Dark Matter & Dark Energy - What's the Deal?

Dark Matter and Dark Energy: What’s the Deal?

Science has made some incredible leaps in recent years. We’re currently dissecting and understanding the universe like never before, using state of the art technology, logic, mathematics, and physics to discover the boundless potential and complex workings of all that we are, were and will be. Never before in human history have we understood so much about the cosmos. Yet two major aspects of it still elude us – those of dark matter and dark energy.

And when we say major, we mean major. Experts estimate that dark energy makes up 68.3% of the universe as a whole. When combined with dark matter (which contributes 26.8%), the two make up 95.1% of the total mass-energy content. Which means that ordinary matter and energy, i.e. the things we actually see and understand, make up just 4.9% of the universe. So, the hundreds of billions of stars, planets and galaxies that we actually know about and can comprehend make up less than 5% of everything there is. The rest is composed of this ultra-mysterious stuff that no one sees or understands. Pretty freaky, isn’t it?

But, can we shed even a little light on these dark mysteries? Well, we can at least understand (or begin to understand) their significance and roles in the cosmos. Let’s start with dark energy, as it is the most prevalent form of energy there is.

In the 1990s, scientists discovered that the universe was expanding at an alarming rate, far faster than what was previously predicted or understood. And it’s not that stars and galaxies are moving away from us, or that we on Earth are receding from other celestial bodies. Rather, space itself is expanding and taking the physical forms of matter with it.

Scientists hypothesize that this rapid expansion of space is the result of dark energy, and that dark energy works to counteract gravity. Astrologers and physicists initially believed that gravity would cause the universe to eventually stop expanding, or at least expand at a slower rate. However, leading thinkers have now radically changed their beliefs, given that the universe is showing no signs of slowing up. Therefore, dark energy, the force responsible for the expansion of space, must be able to in some respects beat gravity, the force that draws matter together.

But what scientists still don’t understand is what dark energy IS. That is, its properties and composition. Einstein first theorized the concept of dark energy, calling it the “cosmological constant.” While he used the term to suggest a static universe – a later regret of his – the idea of a great unknown shaping what we see, is something that has since been proven almost certainly correct. And as more space is created, more energy is pumped into the universe, expanding ever-outwards. In short, dark energy is simply a natural and fundamental product, despite being currently inexplicable.

Another theory is that dark energy is composed of something called “quintessence,” taken from an ancient Greek term meaning “fifth element.” According to some experts, quintessence is a mysterious form of energy that repels particles away from each other. As it is theoretically stronger than gravity, the rate of repulsion is far greater than the rate of attraction – and so, the universe expands that way.

Yet another theory argues that dark energy and dark matter are made from the same exotic substance, and that dark energy is actually a by-product of decayed dark matter. And then, there are some theories which suggest that dark energy doesn’t even exist at all, and that the evidence for cosmic acceleration is inconclusive, meaning it could all simply be an illusion. That last one seems unlikely, but it does highlight that scientists still have no idea what dark energy is or how it works. So, it’s understandable that some may believe that it isn’t even real.

Dark matter is another major component of the universe and may in fact be responsible for kick-starting all of creation. Dark matter has an incredibly strong gravitational pull – or at least, it has an incredibly strong impact on how standard gravity works – and many scientists believe that it played an integral role in the forming of the very first stars and galaxies. While no-one can physically see dark matter, we know that it exists by observing its gravitational effects on the regular forms of matter surrounding it. The creation, movement, and continued existence of galaxies, for example, simply cannot be explained without taking into account some other extremely strong yet unobserved presence.This is dark matter.

But, like dark energy, scientists are stumped on what it actually is. Normal forms of matter are called baryonic matter – composed of protons, neutrons, and electrons. However, the general consensus is that dark matter is made of some form of non-baryonic substance – which, naturally, we’re yet to understand.

Researchers have landed on one pretty pleasing acronym, though: WIMPS. Which stands for ‘weakly interacting massive particles’. These are hypothetical particles that hypothetically exist but have yet to be detected by modern technology. Their interactions with normal forms of matter are reportedly so weak that they are extremely difficult, if not impossible, to detect. And so, they offer one possibility on what dark matter is made of.

We’ve also settled on something called neutralinos, as a likely building block for dark matter. A neutralino is an again hypothesized heavy particle that was produced in the early universe and is thought to have been responsible for the observable actions of dark matter way back when. Although, of course, the neutralinos themselves have never been observed.

One final candidate is the sterile neutrino. Neutrinos come from the sun and pass through Earth, but because they don’t interact with normal forms of matter, we’re physically unaware of them. Dark matter could be composed of a hypothetical form of neutrinos, as they may interact with normal forms of matter via gravity.

So, all in all, it’s one helluva head-scratcher. With ongoing experiments – including at the Large Hadron Collider – it feels as if we are nearing a breakthrough, especially with dark matter, but we’re still none-the-wiser. Dark matter and dark energy are two of the most prominent yet frustrating components of space. We know they exist – the proof is there. Yet no one knows what they are, what they’re made of, or how they operate. We’re still waiting for that Eureka moment, but when it comes it could transform our understanding of everything.