3. How Fast the Universe Expanding?
There are a lot of changes
happens to the universe. Based on
the study of the NASA the expansion
or contraction happens to the
universe depends to its content and
past history.
The expansion of the
universe will slow down or even
become a contraction, where in the
dark energy will drives in towards the
increasing rates of expansion.

4. HUBBLE
The current rate of
expansion is usually expressed in
HUBBLE CONSTANT =
kilometers/second/ Megaparsec or
per second.
“ the hubble ship found that the
universe was not static, but rather
was expanding ”

5. 1920’s Discoveries by HUBBLE
The discovery of Edwin
Hubble is revolutionary because the
variable stars that he discovered had
a characteristic patterns resebling a
class of stars called “CEPHEID
variables” – had shown tight
correlation between the period of it
and its intrinsic brightness.
CEPHEID variable

6. CEPHEID variable
In Cepheid variable by
knowing its luminosity of a source it
is possible to measure the distance
to that source by measuring how
bright ir appears to us: the dimmer it
appears the farther away it is. Thus,
by measuring the period of these
stars (and hence their luminosity)
and their apparent brightness,
Hubble was able to show that these
nebula were not clouds within our
own Galaxy, but were external
galaxies far beyond the edge of our
own Galaxy.
CEPHEID variable

8. How Old is the Universe?
There are a lot of
possibilities and the estimation of the
real age of the universe.
The astronomers look in the
years that the Big Bang occurred it
is about 12 – 14 Billion years ago,
and the solar system it is thought to
be 4.5 Billion tears old and the
human have existed as a genus for
only a few million years.

9. Two ways of Estimating the Real age of the UNIVERSE :
• BIG BANG
• OLDEST STAR

10. Older than the Older Stars?
Astronomers can place a
lower limit to the age of universe by
studying Globular clusters
Global clusters - dense collection of
roughly million of
stars.

11. Older than the Older Stars?
Life cycle of a stars are depends upon its
mass. High mass – much brighter thus rapidly
burn through their supply of
hydrogen fuel.
Low mass – low bright
Life span or Brightness
Sun – brightness for approx. 9B years
Half massive – 20B years
2x massive – 300M years
10x massive – 20M years

12. Older than the Older Stars?
All of the Global clusters can serve
as cosmic clock.
Global clusters – more than 20M
years it burn its
fuel and it is less
massive than 10
solar masses.

13. BIG BANG
In extrapolating back to Big
Bang, the cosmologist use the
“HUBBLE Constant“
- this constant is a measure of the
current expansion rate of the
universe. But it depends on the
current density of the universe and
on the composition of the universe.

14. AGE Crisis?
The contradictions :
1. The measurement of the
HUBBLE constant is incorrect.
2.The Big bang theory is incorrect
3.That we need a form of matter like
cosmological constant implies al
older age for a given observed
expansion rate.