Deep in the cosmic microwave background—the leftover radiation from the Big Bang—there’s a strange, frigid void called the Cold Spot. It’s colder than it should be, and it’s too big to be explained by normal cosmic fluctuations. One wild theory? It could be evidence of a parallel universe that collided with ours long ago. More likely, it’s just an unusually empty region of space, a vast “supervoid” where fewer galaxies exist. Either way, it’s one of the biggest cosmic mysteries out there.
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