Blue-eyed Humans Have A Single, Common Ancestor
New research shows that people with blue eyes have a single, common ancestor. A team at the University of Copenhagen have tracked down a genetic mutation which took place 6-10,000 years ago and is the cause of the eye colour of all blue-eyed humans alive on the planet today. What is the genetic mutation "Originally, we all had brown eyes," said Professor Hans Eiberg from the Department of Cellular and Molecular Medicine. "But a genetic mutation affecting the OCA2 gene in our chromosomes resulted in the creation of a "switch," which literally "turned off" the ability to produce brown eyes." Limited genetic variation Variation in the colour of the eyes from brown to green can all be explained by the amount of melanin in the iris, but blue-eyed individuals only have a small degree of variation in the amount of melanin in their eyes. Nature shuffles our genes The mutation of brown eyes to blue represents neither a positive nor a negative mutation.
Physicists Create Quantum Link Between Photons That Don't Exist at the Same Time
Now they're just messing with us. Physicists have long known that quantum mechanics allows for a subtle connection between quantum particles called entanglement, in which measuring one particle can instantly set the otherwise uncertain condition, or "state," of another particle—even if it's light years away. Now, experimenters in Israel have shown that they can entangle two photons that don't even exist at the same time. "It's really cool," says Jeremy O'Brien, an experimenter at the University of Bristol in the United Kingdom, who was not involved in the work. Entanglement is a kind of order that lurks within the uncertainty of quantum theory. Entanglement can come in if you have two photons. Now Eli Megidish, Hagai Eisenberg, and colleagues at the Hebrew University of Jerusalem have entangled two photons that don't exist at the same time. In recent years, physicists have played with the timing in the scheme. So what's the advance good for?
Quackwatch
Atom Inside Photographed - science
Last updated 10:48 27/05/2013 ANETA STODOLNA/ FOM Institute Four-by-four-millimetre images showing the bull's eye-like rings of electron wave functions inside hydrogen atoms. Redder areas reflect a higher density of electrons than bluer areas. The two images represent hydrogen atoms that had been fired on by differently colored lasers, resulting in slightly different quantum wave functions. Talk about taking a tough shot. Snapping a picture of the inside of an atom - the electrons, the protons, the neutrons - is no easy task. Instead of having the ability to describe where a particle is, quantum theory provides a description of its whereabouts called a wave function. Wave functions work like sound waves, except that whereas the mathematical description of a sound wave defines the motion of molecules in air at a particular place, a wave function describes the probability of finding the particle.
Understanding the Fourier transform » #AltDevBlogADay
Yes, I realize that after reading the title of this post, 99% of potential readers just kept scrolling. So to the few of you who clicked on it, welcome! Don’t worry, this won’t take long. A very long time ago, I was curious how to detect the strength of the bass and treble in music, in order to synchronize some graphical effects. What I found was the Discrete Fourier Transform (DFT), which looks like this: This formula, as anyone can see, makes no sense at all. Eventually, I was able to visualize how it works, which was a bit of a lightbulb for me. Disclaimer: my math skills are pitch-patch at best, and this is just intended to be an informal article, so please don’t expect a rigorous treatment. A quick bit of background – what does the Fourier transform do? The time domain representation (a series of evenly spaced samples over time)The frequency domain representation (the strength and phase of waves, at different frequencies, that can be used to reconstruct the signal)
Mathematical breakthrough sets out rules for more effective teleportation
For the last ten years, theoretical physicists have shown that the intense connections generated between particles as established in the quantum law of ‘entanglement’ may hold the key to eventual teleportation of information. Now, for the first time, researchers have worked out how entanglement could be ‘recycled’ to increase the efficiency of these connections. Published in the journal Physical Review Letters, the result could conceivably take us a step closer to sci-fi style teleportation in the future, although this research is purely theoretical in nature. The team have also devised a generalised form of teleportation, which allows for a wide variety of potential applications in quantum physics. Once considered impossible, in 1993 a team of scientists calculated that teleportation could work in principle using quantum laws. “We have also found a generalised teleportation technique which we hope will find applications in areas such as quantum computation.”
Bayes' Theorem
An Intuitive Explanation of Bayes' Theorem Bayes' Theorem for the curious and bewildered; an excruciatingly gentle introduction. Your friends and colleagues are talking about something called "Bayes' Theorem" or "Bayes' Rule", or something called Bayesian reasoning. They sound really enthusiastic about it, too, so you google and find a webpage about Bayes' Theorem and... It's this equation. So you came here. Why does a mathematical concept generate this strange enthusiasm in its students? Soon you will know. While there are a few existing online explanations of Bayes' Theorem, my experience with trying to introduce people to Bayesian reasoning is that the existing online explanations are too abstract. Or so they claim. And let's begin. Here's a story problem about a situation that doctors often encounter: What do you think the answer is? Next, suppose I told you that most doctors get the same wrong answer on this problem - usually, only around 15% of doctors get it right. No, it does not!
Quantum gravity takes singularity out of black holes - space - 29 May 2013
Falling into a black hole may not be as final as it seems. Apply a quantum theory of gravity to these bizarre objects and the all-crushing singularity at their core disappears. In its place is something that looks a lot like an entry point to another universe. Most immediately, that could help resolve the nagging information loss paradox that dogs black holes. Though no human is likely to fall into a black hole anytime soon, imagining what would happen if they did is a great way to probe some of the biggest mysteries in the universe. According to Albert Einstein's theory of general relativity, if a black hole swallows you, your chances of survival are nil. Eventually, you'll reach the singularity, where the gravitational field is infinitely strong. The same problem crops up when trying to explain the big bang, which is thought to have started with a singularity. Information paradox In this new model, the gravitational field still increases as you near the black hole's core. Recommended by
