Colloquiums - or should we say colloquia? - may not be everybody's cup of Lapsang Souchong. One is reminded, for example, of the Oxford professor who, on receiving a note from a colleague inviting his participation in a series of "weekend mathematical colloquia, fora that may provide much needed computational stimuli for the mens profani vulgi", replied: "We have better things to do with our Sunday mornings than sit on our ba and do sa".
But then, a colloquium just now and then may do you good. If it is some time since you have had one, may I recommend just such a gathering which will take place tomorrow afternoon beginning at 5 p.m. The Museum Building, Trinity College Dublin, is the venue for the John Joly Colloquium 2001, and the focus will be on "The Measurement of Geological Time".
Now some colloquia are disappointingly narrow in their scope. They may concentrate, for example, on "The evolution of the romantic novel during the pontificate of John Paul I", or "The distribution of Ficedula hypoleuca in the 1950s on the Saltee Islands". But that the organisers of John Joly 2001 have avoided such a trap is clear from the title of the opening lecture: Prof G.J. Wasserburg of the California Institute of Technology will speak on "The first five million years of the solar system and a view of the preceding 10 billion years". Prof Michael Summerfield, who follows, is slightly less ambitious: his contribution is limited merely to "The measurement of geologic time in the last five million years".
Clearly, as you will have gathered, geological time is very, very long. Indeed, if you were to encapsulate eternity in a single day, and relate, say, the last five billion years of the Earth's history to the 24-hour clock, the first forms of life would have appeared by eight in the morning.
By nine o'clock that evening there would still be no land plants, nor any animals with backbones. The earliest forms of man appear only a minute and a half before the end of the 24-hour period, and homo sapiens takes to the earthly stage only two seconds before midnight.
But geologists measure eternity in quite a different way. They think of time in terms of eras and periods, and tie down significant events even more precisely to an age or epoch.
You will no doubt learn more about this from the last lecture of the day, and something also about the man commemorated by the event itself. Dr Patrick Wyse Jackson is of TCD, and his contribution is entitled "John Joly's determination of the age of the Earth".