By now you’ve probably heard the news – on 11th February 2016, the LIGO (Laser Interferometer Gravitational-Wave Observatory) Scientific Collaboration announced that they had detected gravitational waves for the first time. But what exactly are these gravitational waves? And why do they have such a profound impact on science as a whole?
So what are Gravitational Waves? And why are they formed? Essentially, Gravitational Waves are ripples in the fabric of spacetime which travel outward from their origin at the speed of light as waves, transporting energy through a phenomenon known as Gravitational Radiation. This was first predicted by physicist Albert Einstein in 1916 as part of his theory on General Relativity. A more thorough breakdown is as follows – Spacetime, the very nature of reality, is warped by physical objects of given mass, causing a curvature in spacetime and resulting in the phenomenon we call gravity. Just like, for example, a ball thrown into plastic sheet supported at the end would warp the sheet around it, causing the center of the plastic to dip. However, as objects move around in spacetime, the curvature begins to change to correspond to the location of said objects. When these objects have enough mass, and in the right circumstances (such as, in this case, two black holes merging), they will create discrepancies in the curvature big enough to send out ripples in the fabric of spacetime, or gravitational waves. Going back to the plastic sheet analogy, if two balls were crashed in the center with enough force, ripples would be sent out through the sheet. Another ball, say, on the other end, would bob up and down on the troughs and crests of these ripples, which is very similar to the effect gravitational waves create, except with planets instead of balls, and spacetime instead of the plastic. Until LIGO’s breakthrough recently, we have never observed gravitational waves directly, although they have been predicted from indirect observations.
So how did LIGO detect them? LIGO used a groundbreaking new experimental device called an interferometer. The basic principle of an interferometer is that it measures distortions in spacetime by splitting a laser into two and sending the resulting beams to remote locations in space. Since gravitational waves distort spacetime, if the lasers do not perfectly align when they return, gravitational waves are indicated.
But why are these gravitational waves so important to the science community? And what does this mean for the future of science? LIGO’s discovery opens up a multitude of crazy possibilities for science – from the quantum nature of reality to a greater understanding of particle-wave duality. But one of the most important things this does is lets scientists discover and track objects that do not emit light, such as black holes. Scientists can pick up on the gravitational waves bodies that do not emit light emit, and use this to pinpoint the object and study it. It also helps us understand more and build new theories from Einstein’s General Theory of Relativity. And, perhaps most important of all, it lets us discover more about the very nature of stars and the history of the cosmos, all the way to letting us uncovering the secrets about the dawn of the universe; about The Big Bang.