## The Clock Ambiguity

I have argued that a standard approach to defining time in quantum gravity leads to absolute ambiguity in the fundamental laws of physics. To pursue the implications of this line of reasoning A. Iglesias and I have considered theoretical frameworks where the laws of physics are drawn at random.

More recently I have concluded that linking the clock ambiguity with the random selection of physical laws is not well motivated. In particular that approach is in deep conflict with my work on the origin of probabilities, which leads me to conclude that the clock ambiguity cannot lead to a well-defined distribution (with a quantified measure) from which random laws can be drawn. So currently (as of 2016 when I write this) I see the work below as really two bodies of work, one stating the clock ambiguity and the other studying the interpretation of laws of physics randomly drawn from a distribution set up by hand.

The clock ambiguity was first stated in section 2.3 of paper 1), and developed further in sections I-III of paper 2). The rest of the work cited below considers the interpretation of physical laws drawn from an ensemble, and you can already see in paper 4) strong signs of that project being treated separately from the clock ambiguity as our thinking has evolved.

#### Technical work

1) The Theory of Everything vs the Theory of Anything Lect. Notes Phys. 455 (1995) 323-332 (First mention of the clock ambiguity in a paper)

2) The clock ambiguity and the emergence of physical laws Phys.Rev. D77 (2008) 06350 (First thorough discussion of this topic)

3) The clock ambiguity: Implications and new developments Fundam. Theor. Phys 172 (2012) 53-68** **

4) Lorentz symmetry from a random Hamiltonian Phys.Rev. D91 (2015) 4, 043529

**Technical Talks**

Perimeter Institute Colloquium 10/22/08

FQXi conference 2009 (9 min)

#### Accessible material for non-experts

This article in Discover Magazine (Aug 3 2010) covers some of this material especially nicely.

Also, see this FQXi article and this Closer to Truth interview.