So the actual news here is that someone did the math for Breakthrough Starshot?

Scientists estimate roughly 100 million individual lasers will be needed to generate the required optical power of about 100GW.

Oof...

Where are the LightSail-Probe send to us by Aliens?

Good old Fermi Paradox. On the other hand, if other civilizations sent light-sail probes to our solar system, would we even be able to detect them? And then of course there are some who believe that ʻOumuamua was a light-sail probe. Maybe they pass through here all the time.

Another thing to consider though: Why would they send probes here? I imagine sending probes to investigate neighbouring star systems would be exciting the first dozen or so times, but then there's ever-increasing costs and time-frames, while the public interest wanes and scientists see diminishing returns. At some point, funding for the project stops, and so do the probes.

This bring me to one question: Why there is so much water on Earth and so few on the moon.

Water is pretty abundant in our solar system, but if a planet is close enough to the sun for it to evaporate, it needs enough gravity for the water vapour not to be blown away by the solar wind.

Empirically, from the habitable zone with Mars, moon, Earth , we are at 1 in 3 chance to have mass water formation. And the odd, of an exoplanet colliding with one planet in habitable zone must be far less. I guess we're alone!

The Rare Earth Hypothesis. We have found exoplanets with liquid water, but so far they've all been tidal locked, which may make it harder for life to emerge, and harder for it to migrate from oceans to land.

I don't think we're alone in the universe, but I do think we're pretty rare. And I think FTL travel is impossible, which explains why no alien civilizations have been able to explore our solar system.