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Wed, Apr-27-2016 03:37:18

Atoms of space theory


String theory, loop quantum gravity, causal-set theory: these are just a few of the approaches that theorists have taken. Naturally, proponents of each are convinced the others are misguided or even downright unscientific. But when you take a step back from the dispute, you notice all agree on one essential lesson: the space-time that we inhabit is a construction. It is not fundamental to nature, but emerges from a deeper level of reality. In some way or other, it consists of primitive building blocks — “atoms” of space — and takes on its familiar properties from how those building blocks are assembled. These “atoms” are clearly nothing like ordinary atoms such as hydrogen or oxygen. For one thing, they are not tiny, because the word “tiny” is a spatial description and these atoms are supposed to create space, not presuppose it. Yet many of the same principles apply. Water, for example, consists of H2O molecules. It can undergo a change of state — freezing or boiling — as those molecules rearrange themselves into new structures. The same might be true of space. If those atoms can assemble themselves into space, presumably they could also reassemble into other structures. And that might explain many of the mysteries of modern physics. Consider black holes. If,you fell into one, Einstein’s theory predicts your timeline would end. You would die, but that’d be the least of it. The atoms in your body would simply cease to be. Instead of ashes to ashes, you’d have ashes to ... nothingness. The new emergent space-time theories suggest a different picture in which space undergoes a change of state in a black hole. The black hole does not have an interior volume; its perimeter marks where space melts. The result is a new state that is no longer spatial and is scarcely even imaginable in human terms. If you fell in, you would probably still die, but the atoms in your body would still carry on in some new form. Consider, also, the big bang. Like black holes, it has always posed something of a paradox. The ordinary laws of physics, operating within time, are inherently unable to explain the beginning of time. According to those laws, something must precede the big bang to set it into motion. Yet nothing is supposed to precede it. A way out of the paradox is to think of the big bang not as the beginning but as a transition, when space crystallized from a primeval state of spacelessness.