The Short Story of Almost Everything.
“The Cosmos is all that is or was or ever will be.
— Carl Sagan
The universal origin story known as the Big Bang postulates that, 13.7 billion years ago, our universe emerged from a singularity — a point of infinite density and gravity — and that before this event, space and time did not exist (which means the Big Bang took place at no place and no time).Until around a few hundred million years or so after the Big Bang, the universe was a very dark place. There were no stars, and there were no galaxies. After the Big Bang, the universe was like a hot soup of particles (i.e. protons, neutrons, and electrons). The Hubble Space Telescope has found not one or two, but as many as 6 galaxies that are dead, as far as their role of birth giving of first stars is concerned. The Hubble Telescope was looking back in time to a period when the universe was some 3 billion years old.
Credit: JWST/NASA/ESA/STsI
The very first stars might have appeared when the Universe was only 100 million years old, or less than 1 percent of its current age. Since then, the rapid expansion of space has stretched their light into oblivion, leaving us to seek clues about their existence in cosmic sources closer to home. Prior to the formation of the first galaxies. As the elements that make up most of planet Earth had not yet formed, these primordial objects – known as population III stars – were made almost entirely of hydrogen and helium. They formed in small protogalaxies that evolved from density fluctuations in the early universe. and helium, the physics of star formation favored the creation of bodies that were many times more massive and luminous than the sun. stars exploded as supernovae, dispersing heavy elements throughout the universe. Since HD 140283 is a Population II star, it is older. In fact, it is the oldest star with a well-determined age. Because of this, astronomers colloquially call the star “the Methuselah star.” Initial estimates of its age were in excess of 14 billion years. Population I stars are younger and contain more heavy elements, while Population II stars are older with fewer heavy elements. The very first stars – described as Population III – are older still, their existence coinciding with cosmic distances that put them well out of sight of even our best technologies.
It thus appears that the first generation of stars in the Milky Way galaxy was formed at about the time the "Dark Ages" ended, now believed to be some 200 million years after the Big Bang. Galaxies, we think, begin building up in the first billion years after the big bang, and sort of reach adolescence at 1 to 2 billion years. After the Big Bang, space was made up almost entirely of hydrogen and helium. Some astronomers think that gravity pulled dust and gas together to form individual stars, and those stars drew closer together into collections that ultimately became galaxies. The oldest known galaxy in existence remains GN-z11, which formed around 400 million years after the Big Bang. Researchers discovered the ancient galaxy after finding a photo of it in the ALMA archive. In the beginning, there was an infinitely dense, tiny ball of matter. Then, it all went bang, giving rise to the atoms, molecules, stars and galaxies we see today.
The life cycle of the Sun began roughly 4.6 billion years ago and will continue for almost another 8 billion years when it will have depleted its supply of nuclear fuel and collapse into a white dwarf. The Sun and all our planets in the solar system began as a giant cloud of molecular gas and dust. Then, about 4.5 billion years ago the cloud collapsed. From this collapse, dust and gas began to collect into denser regions. As the regions pulled in more matter, conservation of angular momentum caused it to begin rotating while increasing pressure caused it to heat up. Most of the material ended up in a ball at the center while the rest of the matter flattened out into a disk that circled around it. The ball at the center would eventually form the Sun while the disk of material would form the planets. The Sun spent about 100,000 years as a collapsing protostar before temperatures and pressures in the interior ignited fusion at its core. And just a few million years later, it settled down into its current form.
We know that Mercury and Venus will not be able to outrun the expanding Sun, and will be engulfed and incinerated. Earth may just outrun the swelling red giant but its proximity, and the resulting rise in temperature, will probably destroy all life on Earth, and possibly the planet itself.
(Given that this system is an analog to our own solar system, it suggests that Jupiter and Saturn might survive the Sun’s red giant phase, when it runs out of nuclear fuel and self-destructs.)
The red-giant phase typically lasts only around a billion years in total for a solar mass star, almost all of which is spent on the red-giant branch. The horizontal-branch and asymptotic-giant-branch phases proceed tens of times faster. Our sun is expected to move through a few phases when it dies. So, what about the end of Cosmos?
In either case, you could never get to the end of the universe or space. Scientists now consider it unlikely the universe has an end — a region where the galaxies stop or where there would be a barrier of some kind marking the end of space. In the unimaginably far future, cold stellar remnants known as black dwarfs will begin to explode in a spectacular series of supernovae, providing the final fireworks of all time. That's the conclusion of a new study, which posits that the universe will experience one last hurrah before everything goes dark forever. Eventually, they too will burn out until the very last star in the universe ceases to exist. In about 100-trillion years, the universe as we see it will no longer exist, yet the universe will be far from dead.
Trillions of years in the future, long after Earth is destroyed, the universe will drift apart until galaxy and star formation ceases. Slowly, stars will fizzle out, turning night skies black. All lingering matter will be gobbled up by black holes until there’s nothing left. Yep. But only in the Big Crunch theory or in the scenario where this universe is actually infinite, but with sections in it. In the the Big Crunch theory basically the universe falls back into itself. It compresses itself back into the initial point of energy and eventually that point of energy will expand again and the cycle of time continues.
