Tue, 25. February 2014
Astro-Speaker Watch - February 2014 (2)
MAS has been trying to get Brian Schmidt (ANU) for several years. After he won the 2011 Nobel Prize for Physics it became even harder but Brian finally got here this month and it was a gala event put on by UWS and MAS.
Brian Schmidt opening MAS Astrophotographic Exhibition, Magnitude III, before the talk
Brian opened the MAS Magnitude III photographic Exhibition and then headed into the large UWS lecture theatre to give his talk to 350 people.
Brian Schmidt preparing his presentation.
He was introduced to the audience by Dr. Ragbir Bhathal (UWS), Director of Campbelltown Rotary Observatory.
Dr Ragbir Bhathal introduces Prof. Brian Schmidt.
Brian's talk, "The Accelerating Universe" was an account of how his research led him to discover (jointly with Saul Perlmutter and Adam G. Riess) that the expansion of the Universe is accelerating.
Professor Brian Schmidt: The Accelerating Universe.
Vesto Slipher was the first to discover that most of the other galaxies are moving away from us. This was built on by Edwin Hubble, who determined the relationship between galaxy speed and distance, known as the Hubble Constant.
Slipher's contribution.
Hubble's work led to the realisation that the Milky Way is not an island Universe but a galaxy like billions of others and to the conclusion in 1929 that the Universe is expanding.
Hubble's Contribution.
In the early 1990s, Brian decided to commit his time to determining the age of the Universe and to discovering its fate. This meant determining whether the Universe would continue expanding at its present rate or whether the gravitational pull of its contents were enough to slow it down and eventually lead to a Gnab Gib.
Closing in on the solution.
About that time, it was discovered that there was a fairly strong relationship between the observed light curves of Type 1a Supernovae and their distance. This relationship was strengthened by the Phillips Relationship, following impressive work done by Dr. Mark Phillips (a guest speaker at the Macarthur Astronomy Forum only a few months earlier, in May 2013).
This culminated in the gathering of data, as shown in the graph below, which shows that the more distant objects were receding too fast for a static or slowing expansion of the Universe. The more distant the object, the more it was accelerating from us.
To the surprise of all astronomers, it was discovered that the expansion of the Universe was accelerating!
Eureka!
The team headed jointly by Brian Schmidt and Adam Reiss published its findings at the same time as a competing team, headed by Saul Perlmutter:
- "Observational Evidence From Supernovae For An Accelerating Universe And A Cosmological Constant" by the High-Z Supernova Search Team (Schmidt and Riess).
- "Measurements of Omega And Lambda From 42 High-Redshift Supernovae" by the Supernova Cosmology Project (Perlmutter).
The two competing publications.
This talk was video-recorded by UWS but I don't know if it will be released publicly. In the meantime, I am sure that Brian has given this talk more times than he would care to remember and a previous version of "The Accelerating Universe" talk is available > Here <
I hope that in the not too distant future, Professor Brian Schmidt will return as a guest speaker at the Macarthur Astronomy Forum, to talk about more recent work, without all the hoopla involved with this particular visit.