There are 100 billion galaxies we can see from our planet Earth. But what else is out there?
At present, more is unknown than known when it comes to the universe. However, astronomers are still actively searching for answers. The eighth annual “Expanding Canada’s Frontiers” symposium, organized by the U of T Astronomy and Space Exploration Society was held on Friday, January 28, 2011 at Convocation Hall. This year the event was called “Unravelling the Universe,” and featured three speakers: Dr. Alexei Filippenko of UC Berkeley, Dr. Michel Levebvre of the University of Victoria, and Dr. Gilbert Holder.
Filippenko is one of the world’s most widely cited astronomers, having published over 620 scientific publications. In addition, he has developed a robotic telescope, the Katzman Automatic Imaging Telescope, which conducts the most successful nearby Lick Observatory Supernova Search. His research involves supernovas, black holes, active galaxies, and the expansion of the universe.
In Filippenko’s talk, the audience learned that exploding stars — called supernovas — are very luminous once they explode, but then fade away quickly. A galaxy produces one supernova every century, but with the 100 billion galaxies there are to observe, we never have to fear that astronomy students will run out of stars to study.
Filippenko is especially passionate about the subject of the expanding universe. Thanks to its uniform expansion, most nearby galaxies are moving away more slowly than those that are far away, he explained.
Not only a remarkable orator, Filippenko also amused the crowd with some jokes. The audience burst into laughter as he explained that the general public usually mixes up cosmology and cosmetology, remarking, “I do not give makeup exams.”
The next speaker was Dr.Lefebvre who founded the Canadian ATLAS collaboration, which contributed to the creation of a particle detector that studies proton collisions from the Large Hadron Collider in Geneva.
In his talk, Lefebvre shed some light on the constitution of the universe. He explained that we only know about four per cent of the universe’s makeup. The remainder is composed of things scientists cannot explai using conventional physics. For example. dark energy accounts for 73 per cent, dark matter makes up 23 per cent, while 3.6 per cent is intergalactic gas, and 0.3 per cent is made up of stars.
It therefore comes as no surprise when Lefebvre says that we are in fact “the debris of the universe.” Dark matter is an intrinsic property of space, showing that empty space can be made up of energy. In fact, Einstein was the first to realize that empty space is not made up of absolutely nothing. Dark matter is another mysterious aspect of space, but we at least know that it is not a part of planets or stars, nor is it antimatter, since there are no gamma rays, which would normally be produced when matter mixes with antimatter. It is more widely believed that dark matter is composed of exotic particles such as WIMPs (Weakly Interacting Massive Particles) or axions.
Lefebvre also spoke of a possible fate of the universe: dark energy may become attractive instead of repulsive, at which point the universe will slow down and eventually come to a halt.
Dr. Holder, whose main research interests involve astrophysics and cosmology, primarily studies cosmic microwave background. He further emphasized Lefebvre’s point on how much is left to discover about the universe.
Holder explains, “96 per cent of the universe makes no sense.” The universe is expanding at a rate of one foot per nanosecond. One nanosecond after the Big Bang, the first photon and neutron were created. One minute after the Big Bang, helium, lithium, and hydrogen appeared. It then took 300,000 years to form the first atom.
Astrophysics, as Holder explains, “explores matter and space in the largest dimension.” Where are the edges of the universe? Astronomers have yet to agree on an answer, but have proposed that it is either infinite or it wraps around itself.
Much to our relief, the sun will die slowly rather than explode in a supernova. The properties of space are just beginning to be discovered. An exciting future in space exploration awaits us.
