Abstract

Brane theory or M-theory requires seven additional dimensions beyond the four of standard space-time. I suggest that observational evidence for the existence of at least one of these additional dimensions can be found in the phenomenon that Rudolph Carnap called the “now” problem. I will argue that the main difficulty in explaining the “now” phenomenon is that it cannot be resolved within a conventional 4-dimensional spacetime, but it has a very natural and almost intuitive explanation in a higher dimensional continuum. A brane model for the universe not only provides a straightforward explanation for all of the observed properties of the “now” moment, including the asymmetry between the past and the future, it also eliminates the familiar paradoxes of time travel because the brane model does not allow time travel, which would entail a forbidden departure from the brane. The brane model provides a natural physical context for what philosophers call “presentism” because the brane exists only in the moving “now” or present moment at each spatial point.