Nobel laureate Frank Wilczek shows just how strange the universe is, writes Dick Ahlstrom
Surprisingly, nothing is not as it seems when it comes to studying the universe. It is a place where "empty" space not empty, and where space actually weighs something.
It is for this reason that Nobel laureate Prof Frank Wilczek chose The Universe is a Strange Place as the title of his Hamilton Lecture, given on Tuesday evening at the Dublin Institute of Technology.
An accomplished practitioner of achieving the public understanding of science, Wilczek showed just how strange our universe is using simple explanations, analogies and even jokes. Always engaging, he gave people an idea of how the universe works and why "strange" is a completely appropriate word for it.
Chief among the strange things about our universe is the idea of empty space. "Empty space isn't empty at all," says Wilczek. It is every bit as substantial as ordinary matter. "Not only is empty space substantial, it is the main thing and it weighs something."
He helped show just how powerful empty space can be in the work which led to his sharing of the 2004 Nobel Prize in physics with David Gross and H David Polizer, for the discovery of a phenomenon known as "asymptotic freedom".
Protons and neutrons inside an atom are bound together by a powerful force, but the quarks and gluons which make up the protons and neutrons are barely attracted to one another at all - at least while they are close together, Wilczek explains.
They enjoy this asymptotic freedom from one another until they are drawn apart. The greater the distance, the more powerful the attraction.
"The empty space is a medium that affects the particles and how they interact with one another," he says. "This is also crucial to the understanding of the early universe," he says, a time just after the Big Bang when the rapidly expanding universe was very hot and very dense.
He has yet to come up with a new name for space in this context, but harks back to the old term and disregarded theory of luminiferous aether or ether. "It is like a new kind of ether. I am trying to come up with a new name, because ether has a lot of baggage with it."
Another of the great mysteries of the universe that makes it so strange is dark matter, says Wilczek who is Feshbach Professor of Physics at the Massachusetts Institute of Technology in Boston and currently on sabbatical at Nordita Research Institute in Stockholm.
Dark matter is an invisible substance which dominates the mass of the universe, accounting for about 25 per cent of mass, compared with just five per cent for the matter we can see.
"It is most of the universe by weight but it is definitely not made out of the stuff we understand, protons, neutrons, quarks," states Wilczek.
"We have some tantalising ideas of what it might be and I am involved in some of these ideas."
The remainder, about 70 per cent of the universe, about which even less is known. "The dark energy for me is more mysterious than dark matter," he suggests.
REACHING AN UNDERSTANDING of what constitutes dark matter would bring much closer a unified theory that accounts for all of the natural observations made by scientists, he says. "It is kind of a grand synthesis that may be coming together in the coming years." This would be an advance on what physicists refer to as the Standard Model which links three of the fundamental forces, but excludes gravity. The Standard Model works well "but it has theoretical shortcomings", Wilczek says. "There are ideas of how to unify it but to get that to work in detail you have to include supersymmetry."
Supersymmetry attempts to advance the Standard Model but requires additional mathematical terms and new kinds of fundamental particles that can serve as dark matter, he says.
The theory suggests that every particle has a symmetric "superpartner" that should be much heavier than its partner. Particles that exist under the Standard Model do not have this property, but perhaps detached superpartners can account for dark matter.
Another candidate for dark matter is the "axion" Wilczek explains. It is a hypothetical particle that could account for the strange characteristics of dark matter including the fact that we can't see it, but can see it interacting via gravity with ordinary matter. Wilczek named the axion, calling it after a popular laundry detergent.
He stresses that these theories do not represent a "mystical vision" exercised by physicists. Scientists produce theories about the formation and structure of the universe based on experiments, facts and observations.
"They relate to observable realities. all of these ideas are coming to a head. It could be nature teaching us or nature teasing us," he says, adding, "It is an exciting time to be a physicist."
He views helping people to understand this work as "very important". "It is a beautiful thing and people should know about it. It is also basic to our lives," he suggests. It is also important because tax payers' money is used to pursue scientific research.
IT ALSO HELPS people to understand what scientists do. "They should have a sense that this is something to be understood and shows the process through which you achieve that," says Wilczek.
The Hamilton Lecture takes place each year on October 16th to celebrate the work of one of the world's greatest mathematicians, Dubliner William Rowan Hamilton.
The event is organised by the Royal Irish Academy, The Irish Times and Depfa Bank. The lecture marks the day in 1843 that Hamilton devised a unique form of mathematics known as Quaternions, which are important today for the study of the physics behind quantum mechanics.