Jonathan Fay (Bristol): Towards a Machian theory of gravity
Is general relativity a Machian theory? Ernst Mach was a visionary physicist and philosopher whose thinking had at least an important catalytic impact on the development of the theory of general relativity. I argue that general relativity falls short of achieving Einstein’s original project of developing a theory consistent with Mach’s relational view of spacetime. GR is only relativistic in a certain limited sense; a truly Machian theory of relativity requires additional criterion be met.
The dynamics should depend only on the relations between directly observable entities, without reference to absolute space or some arbitrarily given constant of nature. I present some specific criterion for this to be the case, and suggest an alteration of general relativity that may accommodate these.
Two intriguing otherwise unexplained numerical ‘coincidences’ in cosmology – namely 1) Dirac’s large number hypothesis and 2) the intriguing relation: (speed of light squared) c2 ≈G∑mi/ri (total Newtonian potential of universe) – provide evidence for the hypothesis put forward.
I will also be willing to discuss some more radical consequences of such a theory in Q&A. Although these will not feature in the initial presentation which will be focused on the material outlined above.
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