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A general cosmology talk, covering two versions of the "Cosmic Web" : the physical network galaxies, clusters and filaments that makes up the large-scale structure of the Universe; and the web of interconnected theoretical ideas we use to understand how it came it being and is evolving.
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THE COSMIC WEBThe Cosmic
Web
BLOG: http://telescoper.wordpress.com
Peter Coles
Spectral Lines turned Astronomy into Astrophysics!
The Hubble Expansion
THE COSMIC WEB
The Cosmic Web of Ideas
Dark matter
Dark Energy
The Big Bang
Cosmic Inflation
General Relativity
THE COSMIC WEB
Light Stretches!
The Cosmic Microwave Background
• Discovered by accident by Penzias & Wilson (1965); Nobel Prize in 1978.
• Thermal (“black body”) radiation with a temperature about 3 degrees above absolute zero
• This radiation was produced when the Universe was 1000 times smaller, and 1000 times hotter
• The “Smoking Gun” of the Big Bang
Why has the Sun got an edge?
What put the Bang in Big Bang?
• A “bang” must involve sound waves…• These could have been generated
during the inflationary era by quantum processes
• These are random noise with a particular spectrum
• Gravity eventually turns these into galaxies and clusters of galaxies
What put the Bang in Big Bang?
• If there was a “Big Bang” there must have been sound waves…
• These could have been generated in the very early Universe
• They started the process by which galaxies and stars eventually formed.
The Big Bang theory is not complete!
• There are an infinite number of possible big bang universes described by the same equations, but with different initial conditions.
• Some expand forever, some recollapse.• We have to use observations to pick
which of the big bang family is closest to our universe.
Dark Matter…..
• Most of the matter in the Universe is dark..
• “Dark Matter” can be detected in galaxies and galaxy clusters.
• Observations suggest 00.25, not enough to close the Universe
• But the Universe appears flat...• ….and it is accelerating!
Weighing Space
• As well as weighing individual objects, it is also possible to weigh the Universe as a whole
• To do this we need “standard rods” or “standard candles” which we view through curved space-time
• This can tell us about the curvature and expansion of space.
Flat Space
Open Space
Closed Space
Dark Energy
• The “Cosmological Constant” () was introduced by Einstein to make a static universe (“my biggest blunder”)
• Now we think of as “vacuum energy” that causes the expansion Universe to speed up..
• The vacuum energy is directly connected to the microscopic physics of elementary particles.
fainter
The Accelerating Universe
• Gravity pulls “normal” matter and energy; it doesn’t push.
• It is possible to engineer anti-gravity, but only with peculiar energy called “Vacuum Energy” or “Dark Energy”
• This is the idea behind inflation in the early Universe ..
• ..and possibly why the Universe accelerates now
“CONCORDANCE”
Precision Cosmology
“…as we know, there are known knowns; there are things we know we know. We also know there are known unknowns; that is to say we know there are some things we do not know. But there are also unknown unknowns -- the ones we don't know we don't know.”
Planck Time!
