  Searches for extra-terrestrial intelligence (SETI) using large survey data
often look for possible signatures of astroengineering. We propose to search
for physically impossible effects caused by highly advanced technology, by
carrying out a search for disappearing galaxies and Milky Way stars. We select
$\sim$ 10 million objects from USNO-B1.0 with low proper motion ($\mu$ $<$ 20
milli arcseconds / year) imaged on the sky in two epochs. We search for objects
not found at the expected positions in the Sloan Digital Sky Survey (SDSS) by
visually examining images of $\sim$ 290 000 USNO-B1.0 objects with no
counterpart in the SDSS. We identify some spurious targets in the USNO-B1.0. We
find one candidate of interest for follow-up photometry, although it is very
uncertain. If the candidate eventually is found, it defines the probability of
observing a disappearing-object event the last decade to less than one in one
million in the given samples. Nevertheless, since the complete USNO-B1.0
dataset is 100 times larger than any of our samples, we propose an easily
accessible citizen science project in search of USNO-B1.0 objects which have
disappeared from the SDSS.
