Download Cosmic Times - Klenk Astronomy

COSMIC TIMES
The History Behind The Big Bang Theory
• 1919
• Albert Einstein’s Theory of Relativity and Law of
Gravitation was confirmed when the light from stars was
bent around the sun
• Einstein’s model also predicted that the universe is
either expanding or contracting
• He didn’t like this so he added a universal (or cosmological
constant) so that the universe would be static
• Sun is not the center of the galaxy
• Galaxy is all-encompassing (only one galaxy)
• Other “nebulae” are still a part of our galaxy
The History Behind The Big Bang Theory
• 1929
• Edwin Hubble discovered that the “nebulae” observed,
are much farther away than we expected, which means
they are their own galaxies
• Hubble also found that objects are moving away from
us
• Red shifted
• Hubble found that objects are moving away, the
universe is expanding.
• Einstein’s original Theory of Relativity called for
expansion, but instead he added the cosmological
constant. Even after these new discoveries, Einstein
was still not convinced.
The History Behind The Big Bang Theory
• 1955
• Albert Einstein passed away
• Cepheid variables had been used to calculate the
distance of far objects, however, they had been used
incorrectly.
• There are two types of cepheid variables.
• Combination of scientists determined that a nova is far
different from a “super”nova.
• Two types of supernovae. (composition)
• Steady State vs. Big Bang
• First studies of radio transmissions
The History Behind The Big Bang Theory
• 1965
• Found microwaves (possible remnant of big bang) CMB
• Ideas of open vs closed universe
• In an attempt to calculate the mass of a galaxy,
Burbidge and others found that there is more matter
than can be see. (dark matter)
• No current explanation (must be miscalculation)
• Begin studying X-rays, but do not currently have a good
way to study things above the atmosphere
• No orbiting telescopes
The History Behind The Big Bang Theory
• 1993
• In 1989, COBE found that the CMB was not completely
uniform.
• Big Bang Theory gets a tune-up: Inflation
• Following Big Bang, Inflation was extremely fast and hot
expansion. After inflation, everything began to slow down and
cool off.
• ROSAT found an area of extremely hot gas.
• Should have diffused away, so something must be holding it in
place.
• Beginnings of dark matter
• Discovery of two different types of supernovae
• Confirmation of existence of gravitational waves,
predicted by Einstein
The History Behind The Big Bang Theory
• 2006
• Discovery of Dark Energy in addition to Dark Matter
• Dark energy is speeding up the expansion of the universe?
• Einstein’s cosmological constant actually accounted for this
• Scheduled launch for JDEM is 2013
• Study Dark energy
Big Bang Theory
• Historically…
• 1912 - Vesto Slipher
• Measured the first Doppler shift (red shift)
• Object in space is moving away from us
• 1922 – Alexander Friedman
• Used Einstein’s relativity to show that the universe might be expanding
• 1924 – Edwin Hubble
• Measured the distance to other galaxies
Big Bang Theory
• Historically…
• 1927 – Georges Lemaitre
• Predicted the recession of nebulae was due to the expanding
• 1931 – Georges Lemaitre
• Followed the logical backward thought…
• So if the universe is far apart now, at some time in the past it was very
close
• Primeval atom
• Before which time & space did not exist
Big Bang Theory
• Historically…
• 1924 – Edwin Hubble
• Series of distance indicators
• 1929 – Hubble’s Law
• the velocity at which various galaxies are receding from the earth is
proportional to their distance from us
• The farther away they are, the faster they are moving
Big Bang Theory
• Historically…
• 1930s (through 1960s)
• Many Non-Standard Cosmological Theories were introduced
• Any cosmological model of the universe that is an alternative to the Big Bang
• Many have disputed parts of the Big Bang theory or the Big Bang theory
as a whole
Big Bang Theory
• Some opponents to Big Bang
• Newtonian cosmology
• Lorentzian universes
• static universe
• Machian universe
• Gödel's universe
• MOND – Modified Newtonian Dynamics
• TeVeS - Tensor-vector-scalar gravity
• Steady state theories
• Tired light
• Dirac large numbers hypothesis
• Plasma cosmology
Cosmic Microwave
Background Radiation
• Possibly the single most influential factor that contributed
to the general acceptance of the Big Bang theory
• The discovery and confirmation of the cosmic microwave
background radiation in 1964 secured the Big Bang as the
best theory of the origin and evolution of the cosmos
The Big Bang Theory
• The universe, originally in an extremely hot and dense
state (singularity or primeval atom),
• That expanded rapidly, (the big bang),
• And has since cooled by expanding to the present state,
• And continues to expand today
What happens from here?
• Two main theories on the universe as a whole:
• Open
• Closed
Open Universe
• The term open universe refers to a universe
which has no physical or practical barriers to it's
continued expansion.
• If the universe is indeed open, then the universe
can continue expanding forever.
• Big Rip
• Big Freeze
• If the universe cannot expand forever, then some
barrier must exist to prevent the expansion.
Closed Universe
• The second model of the universe is one in which the
curvature of space is roughly spherical, because of that
the universe has a finite size
• An object moving in a straight line in a closed universe
would eventually return to its starting point.
Closed Universe
• According to most current cosmological theories,
the universe is closed if it is sufficiently dense,
and therefore possesses enough gravitational
force to stop or reverse the expansion started by
the big bang
• Big Crunch
• Big Bounce
4 Ways for the Universe to End
• The Big Rip: The big rip is a theory that occurs
following general relativity, it states the universe will
continue to expand at an accelerated rate,
eventually reaching a point where life cannot exist.
The accelerated expansion occurs due to dark
energy, leading to everything being ripped apart
into elementary particles.
4 Ways for the Universe to End
• The Big Freeze: The big freeze theory suggests that
the universe will continue to expand until it becomes too
cold to support life. This can only occur for certain
shapes of the universe, which allow it to expand
forever. The heat death theory is related to this and will
occur for all three models of space, and requires a
minimum temperature to be reached. It suggests
everything is evenly distributed and life cannot be
supported.
4 Ways for the Universe to End
• The Big Crunch: The big crunch assumes that the
average density of the universe will stop it expanding and
it will begin to contract. This may cause it to collapse into
a singularity, which may then lead to a big bang creating
another universe. If this is repeated then the universe is
an infinite cycle of universes starting in big bangs and
ending in big crunches.
4 Ways for the Universe to End
• Big Bounce: This suggests that we might be
living in the first of all universes, but are equally
likely to be living in the 2 billionth universe (or any
of an infinite other sequential universes).
• Similar to the Big Crunch (repeated)