A laser beam reflected off a mirror. GIPhotostock/Science Source
3. Unlike the sun or a flashlight, which shines in a broad range of colors combined to produce white light, lasers lase by producing a concentrated beam of a single wavelength, or color.
4. In 2016, scientists created a new type of microlaser, smaller than a red blood cell, which could lead to innovations in medical imaging.
5. That same year, the world’s most powerful laser, China’s Superintense Ultrafast Laser Facility (SULF), fired a single pulse equivalent to 5.3 petawatts — 5.3 quadrillion watts!
6. SULF isn’t the world’s largest laser, however. That would be California’s National Ignition Facility (NIF), about the size of three football fields. The megalaser can deliver the same amount of energy released by a couple pounds of TNT to a target the size of a pea.
7. Ultimately, researchers want to use NIF’s energy to trigger a nuclear fusion reaction, squishing the nuclei of hydrogen atoms together to make helium and producing energy the same way stars do.
8. Speaking of stars, give a big gold one to the true inventor of lasers, whomever that may be. Three scientists shared the 1964 Nobel Prize for work leading to the first lasers, but grad student Gordon Gould designed one before the laureates — one of whom was also his adviser.
9. Gould sued and finally received patent rights in 1977. A fifth scientist actually built the first working laser, in 1960.
10. Since then, lasers have landed a lot of Nobels, including in 2017. That award went to team leaders at the Laser Interferometer Gravitational-wave Observatory (LIGO), who were first to measure long-predicted ripples in space-time.
11. Lasers play a starring role in another measuring method: light detection and ranging. A lidar system shoots out a laser pulse, calculates how long it takes the pulse to bounce back, and determines how far away an object is, like bats using echolocation to find dinner.
A map of hidden buildings found through lidar.
Mark Walters via Sketchfab/CC 4.0;
12. It’s not batty to think lidar will be part of driverless car technology. Engineers are experimenting with it to monitor the vehicle’s surroundings and judge when to brake.
13. Archaeologists use aircraft-based lidar to map a different kind of surrounding: sites hidden beneath dense forest canopies.
14. In 2016, researchers using lidar described vast ancient cities in Cambodia’s rainforests. The extensive urban network reached its zenith in the 12th century and may have been the largest empire on Earth at the time.
15. Astronomers, meanwhile, use lasers to measure real-time turbulence in Earth’s atmosphere. With this information, they can adjust telescope mirrors to account for atmospheric blurring and make sharper images, a technique called adaptive optics.
16. If an aircraft flew into one of these laser beams, the crew could be disoriented. Facilities that use adaptive optics employ spotters whose sole job is to watch the night skies for planes straying too close, ready to flip an emergency shut-off switch.
17. The precision afforded by adaptive optics has resulted in images of exoplanets in other star systems and even two supermassive black holes colliding hundreds of millions of light-years away.
18. The laser-based Strategic Defense Initiative, proposed in 1983 and nicknamed “Star Wars,” soon fell into a metaphorical black hole, but laser weapons aren’t all fiction. The Department of Defense is developing systems that can take down drones and even small planes and boats.
19. Star Wars the movie featured a giant planet-destroying laser, but when scientists shoot lasers at our moon, it’s for peaceful purposes. The beams fire at mirror arrays placed on the lunar landscape by astronauts from several Apollo missions.
20. Aiming lasers at these moon mirrors measures the precise distance to our satellite sidekick, and has revealed that the moon is slowly moving away from us. Hey, Moon, was it something we said?