8 Iconic Doctor Who Things That Scientists Say Are Real

7. Cracks In The Universe

Just like the crack that followed Amy Pond around, indiscriminately hoovering up friends and loved ones, some physicists reckon that there really could be fractures in the fabric of reality itself. These cracks, which scientists call "cosmic strings", are defects in spacetime that formed right at the beginning of the universe and they thread their way through the cosmos. They are essentially one-dimensional ruptures made out of pure energy that splintered spacetime when the universe went from being hot and dense into a phase of rapid expansion and cooling. They would have begun life wound up tightly in the early universe, but have since been stretched to potentially infinite length as it continues to expand. Sounds like pure science fiction, but this is the stuff of reality (well, as close tor reality as theoretical physics can get). These cracks would also supposedly have the equivalent mass of the entire Earth in just one metre of them, meaning that they might generate a gravitational field strong enough to pull unsuspecting spacetime travellers into it. This gravitational field is already thought to be behind some odd lensing effects observed by astronomers, bending the light of whole galaxies around them. It is unclear, however, as to whether these cracks could (a) suck people right out of the spacetime continuum and (b) go unnoticed in someone's bedroom.