young and hot

7/30/2019 Young and Hot

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f Don Lincoln, Fermilab f

When the Universe Was

Young and Hot

Don Lincoln

Fermilab

f


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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 existedbillions of years ago, just a

billion years or so after the big

bang.

Astronomers have thuscreated a time machine of

sorts.


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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 theegg 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 theEarth. Eros named the sky

Uranus and the Earth he named

Gaia. Then Eros made them fall

in love.


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Familiar Cosmology

1 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.


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Modern Cosmology Approximately 15 billion

years ago, all of the matter inthe universe was concentrated

at a single point

A cataclysmic explosion (of

biblical proportions perhaps?)

called theBig Bangcaused the matter to fly apart.

In the intervening years, the universe has been expanding,

cooling as it goes.


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Consequences of the Big Bang

Ifthe universe did come into existencethrough 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 measurabletemperature.

The mix of the elements should be known.


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Doppler Effect

The Doppler effect says

that things moving away

from you look redder than

they would if they werent

moving. Things moving

towards you look moreblue.


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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.


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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.


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Afterglow From the Big Bang


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Afterglow From the Big Bang

In 1964, while working at Bell Labs, Penzias and Wilson discovered a radio

hiss that they couldnt 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)


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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


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Goldilocks Effect

These three plots

show threedifferent 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


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Helium Abundance in the Universe

At the late time (as we shall see) of3 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%


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Summary of Cosmologic Measurements

TheBig Bang theory is consistent with

observations. Specifically

Hubble Telescope can view the universe

~1,000,000,000 years after the Big BangThe 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.


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Thats cute


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No.really..its cute


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Whats so interesting about that?

All the interesting stuff is over

by three minutes.

The universe was in a retirementhome by then.


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The reallyinteresting question

is:

What happened when the

universe was young and hot?


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History of the

Universe

In the beginning, theuniverse was really,

really, hot.

Consequently, things

looked very different

in the beginning.


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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.


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The Big Question

How do you getsomething as hot

as it was during

theBig Bang?

Smash stuff

together!!

Hot!


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E = m c2

Energy is Matter

Matter is Energy

Lots of energy makes

lots of matter

and vice versa!!!!!!


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At Fermilab, we collide elementary

particles at unprecedented energies,

routinely recreating the conditions

fractions of a second after theBig

Bang.

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

We will push our understanding of the

universe even further back in time.

Its gonna be cool!


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What are we going to find?

I dont know!

Supersymmetry, Higgs,Technicolor, particles

smaller than quarks,

something unexpected?

If I knew, it wouldnt be any fun.


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Everything in the Universe

Microwave radiation

super clusters

clusters

galaxies

stars

planets

people

poodles

pigeons

pond scumpoliticians

From the primordial soup!


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Data-Model Comparison


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Data-Model Comparison

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