Researchers have crunched Einstein’s theory of general relativity on the Columbia supercomputer at Ames Research Centre to create a 3-D simulation of merging black holes. The simulation provides the foundation to explore the universe in an entirely new way, through the detection of gravitational waves.
Credit: NASA
Frame from a 3-D simulation of gravitational waves produced by merging black holes, representing the largest astrophysical calculation ever performed on a NASA supercomputer. The honeycomb structures are the contours of the strong gravitational field near the black holes.
Credit: C. Henze, NASA
THE UNIVERSE SEEMS a lot more tangible than it used to. When scientists first started pondering what was ‘out there’, they relied on theoretical formula, speculation and, occasionally, religious belief.
Today we have space cameras taking pictures of galaxies far, far away, and telescopes that can peek back in time, almost all the way to the universe’s origin.
Despite our advances, however, there remains much that we do not understand. And according to many scientists, we still only know part of the story – we can only see the universe, we can’t yet hear it.
Nearly every telescope, camera and universe-monitoring device that we currently use detects waves on the electromagnetic spectrum, such as radio waves or light. Each have different frequencies, from radio waves to gamma rays, but they’re all emitted only by hot bodies, such as suns.
But the universe is filled with another type of wave emitted by any sizeable object, hot or cold, which is going completely unobserved by us. These waves, first predicted by Albert Einstein, are known as gravitational waves, and could be the key to scientists understanding exactly how the universe was formed and predicting how it will develop.
According to Jesper Munch, a physics professor at the University of Adelaide, without being able to observe gravitational waves – or the sound of the universe – our understanding of astrophysics will always be incomplete.
“Imagine you went to a symphony orchestra but you could not hear. You would see all of these people playing the violin and beating the drum and you could imagine what’s happening but it doesn’t really make a lot of sense until you can hear the sound too.
Currently the majority of what we know about the universe is what we can see from hot bodies; detecting gravitational waves is like being able to listen to the universe as well as seeing it,” he says.
The problem is, no one has ever really observed gravitational waves. They were first predicted by Einstein in 1916, but almost 100 years later, we still haven't directly proved that they exist.
Sure, scientists have detected evidence of them – two scientists were even awarded the Nobel Prize in Physics in 1993 for finding compelling evidence of gravitational waves - but frustratingly, they have never actually observed them directly.
Gravitational waves are, by their nature, hard to spot. They’re tiny little ripples in the fabric of space and time that are produced by any massive object that is accelerating. Even gravitational waves produced by the largest of objects are miniscule, and therefore no observatory to date has been sensitive enough to detect them.
However, scientists in the U.S. and the European Union are currently building gravitational wave observatories that are more sensitive than their predecessors by at least a factor of 10. And scientists are convinced that these next generation observatories will be powerful enough to detect gravitational waves – as long as they’re in the right place.
