1. Randy's Introduction.

Venus transit. GA 2004. Dan Bourgault from the Dept. of Physics here at MUN, our co-sponsor for tonight's event, introduced our speaker, Dr. John Percy from the University of Toronto. This lecture, and tomorrow's seminar (pulsating stars), are also thanks to the Harlow Shapley lectureship series of the AAS.

2. Dr. John Percy.

The talk will be about two closely related topics, cosmic evolution, and the evolution of life. The year 2003 was a very important year in the history of cosmology, as we saw a "cosmic convergence" of several results from different experiments that seem to point to one overall set of ideas for cosmic evolution. We have results from Boomerang, WMAP, the Hubble Deep Field, and supernova studies.

The large scale of the cosmos also leads to and ties into closer, and smaller scales. Dr. Percy led us on a brief tour from galactic filamentary structure to the Orion nebula, and how stars and galaxies give birth to most of the common elements (except hydrogen and helium). This leads to the question as to whether there are other planets, and thanks to a technique pioneered by astronomers here in Canada at the Dominion Astrophysical Observatory back in the 1970's, exo-planets have been discovered since 1994 from careful observation of blue and red shifts in the parental stars of these planets.

The discovery of exo-planets leads to the question of whether life could have formed on other planets than the earth, and if so, how. Could extremophiles be examples of how life may have first formed as opposed to the more supportive environmental model that was in vogue? The Drake equation was discussed. An important question here would be how life chemically evolved; the Miller-Urey experiment points towards a possible explanation. It turns out that this experiment's final composition corresponds quite closely with the composition of carbonaceous chondrite meteorites. If such organically complex molecules can form off a planetary sphere in our own solar system, we might be led to expect the same elsewhere. Just as in our solar system, exo-planets could be bombarded by comets and meteoroids, possibly furnishing them with the building blocks for life.

Finally, we close on the possibilities of detecting other earth-like worlds. Enough light would have to be detected in order to determine if the spectra was similar. To detect the presence of this kind of smaller exo-planet in the first place would require blocking of the light from the central star, or detecting the slight dip in light produced by a transit of the planet in front of the star. The talk closed with Fermi's Paradox (if Drake's Equation predicts so many civilisations, why haven't we heard from them?), and the possibilities of radio detections of other civilisations (SETI).

3. Coffee Break.

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David Bourgeois

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