Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Space Time Measurements in Special Relativity   The conventional discussion of apparent distortions of space and time in
Special Relativity (the Lorentz-Fitzgerald Contraction and Time Dilatation) is
extended by considering observations of : (i) moving objects of limited
lifetime in their own rest frame (`transient luminous objects') and (ii) a
moving extended array of synchronised `equivalent clocks' in a common inertial
frame. Application of the Lorentz Transformation to (i) shows that such
objects, viewed with coarse time resolution, appear to be longer in the
direction of the relative velocity $\vec{v}$ by a factor $1/\sqrt{1-(v/c)^2}$
(Space Dilatation) and to (ii) that the moving equivalent clock that appears at
any fixed position in the rest frame of an inertial observer appears to be
running faster than a similar clock at rest by the factor $1/\sqrt{1-(v/c)^2}$
(Time Contraction).
  The actual appearance of moving objects and clocks, taking into account light
propagation time delays, as well as the effect of the Lorentz Transformation,
is also discussed.

5
The categories of this paper are: gr-qc
2
The categories of this paper are: math
33
The categories of this paper are: plasm-ph
12
The categories of this paper are: nucl-th
21
The categories of this paper are: adap-org
25
The categories of this paper are: patt-sol
24
The categories of this paper are: dg-ga
37
The categories of this paper are: supr-con
30
The categories of this paper are: q-alg
17
The categories of this paper are: q-fin
26
The categories of this paper are: bayes-an
8
The categories of this paper are: hep-ex
6
The categories of this paper are: astro-ph
4
The categories of this paper are: cond-mat
11
The categories of this paper are: hep-lat
31
The categories of this paper are: ao-sci