Formation of

the Universe What evidence supports current scientific theory?

Cosmology

Cosmology is the study of the

Nature,

Structure,

Origin,

And fate of the universe.

How did it all begin? Astronomers theorize that the universe came to be in a single moment.

According to this theory, all the matter and energy of the universe were at one time concentrated in an incredibly hot dense region, a form of matter called plasma.

At a super heated state, it was too hot for atoms to form, or other properties such as gravity or electromagnetic forces to occur

And then, Billions of years ago all at once, rapid expansion, and an enormous explosion!!!!!

Then what?

The universe expanded very quickly

-After a few thousand years, some cooling occurred, which allowed for the formation of atoms –

-first Hydrogen and Helium, but it had to cool still more for the other elements to start to form

- As cooling increased, Gravity pulled atoms together into gas clouds that then evolved into stars and young galaxies

Center of Universe?

There is NO CENTER to the universe

Expansion looks the same regardless of

where you are in the universe.

Every point appears to be the center

of the expansion, therefore no point is

the center.

Big Bang evidence

1) Universal expansion and Hubble’s Law

2) Cosmic microwave background radiation

3) Abundance of light elements

1. Hubble’s Law

The rate at which a galaxy is moving is directly proportional to its distance from us.

In other words, the farther away a galaxy is from us, the faster it travels away from us.

Because of this traveling away from us the universe is expanding.

Age of the universe

Since astronomers know how fast the universe is expanding, they can infer how long it has been doing so.

- this is based on evidence of the Red Shift

Now estimated at 13.82 BY

We can’t see the Big Bang

The Big Bang occurred a very long time

ago, before pictures, etc

Astronomers have to use what they can

see now to “see history”

For example, it takes years for some light

to reach us

What we are looking at is “history”

Why Support Big Bang?

Explains the red shift we see today in galaxies What’s a red shift???

Light Spectrum background

Frequency of the visible light waves

and the Doppler Effect

Remember, The Doppler Effect: when a sound is

coming TOWARD us, we hear it at a higher

frequency

When the sound passes us, we hear it at a lower

frequency (sirens)

The same is true for light waves:

When light is moving towards us we “SEE” the

higher frequency end of the spectrum: the blue

spectrum

When light is moving away from us, we “SEE” the

lower frequency end of the spectrum: the red

spectrum

The Universe is Expanding

By looking at a star’s spectrum (lines that indicate what elements are in star) you can determine whether it is moving toward or away from you

Edwin Hubble discovered this phenomenon

How the Universe Expands

The space between galaxies expands, not the galaxies themselves; objects held together by their own gravity are always contained within a patch of nonexpanding space.

Example: raisins in a loaf of bread.

As the dough rises, the overall loaf of bread expands; the space between raisins increases but the raisins themselves do not expand.

Expanding Cake Analogy

Just as all the chocolate chips move apart as the cake

rises, all the superclusters of galaxies move away from

each other as the space of the Universe expands.

Evidence of the Big Bang

2. The cosmic microwave background

(CMB) radiation

The early universe should have been very

hot. The cosmic microwave background

radiation is the remnant heat leftover

from the Big Bang.

WMAP’s Baby Picture of the Universe –

Cosmic Microwave Background

Radiation

Bell Laboratories

Penzias and Wilson (1965) were radio astronomers who worked for Bell Telephone Laboratories.

Found a mysterious microwave signal causing background noise in their radio telescope.

The signal came from everywhere.

Arno Penzias Robert Wilson

COBE

Cosmic Background Explorer (1989)

Probe that looked 15 billion light years

into space to detect tiny temperature

changes.

These temperature changes were

evidence of the heat left over from the

Big Bang.

In Search of The Earliest Photons

Wilkinson Microwave Anisotropy Probe

(WMAP) satellite, launched in 2001

WMAP

In June 2001, Wilkinson

Microwave Anisotropy

Probe (WMAP)

captured the “glow” of

the Big Bang by

detecting temperature

changes just like COBE.

WMAP was much more

precise.

Historical Observations of the CMB & Anisotropy

Cosmic Microwave Background indicates that

Space-time is Flat – Universe could slowly

expand forever

3. Evidence of the Big Bang

The abundance of the light elements H, He, Li

The Big Bang theory predicts that these light elements should have been fused from protons and neutrons in the first few minutes after the Big Bang.

Predicted abundance of elements heavier than hydrogen, as a function of the density of baryons in the universe (expressed in terms of the fraction of critical density in baryons, Omega_B and the Hubble constant)

So what About the future?

Here are some ideas:

Open Universe – The universe will continue to expand

forever.

Big Crunch – The universe will slow in it’s expansion

and gravity will pull all matter back into a single point.

Flat Universe – The universe will slow its expansion

and eventually stop.

Fates of the Universe

Open Universe – little gravity that outward

expansion goes on forever

Closed Universe – gravity will eventually

halt the expansion and draw everything.

Also known as the Big Crunch

Possible Shapes of Space-time,

and the Fate of the Universe

• Closed – Universe would collapse.

• Flat – Universe could slowly expand forever.

• Open – Universe would expand forever.

Expansion of the Universe is

speeding up

Very distant Type 1a Supernovae are not as bright as they should be.

This means the expansion of the Universe is speeding up instead of slowing down or staying the same.

There is something really weird called Dark Energy (not the same as Dark Matter) that is causing this acceleration.

Dark Energy acts like anti-gravity, pushing the Universe apart.

We do not know what this Dark Energy is, but it makes up 73% of the total energy/matter of the Universe.

Composition of the Universe

Suppose all the matter and energy in the Universe is $100 in your wallet or purse.

$73 would be Dark Energy – the mysterious energy that’s pushing the Universe apart faster and faster.

$23 would be Dark Matter – matter that doesn’t give off any kind of radiation, so we can’t see it – but it does have gravity.

So out of your Universe of $100, $96 represents Dark Energy and Dark Matter that have yet to be identified.

Only $4 would be visible matter – the regular stuff we can see, like stars, gas clouds, and dust – the same stuff we’re made of.

Of the visible matter ($4), only one-tenth of it shines as stars. That’s 40 cents out of your total $100. The rest of the visible matter is gas clouds and dust.

Dark Matter

Dark matter – is matter that does not give off

radiation, but still has gravitational properties.

Dark Matter – cannot be seen directly, but its

presence can be detected by observing its

gravitational effects on visible matter.

With out it in our universe, it would be hard to tell

how fast everything would keep expanding.