non-zero time 
component.  A period of time here is taken to be a temporal part 
of the whole universe during some temporal extent (from some 
viewpoint). These may not be the usages of these terms that you 
are used to.

MW: There is of course a time dimension, just as there are spatial
dimensions, but these require a frame of reference etc.

&gt; What is time?  

MW: Just another dimension, like the spatial ones (however many 
there are) but with (apparently) some constraints on the 
direction of travel.
