\begingroup$ Welcome to Physics.SE. I am afraid your question in its current form is not a good fit for this site (and it already attracted a close vote). Your approach is very "natural philosphy"-like, and physics has moved to a point where appeal to everyday concepts like movement is not really helpful. The concepts already get muddy when you look at classical electrodynamics: Does an electromagnetic field move, when it changes? One has to accept that physics is done as fitting mathematical models to measurements and obvervations – and is removed from everyday experience. ... $\endgroup$ Commented Jun 11, 2023 at 10:42
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    $\begingroup$ @SebastianRiese Also, are you saying there's no definition of movement in modern physics? $\endgroup$ Commented Jun 11, 2023 at 10:52
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    $\begingroup$ You don't even need to go to modern physics (in the sense of quantum physics) to see that movement is not a good fundamental concept. Does a standing electromagnetic wave move? But in quantum theory it gets even weirder: We have a particle described by a wave function, but until we measure its position – has it moved? It's state certainly has changed. You can certainly go along and happily define movement – but it is an unwieldy concept if you try to make it a one-fits-all solutions. It will mean different things in different models. $\endgroup$ Commented Jun 11, 2023 at 11:15
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    $\begingroup$ That is a wonderful question and a physical one at that. Incidentally, the entanglement of spins, for example, as well as their destruction, are actually connected with a rotation of the direction of the spin. $\endgroup$ Commented Jun 12, 2023 at 5:05
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    $\begingroup$ Cross-posted to Philosophy. $\endgroup$
    – rob
    Commented Jun 12, 2023 at 9:53

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In the context of quantum mechanics, I'm not sure that this is a well-posed question. The idea of "movement" is something whose definition is obvious in an Aristotelian world made up of things like rocks and ice-cream sandwiches, where we have a physical intuition for their position and whether that position changes. But in quantum mechanics, we talk about wavefunctions, which are extended objects.

Let's think about the classic intro-quantum problem of a particle in an infinitely deep square-well potential. If the particle is free (potential $V=0$) on the interval $0<x<L$, your favorite quantum textbook tells you the states are

$$ \newcommand\ket[1]{\left|{#1}\right>} \newcommand\bra[1]{\left<{#1}\right|} \newcommand\expect[1]{\left<{#1}\right>} \newcommand\braket[3]{\left<{#1}\middle|{#2}\middle|{#3}\right>} \ket n = \psi_n(x) = \sqrt\frac2L\sin\frac{n\pi x}{L} $$

where $n$ is one of the counting numbers $1,2,3,\cdots$, and each of the states has a distinct total energy proportional to $n^2$, that is, $E_n = n^2 E_1$.

If we measure the position of the particle, our expectation value is

$$ \begin{align} \expect{x}_n &= \braket nxn \\&= \frac2L \int_0^L\mathrm dx\ x \sin^2 \frac{n\pi x}L \\&= L/2 \quad\text{(for all $n$)} \end{align} $$

This result tells us that, if we prepared many such particles and measured their positions, the average of those position measurements would be the middle of the well. But the distributions aren't the same. The variance in the position measurements for the state $\ket n$ is given by

$$ \begin{align} (\Delta x)_n^2 &= \expect{x^2}_n - \expect{x}_n^2 \\&= L^2 \cdot \left(\frac{1}{12} - \frac{1}{2n^2\pi^2}\right) \quad\text{(after some work)} \end{align} $$

meaning that the lower-energy particles are more likely to be found near the center of the well, while the higher-energy particles are spread out more uniformly along the well's length.

So adding energy to a particle in a trap doesn't make the particle move. Describing the change that does occur requires you to get into some interpretational details. The most common interpretation of this mathematics is that the state $\ket n = \psi_n(x)$ describes the probability density of locating a zero-sized particle — or at least a particle whose intrinsic size is very much smaller than the other length scales in your problem. But there's an alternate interpretation in which the state $\ket n$ really is all of the information we have about the bound part of the system, and labels like "the particle" are a crutch for those of us who prefer to think about rocks and ice-cream sandwiches. In that sense, increasing the particle's energy doesn't make it move, but it does make the particle wider.

Note in particular that the probability-density interpretation suggests that "the particle" is "really" bouncing around inside of its trap. But the Schrödinger equation actually has a solution which describes a particle bouncing around in its trap. That solution is a superposition of some large number of high-energy/short-wavelength states, which interfere to form a probability density with very narrow $\Delta x$. The eigenstates $\ket n$ that we've given here are "stationary states," whose only change as time evolves is a change in their unobservable complex phase.

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  • $\begingroup$ Isn't making a particle wider, movement too because you change the particle's distribution in the space of the well which can be considered movement also? $\endgroup$ Commented Jul 1, 2023 at 13:42
  • $\begingroup$ Random fluctuations in quantum fields are the only change without movement that comes to my mind. These fluctuations are real and physical and to a certain degree random. Changes happen in potentials instantaneously without needing explicit movement of anything but without forbidding movement too. However, after the moment a fluctuation happens it can cause the movement of something. But fluctuation can happen before the movement. $\endgroup$ Commented Jul 1, 2023 at 14:21
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Annihilation and creation of particle-antiparticle pair is also an example of change without movement.

Wavefunction collapse nor entanglement are also changes without movement if you do not consider information exchange as movement. In these processes, information exchange takes place.

However, if it comes down to the school of philosophy you follow. If consider information exchange as "movement" then, wave collapse and entanglement are changes that involve movement.

Warning:-

Here, by the word "movement", I mean movement through only the spatial direction. Everything in this universe is moving through one or more dimensions of 4D spacetime.

Moreover, an object may seem to be a form of movement in your reference frame but in other refrence frames it may be stationary. Actually, concept of "movement" is not well defined in physics as it is not Lorentz invariant.

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