Science Today – Current Scientific Thinking on the Creation of the Universe
The Big Bang is a theory that describes the creation of everything in the universe. According to this
theory, all the matter in the universe came to existence at the same time during an event known as the
big bang, which happened about 13.8 billion years ago. This was the beginning of everything we know,
the start of time itself.
At that time, all matter was compacted into a single point with infinite density and intense heat called a
singularity. The big bang was not really an explosion, but rather an expansion of the universe originating
from that one singularity. Space did not exist before the big bang. When the big bang happened, after
the initial moments of high, intense energy radiating from the density and heat of the singularity, the
universe expanded rapidly so that everything became less dense and cooled down. In just a few
seconds, the expansion caused the singularity to stretch out across space.
The big bang theory is widely accepted because, so far, all the observations we’ve made of the universe
support this theory. The theory began in 1929 when astronomer Edwin Hubble discovered that
everything in the universe is moving away from everything else. He theorized that everything is
expanding in every direction, still moving from the initial expansion following the big bang. If this
observation was reversed, then this would indicate that the universe was smaller in the past than it is
now. There must have been a time when the universe was only half the size it is now, a quarter of the
size it is now, and so on. If we go back in time far enough, we could theoretically trace the shrinking of
the universe to a time at which there was only an infinitesimally small point, the singularity.
Since there have been no discoveries to dispute this theory, the big bang seems to be the most sensible
theory for how everything in the universe was created.
We have no way to know the exact moment when the universe came into existence but scientists can
look at what happened during the first moments after the big bang occurred. They use quantum physics
to describe the first moments after the big bang. At the beginning of existence, the universe had a
temperature of 1 x 10³² degrees Celsius and only covered a region of 1 x 10¯³³ centimeters. The universe
expanded rapidly. It doubled in size several times in less than a second and cooled during the process.
In time protons and neutrons and elements began to form.
At 380,000 years after the initial event, the universe became transparent so that light could shine
throughout the universe. For the 100 million years or so following, the universe continued to expand
and cool. During this time, small gravitational fluctuations caused particles of matter to cluster
together, collapsing gasses into tight pockets. 100 to 200 million years after the big bang started, stars
formed from these pockets.
Stars clustered together to form galaxies. Some stars went supernova and exploded, shooting out
matter across the universe. This matter includes the heavier elements we find in nature. These galaxies
in turn formed their own clusters, which we know as solar systems. Our solar system formed about 4.6
billion years ago. Our galaxy is the Milky Way.
Today the temperature of the universe is -270 degrees Celsius and our best guess of the size of the
universe is 6.21 x 10²³ miles. The universe is still expanding and the rate of expansion is accelerating.
Most of the ingredients making up the universe come in forms we cannot see. 23% of this material is
dark matter and 71% is made up of dark energy, which is apparently driving the acceleration expansion.
In 2014, a U.S.-led team, headed by scientists at the Harvard-Smithsonian Center for Astrophysics, along
with University of Minnesota, Stanford University, the California Institute of Technology and NASA’s Jet
Propulsion Laboratory, used a specialized radio telescope at the South Pole to hunt for gravitational
waves resulting from the big bang. Einstein predicted these waves 100 years ago but he thought they
would be so feeble they would be undetectable. Current scientists believe they have found the imprint
of these gradational waves left on the “cosmic microwave background”, a soup of elementary particles
left over from the big bang.
Sources:
http://why-sci.com/big-bang/
http://www.space.com/52-the-expanding-universe-from-the-big-bang-to-today.html