Scientists have for decades sought to harness directed energy beams into weapon systems that would be cheaper and more efficient than missiles or rockets. A growing number of countries are developing or deploying their own laser air defenses, and some have already been used in war, by Israel and Ukraine. That is a sign that they are becoming more widely available and could be a mainstay for future warfare. The Australian laser’s maker, Electro Optic Systems, advertises it as able to shoot down 20 drones a minute, at a cost of less than 10 cents per shot. Nicknamed “Apollo” for the Greek god of light, it has about the same level of power as Israel’s highly anticipated Iron Beam air defense laser, which is being built for its own military.