40 websites that will make you cleverer right now. The indexed web contains an incredible 14 billion pages.
But only a tiny fraction help you improve your brain power. Here are 40 of the best. whizzpast.com – Learn about our awe inspiring past all in one wonderful place. khanacademy.org – Watch thousands of micro-lectures on topics ranging from history and medicine to chemistry and computer science. freerice.com – Help end world hunger by correctly answering multiple-choice quizzes on a wide variety of subjects. artofmanliness.com – Blog/site dedicated to all things manly, great for learning life skills and good insights. unplugthetv.com – Randomly selects an educational video for you to watch. coursera.org – An educational site that works with universities to get their courses on the Internet, free for you to use. mentalfloss.com – Interesting articles guaranteed to make you smile and get you thinking. feelgoodwardrobe.com – Find out how the world of fashion really works and what you can do to combat it. lifehacker.com – Learn to hack life!
Why Our Universe Must Have Been Born Inside a Black Hole. “Accordingly, our own Universe may be the interior of a black hole existing in another universe.”
So concludes Nikodem Poplawski at Indiana University in a remarkable paper about the nature of space and the origin of time. The idea that new universes can be created inside black holes and that our own may have originated in this way has been the raw fodder of science fiction for many years. But a proper scientific derivation of the notion has never emerged. Today Poplawski provides such a derivation. He says the idea that black holes are the cosmic mothers of new universes is a natural consequence of a simple new assumption about the nature of spacetime. Poplawski points out that the standard derivation of general relativity takes no account of the intrinsic momentum of spin half particles. This predicts that particles with half integer spin should interact, generating a tiny repulsive force called torsion.
That’s interesting for a number of reasons. This is a Big Bang type event. Personal and Historical Perspectives of Hans Bethe. Fundamentals of quantum mechanics. Glass Half Empty. What if a glass of water was, all of a sudden, literally half empty?
—Vittorio Iacovella The pessimist is probably more right about how it turns out than the optimist. When people say “glass half empty”, they usually mean something like a glass containing equal parts water and air: Traditionally, the optimist sees the glass as half full while the pessimist sees it as half empty. This has spawned a zillion joke variants—e.g., the engineer sees a glass that’s twice as big as it needs to be, the surrealist sees a giraffe eating a necktie, etc.
But what if the empty half of the glass were actually empty—a vacuum? The vacuum would definitely not last long. For our scenario, we’ll imagine three different half-empty glasses, and follow what happens to them microsecond by microsecond. In the middle is the traditional air/water glass. We’ll imagine the vacuums appear at time t=0. For the first handful of microseconds, nothing happens. When the bottle is struck, it’s pushed suddenly downward.