Evidence to support the...
But first, what’s a scientific theory?
• The term “theory” in science has a different
meaning than in our everyday language.
• A scientific theory is NOT a guess or a shot in
the dark explanation for something
• A scientific theory is a plausible explanation
for phenomena in nature supported by
evidence and builds upon scientific laws.
• Scientific law describes a relationship
between factors or what should occur in a
certain situation because of previous
repeated observation.
ex. Newton’s Law of Universal Gravitation
• Scientific theory will try to explain why we
repeatedly see these relationships and
observations through experimental
evidence.
ex. Einstein’s Theory of Relativity
What is the Big Bang Theory?
13.7 billion years ago the universe formed
when an infinitely dense point suddenly
and rapidly expanded in a single moment.
Evidence to Support the Theory
1.Redshift Spectra and Hubble’s Law
• Edwin Hubble observed the line spectra from many
different galaxies in the sky
• most of the spectra for the galaxies were shifted towards
the red end of the spectrum – a redshift
• Hubble concluded that if most of the galaxies were
redshifted, they must be receding in all directions and
the universe is expanding from a single point – BIG BANG
Evidence to Support the Theory
2.Cosmic Background Radiation
In 1965 Arno Penzias and Robert Wilson were using a
new microwave antenna with the intention of using it for
telecommunication.
What they picked up
was microwave
radiation from the sky
in all directions, not
just from stars
But what did that
mean?
Evidence to Support the Theory
Cosmic Background Radiation
Penzias and Wilson unintentionally discovered cosmic
background radiation.
It is believed that this is leftover radiation from the initial
big bang.
Penzias and Wilson later
won a Nobel Prize for their
serendipitous find.
Evidence to Support the Theory
3. Radiation Mapping
Cosmic Background Explorer (COBE) satellite created detailed
maps of the background radiation from distant parts of the universe
in 1992.
Wilkinson Microwave Anisotropy Probe (WMAP) in 2006 provided
even more precise measurements of the radiation.
Evidence to Support the Theory
Radiation Mapping
analysis of temperature differences and microwave
polarization from these maps provided the point of
inflation
Inflation is the idea that the universe expanded
many trillion times its size faster than a snap of the
fingers at the outset of the Big Bang
This breakthrough that enabled scientists to analyze
what happened less than a trillionth of a trillionth of
a second after the Big Bang.
Evidence to Support the Theory
4.Proportion of Matter in Stars
• Simplest atoms, hydrogen, gets cooked into
heavier elements at a high enough temperature
and density (such as the cores of stars).
• In the early hot and expanding universe only
enough time to fuse hydrogen to helium before
expansion and cooling shuts it down.
Isotopes of
Hydrogen
Evidence to Support the Theory
Proportion of Matter in Stars
The theory is 12:1 ratio hydrogen to helium by
number, or 75% 25% by mass, from the Big
Bang.
Most matter detected from the universe fits this
composition supporting the Big Bang Theory.
Evidence to Support the Theory
5. Observation of Distant Galaxies and Stars
An expanding universe is evolving over time. If we look at
the early universe, it should appear different.
Distant galaxies therefore
appear as they did in a less
evolved universe.
These early galaxies are more
disturbed because of collisions
with other galaxies, smaller and
contain fewer heavy elements
Evidence to Support the Theory
6. Expanding Dynamic Universe
According to Einstein, space-time of the universe is expanding
and because of it the galaxies are drifting apart.
Evidence to Support the Theory
Expanding Dynamic UniverseRaisin Bread Analogy
Where do we go from here?
Dark Energy
The unknown energy that is causing the acceleration of
the expansion of the universe.
Supernovae in distant galaxies are further (so dimmer)
than they should be, thanks to an accelerating universe.
They are traveling faster than predicted by their redshift
spectrum according to Hubble’s Law.
Through the study of light from these distant
supernovae, it was determined that the slowing universe
started to speed up again 5 billion years ago.
Where do we go from here?
Dark Matter
• 90% of matter in and between galaxies is of an unknown
form that does not emit or absorb light (so we can’t see
it).
• It can be detected through its gravity by the way it affects
objects we can see.
• Without dark matter, normal matter would have been
unable to clump and form stars and galaxies - and us.
“Normal Matter”
4%
Dark Energy
73%
Dark Matter
23%
CERN HADRON COLLIDER
http://www.youtube.com/user/CER
NTV?blend=9&ob=5#p/c/C193B03B
29D263DE/0/UDoIzvKumGI
• The Large Hadron Collider (LHC) is a gigantic
scientific instrument near Geneva, where it spans
the border between Switzerland and France
about 100 m underground
• It is a particle accelerator used by physicists to
study the smallest known particles – the
fundamental building blocks of all things
• It will revolutionise our understanding, from the
minuscule world deep within atoms to the
vastness of the Universe.