British-based scientists have recreated the conditions around black holes using a water bath, shedding new light on the extraction of energy from the astronomical phenomenon. Matthew Stock reports.
It's the closest we'll ever get to a black hole... inside a giant bath tub at the University of Nottingham. This spiralling vortex is the same as when you pull the plug in a bathtub. It's also a good simulation of an event horizon; a black hole's point of no return where the pulling force of gravity is so strong that nothing - even photons of light - can escape. In the lab, waves are generated at varied frequencies to simulate the ripples in space. SOUNDBITE (English) SAM PATRICK, PHD STUDENT AT UNIVERSITY OF NOTTINGHAM, SAYING: "The key thing about a black hole is that it's got an event horizon. And this event horizon gives rise to some really interesting effects. From the point of view of the water; we can also have an analogue event horizon as seen by the surface waves. So although we don't have a black hole, the surface waves behave as if there were a black hole in the system." A pattern is projected on the water surface and special cameras capture the data. The team has demonstrated a previously theoretical phenomenon known as superradiance, whereby a wave hitting a rotating black hole can extract energy from it. Here, the wave pattern changes when it hits the vortex. SOUNDBITE (English) THÉO TORRES, PHD STUDENT AT UNIVERSITY OF NOTTINGHAM, SAYING: "Basically it says that something happened. And then by analysing more carefully this scattering pattern we can see if the wave has extracted some energy from the vortex. So, basically the idea is that the wave after the vortex has more energy than the wave before." SOUNDBITE (English) SAM PATRICK, PHD STUDENT AT UNIVERSITY OF NOTTINGHAM, SAYING: "We showed that superradiance does exist in our vortex flow. This was quite a big result for us because superradiance is an effect that's been known about since I think around the 1970s but no one had ever actually demonstrated that it exists in these rotational systems from an experimental point of view." The research was published recently in the journal Nature Physics. More experiments are now planned in a bid to better understand black holes; time well spent.....and definitely not down the drain.