While studying The Mysterious Universe astrophysicist concluded that Four Billion Years ago and for a completely unknown reason an invisible force began to hijack the universe’s growth causing its expansion to accelerate leading to more aggressive expansion in its recent few billion years.
Measuring Expansion of Universe
We can compare a galaxy’s distance with its redshift to determine how much the universe has expanded at the different stages of its evolution but that’s easier said than done. Galaxies vary in brightness so much so it becomes very difficult to estimate their distance precisely. A more suitable means to measure cosmic distances would be to take something with a known absolute magnitude known as A Standard Candle.
Then we can calculate its distance by analyzing the dimness of the object relative to how luminous it should be. With this in mind two separate projects The Hi-Zed Supernova Search Team and The Supernova Cosmology Project. Both attempted to measure the expansion of the universe over time by using distant type 1A supernovae as standard candles type.
1A supernovae are super-luminous explosions caused by white dwarf stars in binary systems. They have a relatively consistent brightness and can outshine their entire galaxy. Using these stellar ghosts as cooling cards; the two projects measured the distances of far out objects and then compared this with each object’s respective redshift values.
The Universe Expanded More in Latter Half of Its Life
The unlikely result was that the very distant objects seem to be much further away than the more local objects. It’s as if the universe has expanded more in the latter half of its life or rather its expansion is accelerating. we know that our universe has been expanding at different rates based on what it has been through in its life.
The Dark Energy
At one point it did look to be slowing down as it was once predicted to do so. But then around Four Billion Years ago and for a completely unknown reason an invisible force began to hijack the universe’s growth causing its expansion to accelerate leading to more aggressive expansion in its recent few billion years.
Moving into the 21st century we had opened the path to a new paradigm of astrophysics; the study of Dark Energy.The Dark Energy is the term given to the invisible force that is responsible for the accelerating expansion of the universe. We know barely anything about it. Safer that it appears to work like an anti-gravity force. It exerts a negative repulsive pressure that behaves inversely to gravity which is aiding the universe’s expansion; rather than slowing it down.
The Dark Energy-Dominated Era
Dark energy is notoriously hard to study. It does not interact with light so it cannot be seen nor detected. There are many hypotheses describing its nature and prevalence. What we know is that around 9.8 billion years of cosmic time, this energy became the prevailing energy in the universe marking the beginning of The Dark Energy-Dominated Era.
Matter vis-a-vie Dark Energy
More of Dark Energy pops into existence proportionally as the universe expands. Thus there came a tipping point around 4 Billion Years Ago where the density of matter fell below that of dark energy. Preventing gravity from slowing down the universe’s expansion and instead began speeding it up. This casting the oldest most distant galaxies much further away on a local scale.
The expansion of the universe is very weak and so gravity is able to keep objects such as galaxies held together. Regardless of how big the universe becomes. The massive cosmic voids between galaxies and galaxy clusters are growing from within. Their dark interiors gradually separating galaxies and galactic groups like our local group into their own isolated pockets of space.
Because the expansion of the universe is accelerating thanks to dark energy in time. Space will be growing so quickly that even our nearest galaxies will recede away from us much too quickly for their lights to ever be able to keep up.
Second Eternal Dark Age
The cosmic horizon will begin to draw inwards. This will continue until even our nearest galaxies are flung beyond the cosmic horizon rendering even our local universe invisible. In the very distant future every galaxy’s view of the universe will start and end with its own stars. Nothing but empty darkness beyond the outer rims we will never see another galaxy again.
With galaxies separated from one another they will not be able to merge and will thus eventually stop producing new stars. The Milky Way and Andromeda Galaxies will merge before any of this happens. After that the resulting elliptical galaxy will gradually burn through the last of its stars. Inevitably, the day will come when the last stars of the universe have either gone out or exploded bringing the universe into a Second Eternal Dark Age.
I don’t have any overwhelming qualification to write anything. No specific professional studies on the subject and this was the only reason I wanted to write. The questions became haunting voices with one striking thoughts that ‘I have only one life, only one and I can’t live with these questions’. The moment I die, I will get answers to all my questions but wouldn't be able to tell anyone. Then Let's Find Some Answers.....