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.

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 ”

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

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

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.

Two ways of Estimating the Real age of the UNIVERSE :

• BIG BANG

• OLDEST STAR

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.

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 yearsHalf massive – 20B years2x massive – 300M years10x massive – 20M years

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.

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.

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.