GALAXIE & COSMOLOGY

Galaxies & Cosmology:

On Monday's show, Astronomy Professor Chris Impey discussed the structure of galaxies, exoplanets, the Big Bang, and various other topics in astronomy and cosmology. Regarding the size of the universe, "the current view in the expanding Big Bang picture is that the distance to the edge...as well as we can measure, is about 40 billion light years," he said. The universe in its earliest state consisted primarily of just two elements, hydrogen and helium, and it took a long time for heavier elements to develop, he continued. An earth-like planet could have developed 6-7 billion years ago, "but I don't think we could even imagine a life-form that is a billion years more advanced than us...we don't have the evolution ourselves to imagine it," he noted.

New discoveries of exoplanets are helping to expand our knowledge of the formation of solar systems, and two systems that were recently found have a similar number of planets to ours, Impey reported. Planets are the residue of star formation, happening at the outskirts, he detailed, while our moon, it's hypothesized, may have been formed when a Mars-type object collided with a primeval Earth (moon rocks tend to support this theory). The gas giants like Jupiter and Saturn are like mini-solar systems themselves with rings and moons that probably formed around the same time.

There are around 100 million Earth-like planets in just the Milky Way alone, he estimated, and if you multiply that by the number of galaxies-- 100 billion, you have a staggering number of possibilities for life. After about a trillion years, the universe will fade to black, but interestingly, Impey suggested that "a dark universe doesn't have to be a dead universe." An intelligent species doesn't need to get their energy from starlight, but instead could tap gravitational energy, he surmised.