Today I am feeling very sciencey so i decided to drop an informative thread about the dark sectors of the universe aka dark matter and dark energy. what are these? how were the terms coined? what do we know about them? LET'S LEARN!

To begin with, lets jump back to the 1820s when Charles Messier, a french astronomer took on the arduous task to catalog galaxies so that his colleagues wouldn't mistake them for comets ( what a saint)

He noticed how the galaxies formed clusters, a characteristic which wasn't understood yet. A century and a half later, in the 1920s, studies of groups of clusters of galaxies were revolutionized by Edwin Hubble’s demonstration that spiral and elliptical nebulas are galaxies

Like the Milky Way, located at distances of millions of light-years, which implied that these clusters of galaxies are in fact systems of enormous size. This discovery helped Einstein finally replace the "fudge factor" that he earlier removed from his famed equation of relativity

His equation was beautiful again. After Hubble's discovery, he met Hubble in person to thank him for making his equation complete again. Yet the exact cause why the galaxies were expanding and what was causing it was still unknown. In theory, this was the now replaced constant in

Einstein's equation. Around this time, Fritz Zwicky, a Swiss astronomer in 1933 stated that there has to be something this is causing the galaxies to expand, thus theorizing the concept of the dark sectors for the first time.

He wondered this after observing the motion of galaxies in the Coma Cluster. The cluster of galaxies he observed should have flown apart if there was no additional mass holding them together. Lacking further evidence, his idea was quickly dismissed by the scientific community.

Coming to the year of 1968. Vera Rubin, an american astronomer, who took on a project that none of her male colleagues did, closely observing the spectra of stars in the Andromeda Galaxy to determine their velocities at the Kent observatory.

Her decision to take this on this project soon gave some very surprising results. The rotation curve of the galaxy was flat, meaning the stars in the outer spirals of the galaxy were orbiting at the same speed as stars near the center.

More alarming, the stars in the outer spirals were orbiting so fast they should have flown apart. The mass of visible stars wasn’t enough to hold the galaxy together. There was an extraordinary amount of matter missing. What was it?

The Andromeda Galaxy became the first of many galaxies with unexplainable rotation curves, which Rubin observed with Kent Ford, her colleague. Rubin's decades of discoveries revealed there was much more to the universe than meets the eye. The cosmos was chock-full of dark matter.

And thus due to Vera Rubin's hard work, the scientific community found out how true Zwicky's claims were and thus the dark sectors were discovered. Thanks in large part to Rubin's work, scientists now believe that only about 20% of matter in the universe is visible.

The other 80% is dark matter.
Now for the big question; what is dark matter?

Well, we know what it isn't. It's not made up of 'normal' aka baryonic matter like protons, neutrons, electrons or neutrinos. We know it's stable. We know it's not charged. But there's a lot to know.

On July 23, 1999, NASA launched the Chandra X-Ray Observatory aboard the space shuttle Columbia. A telescope designed to detect X-ray emissions from extraordinarily hot regions of the universe—exploded stars, galaxy clusters, and matter around black holes.

And its contributions to the study of the dark sectors has been enormous.

Below is a composite image of the Bullet Cluster formed when two smaller clusters of galaxies collided. The pink clumps, which are hot gas detected by Chandra in X-rays, contain most of the subclusters’ normal matter. The blue areas show the concentration of total mass, including

Dark matter,as determined by the gravitational lensing. A lot of other galaxies were studied for dark matter & its present everywhere. It interacts only via gravity and doesn't interact w baryonic matter. That's all we know. Scientists have ideas for what dark matter might be.

One hypothesis is that dark matter consists of exotic particles that don't interact with normal matter or light but that still exert a gravitational pull. Several scientific groups, including one at CERN's Large Hadron Collider, are currently working to generate dark matter.

Dark energy is even more mysterious, and its discovery in the 1990s was a complete shock to scientists. Previously, physicists had assumed that the attractive force of gravity would slow down the expansion of the universe over time. But now its popularly theorised

That the reason behind the universe's expansion is dark energy, as mysterious as dark matter. Scientists have no plausible explanation for dark energy. According to one idea, dark energy is a fifth and previously unknown type of fundamental force called quintessence.

Countless simulations run in order to map out the location and structure of these mysterious entities, one shown below. Also they aren't call dark because dark matter and energy are black in color. Its said so because we can't see them.

Now for the crazy part- almost 96% of our universe is comprised of the dark sectors with dark energy taking up 69% energy, dark matter a 26% which leaves us, the baryonic matter a mere 5%
Scary how we are such a small part in the vast unknown!

Countless studies are being performed to understand more about the dark sectors and whats certain is that a discovery will change what we know about the universe. And with this note, I'll end this thread!

P.S: follow @Astropartigirl irl to understand more about the dark sectors, shes a straight up baddie! toodles!