The first law of thermodynamics is: you do not talk about thermodynamics. It’s not a big secret. It’s just a confusing set of observations (called ‘Laws’, because the 12th law of physics is to call all your observations laws and it makes it harder for (some) people to argue with you). It sort of works where it works and doesn’t where it doesn’t. Chemists and mechanical engineers find it, I don’t know, calming. It’s mostly nonsense. We could ignore it, but Cosmologists apply it to lots of Cosmology things (time, the expansion of the universe, etc.)
The whole thing starts on a shaky foundation. The energy and work of a system. Lots of people find it useful to look at heat and other forms of energy in some small, often arbitrary container. It can be extremely useful to figure out how big a boom your bomb might make or how many horsepower that blower might add to your Charger. You know… air conditioning. So we pretend that there are isolated systems, even though the universe doesn’t seem to allow us to isolate ourselves or anything else from it. But, within those ‘systems’ we abstract, there are some ideas that work, sort of, as much as we need them to to do stuff, so long as we pretend that the ‘system’ is closed, which it isn’t. Really, there’s only one system and we can’t isolate us of any of our stuff from it. On that scale (life, the universe, Minecraft) it sort of doesn’t hold together. At small scales, and as an abstraction, even a flawed abstraction, it helps us think about things, given the lack of other ways to think about those things.
L.o.T. #0 (seriously). If two thermodynamic systems are in thermal equilibrium with a third system, they are also in thermal equilibrium with each other. But, of course, this is a tautology based on a pretense (that there are unconnected systems that can be measured against one another). Sure, you can pretend that there can be separate systems, and you can certainly make relative temperature (or other) energy measurements as between them. Highly useful when packing for a long trip, for example. But there’s only one system and we know (or think we know) it’s in equilibrium because:
L.oT. # 1. The total amount of energy in the universe is constant and energy can only change form, it can’t be created or destroyed. This actually seems about right, but we don’t know. If the universe is inside something else, some larger scale structure, there could be some way that the universe could interact with that structure, and that some way could involve energy being gained or lost. It’s not like we have an inventory of all the energy. In fact, cosmologists seem to keep losing some, after which they invent some Dark stuff to keep everything balanced. They also think quantum physics violates this Law, but still refer to it as a Law. It’s all very confusing.
If #1 is true, the universe can’t expand forever (the universe cannot be a perpetual motion machine), yet many cosmologists believe it will do just that. If the universe IS energy, which seems entirely… feasible… then this is also just a thing defined by itself. The universe = the universe. Not much insight there. And by way of repetition, if #1 is true, #2 has to be false.
L.o.T. #2. The level of disorder in the universe is steadily increasing. And, this accounts for the arrow of time (as some processes are irreversible). Cue eggs breaking, messy rooms, and colloidal suspensions. Well, wait a minute, we just said the energy in the universe is a constant, and there’s nothing to make disorder (omelets, dorm rooms, cappuccino) out of but energy. So disorder can’t be increasing. Not universally.
#2 also gets used a lot to prop up the ever-expanding universe. Entropy increases because as the universe gets larger, there are more ways to configure its contents and some of those configurations are disordered and so order becomes less and less statistically likely.
But the universe is only getting bigger in 3D space. It’s getting smaller in MD space. Near the beginning, MD space was massively warped because of all the… umm… mass. As the matter in the universe gets more spread out in 3D space, the average MD warpage of any given unit is decreasing. It’s entirely possible that these are precisely inverse (the author is close to a proof of that but could us some assistance, if anyone is still reading… and even less likely, is even a little convinced, contact frederickthepa@gmail.com).
There’s also this: Throughout the universe, wherever matter gets near each other, it tends to climb an energy gradient. The sun is a shining example. So is a human brain. Or a blue whale. Or a black hole. Why does the universe prefer those arrangement for that stuff? Something about the basic rules of the universe actually FAVOR the gathering of energy even as the universe expands in 3D space. That energy is as appropriately described as an increase in order as humpty dumpty is a decrease. Order and disorder are, from the point of the universe, illusions. There’s just energy and embedded rules for configuring it and some sort of change of state happening.
Which leads us to time. If MD space is shrinking proportionally to 3D space expanding (or any number of other equivalences), then entropy, if it exists, which it doesn’t, is a constant. But we’ve defined time as existing only because entropy increases, which it doesn’t. So what of time, which appears to be universal?
Second Law of writing about thermodynamics: Cliffhangers. Check back for a longer discussion of time. Fourth Corollary of the Second Law of writing about thermodynamics: Teaser. What if the arrow of time is just the arrow of a change of state of the universe (or its topology) from one ordered primarily in MD space to one configured primarily in 3D space. Whether that’s a one-way or return trip, the change in state itself can entirely explain the arrow of time regardless of the particular organization of the energy or whether information about any particular organization is distinct from the energy itself.
L.o.T. #3 This is going to overlap extensively with other articles in this series because the third law is a consequence of our math being in some instances a poor descriptor of the universe. The entropy of a perfectly crystalline solid is zero at absolute zero.
Okay, but there’s no such thing as entropy (at the scale of the universe) and there’s no such thing as absolute zero (which like unicorns, infinity, singularities, and free lunches are a product of our imaginations). The universe is made of energy which can be converted into different forms (including ‘mass’ which is really just an arrangement of energy, why we think of them as two distinct things is entirely a product of our limited and particular perspective). The universe is expanding in 3D space (and contracting in MD space). What’s it expanding into? We have no worthy idea. Well, fine. Is the stuff – photons, hydrogen atoms, cocker spaniels – expanding into nothing or is the fabric of the expanding universe part of the stuff?
Again, we think of them as different things, but the space between the stuff is the universe too. And it’s made of energy just like all the stuff. So as the universe expands in 3D space, it’s pulling itself along (imagine pinching a blanket in its middle and lifting it off, say, a bed into the air. Imagine threading the blanket though a long cylinder leaving the four corners slightly hanging below the bottom of the cylinder. Now imagine a small explosion, a bang, if you will, in which some bits of the explosion grabbed the four corners of the blanket and pulled it out of the cylinder to form a flat blanket once again. As the universe expands, it’s flattening into 3D space and pulling it’s fabric out along with it. Since the fabric is made of energy, then no where within the blanket (really torturing this visual metaphor) is there any place of any real size that can have zero energy (and thus zero temperature). So #3 is badly describing one observed behavior using two referents that don’t exist. And yet still, it’s a “law”.