The final feature for this series is Life. The Universe is such mind-boggling huge place that we are most definitely the best that random chances and selfish genes can produce. NASA defines life as a: “Self-sustaining chemical system capable of Darwinian evolution”.
Dust to dust, ashes to ashes. In the previous vlog we saw how the cyclical formation and destruction of stars leads to a metal rich Intergalactic Medium, and that the presence of metals in the Intergalactic Medium is paramount to the formation of planets.
One of the fundamental laws of the universe is the conservation of Energy. Nothing is created, nothing is destroyed, and all is transformed. And so the death of the original stars brought forth new stars which then died again, adding heavier elements than hydrogen to the composition of the universe.
Our 7th feature is about elliptical galaxies. Elliptical galaxies are the other main class of galaxies we find in our universe. They have a spherical stellar distribution, meaning simply that their stars’ orbits are not in a plane any more, and instead have random orientations.
As we’ve seen in the previous vlog, spiral Galaxies started forming from the primordial protogalaxies about 11 billion years ago. The formation of spiral galaxies is important because it happened at the peak of population II stars formation and allowed for planets to form.
Another important feature in the history of Universe are the proto-galaxies. In the last 30 years we were able to observe only a few dozen of these proto or primeval galaxies, which mostly looked like shapeless blobs with an intense UV emission.
The Universe coming out of the cosmic dark ages was a bleak place. The afterglow of the Big Bang had slipped into infrared radiation and neutral hydrogen was a mist stretching the entire cosmos. But as we learnt, stars soon started shining, piercing and breaking that mist giving way to the Epoch of Reionisation.
The third feature is about Population III stars. These stars are the first lights that shone in the Universe. These stars no longer exist, but affected the environment of the early Universe. They formed between a million and 10 million years after the Big Bang and they were made almost exclusively of hydrogen.
The cosmic microwave background or CMB is my second feature for this series. The CMB is formed by the original photons produced in the Big Bang and was created at the last scattering surface.
The Universe began 13.8 billion years ago in an event called the Big Bang. Throughout its ages the universe has changed a lot, sometimes dramatically, so to appreciate these changes I’m going to discuss the History of the Universe in 10 Features. My first feature is the theory of cosmic inflation.