Abstract
Cosmologists routinely make the assumption that the observed large scale structure in the Universe was shaped by gravity. However, given that the cosmic expansion accelerates, intelligent civilizations which were used to communicating with each other across cosmological distances might have decided to propel themselves closer together so that they would not be pulled apart and lose contact with each other in the distant future due to the accelerated expansion. Could we identify the related motions or artificial clustering of sources in cosmological data sets? I show that the power required to move a star at a constant speed across cosmological distances can be supplied by the nuclear energy production in the star. Assuming that a significant fraction of this power is emitted in the infrared, the James Webb Space Telescope will be able to detect a single stellar-mass object propelled at a constant speed v out to a distance of 10(v/10^4 km/s) Mpc. Detection of the non-gravitational clustering and dynamics of many such sources would provide evidence for a new phenomenon of cosmic engineering.
Abraham Loeb