e-Science : April 2012 Issue 1
CONCEPT INFORMATION (AS DENOTED BY SUPERSCRIPT NUMBERS): 1. Big bang The big bang is thought to be the beginning of the Universe. About 14 bil- lion years ago the expansion of the Universe began, and continues today. Everything in the Universe is receding away from everything else. How do we know this? We can see it! When we look into space, we see light, emitted long ago, that is now just arriving at the Earth. So we see galaxies, some nearby, and some further away. We know the Universe is expand- ing, as we can see, via the Doppler effect, that distant galaxies are racing away from us. The farther away, the faster they are moving. This is exactly what you would expect in an expanding universe. Edwin Hubble, after which the famous space telescope was named, was the first to observe the expansion. Light from more distant objects had taken longer to get here, so when we look farther away, we are looking farther back in time. We can in fact see all the way back to a time about 300,000 years after the big bang. Before that time, the Universe was so hot and dense that all light and matter was coupled together. There were no “free” photons around to be seen. Once the expansion reached a point where light could free itself from matter, these photons began to move off in all directions. Today, we see them from all directions in the sky. Due to the expansion and the Doppler effect, they are redshifted into the longer wavelength microwave band– and are known as the cosmic microwave background radiation. Many telescopes study this radiation and much about the origin and evolution of the Universe has been learned. The latest analysis of the expansion suggests that the acceleration of the Universe is actually in- creasing, which is completely counter intuitive to what we would expect. One might expect that an expanding Universe would eventually slow down to a stop, or even fall back in on itself (a big crunch). However, this doesn’t appear to be the case - and a new phenomenon, called dark en- ergy, is suggested as the cause of the acceleration. No one has any real idea what dark energy actually is, so this is one of the great questions for scientists to figure out in the 21st century.
July 2012 Issue 2