The Big Bang Theory (Part I)

How the Universe began.

Mike StuckeyWarren East High School

Assumptions Made

Assumption 1 :

The universality of physical laws

-> The laws of physics are the same everywhere

FG =GM1M2

d2

FG

=GM

1

M

2

d2

and

Assumptions Made

Assumption 1 :

The universality of physical laws

Assumption 2 :

The cosmos is homogeneous

-> Matter and radiation are spread out uniformly w/ no large gaps or bunches.

Assumptions Made

Assumption 1 :

The universality of physical laws

Assumption 2 :

The cosmos is homogeneous

Assumption 3:

The universe is isotropic

-> same properties in all directions

-> no center and no direction

Assumptions MadeAssumption 1 :

The universality of physical laws

Assumption 2 :

The cosmos is homogeneous

Assumption 3:

The universe is isotropic

CosmologyThe study of the

nature and evolution of the

universe.Not the study of Bill

CosbyNot the study of

cosmetics and beauty supplies.

Imagine

NOTHINGNothing to see !

Nothing to hear !

Nothing to feel !

Nothing to think !

No Matter !

No Energy !

No Time !

No Pizza !!!!!!!!!

Let’s Create

The Universe !!

NOTHINGThen, about 13.7 billion years ago, something

happened …..

A large “explosion”.

A big bang.This is where and when the

universe began.

Energy and time are created, but no matter !!!

The Primeval FireballThe Beginning

Primeval Fireball(The Beginning)

The universe is in an extremely high state of energy, with

temperatures estimated to be greater than 1032 K.

It is just #$?! hot !!!!

But this ball of energy quickly expands and cools, decreasing

the temperature of the universe.

Energy & TemperatureThere is a close relationship between

energy and temperature.

The more concentrated energy there is in a substance the higher that substance’s temperature will be.

The higher a substance’s temperature is the more concentrated energy it

has.

Since the universe is expanding the energy of the universe spreads out decreasing the temperature of the

universe.

This is a key thing to remember!!!!!!!!!!!!

The Heavy Particle EraLets Make Some Protons

Heavy Particle Era

The temperature is greater than 1012 K

Less than 0.000001 seconds after the Big Bang

At these high temperatures (energy), photons collide to produce massive particles and

antiparticles

The most important particles formed are protons and

antiprotons.

Matter & Energy ConversionA matter-antimatter pair is two subatomic particles which are

identical in every way except they have opposite charges.

The antimatter equivalent to a proton is an antiproton.

An antiproton has the same properties as a proton but it has a negative charge.

The antimatter equivalent to an electron is a positron.

A positron has the same properties as an electron except it is positively charged.

Matter & Energy ConversionAt these high temperatures

(energy), photons collide to produce massive particles and antiparticles like protons and

antiprotons.

Antiproton (-)Proton (+)

The amount of matter, m, produced in this collision of photons is determined by the amount of energy, E, of the photons.

E = mc2

If there is more energy available, then more massive particles can be

produced !!!

Heavy Particle Era

The temperature is greater than 1012 K

Less than 0.000001 seconds after the Big Bang

At the end of this era, the universe is a thick soup of

heavy particles, antiparticles and energy.

The most important particles present are the protons.

The Light Particle EraLets Make Some Neutrons & Electrons

Light Particle EraThe temperature is greater than

6x109 K

Less than 6 seconds after the Big Bang

Because of the lower temperatures during this era,

the photons present can’t produce anymore heavy particles. These photons can collide to produce light particles and

antiparticles, like electrons and positrons.

Proton (+)

Electron (-)

Neutron

During this era protons and electrons interact to form neutrons. Antiprotons and

positrons interact in the same way.

At the end of this era the temperature of the universe is below the point where there is

enough energy for matter & antimatter to form from

colliding photons.

The universe consists of heavy and light particles (protons &

electrons) and neutrons.

Just what is needed to start to make atoms!!!

Some of the neutrons decay back into protons and electrons.

The neutrons which survive are very important for the next

era.

Nucleosynthesis Era (Part I)Lets Make Some Nuclei

Nucleosynthesis Era (Part I)

The temperature is around 109 K

Less than 300 seconds after the Big Bang

The neutrons which remain react with the protons to form an isotope of Hydrogen called Deuterium. (1 proton and 1

neutron)The neutrons that don’t form deuterium decay back into an

electron & a proton.

Deuterium fuses to form Helium. At this point the total mass of the Helium formed is about

25% the total mass of the universe.Some Tritium (Hydrogen with 2

neutrons), Lithium and Berylium also form.

In the first 5 minutes after the Big Bang, the protons & neutrons

that formed earlier have formed the first stable nuclei of small atoms.

These atoms still have not captured the electrons because the

temperature is too high at this time.

Nucleosynthesis Era (Part II)Lets Make Some Neutral Atoms

Nucleosynthesis Era (Part II)The temperature is around 3000 K

About 329,000 years after the Big Bang

At these low temperatures the nuclei which have formed can now

capture electrons and become neutral.

This allows light and radiation to pass through the neutral

atoms and expand throughout the universe cooling to around 2.7

K

Matter EraLets Make Some Planets, Stars

& Galaxies

Matter EraThe temperature is less than

3000 K

Over 1 million years after the Big Bang

With the radiation and matter freed from each other, the

pressures which kept the matter from clumping together is now

greatly reduced.

Matter is able to clump together forming galaxies, stars, and the

Earth.

We are still in this era.