Geo Jocks: Gravitational Waves


Thank God for gravity. Without it, Matthew McConaughey would still be lost in the fabric of space-time, Matt Damon screaming expletives on Mars and George Clooney — well, there was nothing it could do for him. Recent films like “Interstellar” and “Gravity,” chock-full of A-list celebrities and stunning visual effects, have explored the relationship between humanity and space and attempted to relay complex physics to the general layperson audience — and they’ve done so to remarkable acclaim. On Thursday, however, the real physicists themselves were in front of the camera with an announcement that sent ripples through the scientific community.

Scientists affiliated with the Laser Interferometer Gravitational-Wave Observatory (LIGO) confirmed last week a phenomenon first-postulated by Albert Einstein: the existence of gravitational waves. In simple terms, they won science for the year, and the possibility of a Nobel Prize candidacy for the principal investigators has already been floating around. More importantly, however, we may finally be able to get down to work on time travel.

To begin to understand gravity and its relationship to space-time, first imagine a large sheet held taut at all ends so there are no wrinkles or folds. Without any objects resting on top, the sheet remains taut and flat. But then consider the effect of dropping a bowling ball into the middle of the sheet. The fabric bends around the bowling ball. In this analogy, the sheet represents the space-time fabric of the universe and the bowling ball a large, dense object like the Earth.

These heavy objects can emit pulses of gravitational energy that behave as waves, bending space-time. First predicted by Einstein in 1916, scientists theorized about their existence over the course of the 20th century, before the initial detection this past fall. How do we know they exist? Using a technique called laser interferometry, LIGO researchers observed a passing gravitational wave emitted from the collision of two black holes 1.3 billion years ago. A laser beam, reflected down two identical tracks, bounces back and forth at precisely-measured lengths. As the gravitational wave moved through the measuring device, it altered the length of the tracks relative to each other in a distinct stretching and squeezing pattern, signalling the alteration of space and time, and indicating the wave’s passing.

While the confirmation of their existence is remarkable, there are many questions still surrounding gravitational waves; notably, the observation of their postulated quantum particle, the graviton. Though not exactly categorized under the field of geology, the recent Advanced LIGO discovery adds to our understanding of the universe and supports the mechanisms we understand as fundamental to physics and relativity.