Philosophic Noodling (was Re: Internet Health)

Levi Pearson levipearson at gmail.com
Wed Oct 6 00:26:43 MDT 2010


On Tue, Oct 5, 2010 at 11:36 PM, Michael Torrie <torriem at gmail.com> wrote:
> On 10/05/2010 11:02 PM, Levi Pearson wrote:
>> Although you're correct that temperature is only a meaningful
>> measurement in aggregate (i.e. a large number of molecules), time is a
>> fundamentally different thing.  To modern physics, the dimension of
>> time is just as real and fundamental as the dimensions of space
>
> Depends on what you are talking about.  No Physicist would argue that
> time is a fourth spatial dimension, which is what dimensions typically
> refer to.

Did I say it was a spatial dimension?  No.  I said it was as real as
the spatial dimensions, which clearly implies that it is not itself a
spatial dimension.

> Time can be referred to as a dimension when you're talking about an
> object's position space and time.  You can put whatever unit you want on
> the axis of a graph and it becomes a "dimension."

Yes, thus all the nice graphs of light cones and whatnot.  But a
dimension doesn't have to be graphed.  It's a mathematical concept
referring to one of the degrees of freedom in a system.  In the
mathematical models for spacetime used in general relativity, there
are four dimensions, three of which correspond to spatial dimensions
and one of which corresponds to time.  In the state space model of
quantum mechanics, you can deal with an infinite number of dimensions.

> But time is definitely not a spatial dimension.  For example, in the
> theories that the universe is 10 or 11-dimensional, time is not one of
> those dimensions.  In fact no one really knows what "time" is.  Some
> theories have postulated that time doesn't really exist, but is merely
> an observation of movement.  IE it's the observation of entropy that we
> perceive as "time."  Fascinating stuff, actually.

I did mention that some philosophers have denied the "reality" of
time, but some of them also put distance in the same category of
mental construct as time.  Physical quantities like length and mass
are as prone to relativistic effects as time is, so it's hard to
single out time as particularly "unreal" in that respect.

        --Levi


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