Wednesday, February 17, 2016

Gravity Waves, Relativity and Quantum Physics: Part I

The recent finding of gravity waves produced by the merger of two distant black holes has been taken as yet another confirmation of Einstein's Theory of General Relativity. There have been various such confirming measurements, including the gravitational redshift and lensing of light and non-Newtonian, changes in the orbit of Mercury. But the deeper significance of this latest discovery lies in what it may say about the rival grand theory, quantum physics. The Standard Model of modern physics has proven remarkably good at accounting for the known elementary particles (fermions, hadrons and bosons). The measurement of the Higgs boson in 2012 was an astounding confirmation of our most basic understanding of the origin of mass. Despite the “spookiness” of some of the predictions of quantum physics – such as quantum entanglement – many of its strangest have been verified.

Indeed, the Standard Model is rather too perfect. It seems to account for most of the basic parameters of matter and energy including three of the four fundamental forces: —electromagnetic and the weak nuclear (unified as electro-weak) and the strong nuclear interaction (which holds together the atomic nucleus). But it cannot explain gravity, dark matter or dark energy (thus leaveing out 95% of what we believe to be the universe). In trying to extend its reach – to achieve a grand unified theory to include gravity –- physicists have so far failed to find the new phenomenon that would hint at new physics in the form of supersymmetry or string theory. The Standard Model explains what it does so perfectly that those seeking to take it further cannot seem to find any of the discrepancies that might point the way to a Grand Unified Theory of Everything.

General Relativity, on the other hand, has been confirmed in every case. It provides a coherent theory of the universe as framed by spacetime and the speed of light. It does not explain the Big Bang or the menagerie of fundamental particles. Rather, General Relativity describes how mass interacts with space and across time. Mass deforms spacetime and matter and energy – including gravity waves – travel in straight lines along the bends. Einstein's famous equation – the E=MC2 of Special Relativity – does not explain why mass and energy are interchangeable but provides a way to measure the transformation of one into the other within the limitation imposed by the speed of light (which cannot be exceeded).

Relativity is in essence a top-down theory. It begins with Einstein's grand view of the very nature of spacetime, the basic fabric of the universe. Quantum physics is more bottoms-up, seeking to discover the basic pieces of reality. Relativity is a complete and verified theory within its defined area. The Standard Model of quantum physics is incomplete within its domain. It may be that relativity is somehow the more fruitful way to think about the universe. For Einstein, gravity is not a force, as it was for Newton, but an artifact of mass bending spacetime. Quantum physics again treats gravity as a force and seeks to find its particle, the “graviton.” But what considerations may be drawn from looking at quantum physics in light of relativity, instead of trying to extend it to account for gravity? The key may lie in pondering more deeply mass, light and the role of the observer.

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