Dyson Spheres Around Black Holes Could Reveal Alien Civilizations, Scientists Say

[cstanleytech]

3. If any Dyson spheres can be built I do not think we will find any within a galaxy rather we will

probably find them in the space between galaxies where there are fewer chances of a passing star or other body causing problems.
As for the argument being made by some that they cannot exist because none have been detected by thermal emissions I kind of doubt that any civilization that could build one would let a source of potential energy like thermal energy get away untapped so why should we expect to detect them via thermals?