Friday, March 18, 2011

A Story Told to the Darkness

Exordium: Who am I to tell a story to a lack? To belt out an unwritten song to an empty auditorium? To lift mood and change, the body and mind's fluids, hormones, expansions and contractions--the stuff of life--into the space of (what seems like) cosmic night? The unpregnant emptiness that does nothing but receive our waste, our entropy? I will justify myself by means of an overwrought metaphor.

Overwrought metaphor: for centuries, speculative cosmology troubled itself with the question of why the sky is dark at night. For if the universe were truly infinite, every line of sight would eventually terminate in a star. Hence, the night sky should be as bright as day. Many suggestions were offered, but none were satisfactory. Perhaps the most plausible was that the light of extremely distant stars was absorbed by interstellar gas, or particles, or what have you. That's fine. But, if the universe had existed infinitely long, that interstellar gas would have achieved incandescence long ago, and so--again--the night sky should be bright as day.

Overwrought metaphor, paragraph 2: No explanation was forthcoming. Then general relativity came on the scene, but the original cosmological models posited by Einstein (1917) and De Sitter in (1918) didn't fully address the issue either. (Why they failed would take us into explaining why they thought the geometry of the universe was non-Euclidean, and I am lazy.) It was only with Hubble's publication in 1929 of the relation between the distance and red-shift of far-away galaxies (and the interpretation of this as a Doppler effect) that the idea that space itself was expanding. This allowed for a finite, but unbounded universe where not every line of sight in the night sky terminated in the surface of the star.

Conclusion of overwrought metaphor: so, the reason the sky is dark at night is because space itself is expanding.

Supplementary material: the analogy used to unpack what "space itself expanding" means is usually run in two dimensions. Imagine our universe had only two spatial dimensions. Universal expansion, in this case would require you to imagine those two dimensions curved in a third dimension which we are insensible of. So we live our lives on the surface of a balloon, for example, and the balloon itself is expanding. Now imagine our three spatial and fourth time dimension curved in an even higher-dimensional space (you can't, but it makes sense mathematically). So yeah.

Explanation of the digression: now if we conflate cosmological space with a more colloquial sense of space, we have a reason for the darkness. It is a consequence of the fact that the indefinite multiplicity of things will never fill us up. This is a conclusion I need right now.

Consider: "Those who expect to reap the blessings of freedom must, like men, undergo the fatigue of supporting it."


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