Download - The Cosmic Web - Evening Lecture at Sussex University on 9th December 2013

THE COSMIC WEBThe Cosmic

Web

BLOG: http://telescoper.wordpress.com

Peter Coles

The Hubble Expansion

2dFGRS

UDS

THE COSMIC WEB

The Cosmic Web of Ideas

Dark matter

Dark Energy

The Big Bang

Cosmic Inflation

General Relativity

THE COSMIC WEB

The Stretching of Light!

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

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

Planck Time!

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 infinitely many 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 of space-time.

Flat Space

Open Space

Closed Space

Dark Energy

• The “Cosmological Constant” () was introduced by Einstein to make a static universe (his “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.”