Recent observations of ultra high energy cosmic rays and gamma rays suggest that there are small violations of Lorentz symmetry. If there were no such violations, then the GZK cut off would hold and cosmic rays with energy ∼1020 eV or higher would not be reaching the earth. However some such events seem to have been observed. This has lead to phenomenological models in which there is a small violation of the Lorentz symmetry or the velocity of light. However recent (...) approaches which no longer consider a differentiable spacetime manifold already predict such violations. Similarly there are other theoretical reasons which also point to this. We briefly discuss some of these approaches and observe that Lorentz Symmetry violations can be tested by data from NASA’s GLAST satellite due for launch. (shrink)

An implication is a proposition, a consequence is a relation between propositions, and an inference is act of passage from certain premise-judgements to another conclusion-judgement: a proposition is true, a consequence holds, whereas an inference is valid. The paper examines interrelations, differences, refinements and linguistic renderings of these notions, as well as their history. The truth of propositions, respectively the holding of consequences, are treated constructively in terms of verification-objects. The validity of an inference is elucidated in terms of the (...) existence of a chain of immediately evident steps linking premises and conclusion. (shrink)

Do we remember what pain feels like? Investigations into this question have sometimes led to ambiguous or apparently contradictory results. Building on research on pain memory by Rohini Terry and colleagues, I argue that this lack of agreement may be due in part to the difficulty researchers face when trying to convey to their study's participants the type of memory they are being tasked with recalling. To address this difficulty, I introduce the concept of 'qualitative memory', which, arguably, is the (...) sort of memory we have of what red looks like yet lack with respect to pain. I also briefly address a number of consequences the acknowledgment of qualitative memory would potentially have for philosophy, arguing that if we fail to have qualitative memories of certain sensations, such as pain, the standard philosophical accounts of experience, rational choice, and the sources of moral action may all need revision. (shrink)

Susan Schneider argues that physicalism must be false if abstracta are part of the physicalist's dependence base. In opposition to her view, here I set out some reasons to think that abstracta in general, including abstracta that are woven into the dependence base, are something physicalists can countenance with consistency.

This chapter contains sections titled: I II III IV V VI VII VIII IX X.

The problem of finding irreducible representations of a simple Lie group that decompose into just pure replications of a representation of a subgroup is considered. Replications involving tensor representations of the orthogonal groups are studied in detail using counting groups whose representation dimensions correspond to branching multiplicities. Replications involving spinor and mixed tensor representations are briefly considered.