The BIG Bang. 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.

The BIG BangThe BIG Bang

Hubble TelescopeHubble TelescopeThis 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.

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 CosmologyAncient 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.

In 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 Cosmology

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.

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.

Modern Cosmology

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.

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

Consequences of the Big Bang

If the universe did come into existence through a cataclysmic explosion, there should be some evidence. Four forms which will be discussed are:

The universe should be expanding

The universe should have a measurable temperature.

The mix of the elements should be known.

Matter should be evenly distributed

If the universe did come into existence through a cataclysmic explosion, there should be some evidence. Four forms which will be discussed are:

The universe should be expanding

The universe should have a measurable temperature.

The mix of the elements should be known.

Matter should be evenly distributed

Doppler Effect

Doppler Effect

The 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.

The 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.

Cosmic SpeedometerCosmic SpeedometerWhen a galaxy is moving away from us,

light waves travelling to us are red-shifted

Hubble measured the spectrum of these galaxies and found the spectral lines to be red-shifted

When a galaxy is moving away from us, light waves travelling to us are red-shifted

Hubble measured the spectrum of these galaxies and found the spectral lines to be red-shifted

The faster the recession, the greater the red-shift

Edwin HubbleEdwin

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.

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

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

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

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

Helium Abundance in the Universe

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

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%

The Big Bang theory is consistent with observations. Specifically ……….

The Big Bang theory is consistent with observations. Specifically ……….

Doppler Red ShiftDoppler Red Shift

• light coming from other galaxies is shifted to the red end of the spectrum

• indicates galaxies are moving away from each other and US

• universe is expanding.• more red shift in distant galaxies - moving away faster - consistent with theory

• light coming from other galaxies is shifted to the red end of the spectrum

• indicates galaxies are moving away from each other and US

• universe is expanding.• more red shift in distant galaxies - moving away faster - consistent with theory

CMBCMB

Cosmic Background Radiation - 3K temperature everywhere - leftover heat energy from big

bang

Cosmic Background Radiation - 3K temperature everywhere - leftover heat energy from big

bang

Element CompositionElement Composition

Universe is mostly hydrogen - the first element that would have been made after the Big Bang.

Hydrogen 73%Helium 26%Everything else 1%

Universe is mostly hydrogen - the first element that would have been made after the Big Bang.

Hydrogen 73%Helium 26%Everything else 1%

UniformityUniformity

Matter should be uniformly distributed throughout the universe

- galaxies are evenly distributed

Matter should be uniformly distributed throughout the universe

- galaxies are evenly distributed

The really interesting question is:

What happened when the universe was young and

hot?

The really interesting question is:

What happened when the universe was young and

hot?

History of the Universe

History of the Universe

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

Consequently, things looked very different in the beginning.

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

Consequently, things looked very different in the beginning.

Summary: Timeline of the Universe

Summary: Timeline of the Universe

The Big QuestionThe Big QuestionHow do you get something as hot as it was during the Big Bang?

Smash stuff together!!

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!!!!!!