Cosmic beginnings -The Universe/History of The Big Bang
Theories on Universe Beginning
We on Earth think of the Universe as a vastness containing everything we know of --- and much that we cannot even imagine. For millennia, humans have struggled to make sense of what they see all around them. They have observed, and conjectured, trying to articulate an explanation for a puzzle whose piece are slowly being revealed with each scientific breakthrough .
The investigations of astronomy, astrophysics and mathematics join the cosmological enquiries of seeking minds in all cultures and at all times- those of philosopher, scientists, religious scholars and poets. Questions about the universe have always involved beginnings and endings. Now science is finding answers to questions long answers only by means of myth.
THE BIG BANG
Accepted astrophysical theories posit that at one point there was nothing: no stars, planets, or galaxies-not even space itself. The matter that makes up everything that now exists was con- centrated in a single, extremely dense point known as a singularity.
The force of gravity in a singularity is so great that the fabric of space- time curves in on itself. In an instant known as the big bang, however, the contents of the primordial singularity escaped and formed the universe.
The big bang is catchy shorthand for a complex astrophysical theory, backed up with sophisticated calculations. The term was coined in the 1950s by British astronomer Fred Hoyle, a proponent of a theory of the universe as a steady state. In fact, Hoyle used the term derisively. Though the name stuck, it gives a false impression, making it seem as though the event that unleashed all the en- ergy of the universe almost 14 billion years ago was an explosion.
Astrophysicists see the big bang more as an instantaneous expansion that within a few seconds created nuclear reactions and produced the protons, neutrons, and electrons that form the structure of matter today. Not long after, the nuclear reactions stopped. The universe was roughly one-quarter heli- um, three-quarters hydrogen-a ratio exhibited in the universe's oldest stars today. The formation of the universe played out over billions of years. Our own Earth, along with our solar system, is a product of a stellar explosion almost five billion years ago.
The story of the universe still is being written and refined. By all scientific accounts, it continues to expand, and the question of an eventual end looms large in current investigations.
The universe itself provides some concrete support for the big bang theory in the form of cosmic background radiation, the “afterglow" of the cosmic inflation. In 1965, engineers looking for the source of the static interfering with satellite communications found a consistent signal emanating from every point in the sky at the wavelength predicted for this radiation.
FACT: astronomers can map the temperature of cosmic microwave background radiation as it was only 380,000 years after the big bang.
10^-35 SECONDS LATER Big bang's energy turns into matter
10^-5 SECONDS LATER
Universe's natural forces take shape
3 SECONDS LATER
Nuclei of simple elements formed
10,000 YEARS LATER Universe's energy becomes radiation
300,000 YEARS LATER Energy in form of matter equals energy in form of radiation
300,000,000 YEARS LATER Gas pocket density increases; stars form.
Space-Time: single entity that relates space and time in a four dimensional structure, postulated by Albert Einstein in his theory of relativity.
Concept of an expanding universe whose average density remains constant, in who is matter is continuously created to form New stars and galaxies at the same rate that old ones recede from sight.
COSMIC MICROWAVE BACKGROUND RADIATION - as mapped by satellites, validates the big bang theory. Pictures taken by the Cosmic Back- ground Explorer (COBE) showed hot spots that could be correlated to the gravitational field of the fledgling universe: The 2001 Wilkinson Microwave Anisotropy Probe (WMAP) brought out even more details, as shown here. Telltale hot spots show as red flecks in the image. The Planck Mission, launched in 2009, is making the most accurate map to date of background radiation.
In next chapter we Discuss about ⭐ STAR.