Still waiting to bag the big one
It was supposed to be the first great scientific discovery of the 21st Century - or so many researchers thought when they rushed down to the bookmakers to place bets at what were deemed at the time to be ludicrously generous odds.
The physicists believed that they were close to making the first direct detection of , the ripples in space-time generated by supernovas and coalescing .
Their confidence was buoyed by the knowledge that colossal new machines in the and that were finally capable of making the crucial breakthrough were just coming online.
They simply couldn't believe their luck when a sceptical offered to pay out £500 for every pound wagered if someone could bag a gravitational wave before 2010.
That was over five years ago. Today, just a few months shy of the decade's end, many of those same scientists that... er, um, they still haven't detected a gravitational wave.
I am being a bit tongue-in-cheek here because the international team's "non-detection" is actually a lot more remarkable than I make out - and I'll explain why in a moment.
But let me first back up a little and dwell on the significance of gravitational waves.
These elusive phenomena are an inevitable consequence of . If what we understand about Einstein's theory of gravity is correct - and we believe that it is - then they must be out there.
It is just a question of having the necessary sensitivity to detect them, because, unlike electromagnetic waves - the light we see all around us - gravitational waves are predicted to be extremely weak.
If one were to pass through your body, it would alternately stretch your space in one dimension while squashing it in another. Such changes, though, would be fantastically small.
hunting for this disturbance bounce lasers down L-shaped tunnels that are hundreds or thousands of metres long. They aim to find deviations in the experimental set-up that can be equivalent to one one-thousandth of the width of a proton, one of the particles that makes up all atoms.
There are a few of these facilities dotted around the globe - the Ligo network in the US, and the Geo 600 and Virgo establishments in Europe.
Any accelerating mass should send gravitational waves radiating outwards at the speed of light; but only really big events, such as exploding stars and merging black holes, are expected to disturb space-time sufficiently to register at the observatories.
Being able to routinely detect gravitational waves would bring a step change in astronomy.
It would allow scientists to probe those places where technology that is dependent on light - that is, traditional telescopes - cannot go: to the edges of black holes, for example; and back beyond when we think that the first light pushed out across the Universe, to the very first moments after the Big Bang.
The itself ought to have produced copious gravitational waves, and these should still be washing over us even now. And this brings me back to that non-detection.
The fact that the Ligo and Virgo Collaborations haven't yet seen this background signal in their super-sensitive equipment is itself very interesting to scientists. That's because the strength of this cosmic hubbub should be directly related to the way the Universe was in the first minute after the Big Bang and the physics occurring at that time.
Put another way, the non-detection puts new, tighter limits on the models used by cosmologists to describe the earliest events.
The gravitational wave seekers will get there eventually. Their equipment is being upgraded to become even more sensitive. The detection may not come soon enough to wipe the smile off the bookmakers' faces; but it will come.
And I'll leave you with a new picture of (LP). This is a demonstration spacecraft being built in the UK. It's a forerunner to a very big that will attempt to detect the gravitational waves emitted when gargantuan black holes at the centres of galaxies merge.
LP should fly in 2011 to trial the critical technologies needed by the full mission.
The engineering involved is astonishing and I'll blog about it at a future date.
±õ’m 
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