Why we're here

It doesn't seem as though the universe should exist. It is common to think there should be a reason--a truthmaker--for why the universe exists as opposed to not existing.

Which is a mighty peculiar thing, since we've certainly never had any observations of a non-existent universe, nor can we even properly imagine it (in my opinion). All we have is the assumption that the pre-natal and natural state of anything is non-existence, or absence; accordingly, there must be something else, some kind of metaphysical mechanism, that causes that non-existence to become existence.

This stems from our observations about causality, perhaps coupled with innate physical intuitions. Maybe it isn't so peculiar to have this belief, then, since every time that we witness an effect in everyday life, it is preceded (anteceded) by a cause. Hence cosmological arguments; hence the conclusion that there must have been either a single "unmoved mover" or an infinite chain of antecedent causes to explain the universe's existence. Well, that or the universe shouldn't exist at all, being causeless.

I wonder if we're really justified in this conclusion. We have never witnessed something come from nothing (which is presumably what must have happened when a pure void became material substance?) but then... we have truthfully never witnessed "nothing". As our scientific instruments grow more and more powerful, we end up discovering that even that which has appeared empty before--vacuums, space--is nonetheless filled with a frothing mass of virtual particles and other bizarre fauna of the micro-universe. (See, e.g., this Wikipedia article on the vacuum state).

And if there is always something there materially... I guess then we have to suppose that those minute, practically non-existent material bits must be able to exert causal influence on other bits of matter. In that case, how can we be sure that it's even physically possible for the universe (or at least matter) not to exist? Maybe it is logically possible, infosofar as we can imagine it (which I have my doubts about, as I said before). Metaphysically possible? Hmmm....

Consider another Easter egg laid by the goose of science: the first law of thermodynamics. The total amount of energy in an isolated system must remain constant, though it may change form. (Similarly so with physical information, as came up in the black hole information paradox. I believe the conservation of one quantitiy--information or energy--may be derived from the other.) If the universe is an isolated system, and if we presume that this law holds invariably, then we must conclude that the universe has always existed--or rather that the energy within it has always existed, which is close enough for our purposes, since energy may be converted to matter.

Thus, the laws of physics do not allow the energy of the universe to come into or out of existence--thus, we must presume it has always existed.

But then, all I'm doing is shifting the question back a step. Now we ask instead, "Why is it that the total energy in the universe equals a positive value, not a zero or negative value?"

I don't know. Should we expect there to be a reason that gravity exists? That time exists? Some physicists do look for causes there, I suppose. And to a certain degree, we may get explanations about gravity and other forces as they (we think) split off from a single unified source in the very early universe. Still, if we accept that laws or forces need no justification for their existence, maybe we shouldn't expect a justification for the existence of energy either?

Edit as of 07-05-2009: I should clarify that under some theories, the total energy of the universe actually does add up to zero; it just that the way it's distributed gives us the material and energy formations we're used to. (I think gravity is typically suggested as the negative counterpart for the energy released during the Big Bang. Here's a handy and relevant (though brief) link for further reading).

Motion Mountain

Motion Mountain - The Free Physics Textbook (by Christopher Schiller) is positively amazing. It is a freely available online physics textbook aimed at attracting a wide variety of personality and thinking types (image/verbally oriented; male/female; composer/competitor; experimentally/theoretically inclined; scientific/humanity minded). I am not very far into it yet, but it has succeeded very well with me. I am really enjoying that it approaches physics from a very philosophically-minded standpoint--for example, Schiller describes time as that which allows contradictions to inhere within the same entity--provided that said contradictions occur at different times, of course. He talks about the notions of measurement, observation, and distinguishing objects from their environment (and how this relates to permanence versus variability).

Furthermore, it contains challenges at the end of each chapter to get you thinking more in-depth about the subject, and many of them are very conceptual rather than mathematical. Not that it's a bad thing at all to develop mathematical facility, but the mathematical detail happens to be (unfortunately) the area of physics I enjoy least. Throughout the chapters, Schiller asks us to ponder such questions as, do events exist? Do clocks even exist, really? What are the necessary conditions for velocity to be a part of the world? He also includes pleasant little historical details and social contexts. And he quotes from Wittgenstein's Tractatus often at the beginnings of sections, which is kinda fun =P.

I think he's done an admirable job making the book appealing to those from the humanities (such as myself--although I do have a bit of a computer science background in my distant past, and I'm very fond of logic). I can tell that I am going to enjoy the rest of this book immensely. It is astounding to me that someone took the effort to put this incredible resource together for free. Thank you so much, Christopher Schiller: I deeply appreciate your work.