What makes up 96% of the universe? Only God knows!

A popular hypothesis is that dark matter is formed by exotic particles that don’t interact with regular matter, or even light, and so are invisible. Yet their mass exerts a gravitational pull, just like normal matter, which is why they affect the velocities of stars and other phenomena in the universe. [Video: Dark Matter in 3D]

However, try as hard as they might, scientists have yet to detect any of these particles, even with tests designed specifically to target their predicted properties.

“I think on the dark matter side there is some discouragement among the people who are kind of mid-career,” Panek said. “They went into this field thinking, ‘OK, we’re going to solve this problem and then we’ll build from there.’ But 15, 20 years later, they’re saying, ‘I’ve invested my career in this and I don’t know if I’m going to find anything in my lifetime.'”

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