Riddles of dark matter and dark energy may be solved
Now that gravitational waves have been detected, a completely novel means of looking at the universe is emerging
The silhouette of a scientist against a visualisation of gravitational waves. Photograph: EPA/Julian Stratenschulte
The motto of the Pythagoreans was “All is Number” and Pythagoras may have been the first person to imagine that the workings of the world might be understood in mathematical terms. This idea has now brought us to the point where, at a fundamental level, mathematics is the primary means of describing the physical world. Galileo put it this way: the book of nature is written in the language of mathematics.
With this language, we can do much more than just describe physical systems; we can predict completely new phenomena. William Rowan Hamilton predicted conical refraction using a mathematical model. Although this had never been seen before, his predictions were soon confirmed by observations. James Clark Maxwell formulated a system of equations for electromagnetic fields and found wave-like solutions to them. It was a scientific triumph when Heinrich Hertz generated radio waves in the laboratory. Now we can hardly envisage a world without wireless.
One hundred years ago, Albert Einstein produced his general theory of relativity. One of the many startling implications of this theory was that matter converted into energy could radiate outwards in the form of gravitational waves – ripples in the fabric of spacetime. Einstein himself believed that these waves would be too weak to be detected but, one hundred years later, they have been found.
Last month, Kip Thorne, a theoretical physicist and co-founder of the Ligo experiment, addressed the Literary & Historical Society at UCD when the society presented him with the James Joyce Award. Prof Thorne is an expert on the astrophysical implications of general relativity and has made major contributions to our knowledge of black holes.
Ligo (Laser Interferometer Gravitational-Wave Observatory) is a large international physics experiment and observatory to detect gravitational waves and to develop tools for observational astronomy using gravitational waves. About 1,000 scientists from nearly 100 countries are involved. Just a year ago, gravitational waves were detected: the same event was measured at two centres, one in Louisiana and one in Washington State. This event, a collision of two black holes, occurred 1.3 billion years ago and the energy released corresponded to the conversion of three solar masses into gravitational waves.
Our understanding of the universe changed when Galileo pointed a telescope at Jupiter. A new window on the world opened up in the 1950s, when radio astronomy revolutionised our understanding – we could see the universe in a “new light”. Now that gravitational waves have been detected, a completely novel means of looking at the universe is emerging. Who knows where it may lead us? The riddles of dark matter and dark energy may be solved.
The current state of physics is unsatisfactory: there are inconsistencies between general relativity and quantum mechanics. A comprehensive theory of quantum gravity is the goal but this is a formidable task and new mathematical breakthroughs may be required to attain it. If you struggle with maths, take comfort from Einstein’s words: “Do not worry about your difficulties in mathematics. I can assure you that mine are still greater.”
On November 21st, Prof Sheila Rowan, Chief Scientific Advisor for Scotland, will deliver a DIAS Statutory Public Lecture at UCD, Gravitational Waves, a New Astronomy (admission free but booking required). Peter Lynch is emeritus professor at the school of mathematics & statistics, University College Dublin. He blogs at thatsmaths.com. His book That’s Maths has just been published by Gill Books