I am unaware of this. Seems dubious.
There is an argument--along the lines of the Fermi Paradox. It goes like this:
The Sun is a 3rd-generation star. If there are lots of intelligent ETs, they've been around for thousands or millions of years, and their technology would appear godlike to us. Even at 5% of the speed of light, there has been ample time for every star to be visited.
One strategy would be to build 'von Neumann' robots. Programmed to select a star at random, gather all data, and build a copy of themselves from local materials. Dump the entire database into the copy; then both vehicles randomly go to two more stars. You get an exponential explosion of probes, each knowing everything its ancestors did. The payoff: every once in a while, one of the probes wanders home and dumps its data. A huge payoff for a modest investment.
The problem is that there ought to be a traffic jam of probes right here, right now. We do not observe them. Hence either there are no intelligent ETs or the difficulty of achieving even 5% of "c" are insurmountable.
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Incidentally, the book "Rare Earth" makes distressingly-persuasive arguments which lead to the conclusion that we are the only intelligent species in the Universe--or maybe only the Milky Way Galaxy. Recommended reading.
--Boris