Maybe not. But strange and wonderful things are happening beneath the Yorkshire Moors, where scientists are chasing some of the great riddles of the universe. A brisk 10-minute walk from the mineshaft lies the cavernous extension of the Boulby Underground Laboratory for Dark Matter Research, which opened last summer at a cost of [Pound sterling]3.1 million. In brilliantly lit rooms hewn out of the rock, sheltered from the interference of cosmic rays that constantly rain down on the sunlit world aboveground, scientists tend supersensitive experiments. The task at hand: to search for a breed of subatomic particle needed to make sense of how the universe works.
There’s been plenty of progress of late. But as things often go in cosmology, answers only seem to lead to new, more disturbing questions. In recent years scientists have figured out how old the universe is (13.7 billion years) and what it’s made of (we’ll get to that), they’ve confirmed that it all started with the big bang (though much may have gone on beforehand), and they’ve sent up the Wilkinson Microwave Anisotropy Probe (WMAP) to map the afterglow.
If that sounds reassuring, consider a paper in last week’s issue of Nature. Dr. Jeffrey Weeks, a mathematician in New York, uses these very maps to argue that the universe may be shaped with 12 sides, and that passing through one side would only put you instantaneously on the opposite side, light years away from where you started. This notion of a finite hall-of-mirrors universe has elicited skepticism from some astronomers, but their alternative isn’t much better: an infinite stretch of mini-universes, of which ours is only one. Before you get woozy, though, let’s get back to basics:
How big is the universe?
It’s getting bigger all the time, but the shocking news of recent years is that the pace of expansion is far greater than previously thought. In 1998, astrophysicists discovered that “Type 1a” supernovae–a class of exploding stars–were fainter than they should be given their distance from Earth. From this they concluded that universe’s expansion hasn’t slowed since the big bang, it’s accelerated.
What would make that happen ?
A new mystery force, called dark energy, may work against gravity, driving the galaxies faster and faster apart. (Einstein posited something similar, then changed his mind.) If dark energy is growing in strength, it can’t simply be leftover oomph from the big bang. Some answers might be forthcoming from NASA’s Supernovae Acceleration Probe, to be sent up in 2008. The giant telescope would allow astronomers to see farther away, and thus farther back in time, to earlier supernovae explosions. That will hopefully lead to a clearer sense of how dark energy behaved in the past.
So what would the existence of dark energy mean?
Trouble. Scientists used to think that the universe would either collapse back in upon itself as the momentum of the big bang finally petered out (the “big crunch”), or it would continue to expand forever. This year a team of scientists at Dartmouth College proposed another fate: the “big rip.” If the power of dark energy continues to grow, eventually it will overpower gravity and rip apart everything from galaxies to individual atoms. But don’t cancel any holiday plans just yet. A big rip wouldn’t come for another 22 billion years.
What is the universe made of?
As scientists observe distant galaxies with ever more powerful telescopes, they’ve calculated that the galaxies are too lightweight to be swirling around as violently as they do. They can tell by measuring the starlight, a rough indication of how heavy the galaxies should be, and the speed with which the galaxies spin; a denser galaxy should spin faster, like a ballerina who moves her arms to her side. What unseen material could be making these galaxies more massive than they appear? Mysterious, theoretical stuff called dark matter. Recent data from WMAP suggests that dark matter in fact accounts for 90 percent of creation.
What exactly is dark matter made of?
This is where the tiny particles come in. If dark matter exists, some kind of dark-matter particle must have been created at the moment of the big bang. If so, it’s unlike anything we’ve experienced: it doesn’t reflect light and it barely interacts with anything else. (Hence the acronym WIMP, for Weakly Interacting Massive Particle.) Billions of WIMPs could be passing through your body right now, and you wouldn’t feel a thing.
How do we know WIMPs really exist?
We don’t, not with any certainty. That’s what the Anglo-American team at Boulby and others are seeking to remedy. But how do you spot a particle that’s so shy of leaving a mark? The answer is to devise experiments that won’t show WIMPs themselves but will register their occasional collisions with the nuclei of atoms. It’s sort of like playing billiards with an invisible cue ball. Some detectors at Boulby contain chemicals that give off a characteristic flash when a nucleus is hit by a WIMP. The detectors are placed underground so that the rock shields them from just about everything–except the WIMPs, which pass right through.
Why should we care ?
Because these are the most basic questions about the nature of our world. Says Prof. Carlos Frenk, an astrophysicist at Durham University in Britain: “One of the greatest achievements of mankind would be to find out what is keeping the galaxies together.” If nothing else, the quest will keep astronomers off the streets.
