Bruno, This I know... yet I want to say that it doesn't necessarily make time *spatial*. But, I can't say exactly what that would mean. It seems to me that the word "spatial" becomes less meaningful if time is said to be spatial...

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--Abram On Tue, Jan 6, 2009 at 1:57 PM, Bruno Marchal <marc...@ulb.ac.be> wrote: > > Abram, > > With General Relativity, time is so geometrical that you can make it > circular. > (Cf the Gödel's solutions to Einstein's GR Equation, which gives hope > to some to build a time machine, and even infinite computers!). > > Give me just a sufficiently massive cylinder ... > > Bruno > > > On 06 Jan 2009, at 12:51, Bruno Marchal wrote: > >> >> Abram, >> >> I agree with Brent. In relativity theory space and time are >> intermingled in a geometrical way to give the Minkowski structure. >> Actually you can make it into an Euclidian space by introducing an >> imaginary time t' = sqr(-1)*t = it. The metrics becomes dx^2 + dy^2 + >> dz^2 + dt'^2. >> In quantum mechanics the possible position of an object on a line >> gives >> rise to an hermitian space: it is infinite dimensional, but there is >> still a geometrical structure, with notions akin to angles and >> distances. Of course mathematician have far more general notion of >> dimensional spaces, some of which have nothing to do with geometry. In >> physics metrics play always some role somewhere though. >> >> Bruno >> >> >> Le 06-janv.-09, à 02:59, Brent Meeker a écrit : >> >>> >>> Abram Demski wrote: >>>> Thomas, >>>> >>>> If time is merely an additional space dimension, why do we >>>> experience >>>> "moving" in it always and only in one direction? Why do we remember >>>> the past and not the future? Could a being move in some spatial >>>> dimension in the same way we move through time, and in doing so >>>> treat >>>> time more like we treat space? Et cetera. >>>> >>>> To my knowledge, modern physics treats many things as "dimensions": >>>> not just time and space, but also forces such as electromagnetism. >>>> This does not imply that such things are spatial in nature. A >>>> dimension is just a variable. Unless you think there is something >>>> particularly spatial about time? >>> >>> There is something spatial about time, duration is measured along >>> paths in >>> space. Coordinate time is mixed with space by Lorentz symmetries. >>> But it's >>> still different from space. Lee Smolin and Fotini Markopolo have >>> argued that >>> time must be considered fundamental (no block universe). >>> >>> Brent >>> >>> >>>> >>> >> http://iridia.ulb.ac.be/~marchal/ >> >> >> > > > http://iridia.ulb.ac.be/~marchal/ > > > > > > > -- Abram Demski Public address: abram-dem...@googlegroups.com Public archive: http://groups.google.com/group/abram-demski Private address: abramdem...@gmail.com --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Everything List" group. To post to this group, send email to everything-l...@googlegroups.com To unsubscribe from this group, send email to everything-list+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/everything-list?hl=en -~----------~----~----~----~------~----~------~--~---