Amit Hagar

In their book The Road to Maxwell's Demon Hemmo & Shenker re-describe the foundations of statistical mechanics from a purely empiricist perspective. The result is refreshing, as well as intriguing, and it goes against much of the literature on the demon. Their conclusion, however, that Maxwell's demon is consistent with statistical mechanics, still leaves open the question of why such a demon hasn't yet been observed on a macroscopic scale. This essay offers a sketch of what a possible answer could look like.

Loop quantum gravity predicts that spatial geometry is fundamentally discrete. Whether this discreteness entails a departure from exact Lorentz symmetry is a matter of dispute that has generated an interesting methodological dilemma. On one hand one would like the theory to agree with current experiments, but, so far, tests in the highest energies we can manage show no such sign of departure. On the other hand one would like the theory to yield testable predictions, and deformations of exact Lorentz symmetry in certain yet– to–be–tested regimes may have phenomenological consequences. Exposing their shortcomings, here I discuss two arguments that exemplify this dilemma, and compare them to other cases from the history of physics that share their symptoms.

Scientific realism is dead, or so many philosophers believe. Its death was announced when philosophers became convinced that one can accept all scientific results without committing oneself to metaphysical existence claims about theoretical entities (Fine 1986, 112). In addition, the inability of self–proclaimed scientific realists, despite recurrent demands, to distinguish themselves from their rival anti–realists (Stein 1989) didn’t exactly help their cause. If realists cannot identify the key feature or features that set them apart from their opponents, then there is really no need to conduct a debate on scientific realism, is there?