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
On Tue, Jan 6, 2009 at 1:57 PM, Bruno Marchal <marc...@ulb.ac.be> wrote:
> With General Relativity, time is so geometrical that you can make it
> (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 ...
> On 06 Jan 2009, at 12:51, Bruno Marchal wrote:
>> 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
>> 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.
>> Le 06-janv.-09, à 02:59, Brent Meeker a écrit :
>>> Abram Demski wrote:
>>>> If time is merely an additional space dimension, why do we
>>>> "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
>>>> 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).
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