Harvard professor helped locate 'cosmic background microwave radiation' left over from the Big Bang, writes Dick Ahlstrom
We know more than ever before about our universe, its age, how it was formed and the fact that it is expanding. The only problem is 97 per cent of its content is a total mystery to us.
Cosmology remains one of the most challenging of research areas, dealing as it does with the creation of the universe. One of two researchers who in the 1960s helped to change it from whimsy to a real science visits University College Cork this evening to deliver a lecture on how this was achieved.
Dr Robert W. Wilson and fellow scientist Dr Arno Penzias discovered the telltale signs of heat left over from the Big Bang, the event that created the universe. It languished as a fanciful theory that up until then suffered from a lack of evidence. The two shared a Nobel Prize in 1978 for their work.
"Cosmology as a science has really grown up since the mid-1960. Prior to that it was really just speculation," says Dr Wilson who delivers a talk in the UCC President's Distinguished Guest Lecture Series tonight.
"Now there are a lot of things known," he told Science Today earlier this week. Wilson is senior scientist at the Smithsonian Astrophysical Observatory at Harvard in Massachusetts.
He and Penzias greatly advanced cosmology with their discovery of "cosmic background microwave radiation" left over from the Big Bang. The Big Bang theory holds that the universe and space-time formed and began to expand from an infinitely small point after an infinitely powerful explosion.
The Big Bang theory gained pace following the discovery by astronomer Edwin Hubble in 1929 that the galaxies he could see in his telescope were moving away from one another at colossal speeds. The notion of an initial explosion helped to explain the expanding universe and also began to answer questions left behind by Albert Einstein and his "cosmological constant" which attempted to explain why the universe didn't just collapse due to gravity.
Dr Wilson and Penzias delivered the breakthrough in 1964 when as young radio astronomers they accidentally detected the cosmic microwave background. "We were actually looking for something else," he says.
They were attempting to calibrate their radio antenna by looking for a zero reading in a quiet corner of the radio wave spectrum. "Fortunately we set up at a frequency where we didn't expect to find anything," somewhere with no background noise and quiet enough to read the very weak microwave signal.
Instead of no reading they received a persistent radio signal coming to them from all directions. "We kept trying to figure out where it came from. We ended up living for nine months with this thing." Only after discussing it with another research group who were looking for the same signal did they realise what had been discovered. "When we got together it was clear we had produced what they were looking for," says Dr Wilson.
People get confused about the microwave background but Dr Wilson argues it is quite straightforward. "It is really thermal radiation, like holding your hand up to the oven," he explains. It is possible to measure its actual temperature, 2.73 degrees C, he adds.
Measuring the radiation allowed scientists to date the Big Bang event to 13.7 billion years ago. The unimaginable heat is now gone, spread out over the universe which continues its expansion today.
The cosmic background microwave radiation is the bit that is left behind as it dissipates in the distance. "All that is left is the very longest wavelength radiation that we know as radio waves," says Dr Wilson.
Our current understanding of the universe remains weak despite these discoveries. For example, we see only about 3 per cent of all the universe's mass/energy. About 72 per cent is made up of invisible "dark energy", a concept accepted only in the last five or so years, he says. "We have no idea what that is," admits Dr Wilson. Another 25 per cent is "dark matter", probably bits of ordinary matter, "but we also don't know what that is," he adds.
Still shrouded in mystery is the ultimate fate of the universe. Current thinking suggests it will expand until the stars eventually go out, but we don't know. "It comes down at this point to the dark energy," says Dr Wilson. We know the universe is expanding at an increasing rate, but is the dark energy pushing this increase or will it act as a brake? We await answers.
Wilson's free talk is at 7 p.m. tonight in Boole Lecture Theatre Three, UCC. The UCC series includes two lectures earlier in the day, a reading by Richard Ford at 2.30 p.m. in the Aula Maxima and a 4 p.m. lecture by Prof Roy Foster in Boole Lecture Theatre Two
