Is Dark Matter Real? Most Experts Say Yes, but Its Still Hotly Debated

Key Takeaways on if Dark Matter Exists:

• Dark matter is real, according to most experts. However, some scientists still debate if it is real or not, and we do not know much about it.
• Dark matter is a mysterious and invisible substance that is thought to make up a large part of the universe and does not reflect or absorb light. First described back in the 1930s, we still know very little about this mysterious matter.
• It’s highly unlikely that a human would come into contact with dark matter. However, if they did, it would likely be fatal.

A mysterious and invisible substance known as dark matter is thought to make up a large part of the universe and does not reflect or absorb light. First described back in the 1930s, we still know very little about this mysterious matter, and some still question whether it truly exists.

“Dark matter is basically an invisible component of matter,” explains Shyam Balaji, a Postdoctoral Research Fellow in the Department of Physics, King’s College London, who studies dark matter. “All the stuff that we are made of — all the baryonic matter as we call it — the stars, planets, people, all the chemical elements that you see in the universe; all of that stuff is only a very small component of the actual matter.”

That baryonic, or “normal matter,” makes up only around 5 percent of all matter in our universe. Dark matter, on the other hand, is thought to comprise as much as 27 percent of the entire cosmos, accounting for up to 85 percent of the total mass.

Is Dark Matter Real?

Many scientists — though not all — are in agreement that dark matter exists. However, there is still much about it that is poorly understood, and it remains an ongoing area of research, as researchers strive to trace and observe it.

“Dark matter could be many things,” says Balaji. “At this point, we don’t know exactly what dark matter is made of, or what its properties are, or how strongly it interacts with normal matter.”

Read More: The Heart of the Milky Way May Host a New Form of Dark Matter

Evidence that Dark Matter Exists

Nobody, no scientist or astronomical agency, has directly observed dark matter to date. Though there is no record of direct observation of this invisible matter, there are still telltale signs that it does exist.

“We know that it exists by basically performing a series of experiments and observations,” says Balaji. “We have a lot of strong hints that it exists.”

One of these is gravitational lensing, which astronomers use to observe the universe. This occurs when a huge space object — such as a large galaxy cluster — warps space, causing light to bend around it.

“It basically acts just like a lens,” says Balaji, meaning that objects beyond it can appear magnified to a great extent. That suggests that there is more matter in those large objects than what we can observe as well, Balaji explains, and it is dark matter that is thought to be largely responsible for the lensing effect.

Researchers continue to work towards finding and detecting dark matter. That involves the construction of sensitive sensors built deep underground, shielding them from radioactivity that could mess up their findings. One of the largest sensors to date is operated 4850 feet underground at the Sanford Underground Research Facility in South Dakota. These sensors track the interactions of subatomic particles with liquid xenon or argon. More too are on the way, that could one day find dark matter or shed some light on what it is.

What Would Happen if We Touched Dark Matter?

It’s unlikely that any person will be touching dark matter anytime soon. That’s because by its very nature, it interacts weakly with normal matter. It does not interact with light nor with electromagnetic radiation. It only appears to interact with gravity.

“If it was strongly interacting, dark matter would just be a normal form of matter,” says Balaji. One dark matter theory is that its particles are what are known as “weakly interacting massive particles,” or fittingly named WIMPS.

Yet, dark matter, when it collides with its own anti-particle, can result in “annihilation” or it can decay into other forms of particles. In a sense, then, a person could touch or interact with the results of those interactions.

“It would be the products of dark matter, not dark matter itself, that you’re interacting with,” says Balaji.

Could Dark Matter Kill You?

Whether or not dark matter could kill a person is evidently a question of note for some scientists. In 2019, researchers published a paper exploring whether the human body could act as a dark matter detector.

They believed that if dark matter of a certain size, macro size rather than the small weakly interacting WIMP, existed, it would collide with normal matter from time to time, punching a bullet-sized hole in a person every now and again. So, the researchers posited that unexplained bullet wounds could point to the existence of large dark matter clumps. That this has not and does not occur suggests that dark matter particles of this kind don’t exist, thankfully.

Another floated possibility is that some forms of dark matter are formed of microscopic black holes with the mass of an asteroid; known as primordial back holes. These tiny black holes, which according to theory, are believed to have come into being shortly after the outset of the universe during the Big Bang. A collision with a person here on Earth would be unpleasant and undoubtedly fatal, but also incredibly unlikely.

“The flux of them that would pass through Earth would be so incredibly tiny because they’re so heavy,” says Balaji. “So, the chances of it hitting us is so astronomically tiny that there’s just no way, practically speaking, that I could see it happening.”

“You’d have to be extremely, extremely unlucky, like extremely unlucky to the power of a huge number for it to happen,” he adds. “Even if we do make a discovery, it would be a very weakly interacting form of dark matter, and definitely not something that could hurt humans in any way.”

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