We live in a three- dimensional world - or do we? We may need as many as 11 dimensions to explain experimental findings, according to a Science Week Ireland presentation. Dick Ahlstrom reports
Looking at the world from a three-dimensional perspective is just not enough to explain the latest findings from experimental physics. Theoreticists believe there should be at least 11 dimensions if they are to unify all experimental findings, from the tremendous power of black holes to the mysterious world of the sub-atomic particle.
Such was the wide scope of a lecture last night at the Dublin Institute for Advanced Studies entitled, "Hidden Dimensions". Prof Werner Nahm of the School of Theoretical Physics delivered the talk, one of a series offered by the Institute as part of Science Week Ireland. "It is about the idea of having more than three dimensions plus time," he says. "In my area of physics it really has become a necessity. Four dimensions is just not enough to get a theoretically consistent theory."
The challenge, he says, was to unify all areas of observational physics into a single "theory of everything". Such a theory would encompass gravity, electromagnetism and also quantum mechanics, which describes the world of the atom and how particles there interact.
Creation of a unified theory has proved difficult, however, because of the need for extra dimensions, ones that remain hidden.
The possibility that hidden dimensions existed was an enjoyable diversion among physicists and mathematicians in the 1800s, he says. Spiritualism was popular at the time, and some scientists postulated that ghosts could be explained because they could exploit dimensions that were hidden from mortals.
The pursuit of extra dimensions became something much more real after Albert Einstein presented his theories of gravity and relativity. This resisted merger with existing theories of electromagnetism and theoretical physicists led on to the idea of adding more spatial dimensions to the mix.
As new theoretical areas opened up, for example, quantum mechanics and string theory, the problems of unifying them into a single theory multiplied, Prof Nahm explains. The notion that there might be as many as 22 separate dimensions was proposed in 1969 but "no one really believed it", he says.
Current theories have made this much clearer, he believes. "We really know how many we need all together, 11 dimensions, the four we know and seven hidden ones." These would be enough mathematically to unify known forces into a single theory. The challenge, however, is where to find these hidden dimensions, Prof Nahm says.
"They could be curled up into very small radii at a size where they physically are not accessible by current experiments." Another idea is that they could co-exist alongside the four we know already but can't easily be observed from our vantage point. It may take gravity waves or some other source combined with an antenna to expose these hidden dimensions and show us where they are.
This is why physicists are anxiously awaiting the opening of the Large Hadron Collider at CERN near Geneva in 2007. This atomic accelerator will smash atoms together at higher energies than ever before and may help to expose some of the hidden dimensions, says Nahm. "When energy and particles seem to disappear they might be going into the hidden dimensions."
A closer look at black holes, the super-massive gravity sources out in space, may also give us a look at the hidden dimensions, he believes. They combine enormous gravity with ultra-dense matter where particles interact at very close quarters. Black holes may be the natural location to begin searching for a place where all of the 11 expected dimensions co-exist in an obvious way.
Science Week Ireland, what's on today:
- What time is it? A brief history of telling the time, 2 p.m., Waterford Institute of Technology, contact Noel Mulligan, 066- 714-5626.
- Genetically modified plants: fact, fiction and perception, 8 p.m., University College Cork, contact William Reville, 021- 490-2325.
- Genetic origins of the Irish, 8 p.m., Institute of Technology Tralee, contact Noel Mulligan, 066-714-5626.
- The history of encryption, 7.30 p.m., Institute of Technology Sligo, contact Maria Keeney, 071-55355.
- Science against crime, noon, Dublin Institute of Technology Kevin Street, contact John Cassidy, 01-402-4779.
- What do we eat? Learning to read food labels, 5 p.m., Dublin City University, contact Sharon Sheehy, 01 700-8975.
- Molecular spies: messages from molecules, 6 p.m., Royal Irish Academy, contact Pauric Dempsey, 01-638-0915.