The most convincing theory to the
start of the universe, galaxies are
moving away from us moving faster as
they get further away so something
must have started them moving,
probably a big explosion......"big bang"
according o this theory all matter and
energy in the universe must have been
compressed into a tiny space then
exploded from that 'point' and started
expanding.
this is the expansion that's still
happening now can use the
current rate of expansion to
estimate the universes' age our
guess is 14 billion years
another theory is the "steady state" theory
which says the universe has always been
the same as it is now and always will be,
based on the idea that the universe seems
to be very similar everywhere the theory
explains the expansion by saying that
matter is being created in the spaces
where the universe expands
the discovery of cosmic microwave
background radiation was strong evidence
for the big bang theory and strong
evidence against the steady state theory
Cosmic microwave background radiation
there's a uniform microwave radiation
from all directions
its low frequency electromagnetic
radiation(mainly microwave)
coming from all parts of the
universe
the big bang theory is the only
one which can explain CMBR
just after the big bang whilst
everything was very hot everything in
the universe emitted high frequency
radiation as the universe cooled due
to its expansion the radiation has
dropped in frequency and is now
seen as microwave radiation
nearly all astronomers
agree there was a big bang
yet some still believe in
"steady state" as they say
evidence points in "steady
states" direction or don't
want to admit they were
wrong
there are problems with
"big bang" theory as it
doesn't explain all
observations
the big bang theory says the
universes expansion should
be slowing down yet it
seems to be speeding up
it doesn't explain what caused
the big bang or what it was
like, if anything before the big
bang