How unique or unusual is water that it expands as it freezes rather than contracting? And are there any other weird ‘gimmicks’ about state changes in other substances?
The is one unusual property of water but it is very strange in a number of other ways as well. The list of those is so long I will have to give it to you as a cite. Nothing about it is normal and surprisingly little is well understand about why it has many of the properties it does. However, it is very important for it to have the properties it does for life as we know it to exist. The fact that ice floats because it is less dense than liquid water is an example. If it didn’t, ice would sink to the bottom of colder parts of the ocean and even large lakes and never fully melt.
I always thought that since the volume vs. temperature graph for water is the inverse for other substances that someone would figure out a way to exploit this into some type of perpetual motion machine.
I wouldn’t really say that it’s inverse. Water does decrease slightly in volume as cools. For most of its liquid temperature curve, it acts pretty much like other chemicals. The big surprise happens in just the last few degrees. Again, this is one of its unique and surprising differences - the fact that cold water sinks but frozen water floats is sort of mind-boggling in its importance. Good luck getting stable water temperatures without that.
There are some other substances that increase in volume when transitioning to solid state - acetic acid for one, gallium for another. Old thread:
BTW, since gallium melts at slightly above room temperature, one caution on storing it is to leave space for expansion in any container liquid gallium is poured into, and avoid glass or metal containers which may be broken by the expansion (use plastic tubs).
… which would leave most of the Earth’s topsoil largely inacessible to, and useless for, life.
That water, a most common and important compound, has such magical properties gives good support to the “Goldilocks Hypothesis”: that the values of physical constants are tuned very precisely to make the universe an exciting and lively place.
Rather it gives support to the weak anthropic principle that if ice didn’t float on water we would not be here in our current form to make the observation that ice doesn’t float on water.
The so-called Goldilocks hypothesis as you’ve explained it is pure magical thinking unworthy of a 21st century human.
Wow. Even setting aside religious interpretations, there is a consistent theory that all possible universes exist, but only some have the capability for intelligent life.
But with such peremptory and close-minded dogmatism, you’ll fit in real well here at SDMB, LSLGuy. 
!
I like it.
I did state that pretty strongly, didn’t I? Oh well, say enough stuff and I’m bound to hit offkey now and again.
OTOH …
I don’t see how this:
which is eminently reasonable leads to this:
The latter seems to me to be saying an intelligent designer created this particular universe specifically and deliberately to ensure the constants led to life. We could perhaps bicker about whether there’s an intelligent designer, but it’s clear that this idea has causation flow from “desire (however formed by whoever / whatever) for a life-supporting universe” to “the particular physical parameters we observe.”
IMO that’s religious bunk in a flimsy scientific wrapper.
The WAP runs the causation the other way: universes whose physics are life-incompatible may well exist but will have no observers as we would recognize them. Universes whose physics are life-compatible may (not will) develop observers as we would recognize them. Such as ourselves in this particular universe at this particular time.
If I’ve misunderstood your perspective, feel free to enlighten me. I’m not quite as closed-minded as I sounded at first. 
Your first paragraph summarizes my own very tenuous perspective. (* - though I wouldn’t rule out other models, even Leibniz’ “best possible”!!) As you imply: Cogito, ergo we live in a “Goldilocks” world.
If you think this is an abuse of the word choice “Goldilocks”: Sorry.
Ahh, thanks for clarifying. No, I think Goldilocks is a perfectly cromulent word here.
What punched my hot button was “… tuned very precisely to make the universe an exciting and *lively *place.” I read “make” as “cause to be” with the implication that somebody/something did the tuning with an *a priori *goal of a life-full outcome.
Sorry to snap at you.
Apology accepted, LSLGuy. Indeed, kudos! Retractions are as rare as four-leaf clovers! 
Let me expand on this a bit. It’s off-topic, so I’ll Spoiler it.
[SPOILER]Imagine a computer program which emulates human consciousness perfectly. Would it experience human emotions, and even utter Cogito ergo sum ? Many scientific types would answer “Of course.” After all, it is emulating a human perfectly.
Now what about a computer program emulating some made-up alien life? The computer program would have instinct or “consciousness” in proportion to the sophistication of its programming. But what is that programming? Just a mathematical abstraction – and that mathematical abstraction has its existence whether it’s written down on a piece of paper (or fed into a tape reader) or not!
If mathematical abstractions are real, then the worlds they depict are real. Our universe exists, as do infinitely many similar universes, as well as ones where nucleons have five quarks instead of three, etc. etc. And the entities within those abstractions complex enough to experience consciousness … do indeed experience consciousness!
(Feel free to send the men in white coats to take me away to the funny farm!)[/SPOILER]
Nobody else wants to play on the OP any more so I’ll continue your proposed hijack.
I think your ideas are sound, but IMO you’re playing a bit fast & loose with the word “exist”. An idea has a different sort of “existence” than a table does. I can’t set my beer on the idea of a table, nor a drawing of one. I can only set my beer on a real actual table made of real solid matter. Not even an accurate finite element model of the mechanical structure of a table will hold my beer. It takes a real table; one as real as my beer.
I’d argue there are three different layers of reality in your example:
A) If a program could possibly exist, then in some sense it already does.
B) If a written but unexecuted program could actually run, then in some sense it already has. IOW, in some sense the run & results already exist.
C) If a program has been run to simulate a thing, then in some sense that thing exists.
Each of those statements is kinda true, but mostly false. And each refers to a very different level of reality. I do not believe you (anyone) can successfully make the argument that “exists” is a transitive relationship like greater-than “>” and therefore the possibility that a simulation *could *be created is the *exact same thing *as the *reality *of whatever this so-far imaginary program would simulate on so-far imaginary hardware if it was (counterfactually) actually run.
NOAA http://www.noaa.gov/ spends lots of money & CPU cycles simulating hundreds of thunderstorms every day. But nobody has ever gotten wet from even one of them. NOAA could, but hasn’t, created code that would generate hurricanes with 500mph winds. That non-existent app has not yet blown over every building in Miami. Nor will it ever, even if first written and then run.
Switching gears …
If we assume (and it is nothing but an assumption at humanities’ current level of knowledge) that there’s no connection possible between universes with diverse physics, then from a practical perspective whether they exist or not is unknowable. So one can safely assume none or every possibility at once or anything in between with no fear of being decisively contradicted.
IMO from an *operational *perspective the best answer is none. The fact we have no evidence implies (weakly) that they’re not there. Admittedly, absence of evidence is only weak evidence of absence. But at the same time, from an *operational *perspective it makes no sense to clutter our simulation with millions of other universes that must be accurately simulated only to have them have no impact on the results that count; the ones in our universe. It’s just as easy to not bother computing all that stuff only to discard it. Parsimony of energy implies the real multi-universe “thinks” like this. But that’s a guess, not a fact.
Pragmatically we may as well ignore “alternate universes”, whether they exist or not. And we can’t prove their existence. But if that model is not correct, we’re back to the question: Why does a Goldilocks Universe exist?
Without proving that “all possible worlds exist,” one of the greatest geniuses may have hinted at a reason that it is correct:
<unhijack> Hydrogen is the single most common element in the galaxy … Oxygen is the third most common … water is magically abundant </unhijack>
Better yet, divide it into three parts.
The stronger version of the Goldilocks Hypothesis is that, if the fundamental physical constants of the universe were just a bit different from what they are, then there could be no physical matter at all! The fundamental forces wouldn’t work the way they do; quarks could not coalesce into protons and neutrons; matter as we know it could not exist. The entire universe would consist of a vast field of complex probability wave functions that would not be able to interact in ways to create anything.
Hypothetically, if there is a multiverse of many universes, the majority of them would probably be like that; a universe properly tuned for anything to exist would be a statistical rarity!
What a fucking waste of an entire universe, I say!
So that’s the stronger Anthropic Principle: If the fundamental constants were just a little different, not only would there be no advanced intelligent life forms around to take note of the fact, but there would indeed be nothing at all there!
We live in a Goldilocks Universe indeed!
Cite: Somewhere among Professor Matt Strassler’s well-written pages on particle physics, frequently cited in SDMB threads, I saw a few pages that discussed this, with diagrams showing how the fundamental particles and forces would interact under various assumptions. I’ll come back with a link RSN if I can find the exact pages again.
Okay, I think these are the two pages from Strassler that I mentioned just above:
The Known (Apparently-) Elementary Particles. Describes, including illustrations, the known fundamental particles and forces in the universe as we know it.
The Known Particles — If The Higgs Field Were Zero. Describes how the universe would be if the Higgs Field were, on average, zero. Allegedly, all the forces and particles would work out much more simply than the actual universe we see. But, inasmuch as no atoms could form, that universe would be far from “exciting and lively”!