A few years after they launch Starshot, when Moore’s Law has halved the cost, doubled the speed, and quadrupled the camera resolution, they’ll launch Starshot II, which will then beat its predecessor to Alpha Centauri by ten years.
If star travel was possible (it’s not), and if there were other sentient beings in the galaxy (there aren’t), they would have arrived, be arriving, and left calling cards everywhere in the form of self-perpetuating robots. The proof that there is no life anywhere else in the universe? Many would have by now had millions of years headstart to be here, and they aren’t here...
That could actually happen. Faster interstellar ships will pass by their predecessors from years before. From the perspective of the crews in the slower ships, the crews in the newer and faster ships will be time travellers, visitors from the future.
This has the makings of a good science fiction story.