Transcript The Big Bang Theory

The Big Bang
Theory
* A small disclaimer: the Big Bang theory
is taught as a theory. I am not trying to
change your beliefs in any way. I am just
simply stating some observations made
by some really smart people!
What is the Big Bang Theory?
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The theory states
that the universe
violently expanded
in a single event
called the “Big
Bang”.
Occurred 10-20
billion years ago.
The universe has
been expanding
since.
Notes of Concern!
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It is believed that all matter and radiation was
packed into a primeval fireball no larger then
the period at the end of this sentence.
There was no “bang” or “explosion”, it is just
a term.
Since there was no space prior, the big bang
was more of an unfolding of space and
matter from a very small region. Also time as
we know it started.
What was created at the onset of
the Big Bang?
Matter (Something that has mass and takes up space.)
 Energy ( ex. Radiation /Light )
 Time (A condition which has a past, present and future.)
 Space (What the universe filled in.)
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The first second
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In one-millionth of a
second after the Big
Bang, the Universe
was a hot, seething
mass of radiation and
exotic particles.
This mass expanded
and cooled, forming
protons, neutrons and
electrons (subatomic
particles).
Minutes later……..
These
subatomic
particles
grouped
together
forming the first
atoms of
hydrogen and
helium.
After several billions of years…
GRAVITY caused clouds of gas to collapse,
forming planets, stars, and galaxies.
And today…
The present day Universe continues to expand.
Galaxies and stars are continuing to move away
from one other.
SO WHY DO SCIENTISTS
BELIEVE THIS THEORY?
The Big Bang is accepted because of
three very persuasive pieces of evidence.
1. Red shift
2. The relative amounts of certain
chemical elements in the universe
3. The existence of cosmic radiation
detected by microwave telescopes
1. Red Shift
When a star or galaxy's light is looked at
through a special instrument called a
spectroscope, scientists observe that the
wavelengths have shifted toward the red end
of the spectrum.
Red shift cont…
The red end of the spectrum has longer
wavelengths, thus meaning the object is
moving AWAY from the observer.
Example: When you hear an ambulance
siren approaching, and then moving away.
2. Chemical Make-up
Since, according to this theory, all matter was created at
the Big Bang, the Universe today retains an imprint of its
initial cosmic mixture.
Astronomers can analyze a star’s
chemical make-up and the ratio of
hydrogen to helium.
The amounts of these gases agree with
what the Big Bang theory predicts.
The most convincing piece of
evidence…
COSMIC BACKGROUND
RADIATION
3. Cosmic Background
Radiation
The last signs of heat left over from the
Big Bang.
 That original energy has cooled to -455F
(a hundred million times cooler than a
typical birthday candle!)
 Can be detected by microwave
wavelengths.
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How will it end?
The ultimate fate of our
universe will be
determined by the
competition between the
outward expansion:
(Momentum of matter),
and the inward pull of
gravity
(I’ve been told, in the end,
gravity always wins)
The future of uncertainty
There are several interesting scenarios,
ranging from never ending expansion, to a
contraction inward called the Big Crunch.
 It all depends on the density of the
Universe, and that depends on the amount
of matter it contains.
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