The answer to the question: 'WHAT IGNITED THE BIG BANG?'
The universe before and after the Big Bang, until the next Big Bang.
Explained as simply as possible.
The matter (and radiation) hurled
into space by the big bang forms our universe
.
Observations show that all galaxies originate from a single point and keep moving further and further away from that point.
The universe keeps expanding so the distances between the groups of galaxies keep increasing. Since the counter effect of
the gravitational pull between objects in space is negligible compared with the rate at which the universe is expanding,
the universe continues to expand. The momentum that propels the expansion of the universe was launched by the big bang.
The energy radiated by the sun is generated by nuclear fusion. Once it has used up the nuclear fuel, the sun will die.
However, that will not be for a very long time. The sun is thought to be halfway through its life span and has enough nuclear fuel
to keep it going for another 4.5 billion years.
The sun draws its energy from the nuclear fusion of hydrogen into helium. The current theory is that the waste product of this
nuclear fusion goes into the core, because helium is heavier than hydrogen, so the active region of a star increases over time
(nuclear fusion occurs where hydrogen is under the greatest pressure). Therefore, as the sun ages it will radiate more energy.
When the sun was first formed, it was only 75% as bright as it is now.
A certain time, evolution (or technology) can gradually adapt. But eventually life on earth, will cease to exist.
echo "This is the most plausible scenario of the extinction of life on the earth.
By the time the sun is at its brightest, its diameter can have increased to such an extent that it can have swallowed up the earth.
(When a star reaches this stage in its evolution, it is known as a red giant.) If a star is heavy enough and becomes hot enough,
the helium atoms start to fuse to form carbon, then oxygen, then neon, then silicon, and then iron. At that point, any further
nuclear fusion absorbs energy rather than releasing energy.
The named elements are most abundant (silicon is sand, and oxygen combined with hydrogen is water).
The current theory is, that sooner or later the presence of water and a suitable climate will automatically lead to the emergence
of life. And given the nature of nuclear fusion reactions, water is one of the most abundant compounds.
Small stars implode and end up as white dwarfs, while large stars explode in a supernova explosion which hurls the heavier elements,
formed in the stars, out into the galaxy. As much as 50% of the mass of a star can be hurled into the galaxy. The collapsed remnants
of the star can form a neutron star (a celestial body that consists almost entirely of neutrons) or a black hole (an object that has
a gravitational field so high that even light cannot escape).
The Kepler's Supernova, (Chandra X-ray Observatory).
Out of measurements follows that the big bang took place 13.7 billion years ago.
Over a period of approximately 400.000 years, the substance that was hurled into space by the big bang cooled to form atoms - mainly
hydrogen, helium and lithium atoms.
It took approximately 200 million years for enough hydrogen to accumulate to initiate the creation of galaxies. In the beginning, there
was a massive star in the middle surrounded by clouds of hydrogen and other large stars. Clouds of hydrogen are the birthplaces of stars
because they gradually accumulate and form a ball. Once the gravity at the core and the temperature are sufficiently high, it causes
nuclear fusion to ignite, and the star is formed.
All that remains of the star, in the middle of our Milky Way, is a black hole with a mass of 3.7 million solar masses.
Stars with greater mass combust more rapidly. The first large stars died just one billion years after the big bang. The explosion of
these stars created the galaxy we know today, with heavier elements and without a massive star in the middle. Just 9.2 billion years after
the big bang enough hydrogen had accumulated to ignite our sun.
Some of the matter that was hurled into the galaxy as the stars exploded went out into space and some of it was pulled into orbit by the
gravitational fields of stars and gas clouds. That was how the planets were formed. The planets consist of matter that was hurled into the
galaxy by exploding stars.
The Andromeda Galaxy is our nearest galaxy.
It is 2.7 million light years away and is moving towards our Milky Way at a speed of 120 kilometers per second. It is estimated to be 250.000 light years in diameter.
Galaxies occur in groups. The Local Group, to which our galaxy belongs, is a cluster of more than 40 galaxies. It is approximately 10 million light years in diameter.
Some of our neighboring galaxies are moving towards us and will eventually merge with our galaxy. But the groups of galaxies are moving away from one another.
Cross section of our galaxy.
The solar systems revolve around the black hole at the center. Our sun travels at a speed of 217 kilometers per second and takes approximately 240 million years to
complete a single revolution. Our Milky Way is approximately 100.000 light years in diameter.
A small part of the galaxy will be absorbed by the black hole. The rest of the galaxy will move in ever widening orbits that escape the gravity of the black hole and
eventually move out into space.
This picture shows the center of the Milky Way in false colors. The bright point in the center is an explosion of X-rays near Sagittarius A. The X-rays increased
extremely over a period of a few minutes and continued to radiate for approximately three hours before dying out. It is highly likely that this was because material
that fell into the black hole. NASA/MIT/F.Baganoff et al
The gravitational pull decreases as the distances increase. Despite the fact that there is still a very small gravitational pull even when very large distances are
involved, celestial objects can continue to move away from one another. If the speed at which two celestial objects move apart is, for example, initially 100
kilometers per second, and over a period of two years it drops to 99.14 kilometers per second, at the end of another two years there will have been a slighter decrease
in the speed because the distance has become greater, so in this case the speed will drop to 99.02 kilometers per second. Two years after that it will have dropped
to 99.002 kilometers per second and so will take an infinite amount of time to drop to 99 kilometers per second. The distances between the groups of galaxies are now
so huge that we can say with certainty that they will continue to move away from one another.
The black holes that remain continue to attract matter as they travel through space, so the amount of matter they contain continues to increase or they may become
part of heavier black holes that they come into contact with.
It is possible for celestial bodies to collide, but they are far more likely to spend very long times revolving around one another before they come together.
It will also happen that objects travel in ever widening orbits that take them out of the gravitational field.
New matter comes mainly from other universes. A universe is the matter and radiation that was hurled into space by the big bang. Our universe is expanding but there are
more universes and they are also expanding, so after a certain time objects from different universes intersect with one another.
The pull-in range for matter that is travelling relatively slowly can be more than 10 million light years in diameter. For matter, that is approaching the speed of light,
and for light itself, the diameter of the pull-in range will be relatively small. (Electromagnetic radiation contains energy, and energy can be converted into matter,
so the mass also increases when light is absorbed.)
As mass increases, gravity increases and compresses the matter.
In the case of a black hole, the diameter becomes smaller when adding more matter.
The diameter
of a black hole after a star collapsed can be no more than that of a pea. The diameter just before the big bang is no more than just the size of an atom.
There also can be antimatter reactions since the matter is mainly coming from other universes.
Once the pressure and the temperature, at the core, reach a critical threshold, a reaction ignites that produces another big bang. This is what ignited the big bang.
The reaction converts matter into energy and everything explodes at enormous speeds.
It can sometimes take billions of years for a star to use up all of the nuclear fuel, while a big bang occurs in an instant.
The period during which stars shine is very short (100 billion years?) compared with the time it takes for enough matter to accumulate to create a big bang.
The dating of the big bang
It is possible to measure speed of galaxies with redshift. The Doppler effect of light means that color changes with speed. If we can measure the speed and we know
that all galaxies originate from a single point, it is possible to calculate how long ago the big bang occurred.
Proceeding on this basis, the Belgian priest and scholar Georges Lemaître, who discovered the big bang in 1931, worked out that the big bang occurred
approximately 15 billion years ago.
A more complicated method (cosmic background radiation) has enabled modern physicists to calculate to within one percent that the big bang occurred precisely
13.7 billion years ago.
The possibility of carrying out measurements with this degree of precision, was one of the reasons for the launching of the WMAP satellite.
Artist's depiction of the WMAP satellite gathering data to help scientists understand the Big Bang.
You have been formed now and why shouldn't that happen again?
I can imagine that you might think at first, the chance is very small. But big bangs keep occurring. If we look back, there have been an infinite number of Big Bangs
and if we look forward, there will be an infinite number of Big Bangs yet to come.
This document has been translated, in February 2008, from dutch to english by a professional translation agency.
