Star Power: The Special Effect of Einstein's Theory of Relativity

TOM RIVLIN DELVES INTO OUR SEARCH FOR GRAVITATIONAL WAVES, AND THEIR SURPRISING CONNECTION TO A HOLLYWOOD BLOCKBUSTER

Imagine being part of a team that achieves the highest award possible in the world of filmmaking. Now imagine doing the same for physics.

Now imagine doing both in three years.

In 2015, the London-based visual effects studio Double Negative won an Academy Award for their work on the 2014 film Interstellar. Directed by UCL’s very own Christopher Nolan, Interstellar was a sci-fi blockbuster about a journey to a supermassive black hole. To create the visuals for the black hole, they consulted a professor of theoretical physics at Caltech, Kip Thorne, who worked with Double Negative to make the black hole look as realistic as possible.

Professor Thorne did this by creating simulations of a black hole, creating arguably the most advanced physics engine ever used on screen. It was so advanced they even used the work to write scientific papers. Although Thorne wasn’t explicitly credited as a winner of the Academy Award for Best Visual Effects, it would not have been achieved without his extraordinary input.

Fast-forward to October 2017, and Kip Thorne was in the news again for a different reason: he was one of three winners of the Nobel Prize in Physics. Over 40 years ago, Thorne helped ‘break ground’ on the theories that would eventually lead to a project called the Laser Interferometer Gravitational-Wave Observatory (LIGO): a multi-million-dollar, multi-national, multi-decade experiment to detect some of the most elusive signals in the universe: gravitational waves.

What both accomplishments have in common is Albert Einstein’s Theory of General Relativity, a cornerstone of modern physics. It is one of two fundamental theories of reality, describing how space and time can be warped by objects with mass. Einstein wrote down the equations which govern it, the Einstein field equations, 102 years ago, and since then it has passed every experimental test ever thrown at it, to exquisite accuracy.

In Interstellar, it was vital for Professor Thorne and the team to solve the Einstein field equations to work out what a black hole would actually look like up close (we’ve never been able to look at a real black hole before). This created the mind-bending visuals Interstellar won its Oscar for.

For LIGO, the equations were what initially predicted the existence of gravitational waves. According to these, it should be possible for an object with mass to warp space and time in such a way that they ripple. Just like dropping a pebble in a pond, if a massive object perturbs spacetime, then that spacetime can wobble like a wave.

The problem is, these effects are mind-bogglingly tiny, only becoming noticeable when the object is planet- or star-sized. It was only in 2015, 100 years after Einstein devised his equations, that the first gravitational wave was detected for certain by the LIGO team. This wave arose from a dramatic event: two black holes, each with a mass over 20 times that of the sun, colliding. The event happened over a billion light-years away, and by the time the waves reached Earth, they were perturbing spacetime by less than 1% the width of an atomic nucleus. Nevertheless, it was detected, and has confirmed yet another prediction made by Einstein’s amazing theory.

Detecting gravitational waves is interesting alone (enough to win a Nobel Prize), but it also marks the beginning of something incredible: a brand new era of astrophysics. Since the dawn of time, we have more or less had only one tool to study astronomy: electromagnetic waves. Visible light, for example, one example, was used by the first stargazers to learn about the night sky. The most advanced telescopes can detect radio waves, gamma rays, UV light, X-rays, and more from the cosmos, but all of them are just different types of electromagnetic wave.

But now that we know gravitational waves exist, we can use them to study the cosmos. LIGO was designed to detect waves of a small range of frequencies, which means only a select number of phenomena are open to exploration. However, in the future, we’ll be able to build a huge range of varying gravitational wave detectors, tuned to all sorts of different frequencies, just like the vast array of telescopes we have for electromagnetic waves. We’ll be able to use them to learn about binary stars, supernovae, and even the primordial ripples of the dawn of the universe. And we’ll reflect on 2015 being the year that it all started: the year we opened a new set of eyes to gaze at the heavens with.

That’s worth a few awards if you ask me.

Featured image: unsplash