Big%20Bang%20Theory%20

1
Big Bang Theory A History
1927 Belgian priest Georges Lemaître proposes
that the universe began with the explosion of a
"primeval atom". Einstein develops a
mathematical model of how gravity works on the
scale of the entire universe and discovers that
his equations suggests that the universe should
be expanding. Believing this to be nonsense he
adds a fudge factor called the cosmological
constant to recreate a steady-state
universe. 1930s Hubble observes the expansion
of the universe Hubble's law George Gamov
suggests that if the universe is expanding then
at one point in time it must have been very
small, and very hot Fred Hoyle an opponent of
the expanding universe theory coins the term Big
Bang to ridicule the theory. Hoyle's
steady-state theory explained the expansion in a
way that didn't require the universe to have ever
been small The debate continued until the
discovery of the Cosmic Microwave
Background radiation.
2
The Cosmic Microwave Background
Proves that the universe was once small! George
Gamov's theory suggested that once the universe
was so small that it must have been hot enough to
generate nuclear reactions like in the centre
of a star. This early universe would have
initially been opaque to light, but then as it
expanded the light would escape as a hot
blackbody radiation.
This radiation would cool as the universe
expanded until after 13 billion years (the
present age of the universe) it would be 2.7 K,
or microwave radiation. Penzias and Wilson from
Bell Labs in the early 1960s built a microwave
receiver for satellite communications and
noticed that where ever they pointed their
receiver they picked up a strong background
noise. Turns out that they were receiving
this microwave radiation created from beginning
of the universe.
3
The COBE satellite in 1990 revealed that the
radiation is not perfectly smooth but has ripples
the formation of galaxies and structure in the
universe
4
Solves Olber's paradox
5
Future of the universe depends upon it's
density compared to the critical density
6
Dark Matter COBE showed us that the
universe is flat (ripples look the same in all
directions) BUT not enough visible matter in the
universe to reach critical density In fact for
the universe to be flat it must contain over 90
dark matter! Also the rotation curves of
galaxies suggest that galaxy halos are
dominated with dark matter. Maybe galaxies
formed in dark matter gravitational wells.
7
What is Dark Matter? MACHOs WIMPs MOND
8
Dark Energy In fact the universe is expanding
more quickly than it should be. Supernova
observations. Big Rip