The philosopher in the street, who has not suffered a course in quantum mechanics, is quite unimpressed by the [Einstein-Podolsky-Rosen] correlations. He can point to many examples of similar correlations in everyday life. The case of Bertlmann’s socks is often cited. Dr. Bertlmann likes to wear two socks of different colours. Which colour he will have on a given foot on a given day is quite unpredictable. But when you see that the first sock is pink you can be already sure that the second sock will not be pink. Observation of the first, and experience with Bertlmann, gives the immediate information about the second. There is no accounting for tastes, but apart from that there is no mystery here. And is this [Einstein-Podolsky-Rosen] business just the same?
John Bell began his now famous paper with the above paragraph. The Bell Inequality started off like so many other great theories in science – as a simple thought experiment. Its conclusions were not so simple, however, and would lead the way to the end of Einstein’s idea of local hidden variables, and along with it his hopes for a deterministic universe. In this article, we’re going to look at the Bell inequality in great detail. Our guide will be a chapter from Jim Baggots’ The Quantum Story, as it has one of the best descriptions of Bell’s theory I’ve ever read.
Continue reading “Bertlmann’s Socks and the Nature of Reality”
During the early 1900’s, [Einstein] was virtually at war with quantum theory. Its unofficial leader, [Niels Bohr], was constantly rebutting Einstein’s elaborate thought experiments aimed at shooting down quantum theory as a description of reality. It is important to note that [Einstein] did not disagree with the theory entirely, but that he was a realist. And he simply would not believe that reality was statistical in nature, as quantum theory states. He would not deny, for example, that quantum mechanics (QM) could be used to give a probable location of an electron. His beef was with the idea that the electron doesn’t actually have a location until you try to measure it. QM says the electron is in a sort of “superposition” of states, and that asking what this state is without measurement is a meaningless question.
So [Einstein] would dream up these incredibly complex hypothetical thought experiments with the goal of showing that a superposition could not exist. Now, there is something to be said about [Einstein] and his thought experiments. He virtually dreamed up his relativity theory while working as a patent clerk at the ripe old age of 26 years using them. So when he had a “thought” about something, the whole of the scientific world stopped talking and listened. And such was the case on the 4th of May, 1935.
Continue reading “The Eulogy of Local Hidden Variables”
Our story begins a little over one hundred years ago in Bern, Switzerland, where a young man employed as a patent clerk went off to work. He took the electric trolley in each day, and each day he would pass an unassuming clock tower. But today was different, it was special. For today he would pose to himself a question – a question whose answer would set forth a fascinating dilemma.
The hands of the clock appeared to move the same no matter if his trolley was stopped or was speeding away from the clock tower. He knew that the electromagnetic radiation which enabled him to see the clock traveled at a finite speed. He also knew that the speed of the light was incredibly great compared to the speed of his trolley. So great that there would not be any noticeable difference in how he saw the hands of the clock move, despite him being at rest or in motion. But what if his trolley was moving at the speed of the reflected light coming from the clock? How would the hands of the clock appear to move? Indeed, they could not. Or if they did, it would not appear so to him. It would appear as if all movement of the clock’s hands had stopped – frozen in an instant of time. But yet if he looked at the hands of the watch in his pocket, they would appear to move normally. How does one explain the difference between the time of the clock tower versus the time of his watch? And which one was correct?
There was no way for him to know that it would take three years to answer this question. No way for him to know that the answer would eventually lead to the discovery of matter and energy being one and the same. No way to know that he, this underemployed patent clerk making a simple observation, would soon unearth the answer to one of the greatest mysteries that had stumped every mind that came before his – the very nature of time itself.
Now it might have taken Einstein a few years to develop the answer we now know as the Special Theory of Relativity, but it most certainly took him no longer than a few days to realize that Isaac Newton…
must be wrong.
Continue reading “The Spooky Nature of Electromagnetic Radiation”
8 years ago, for the 100th anniversary of the theory of relativity [Tom] decided to test the general theory of relativity.
As he was going to Mt Rainier (5400ft high) with his children for the weekend, he brought in his van 3 cesium clocks while leaving other atomic clocks at his home for comparison. The theory behind the test is that if you’re are at higher altitudes, then your speed (in a galactic coordinate system) is higher than the one you’d have at sea level and therefore time would go “slower” than at lower altitudes.
[Tom] brought 400 pounds of batteries, 200 pounds of clocks and left his car turned on during his 2 days stay in the ‘Paradise Lodge’. He used 120V DC to AC converters and chose to bring 3 cesium clocks to have a triple redundant setup. When he came back home, he had the good surprise of finding a time difference of 23ns. This is a great application for those rubidium sources you’ve been scavenging.
[Thanks Indyaner via Reddit]
Earlier this year we saw the Einstein robot that is being developed to facilitate human facial emotions in robots. [David Hanson], the man in charge of this project, has given a TED talk on his work that includes a show-and-tell of his most recent progress. We’ve embedded the video after the break for your enjoyment.
The Einstein robot (head only in this video) shows off the ability to recognize and mimic the facial emotions of the person in front of it. There is also video of a Bladerunner-esque robot looking around a room, recognizing and remembering the faces of the people it sees. [David] makes a very interesting proclamation: he’s trying to teach robots empathy. He feels that there is a mountain of R&D money going into robots that can kill and not much for those that can sense human emotions. His hope is that if we can teach empathy, we might not be annihilated when robots become smarter than us.
That’s not such a bad idea. Any way you look at it, this talk is interesting and we wish the five-minute offering was five-times as long. But [Mr. Hanson’s] facial hair alone is worth clicking through to see.
Continue reading “Robot Einstein could save humans from killbot destruction”
Researchers at UC San Diego have been working on a robot that learns facial expressions. Starting with a bunch of random movements of the face “muscles”, the robot is rewarded each time it generates something that is close to an existing expression. It has slowly developed several recognizeable expressions itteratively. We have a few questions. First, are we the only ones who see a crazy woman with a mustache in the picture above? Why is that? What makes [Einstein] look so effiminate in that picture? Secondly, what reward do you give a robot? You can actually see this guy in action in a video after the break.
Continue reading “Robots learning facial expressions”