Just looking at your DNA won't tell you – the human genome is 99% identical to a chimpanzee's and, for that matter, 50% to a banana's. We do, however, have bigger brains than most animals – not the biggest, but packed with three times as many neurons as a gorilla (86bn to be exact). A lot of the things we once thought distinguishing about us – language, tool-use, recognising yourself in the mirror – are seen in other animals. Perhaps it's our culture – and its subsequent effect on our genes (and vice versa) – that makes the difference. Scientists think that cooking and our mastery of fire may have helped us gain big brains. But it's possible that our capacity for co-operation and skills trade is what really makes this a planet of humans and not apes.
It's a question we don't yet have the tools to answer. Einstein's general relativity says that when a black hole is created by a dying, collapsing massive star, it continues caving in until it forms an infinitely small, infinitely dense point called a singularity. But on such scales quantum physics probably has something to say too. Except that general relativity and quantum physics have never been the happiest of bedfellows – for decades they have withstood all attempts to unify them. However, a recent idea – called M-Theory – may one day explain the unseen centre of one of the universe's most extreme creations.
We spend around a third of our lives sleeping. Considering how much time we spend doing it, you might think we'd know everything about it. But scientists are still searching for a complete explanation of why we sleep and dream. Subscribers to Sigmund Freud's views believed dreams were expressions of unfulfilled wishes – often sexual – while others wonder whether dreams are anything but the random firings of a sleeping brain. Animal studies and advances in brain imaging have led us to a more complex understanding that suggests dreaming could play a role in memory, learning and emotions. Rats, for example, have been shown to replay their waking experiences in dreams, apparently helping them to solve complex tasks such as navigating mazes.
You really shouldn't be here. The "stuff" you're made of is matter, which has a counterpart called antimatter differing only in electrical charge. When they meet, both disappear in a flash of energy. Our best theories suggest that the big bang created equal amounts of the two, meaning all matter should have since encountered its antimatter counterpart, scuppering them both and leaving the universe awash with only energy. Clearly nature has a subtle bias for matter otherwise you wouldn't exist. Researchers are sifting data from experiments like the Large Hadron Collider trying to understand why, with supersymmetry and neutrinos the two leading contenders.