The origin and birth of the stars

1. THE ORIGIN AND EVOLUTION
OF OUR UNIVERSE

2. THE BIG BANG THEORY

3. The Big Bang Theory is the leading explanation about how the universe
began. At its simplest, it says the universe as we know it started with an
infinitely hot, infinitely dense singularity, then inflated — first at
unimaginable speed, and then at a more measurable rate — over the next
13.8 billion years to the cosmos that we know today.
Because current instruments don't allow astronomers to literally peer back
at the universe's birth, much of what we understand about the Big Bang
Theory comes from mathematical formulas and models. Astronomers can,
however, see the "echo" of the expansion through a phenomenon known as
the cosmic microwave background.

4. A 2013 map of the background radiation left over from the Big Bang, taken by the ESA's Planck spacecraft,
captured the oldest light in the universe. This information helps astronomers determine the age of the
universe.

6. THE FIRST SECOND, AND THE
BIRTH OF LIGHT

7. Around 13.7 billion years ago, everything we know of was
an infinitesimally small singularity, a point of infinite
denseness and infinite heat. Then, explosive expansion
began, ballooning our universe outwards faster than the
speed of light. This was a period of cosmic inflation that
lasted mere fractions of a second — about 10^-32 of a
second, according to physicist Alan Guth’s 1980 theory that
changed the way we think about the Big Bang forever.

8. When cosmic inflation came to a sudden and still-mysterious end, the more
classic descriptions of the Big Bang took hold. A flood of matter and radiation,
known as “reheating,” began the process of populating our universe with the
stuff we know today -- particles, atoms, stars, galaxies and so on.
This was all still within the first second after the universe began, when the
temperature of everything was about 10 billion degrees Fahrenheit (5.5 billion
Celsius), according to NASA. The cosmos now contained a vast array of
fundamental particles such as neutrons, electrons and protons -- the eventual
building blocks or raw material for everything we see today.

9. Sometimes called the "afterglow" of the Big Bang, this light is
more properly known as the cosmic microwave background
(CMB). It was first predicted by Ralph Alpher and other scientists
in 1948, but was found only by accident almost 20 years later.
Arno Penzias and Robert Wilson, both of Bell Telephone
Laboratories in Murray Hill, New Jersey, were building a radio
receiver in 1965 and picking up higher-than-expected
temperatures, according to NASA. At first, they thought the
anomaly was due to pigeons and their dung, but even after they
cleaned up the mess and killed the pigeons that tried to roost
inside the antenna, the anomaly persisted.

10. THE STEADY STATE THEORY
The steady state theory explains that the universe
did not originate from an explosive beginning,
because it did nit have a beginning.
The universe is always expanding but maintaining a
constant average density, matter being continuously
created to form new stars and galaxies at the same
rate that old ones become unobservable as a
consequence of their increasing distance and
velocity of recession.

11. A steady-state universe has no beginning or end in time;
and from any point within it the view on the grand scale--
i.e., the average density and arrangement of galaxies--is
the same.

12. Multiverse Model
Multiverse Theory, which states that there may be
multiple or even an infinite number of universes
(including the universe we consistently experience) that
together comprise everything that exists: the entirety of
space, time, matter, and energy as well as the physical
laws and constants that describe them.