F Don Lincoln, Fermilab f When the Universe Was Young and Hot Don Lincoln Fermilab f

f Don Lincoln, Fermilab f

When the Universe Was Young and Hot

Don LincolnFermilab

f


Hubble Telescope• This image is taken of galaxies

that are billions of light-years away. Light takes a very long time to travel to Earth.

• Consequently, this photograph is of the conditions that existed billions of years ago, just a billion years or so after the big bang.

• Astronomers have thus created a time machine of sorts.


Ancient Greek CosmologyIn the beginning there was an empty darkness. The only thing in this void was Nyx (Chaos), a bird with black wings. With the wind she laid a golden egg and for ages she sat upon this egg. Finally life began to stir in the egg and out of it rose Eros, the god of love. One half of the shell rose into the air and became the sky and the other became the Earth. Eros named the sky Uranus and the Earth he named Gaia. Then Eros made them fall in love.


Familiar Cosmology1 In the beginning God created the heaven and the earth.

2 And the earth was without form, and void; and darkness was upon the face of the deep. And the Spirit of God moved upon the face of the waters.


Modern Cosmology• Approximately 15 billion years

ago, all of the matter in the universe was concentrated at a single point

• A cataclysmic explosion (of biblical proportions perhaps?)

called the Big Bang caused the matter to fly apart.

• In the intervening years, the universe has been expanding, cooling as it goes.


Consequences of the Big Bang

• If the universe did come into existence through a cataclysmic explosion, there should be some evidence. Three forms which I will discuss are:

– The universe should be expanding

– The universe should have a measurable temperature.

– The mix of the elements should be known.


Doppler EffectThe Doppler effect says that things moving away from you look redder than they would if they weren’t moving. Things moving towards you look more blue.


Edwin Hubble

• Using the Doppler effect, Edwin Hubble discovered that objects that were further away move away faster (and, hence, were redder) than nearer objects.

• This discovery showed that the universe was expanding and still provides one of the best measurements of the age of the universe.


Black Body Radiator

Universe

• A black body radiator is one which absorbs all light which is incident on it.

• Such a body can also emit light, if sufficiently hot.

• The universe should thus have a temperature and an ‘afterglow’.


Afterglow From the Big Bang


Afterglow From the Big Bang

• In 1964, while working at Bell Labs, Penzias and Wilson discovered a radio hiss that they couldn’t make go away.

• They had (by accident!) discovered the remnant ‘echo’ of the Big Bang

• The universe was shown to have a temperature of 2.726K (-450 °F)


COsmic Background Explorer

• In 1992, COBE announced a measurement that showed that the background radiation was not quite uniform (although nearly so)

• This measurement records information approximately 300,000 years after the Big Bang


Goldilocks Effect• These three plots

show three different effects, each 10% less than the one larger than it.

• You can see how seeing a small effect first requires removing the bigger one.

Full, 10%, and 1%

10% and 1%

1%

Full only

10% only


Helium Abundance in the Universe• At the late time (as we shall see) of

3 minutes in the history of the universe, atomic nuclei were created.

• Big Bang theory predicts that the relative abundances of hydrogen and helium were:

– Hydrogen 76%

– Helium 24%

– Lithium 1 part per 1010

• Due to nuclear fusion in stars since the Big Bang, current abundances:

– Hydrogen 73%

– Helium 26%

– Everything else 1%


Summary of Cosmologic Measurements

• The Big Bang theory is consistent with observations. Specifically

– Hubble Telescope can view the universe ~1,000,000,000 years after the Big Bang

– The COBE satellite can view the universe ~300,000 years after the Big Bang

– The Hydrogen/Helium ratio can view the universe ~3 minutes after the Big Bang

• To which a particle physicist replies….


That’s cute……


No….really…..it’s cute……


What’s so interesting about that?

All the interesting stuff is overby three minutes.

The universe was in a retirement home by then.


The really interesting question is:

What happened when the universe was young and hot?


History of the Universe

• In the beginning, the universe was really, really, hot.

• Consequently, things looked very different in the beginning.


Consider an Ice Cube

• Heat it and it– Melts

– Boils

– Turns to steam

– H2O breaks up into hydrogen and oxygen atoms

– The electrons get ripped off the atoms and electrons and atomic nuclei scurry around

– Atomic nuclei get broken up into protons and neutrons

– Protons and neutrons get ripped apart into particles called quarks.


The Big Question

How do you get something as hot as it was during the Big Bang?

Smash stuff together!!

Hot!


E = m c2

Energy is MatterMatter is Energy

Lots of energy makes lots of matter

and vice versa!!!!!!




At Fermilab, we collide elementary particles at unprecedented energies, routinely recreating the conditions fractions of a second after the Big Bang.

In the spring of 2001, we will resume operations after a five year upgrade.

We will push our understanding of the universe even further back in time.

It’s gonna be cool!


What are we going to find?

I don’t know!

Supersymmetry, Higgs, Technicolor, particles smaller than quarks, something unexpected?

If I knew, it wouldn’t be any fun.


Everything in the UniverseMicrowave radiation

super clusters

clusters

galaxies

stars

planets

people

poodles

pigeons

pond scum

politicians

From the primordial soup!


Data-Model Comparison


Data-Model Comparison

Documents

F Don Lincoln, Fermilab f When the Universe Was Young and Hot Don Lincoln Fermilab f