The universe is packed with riddles, but few are as stubborn—or as fascinating—as dark matter. First proposed in 1933 by astronomer Fritz Zwicky, this elusive substance refuses to play by the rules: it doesn't shine, absorb, or interact with light in any way. In fact, we can't see it at all. And yet, its invisible pull shapes galaxies, hinting that something massive—and mysterious—is out there.
After nearly 100 years, and with help from NASA's Fermi Gamma-ray Space Telescope, researchers may have finally "seen" dark matter for the first time.
If this proves to be true, it'll be a significant development for science. Dark matter's ability to hide in plain sight is legendary. It can't be seen by any tool humans have ever made because dark matter can't emit, absorb or reflect light of any kind, which is how humans and all of our tools see things. That makes dark matter impressively difficult to find.
Tomonori Totani, an astronomy professor at the University of Tokyo, believes he may have succeeded where so many before him have failed. In a study published Nov. 25 in the Journal of Cosmology and Astroparticle Physics, Totani says he may have found dark matter by observing the byproduct of two particles of dark matter colliding with one another.
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The key to this discovery is the theoretical existence of something called weakly interacting massive particles, or WIMPs for short. WIMPs are pieces of dark matter that are larger than protons and don't interact with any other types of particles. When two WIMPs collide with each other, scientific theory suggests that they annihilate one another, and the resulting reaction produces gamma rays.
Totani used data from NASA's Fermi Gamma-ray Space Telescope to find what he believes are the gamma-ray emissions from these annihilation events, which, if accurate, would prove that dark matter exists -- or at least put scientists on the right track to confirming its existence.
Scientists theorize that roughly 27% of the universe's total mass-energy is made up of dark matter. NASA
Why is dark matter so difficult to find?
NASA describes dark matter as "the invisible glue that holds the universe together." Dark matter is everywhere. Theories suggest that only 5% of matter is the ordinary stuff that you and I can see, whereas dark matter makes up 27% of the pie. The rest is dark energy, which is yet another mystery that science has yet to solve.
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