Sailing on light for fun and profit. What if we shoot lasers at lightsails? Does life increase the entropy of the universe?

Sailing on light for fun and profit. What if we shoot lasers at lightsails? Does life increase the entropy of the universe?
Why is it so hard to predict solar eclipses? How did Newton and Halley team up to solve it? What have we learned from solar eclipses since then?
What’s the deal with redshift? How can we actually interpret velocities when it comes to cosmic expansion?
Is light made of waves or particles? Is matter made of waves or particles? What does it mean for matter to “wave”, anyway?