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A ( very ) Short Story of the Big Bang. Andrzej Radosz Institute of Physics Wroclaw University of Technology email@example.com. 1. Introduction: night sky’ paradox 2. How big is Universe? 3. Hubble’s discovery 4. Three principles 5. Scale parameter 6. Closed , open or flat.
Institute of Physics
Wroclaw University of Technology
2. How big is Universe?
3. Hubble’s discovery
4. Three principles
5. Scale parameter
6. Closed , open or flat.
7. How old is Universe?
8. What was before Big Bang?
9. WHAT IS THE FATE OF THE UNIVERSE?
1692 -I. Newton: the Universe is infinite otherwise it should
have collapsed (gravitational attraction)
1736 -E. Halley: the Universe is finite otherwise the night
sky should be bright
1821 -W. Olbers: in the infinite, homogenous universe
energy reaching the Earth should be infinite (night
1990 -S. Hawking:at the beginning of the XX century the
night sky- paradox was the only cosmological
Eerie, dramatic pictures from the Hubble telescope show newborn stars emerging from "eggs" — not the barnyard variety — but rather, dense, compact pockets of interstellar gas called evaporating gaseous globules (EGGs). Hubble found the "EGGs," appropriately enough, in the Eagle nebula, a nearby star-forming region 7,000 light-years from Earth in the constellation Serpens
View all images
One of the nearest globular star clusters, called NGC 6397, resembles a treasure chest of glittering jewels. The cluster is located 8,200 light-years away in the constellation Ara.
Stellar swarm, M80 (NGC 6093), one of the densest of the 147 known globular star clusters in the Milky Way Galaxy. Located about 28,000 light-years from Earth, M80 contains hundreds of thousands of stars, all held together by their mutual gravitational attraction.
165 000 LY
NGC 1313, (13.5 M light years)a bright but rather isolated galaxy classified as a barred spiral galaxy (although with very short and irregular spiral arms). This galaxy has recently (within the past billion years) collided with a satellite galaxy, and the material at the bottom-right of this picture are the remains of the satellite galaxy.
19.1 megaparsecs -
60 M LY
Our galaxy is just one of thousands that lie within 100 million light years. Galaxies tend to cluster into groups, the largest nearby cluster is the Virgo cluster a concentration of several hundred galaxies which dominates the galaxy groups around it. Collectively, all of these groups of galaxies are known as the Virgo Supercluster. The second richest cluster in this volume of space is the Fornax Cluster, but it is not nearly as rich as the Virgo cluster.
Number of galaxy groups within 100 million light years = 200
Number of large galaxies within 100 million light years = 2500
Number of dwarf galaxies within 100 million light years = 25000
Number of stars within 100 million light years = 200 trillion
The Virgo cluster is a massive cluster of galaxies which dominates the Virgo supercluster. There are roughly 2000 galaxies in this cluster (although ninety percent of them are dwarf galaxies). This cluster has a diameter of approximately 15 million light years which is not much larger than our Local Group but it contains fifty times the number of galaxies.
It is not possible to get a good photograph of the entire Virgo cluster because the galaxies are rather faint and small objects scattered across 15 degrees of the sky. Below is photograph of the centre of the cluster showing the inner 4°x4° region. Most of the brightest objects in this picture are galaxies. The elliptical galaxy in the centre is M87. On the right can be seen two other large elliptical galaxies - M86 and M84. To the left of M87 is another large elliptical galaxy M89 and above M89 is the large spiral galaxy M90.
Hubble telescope was used to observe 19 galaxies out to 108 million light-years. They discovered almost 800 Cepheid variable stars, a special class of pulsating star used for accurate distance measurements. Here is a picture of one of those galaxies. It is the spiral galaxy NGC 4603, the most distant galaxy in which Cepheid variables have been found. It is associated with the Centaurus cluster, one of the most massive assemblages of galaxies in the nearby universe.
A rare and spectacular head-on collision between two galaxies appears in this Hubble telescope picture of the Cartwheel Galaxy, located 500 million light-years from Earth in the constellation Sculptor.The striking ring-like feature is a direct result of a smaller intruder galaxy — possibly one of two objects to the right of the ring — that careened through the core [close-up image at lower left] of the host galaxy.
Number of galaxy groups in the visible universe = 25 billion
Number of large galaxies in the visible universe = 100 billion
Number of dwarf galaxies in the visible universe = 10 trillion
Number of stars in the visible universe = 20 billion trillion
Almost every object in this image is a galaxy typically lying 5 to 10 billion light years away.
The galaxies revealed here are all shapes and colors, some are young and blue,
whereas others are old, red and dusty.
It is probable that our universe is infinite and has been filled with matter everywhere since the Big Bang There is also good evidence that in the early universe that the universe may have expanded much faster than the speed of light. It is possible to inflate space so that although particles are not traveling fast, the space between particles increases enormously.
The Visible Universe
1929 - E. Hubble’s discovery : nebulae, the distant galaxies, similar to our
own Galaxy, Milky Way, are receding.
First cosmological law (Hubble’s law): velocity of distant galaxy is
proportional to its distance from the Earth
(Hubble constant H=50-100 km/s/Mpsc)
1946 - F. Hoyle:“big bang” - beginning of the Universe
1948 - G. Gamow: the Universe appeared from the hot phase;
remnant of this transition should be a presence of the
radiation (blackbody radiation) of T=5K
1964 – A. Penziasand R. Wilsondiscovered a homogenous and isotropic
radiation, T=2.73 K, Cosmic Microwave Background
1993 – Wrinkles of spacetime
Cosmic Microwave Background, CMB, was discovered by Penzias and
Wilson in 1964. This is isotropic and homogeneous radiation which
corresponds to the blackbody radiation, i.e. radiation
emitted by a black body of temperature .
During the expansion the temperature of CMB diminishes inversely
proportionally to the size of/distances in the Universe.
In fact it was emitted 12 billion years ago when the Universe was
300 000 years old.
At that time the Universe was 1100 times smaller and CMB temperature
was 1100 times higher, .
At more early stages the temperature of that radiation was even higher.
What was its value just after Big Bang?
This is an entropy of the Universe;
Einstein’s General Theory of Relativity
In the homogeneous and isotropic Universethere is only one time-
dependent parameter, which scales the distances, . The actual
distance between points (super-clusters of galaxies !) in the Universe is proportional to this scale parameter
This scale parameter is determined by a dynamical equation. That equation
comes out from equations of general relativity
The first case, k=1, corresponds to finiteUniverse – it has got a sense to
speak about a radius of Universe.
The other two cases are associated with an infiniteUniverse – a Universe
has always been infinite.
First estimation of the age of the Universe is an inverse Hubble constant:
However, assuming that the matter domination era has been the
only period of the Universe history one finds a very precise (how
precise?) estimation of the age of the Universe expressed via Hubble
Approaching to the original singularity, moment of creation, one can see
more and more dense, hotter and hotter plasma. This plasma should
eventually reach extreme stage at the initial moment t=0.
Before that, at the very early stage the special circumstances are reached,
at the so-called Planck’s time
At that time one came across the quantum limit of classical Big Bang
scenario. We could not continue our trip back in time to the initial singularity
because our tools (mathematical tools of general theory of relativity) should
be substituted by tools of quantum gravity. According to quantum gravity
(which in fact has not been yet fully designed) there is no time at all and
there is no sequence of events and there is no “before” or “after”.
At the Planck’s era there is no way to go before because there is no
such a meaning.
GTR claims that
(Luminous) Matter density is 1 proton per cubic meter,
and is 1000 times larger than radiation (CMB!) density (energy density of
matter and radiation are compared). But it is still 5-10% of its critical value...
What our Universe is then: closed, open or flat ?