Cosmology - The Final Frontier
Cosmology is the quest to understand the true nature of our Universe, where it came from and where it is going. It is also about finding our place in the Universe.
Since the 1930's we have known that our Universe is expanding and not static as Einstein believed. By this we mean that the distance between galaxies - the fundamental building blocks of the cosmos - is increasing with time. If we run time backwards then the reverse would happen - galaxies would approach each other and eventually the density of matter would become infinite. This is known as the Big Bang, a time when Einstein's equations predict that the density and temperature of matter should have been infinite.
However it is widely believed by physicists and astronomers that Einstein's equations should not be valid near the Big Bang because they do not include quantum effects. Quantum effects govern the world at very small scales, around the size of the atom and smaller. Trying to understand what actually happened around the Big Bang is one of the biggest questions in physics.
Although we believe the Big Bang happened around 14 billion years ago we are very lucky because tiny clues of that violent era are left for cosmologists to uncover today. Powerful experiments using telescopes such as the Southern African Large Telescope (SALT) can uncover these tell-tale clues. Like a giant jigsaw puzzle researchers can piece these clues together to form a more accurate picture of our Universe and how it began.
The Cosmic
Microwave Background as seen by the recent WMAP satellite. The red and blue
regions represent regions on the sky in which light is slightly hotter or
colder than the average. These tiny temperature fluctuations were mostly
generated as the light traveled through the gravity field of galaxies when
the cosmos was only 400,000 years old. This map therefore gives us a
snapshot of the Universe when it was extremely young, which we can compare
to the distribution of galaxies today, roughly thirteen billion years later.
Picture credit: NASA and the WMAP team.
SALT may be particularly useful in shedding light on one of the strangest properties of our cosmos - dark energy. In the last few years it has become apparent that not only is our cosmos expanding, but the rate of this expansion is speeding up. The source of this cosmic acceleration is completely mysterious and has been dubbed "dark energy" for it is invisible to the naked eye and shows itself only through its effects on the expansion of the Universe. It appears that the cosmos is actually dominated by dark energy and that the matter from which we, and all the stars and galaxies in the cosmos are made, is made is a tiny minority in the cosmos.
Surveys, telescopes and experiments being planned and implemented around the world will, in the next ten years, help fill in the missing blanks about our place in the cosmos and unveil the true nature of the mysterious Universe we call home.
(Kindly contributed by Bruce Bassett, Institute of Cosmology and Gravitation, University of Portsmouth, UK and SAAO, Cape Town, RSA)
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Hubble directly observes Planet Orbiting Fomalhaut.
