Entropy is usually described as a ‘measure of disorder’.
This is not precise. Entropy is actually a measure of possibilities. It is only because there are so many possibilities that are disordered, and so few that we would recognize as order, that this definition is usually glossed over.
The second law of thermodynamics states that entropy increases over time. This causes confusion if you think of entropy as disorder, because order tends to be self-organizing, and thus increasing over time. (The explanation will be that to create order, large amounts of disorder need to happen, and so the second law is not violated.)
It’s much easier to imagine possibilities increasing over time, if you think about how many outcomes can result from a single choice. Now imagine a web of increasing possibilities spreading out over time, each one forging its own path.
This is exactly what the Timeless Multiverse looks like. Thus, entropy can be mapped onto the Schrödinger equation which already describes the spread tree of possibilities that composes the Timeless Multiverse.
Now science is re-investigating the nature of entropy. And that investigation is throwing up hints of the Timeless Multiverse.
https://www.newscientist.com/article/2469972-quantum-disorder-is-dependent-on-who-is-looking-for-it
The idea is that there are two basic kinds of entropy, analogous to the two different types of time. There is thermodynamic entropy, which corresponds to the dimension of time, and informational entropy, which corresponds to the subjective passage of time (which doesn’t, of cause, actually pass – we report each section of timeline as we experience it). Thermodynamic entropy is all the possibilities. Informational entropy talks about the possibilities that we have no knowledge of.
It’s been a long standing argument in physics as to whether these two are the same, mostly because lots of people are fixated on a single universe.
Another interesting entropy fact is that the quantum formula for entropy becomes the classical formula for entropy as the passage of time tends towards zero – i.e. as it approaches the Wheeler DeWitt equation, which was formulated to combine relativity and quantum physics, but ended up doing away with the passage of time, and so not very useful for quantum gravity.
This implies that as you consider the total entropy for the Multiverse, it matches up with the ‘outside’ picture of the Multiverse that the Wheeler DeWitt equation gives us.
What this shows us is that the Second Law of Thermodynamics actually depends on the topology of the Multiverse 🙂