1. The Big Bang Theory
By Marina García, Jade Turner and
Marina Pascual 4º ESO B

2. What is the big bang theory? (Jade)
The Big Bang Theory is the way we explain
what happen for the creation of our Universe. It
is the model that describes the early discovery of
it.

3. When did it take place?
It occurred approximately 13,7 billion years ago.
And the Universe was extremely hot and dense.
There are many hypothesis surrounding the Big
Bang Theory, one of these is that people tend to
imagine a giant explosion, but however it was
not, it is a continuous expansion.

4. TIMELINE:

5. What happened next?
After the initial expansion, the Universe cooled
enough to allow energy to be converted into
various subatomic particles, including protons,
neutrons and electrons.

6. One of the results of the Big Bang:
Forces
One result of the big bang was the formation of the four
basic forces in the universe:
– Electromagnetism
– Strong nuclear force
– Weak nuclear force.
– Gravity
Physicists and cosmologists are working of the Grand
unified theory, which would explain how these four
forces were once united and how they relate to each
other.

7. One of the results of the Big Bang :
Atoms
The majority of atoms that were produced by
Big Bang Theory are hydrogen, helium and
traces of lithium.
Giant clouds of these primordial elements later
coalesced through gravity to form stars and
galaxies, and the heavier elements were
synthesized either within stars or during
supernovae.

8. Result of the observations
The core ideas of the Big Bang, the expansion,
the early hot state, the formation of light
elements, and the formation of galaxies, are
deriver from these observations.

9. How the Big Bang Theory is supported?
Astronomers combine mathematical models with
observations to develop workable theories of
how the Universe came to be. According to
many experts, space did not exist before the Big
Bang.

10. One of the supporters of the Big Bang
Theory: Theory of Relativity
The mathematical support of the Big Bang
Theory includes Albert Einstein’s Theory of
Relativity along with standard theories of
fundamental particles.

11. One of the supporters of the Big Bang
Theory: The Doppler effect
Austrian physicist Christian Doppler discovered that the
frequency of a sound wave depended upon the relative
position of the source of the sound.
As a noisy object approaches you, the sound waves it
generates compress.
This changes the frequency of the sound, and so you
perceive the sound as a different pitch.
When the object moves away from you, the sound
waves stretch and the pitch goes down.

12. What happened:
If we would have looked at the Universe one
second after the Big Bang, we would see a 10
billion degree mass of neutrons, protons,
electrons, positrons, photons and neutrinos.

13. What happened:
Then, as time went on, we would see the
Universe cooling down, the neutrons decaying
into protons and electrons, or combining with
protons to make an isotope of hydrogen.

14. What happened:
As it continued cooling, it eventually reach the
temperature where electrons combined with
nuclei to form neutral atoms.

15. What happened:
Before this ‘recombination’ occurred, the
Universe would have been opaque because the
free electrons would have caused light. But when
the free electrons were absorbed to form neutral
atoms, the Universe became transparent, and that
is why we nowadays see the cosmic background
radiation.

16. Evidence for the Theory:
1. We are sure that the universe had a beginning.
2. Galaxies appear to be moving away from us at speeds
proportional to their distance; this is called ‘Hubble’s
Law’
3. If the universe was initially very hot, we should be
able to find some remnant of the heat (Cosmic
Microwave Background radiation).
4. The abundance of light elements, hydrogen and
helium found in the observable universe.

17. Alternative models to the Big bang
Theory: The Steady-State Model
The steady-state model of the universe suggests
the universe always had and will always have the
same density. It suggests that the universe
generates matter at a rate proportionate to the
universe's rate of expansion.

18. Alternative models to the Big bang
Theory: The Ekpyrotic model
The Ekpyrotic model suggests our universe is
the result of a collision of two three-dimensional
worlds on a hidden fourth dimension.

19. Alternative models to the Big Bang
Theory: The Big Bounce Theory.
The big bounce theory suggests our universe is
one of a series of universes that first expand,
then contract again. The cycle repeats after
several billion years.
Plasma cosmology attempts to describe the
universe in terms of the electro-dynamic
properties of the universe.

20. We do not know where it came from, why it is
here, or even where it is. All we really know is
that we are inside of it and at one time it did
not exist and neither did we.
One of the goals has long been to decide
whether the Universe will expand forever, or
whether it will someday stop, turn around, and
collapse in a ‘Big Crunch’.