Category: Stranger than fiction

German scientists claimed to have broken the speed of light:

Günter Nimtz and Alfons Stahlhofen of the University of Koblenz, Germany, have been researching a phenomenon known as quantum tunnelling. Two prisms are placed together. When a light is shown through the prisms, a detector picks up the light and records information about the photon. However, when the two prisms are separated, Nimtz and Stahlhofen discovered that photons would occasionally “tunnel” between the prisms — arriving at the detector sooner than should theoretically be possible.

The two scientists say they have now tunneled photons “instantaneously” across a distance of up to one meter. Their conclusion, stated in a recent paper, is that the speed limit of special relativity has been violated. Dr. Nimtz claims quantum tunneling is a little understood process that is “the most important” aspect of quantum physics, one that may be responsible for the computational efficiency of the human brain.

Now, color me skeptical of anything that cuts across the scientific establishment consensus, that gets published in popular press and arXiv rather than genuine peer review. My first reaction to this news was, could these professional scientists have made the first-year undergraduate error of confusing group velocity for velocity? As it turns out, yes.

how are these authors measuring an excessive speed of light? In practical terms, most experiments measure light in terms of what is called the group velocity, which is how fast a pulse propagates along an underlying carrier frequency. This can, in some circumstances, lead to the pulses traveling faster than the speed of light in the medium they’re in, but not faster than light in vacuum. Although the setup in the new paper is not entirely clear, they were measuring the arrival time of pulses, which means we’re talking about group velocity rather than the actual speed of light.

Another problem that occurs in these experiments comes from determining when the pulse actually arrived. If you analyze a pulse of light, you find that it is made up of a huge number of frequencies that, as you move away from the fundamental frequency, get lower and lower in amplitude. Once you look at the experimental set up in detail, you find that it is triggering on the pre-pulse noise generated by these high frequency components.

Sorry, but the days of solitary German geniuses laboring in their spare time to overturn all of known physics with their rogue insights is long over. In the meantime, let this be a warning to all others who dare to make the attempt at unseating Einstein:

OK, settling in for the night in Baton Rouge. I’d have loved to have an excuse to visit Don, but that route would have been hundreds of miles out of the way. We’re gonna head up straight through Mississippi to Memphis via I-10/12/55, then cut across Tennessee on I-40, and then take I-65 up through Kentucky and Indiana on our way to Chicago and Wisconsin beyond. Do visit my Twitter for real-time updates from the road. Yes, I know I shouldn’t Twitter and drive, esp while driving a 26ft truck and trailer…

I spent the entire week packing all our possessions into boxes large and small. Tomorrow morning I will pick up a 26ft truck and tow attachment for our small car, and start loading all the detritus of our life here in Dickinson, Texas the past 9 years. Sunday afternoon I will hit the road, and arrive in Marshfield, WI hopefully by Wednesday.

It’s a strange thing, leaving a life behind. The past decade I have grown as a person in every possible way; I’ve picked up a doctorate, my wife picked up two (Pharm D and MD. Both count 🙂 We’ve had two kids, I’ve started a few blogs, and grew a crop of white hair. I’ve got those Reed Richards-esque stripes on both sides now.

In Wisconsin, our life promises to be totally different. Slow rather than fast, stationary rather than always in motion. I am genuinely excited, even the tinge of fear of change just serves to enhance my anticipation.

But first I’ve got to get there. Actually, first I’ve got to load that bloody truck. Tomorrow is going to suck a lot worse than this whole week, cumulative. But then it’s open road… and I’ll be “blogging” the trip via Twitter, so do keep tabs on me Sunday through Wednesday, at http://www.twitter.com/azizhp if you like. Those of you with my cell phone number, do ping me to keep me awake on the road, while you’re at it 🙂

Let’s see where this goes.

Ars Technica summarizes a new article in Nature that suggests that reality is overrated. In a nutshell, any concept of “local realism” is trumped by quantum mechanics. The article abstract reads:

Most working scientists hold fast to the concept of ‘realism’—a viewpoint according to which an external reality exists independent of observation. But quantum physics has shattered some of our cornerstone beliefs. According to Bell’s theorem, any theory that is based on the joint assumption of realism and locality (meaning that local events cannot be affected by actions in space-like separated regions) is at variance with certain quantum predictions. Experiments with entangled pairs of particles have amply confirmed these quantum predictions, thus rendering local realistic theories untenable. Maintaining realism as a fundamental concept would therefore necessitate the introduction of ‘spooky’ actions that defy locality. Here we show by both theory and experiment that a broad and rather reasonable class of such non-local realistic theories is incompatible with experimentally observable quantum correlations. In the experiment, we measure previously untested correlations between two entangled photons, and show that these correlations violate an inequality proposed by Leggett for non-local realistic theories. Our result suggests that giving up the concept of locality is not sufficient to be consistent with quantum experiments, unless certain intuitive features of realism are abandoned.

Thankfully, we remain macroscopic entities. Though hardly unentangled.