Talk:Arrow of time

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Minkowski stress

Displacement due to Minkowski stress is crucial. It is the answer to why there is an arrow of time.
In quantum field theory particles do not have an innate tendency to move towards a specific direction. It is a systemic phenomenon to be calculated; not an innate property.
Particles in Minkowski space are never ideal and point-like. Also moments in time - also known as different states of the evolution of a system - overlap and aren't strictly speparate. Each particle's probabilistic horizon of causality, is squished and pushed afar from some direction, and sucked towards a different direction.

Newton was wrong at the Planck level.
Fundamental particles don't have an innate tendency towards some direction.
Simply their wave functions are causally squished and pushed.

It's all about probabilities.
The stresses of Minkowski space causality exerted on wave functions - define the directivity of displacement of the different states of the evolution of a system, and we call that "arrow of time".

Radiative arrow

This section doesn't make sense, since the a point source ALWAYS radiates out by definition of r>0. An extended source (for example a ring) radiates both inward and outward, although the inward wave reflects outward from the origin.

Perhaps it is referring to the retarded Green's function, but that's also a tautology: we specify initial, not final conditions BECAUSE of the arrow of time. But the noncausal Feynman_propagator is often used instead in QFT.

In summary, I think this section should be removed. Chris2crawford (talk) 01:16, 2 November 2020 (UTC)[reply]

A search of Google scholar (here) shows the phrase "radiative arrow of time" is used in physics. Some of the uses predate Wikipedia. So "radiative arrow of time" is a thing. If you think the section doesn't describe it well, then it should be re-written, but not removed. Richard-of-Earth (talk) 00:22, 8 November 2020 (UTC)[reply]

Hawking's assertion that because of Cosmol.Expansion, there more phase state available in the future half of any model

The title of the suggested thread in the cosmological section should include this. Its meaning is the way that irreversibility couples to expansion. (How can the word "irreversibility" fail to be in spell/checks "mind"? 74.123.17.233 (talk) 19:26, 20 July 2025 (UTC)[reply]