Download TheExpansionoftheUniverse

THE EXPANSION OF THE
UNIVERSE!
Einstein
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The discovery of the expansion of the universe
was first found by Einstein
-Disagreed with this point- as he believed the
earth was static and unchanging.
- In his equation he created what is called the
‘cosmological constant’
- Which proved the universe was static and
unchanging
Friedmann
Considered Einstein made an error, set out to prove
the universe was expanding based on the theory of
relativity.
Assumed
 1. Universe appears the same in every direction you
look
 2. This is true for whatever your viewpoint in the
universe is
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Friedmann Equation
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finding were verified by Belgian
astronomer Georges Lemaitre in 1927
Radius of
curvature of
space increases
with time
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Three models that satisfy his assumptions
1. ‘Closed’ Universe’-(by Friedmann) mutual gravitation of
universe is able to stop expansion, then pulling matter backcontracting it again.
“Flat Universe’-(Dutch astronomer Willem de Sitter in 1912)
universe is just faster enough to balance the force of gravity,
the expansion will slow but not stop.
“Open universe”- universe is expanding so fast gravity cannot
stop it.
Models
Hubble
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Hubble is accredited with the discovery of the
expansion of the universe; this is because in 1924
he discovered Andromeda was not as star, but in
fact a galaxy.
800,000 light years it was further than most stars
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Measured the red shift of the light- which is finding
specific wavelengths of the light. This similar to the
Doppler Effect (relationship between speed and
wavelength)
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measuring the degree of the red shift it possible to
calculate how fast it is moving away
measured more galaxies were mostly moving away
from earth- he also found that the further the object
was from earth, the faster it was moving.
explanation for the expanding Universe is that it is
the space between the galaxies
Hubble’s Law
ν=H0D
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ν = velocity of recession (km s-1 )
D= Distance from us (megapacsecs, Mpc)
H0 = Hubble’s constant aprrox. Equal to 70 km S-1 Mpc-1
1 megaparsec is 3.26 million light years
I.e. If a galaxy 1 megaparsec away will be moving away from
us at a speed of about 70 km/sec
Hubble was also able to find the approximant age of the universe which is
12-14 billion years ago.
Issues
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As technology has improved we have able to more
accurately calculate the expansion of the universe.
As technology advances people will be able even
more accurately find the distance of objects which
will define more clearly Hubble’s constant.
However this is also a problem as Hubble constant,
will change- this will mean everything else must be
readjusted to new constant and may cause major
problems
Friedmann made two assumptions they are
 1. Universe appears the same in every direction you
look
2. This is true for whatever your viewpoint in the
universe is.
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the accepted models are based entirely on these
assumptions, if they were found to be incorrect or
untrue this would completely change the view of the
universe as we would have no model of the universe
and how it works
As these are assumptions they are not known. This
means people do not have enough information to
make definitions on universe the universe works
evidence against the expansion of the
universe
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tired-light theory- this theory suggests that lost energy
disappears from the universe completely-even tho it
goes against the First Law of Thermodynamics;
Paul LaViolette was one of the first people to disprove
the expanding universe theory some of his work
suggested cosmological red shift- which would indicate
that the universe was static
also tested four different techniques which mainly fitted
with his theory where as it was found that scientist’s
regularly change the expanding universe models to fit
their data.
Evidence for the expansion of the
universe
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much more evidence for the expansion of the
universe which does suggest that the universe is
expanding, and not static.
the observation of a 1a supernova, two scientists in
America found that the remnants of the star were
found to be 15% further away than the standard
model predicts.
evidence that the universe is expanding as an open
universe, and the expansion rate is increasing.
Bibliography
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Unknown (1998) Evidence mounts that the expansion of the Universe is accelerating [internet]. Unknown;
Institute of Physics and IOP Publishing. Available From: http://physicsworld.com/cws/article/news/3137
[accessed 22/8/09]
Unknown (2008) Evidence Against the Expanding Universe Hypothesis [internet].Unknown; unknown. Available
from: http://www.etheric.com/Cosmology/redshift.html [accessed 22/8/09]
Wu F. (2009) The Big Bang [internet] Unknown; Unknown Available From: http://highered.mcgrawhill.com/sites/dl/free/0070138354/676284/Chapter_18_TheUniverseBegins.pdf [accessed 23/8/09]
White M (unknown). The Hubble Expansion [internet] USA; UC Berkeley Available From:
http://astro.berkeley.edu/~mwhite/darkmatter/hubble.html [accessed 23/8/09]
Hawking S. (2001). The Universe in a Nutshell London: The Random House Group Ltd.
Andriessen M. Lofts G. Morante R. Barry Mott J. (2009) Physic 1: Preliminary course Australia; John Wiley &
Sons Australia Ltd.