A philosopher-comrade (GdM) recently pointed out Massimo Pigliucci's essay "Is Information Physical? What Does That Mean?". It discusses "... a problem that has much to do with philosophical theories of truth and with the difference between physics and metaphysics".

Well, maybe not. The "problem" under discussion revolves around black-hole event horizons, quantum mechanics, and information theory — all of which are then merrily extrapolated many many orders of magnitude beyond any realms in which they have been tested and verified by observation. Isn't it likely that new physics occurs somewhere in that gap between the known world and the event horizon of a hypothetical tiny collapsed object? Isn't it hubris to imagine that today's rules for computing physical events all apply unchanged in such circumstances?

A metaphorically-rich paragraph of Pigliucci's article observes:

Susskind boldly proposed that the universe itself behaves as a hologram, i.e., that all the information that constitutes our three-dimensional world is actually encoded on the universe's equivalent of a black hole's event horizon (the so-called cosmic horizon). If true, this would mean that "reality" as we understand it is an illusion, with the action actually going on at the cosmic horizon. Baggott ingeniously compares this to a sort of reverse Plato's cave: it isn't the three-dimensional world that is reflected in a pale way on the walls of a cave were people are chained and can only see shadows of the real thing; it is the three-dimensional world that is a (holographic) projection of the information stored at the cosmic horizon. Is your mind spinning properly? Good.

A lovely image — but no exotic physics is needed to raise the same philosophical issues. Look at the situation in complex analysis, where Cauchy's integral formula says that the value of a smooth-enough function is determined by its values on the boundary of a region. Or similarly, consider how a wave equation everywhere inside a volume can be solved by Green's function methods if initial values and boundary conditions are known. No deep magic there.

And in fact, after discussing alternative theories of "truth", philosopher Pigliucci eventually concludes his essay similarly. Far-out science is rather irrelevant, except perhaps as a metaphor. And metaphors aren't "truth"!

(cf. PhysicsEnvy (2001-04-11), ... ) - ^z - 2014-03-03