WiFi in the Sky

November 03, 2009

Quick question: what do black holes and your laptop's WiFi connection have in common? A recently honored astronomer and engineer named John O'Sullivan has the answer. There are lots of astronomy related prizes out there, but the 2009 Australian Prime Minister's Prize for Science, awarded to O'Sullivan, is noteworthy because its impact has been felt far beyond the field of astronomy and astrophysics.

See, way back in 1977, O'Sullivan co-authored a technical paper about how a set of equations known as Fourier transforms could be used to improve the optical images from telescopes that had been distorted by the atmosphere. Fourier transforms are central to modern digital signal processing: they essentially take complex wave signals and break them down into their component parts. Once the "recipe" is known, it is possible to rebuild the signal, or build a signal that effectively cancels out the noise in collected data. Fourier transforms can be applied to any wave: sound waves, water waves, and light waves.

O'Sullivan developed his techniques because he was searching for radio waves emitted by exploding black holes -- a phenomenon predicted by Stephen Hawking in 1974. O'Sullivan didn't find those objects, despite his success cleaning up the distorted inter-galactic radio waves; the remnants of those radio emissions were simply too faint. But his techniques are now central to the wireless Internet revolution, making it possible for us to surf the Web without those pesky cable hookups -- and relatively free of distortion and interference from other radio sources.

So I congratulate O'Sullivan on being so honored, and thank him not just for my wireless connection, but also for improvements to radio astronomy that have yielded images like those below of the galaxy at the center of the Perseus cluster, courtesy of the Chandra Observatory. (The first is a composite image combining optical, x-ray and radio wave imaging; the second is the isolated radio wave image.)