Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Waves on Noncommutative Spacetimes   Waves on ``commutative'' spacetimes like R^d are elements of the commutative
algebra C^0(R^d) of functions on R^d. When C^0(R^d) is deformed to a
noncommutative algebra {\cal A}_\theta (R^d) with deformation parameter \theta
({\cal A}_0 (R^d) = C^0(R^d)), waves being its elements, are no longer
complex-valued functions on R^d. Rules for their interpretation, such as
measurement of their intensity, and energy, thus need to be stated. We address
this task here. We then apply the rules to interference and diffraction for d
\leq 4 and with time-space noncommutativity. Novel phenomena are encountered.
Thus when the time of observation T is so brief that T \leq 2 \theta w, where w
is the frequency of incident waves, no interference can be observed. For larger
times, the interference pattern is deformed and depends on \frac{\theta w}{T}.
It approaches the commutative pattern only when \frac{\theta w}{T} goes to 0.
As an application, we discuss interference of star light due to cosmic strings.

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The categories of this paper are: funct-an
16
The categories of this paper are: stat
12
The categories of this paper are: nucl-th
17
The categories of this paper are: q-fin
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The categories of this paper are: adap-org
15
The categories of this paper are: nucl-ex
2
The categories of this paper are: math
4
The categories of this paper are: cond-mat
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The categories of this paper are: chem-ph
1
The categories of this paper are: cs
36
The categories of this paper are: cmp-lg
27
The categories of this paper are: comp-gas
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The categories of this paper are: acc-phys
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The categories of this paper are: supr-con
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The categories of this paper are: patt-sol
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The categories of this paper are: q-bio