Please note: The Sun exhibition ended on 4 November 2020. To find out what exhibitions and activities are open today, visit our What’s On section.
The film tells the story of a mission to reignite the dying Sun. While the Earth is blanketed with ice, Cillian Murphy’s character, a physicist, is in charge of firing a nuclear weapon into the heart of the Sun to restart it.
This might not be the most plausible sci-fi film in history, but it does raise a couple of interesting questions. The first is simple: could the Sun go out?
The answer is not ‘yes it could’ but ‘yes it will’—in about 5 billion years’ time. Right now, the Sun is halfway through its life, and will continue burning hydrogen for another 5 billion years. After this fuel is gone, it will expand to such a size that it will engulf Mercury, Venus and Earth. Mars, which is further from the sun, may survive and continue to orbit the remains.
Once the Sun has completed this red giant phase, it will collapse under its own gravity. Its huge mass will be retained, but it will have a volume similar to that of Earth. When that happens, it will be known as a white dwarf.
The other obvious question is, could there be an early failure of the Sun, as depicted in the film? The answer here is probably not. When Sunshine‘s scientific advisor, Professor Brian Cox was asked to come up with a scenario for such a failure, he asked around among fellow physicists. Together they decided that something called a ‘Q-ball’ might do it. This isn’t mentioned in the film; only in the DVD commentary.
The idea comes from a theory of physics called supersymmetry. Supersymmetry suggests that every particle has a superheavy partner—a ‘sparticle’. A Q-ball is a superheavy sparticle that could have formed during the Big Bang and would have the ability to break down ordinary matter made of protons and neutrons. If one were to lodge in the heart of a star, it might eat away at the star’s constituent particles like a cancer.
The trouble is, physicists now doubt that supersymmetry is a viable theory. Back in 2007, when Sunshine was released, CERN’s physicists were hoping they’d discover evidence for supersymmetric particles at the Large Hadron Collider (LHC). However, they found none. They also didn’t find any ‘dark matter’ particles as they’d hoped. Dark matter is a hypothetical solution to the anomalous spin of galaxy clusters, which appear to be held together by some invisible matter that exerts a gravitational force. We’ve been aware it might exist since 1933 but have never managed to identify any.
Since the nuclear device carried aboard Icarus II in Sunshine is composed of uranium and dark matter, we have to say the science of Sunshine has bombed out quite badly in the years since its release!
However, none of this has spoiled our love for the movie. Sunshine is a real feast for the eyes and the ears. The CGI of the sun is spectacular, and the film’s soundtrack, written by John Murphy and Underworld, is similarly dramatic. Sunshine is a celebration of the Sun: when promoting the film, Danny Boyle said that, ‘All life is either a bit of a star or is kept alive by its power. How could you not make a film about that?’ It’s a great point. The sun is literally and metaphorically central to our experience of life as humans on planet Earth.
It’s also the inspiration for what might prove a radical new energy source. Every 1.5 millionths of a second, the Sun releases more energy than all humans consume in an entire year. We are trying to recreate that energy generation through the development of nuclear fusion technology.
This uses two forms of heavy hydrogen—deuterium and tritium—as fuel. The idea is to recreate the conditions in the Sun that fuse these two substances together to create helium and release energy. That means we have to heat them to temperatures in excess of 100 million degrees and apply extraordinary pressures that bring them within 10-15m of each other.
This is far from easy, and fusion is taking a long time to bear fruit. Currently we are trying a variety of approaches, including the huge International Theromonuclear Experimental Reactor (ITER) under construction in the south of France. No one yet knows whether any of the approaches will ultimately succeed. However, the potential payoff makes it worth trying. Deuterium is found in seawater, and every cubic metre of seawater can release as much energy as 10 barrels of crude oil. It’s such an enticing prospect—how could we not at least try to bring the Sun down to Earth?
Rick Edwards and Dr Michael Brooks host the award-winning podcast Science(ish), which looks at the science within popular culture. Their book is available here.
