Fair, A-theory and B-theory are strictly Richard Gale's coinage. But Gregory here is talking about something he is calling "B-theory" and attributing it to Einstein. In Richard Gale's coinage, McTaggart's name is literally in the title; A-theory is just a view of time like the A-series, and B-theory like the B-series.Actually, McTaggart's landmark 1908 paper did not say anything about the A/B/C theories, only the A/B/C series — aletheist
Not quite. In Einstein's theory, time is not "the" fourth dimension; it is "a" fourth dimension. The future direction of time depends on your reference frame (SR) and on how spacetime (which is a single entity) is shaped (GR; e.g. in black holes, the shape of spacetime is distorted so extremely that the time coordinate points towards the center).Einstein posited a "block universe" in which time is the fourth dimension of spacetime, such that all "positions" in time are fixed along with all positions in space--consistent with McTaggart's B series (and C series). — aletheist
That ordering is not always defined; in particular, space-like events have no time ordering requisite to call events "earlier and later" ala B-series or having a well defined order ala C-series. Time-like events, mind you, can be ordered, so they can fit. But it's also easy to have events X, Y, and Z such that X,Z is space-like, Y-Z is space-like, but X-Y is timelike. That's the biggest distinction; relativity basically gets rid of "moments". You only wind up with partial ordering; specifically, local ordering.The B series is "[t]he series of positions which runs from earlier to later." — aletheist
"The same theory with another name" implies a two way lexicon. Mapping from B-series to Einstein's conception of time requires a revision.It's the same theory with another name — Gregory
That's another fun thing; relativity has this. The measure of time is a metric; and there are "horizons". From a theoretical POV one person can measure an infinite amount of time to a horizon, and another a finite amount of time (the black hole scenario is one example). Just slipping this in whilst I disagree w you about the other thing.The most profound thing someone has said to me on this forum was that there is no difference bewteen infinity and finitude. — Gregory
From a theoretical POV one person can measure an infinite amount of time to a horizon, and another a finite amount of time (the black hole scenario is one example). — InPitzotl
How's that sitting? — Banno
I think time is best understood with intuition, not reason. — Gregory
It's understood in the doing, the use. — Banno
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