The universe has no shortage of mysteries, many of which have puzzled us for ages. One of the biggest is the existence of something called dark matter. First theorized in 1933 by Fritz Zwicky, dark matter is a theoretical type of matter that can't be seen because it doesn't interact with light or any other form of electromagnetic radiation.
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.
Dark matter can't be seen, so simulations like this one show what dark matter might look like if it were visible. Ralf Kaehler/SLAC National Accelerator Laboratory, American Museum of Natural History
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?
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