Scientists have used indirect measurements of movement to infer the presence of waves for a very long time. For example, how can you tell when it’s windy without going outside? You look to see the movements of the trees or flags or other flexible structures.
Now, scientists at NASA’s Jet Propulsion Laboratory are using lasers to measure gravitational waves. Gravitational waves were predicted by Albert Einstein, but only in the last few years has the equipment gotten sensitive enough to attempt measurements. The scientists face the task of detecting a wave that’s 0.000000000005 meters tall from spacecraft 5,000,000,000 meters away!
Using known masses attached to spacecrafts and lasers that measure the positions of the masses, the scientists hope to detect the movements caused by gravitational waves. Lasers, although very precise, are still too noisy to measure the gravitational waves. (Learn more about noise and using indirect measurements in our “Is there life outside of Earth?” investigation.)
What’s the solution to the noise problem, finding that tiny little wave across trillions of miles? Generate artificial noise in the lab and see if you can still detect the signal. It’s worked in the laboratory, so scientists may soon be able to detect gravitational waves in space.
The ability to detect smaller and smaller motions will enhance the ability of instruments to detect smaller and smaller planets around other stars–perhaps even another “Earth.” Technological innovation is the only limit.