François PASSEBON & Jack WILLIS

HST 2006

present …

If you compress a gas in a pump, it becomes hotter,and if you release the pressure of this gas, it cools

I pump,therefore I am

An animal, or a human body, for example, emitssome infrared radiation that can be detectedby an infrared camera

Color is related to temperature

Dicke and Gamov, two physicists, calculated independently in 1946 and 1948, that as the Universe has cooled, we should be able to detect microwave radiation throughout the sky …

I’m Gamov

I’m Dicke

Longwave-

-length

Lowtemperature

Max Planck, another physicist,had given the explanation of theshape of the radiation in 1900

The colder the body,the longer the wavelenght

… by Penzias and Wilson, two physicistsfrom the Bell labs, who got the Nobel prize in 1978

But, in 1964, the radiation predicted by Gamovwas finally detected, with this antenna …

antenna

PenziasWilson

In fact, the snow that one can see on an untuned TVis also due in part to that radiation emitted by theUniverse as it was just 380,000 years old !

We’ve a lot of

work today !

Original temperature of the radiation : 3000 KToday, it is only 3 KThe cooling says how far the light has travelled13,7 billion years : the age of the Universe

In 1992, the COBE satelite (Cosmic Background explorer)gave the first image of the radiation

COBE was launched on November 18, 1989

In 1992, the COBE satelite (Cosmic Background explorer)gave the first image of the radiation

Before correction of the Earthmovement around the Sun

The final image of the microwaveRadiation

Before correction of the microwaveradiation emitted by our own galaxy

In 2003, the WMAP satelite gave a better resolutionof the small fluctuations of temperature(WMAP = Wilkinson Microwave Anisotropy Probe)

WMAP was launched on June 30, 2001

Whereever it looked, WMAP measured the same data.So, the big-bang must have taken place at the same time everywhere

But we can also observe small fluctuations of temperature, that may have lead to the formation of the galaxies

Small fluctuations, compared to these at the surfaceof the Earth !

To know more about the blackbody spectrum :

Back to the begining

Where does the matter of the universe come from?

1 proton for every 1,000,000,000 photons

How did structures in the universe form?

Ripples + Dark Matter

Albert Einstein, 1905

E = mc2Mass is just condensed

energy

E → m

What was the origin of this early matter (and antimatter) in the Early Universe?

Early Universe

Size: a → 0

Age: t → 0

Temperature: T → very large

T ~ 1/a, t ~ 1/T2

Energies: E ~ T

Based on Einstein’s Relativity + Dirac’s Quantum Theory + Feynman’s

description in Quantum Field Theory

We conclude:

Every particle has an antiparticle

Because of asymmetry, almost all particles and

antiparticles were annihilated except for a small number of particles

Why do we not see this in our evidence?

Dirac predicted the existance of antimatter in 1928

He predicted antimatter would have the same mass but opposite internal properties of matter

1957: particles and antiparticles spinning in same direction behave differently

1964: CP violation shown in weak decays of K0 mesons indicating matter does not behave

exactly as antimatter.

Current evidence suggests:

Density Budget of the Early Universe

● Total Density ~ critical

Theory of inflation, measurement

of microwave background: ΩTot = ~ 1

● Baryon Density smallBig-Bang nucleosynthesis, CMB:

ΩBaryons ~ few %

The Density Budget of the Universe

● Total Density ~ critical

Theory of inflation, measurement of microwave background: ΩTot = ~ 1

● Baryon Density small

Big-Bang nucleosynthesis, CMB:

ΩBaryons ~ few %

● Total Matter Density much larger

Clusters of galaxies

Ωmatter ~ 25%

● Mainly cold dark matter

Enables structure formation

What caused the formation of the structures of the universe and what was

the origin of masses and forces?

Evidence indicates that as the universe cooled after the Big Bang….

These particles began to cluster….

And in these clusters developed patterns….

Such as quarks….

And atoms

How do these particles stay together to form structure?

FORCES

Standard Model: Gravity, Electromagnetic, Strong and Weak

Two Theories describe the forces:

Quantum Electrodynamics and

Quantum Chromodynamics.

Quantum Electrodynamics (QED):

Electric charge Atoms Molecules

Quantum Chromodynamics (QCD):

Colour charge Baryons Nucleus

At current resolution we see the universe as it was ~ 380,000 years

after the ‘Big Bang”

What will we see next?

Perhaps…..

B I G

B A N G