The illusion of reality

The solidity of the world seems totally indisputable. As a fixed thing that you can see and touch, your body is also reassuring the solid.  But beginning with Einstein, modern physics have assured us that this solidity is a mirage. Quantum physics tells us that reality is far beyond human perception and intuition. In other words, our rational mind and common sense are just not capable of understanding the true nature of reality. And, therefore why particles can experience the full weirdness of quantum mechanics, whereas we evidently cannot. "In short, how does the well-behaved, everyday classical world emerge from the schizophrenic quantum realm.

The great Richard Feynman once said that all of Quantm physics can be understood through the double-slit experiment. For the last few weeks I have watched and re-watched the 1979 Douglas Robb Memorial Lectures with Feynman discussing photons – Corpuscles of light. 

Trying to make sense of single-photon behaviour in relation to reflection of multi surfaces. A topic, it seems infinitely more subtle then the high-school treatment of Newtonian optics.  So when one starts to think they are coming to terms with the counter-intuitive nature of light, photons behave even more strangely when pushed through a double-slit experiment.

So photons (particles for that matter) do not have a particular location and velocity; they merely have probabilities of location and velocity meaning a particle is all the possible futures it can have Viz-a-viz the Copenhagen interpretation suggesting that quantum mechanics does not yield a description of an objective reality but deals only with probabilities of observing, or measuring, various aspects of energy quanta.

So all but one of these futures collapses when it is observed. Meanwhile, these futures of the same particle can interfere with each other. Quantum probability is not a mere description of where a particle could be found and could be going, a mere mathematical abstraction, it is an actual property.

The photon in the experiment is all the possible paths it can take, some through one slit, some through the other, and it is interfering with itself. For each photon, measuring devices record one possible outcome of this self-interference.

Then comes the quantum eraser, proposed by Scully and Drühl in 1982. Given the basic principle of complementarity (for each degree of freedom, the dynamical variables are a pair of complementary observables) the precise knowledge of one implies complete unpredictability of the other.

For example, precise knowledge of a particle position implies complete unpredictability of its momentum. Because it’s generally assumed that the mechanism responsible for the loss of the interference pattern is the uncertainty principle, the “which-way” information of the particles is found without disturbing their wave-function.

The reason of the interference loss is the quantum information contained in the measuring apparatus, by means of the entanglement correlations between the particles and the path detectors. The experiment shows that if such quantum information is afterwards erased from the system, then the interference reappears (which would be impossible in the case of a perturbation).

It takes 21 days to change a habit

Yesterday as a part of a presentation I gave at the National Disability Service support worker’s conference, I talked about the old adage, “It takes 21 days to change a habit”. The thrust of my mention was about reinforcement, breaking habits, and building new ones.

We’ve known for years about the neuroplasticity — the brain’s capacity to create new pathways, a crucial part of recovery for anyone who loses a sense or a cognitive or motor ability. But it can also be part of everyday life for all of us. While it is often true that learning is easier in childhood, neuroscientists now know that the brain does not stop growing, even in our later years. Every time we practice an old skill or learn a new one, existing neural connections are strengthened and, over time, neurons create more connections to other neurons. Even new nerve cells can be generated.

Childhood illness and schizophrenia

According to the Journal of Psychiatry Research a study of the birth and hospital records of more than 40,000 young adults in Western Australia, GUT and chest infections in early childhood appear to raise the risk of developing schizophrenia later in life, even if they do not spread to the brain.

Boys who were admitted to hospital at least twice before age three with respiratory or intestinal infections were 80% more likely than others to develop the schizophrenia by the time they were in their mid-to-late 20s.

Previous research has shown an linkage between brain infections, such as meningitis, and schizophrenia, but this study is the first to demonstrate a link with illnesses that rarely involve the central nervous system - suggesting widespread inflammation, and the body's response to it, may be sufficient to disrupt brain development.

In a separate study published last month, Cambridge University scientists wrote that particular infections during pregnancy, such as rubella, were linked to higher schizophrenia risk in offspring. It was possible, they concluded, that some viruses, or viral strains, might similarly have a disproportionate effect on brain development during early childhood.

The God particle and stats...

We all know by now that CERN announced the discovery of the long-sought Higgs particle (or the so called God particle) last Wednesday. This is a discovery about nothing – that is it describes what is occurring in the vacuum. This achievement is huge considering it culminates literally decades of effort by thousands of physicists and engineers spending billions of euros to build the Large Hadron Collider. But the media’s reporting of 5-sigma as a measure of “certainty” was also remarkable.

First the vacuum - A vacuum is a space entirely devoid of matter and so represents a least possible energy state. Peter Higgs, and others realized that the state with least energy needn’t be empty - it can instead be filled with a physical quantity that slows down [electron] and gives mass to everything we know.

As mentioned some media outlets associated 5-sigma as a measure of certainty for the discovery of the Higgs boson. The gold standard for a discovery is a "5-sigma" bump, where sigma is a measure of bumpiness or standard deviation. A bump that high means that the odds are less than 1 in 3.5 million that it was produced by chance.

For instance, the science editor at the Swedish news paper Dagens Nyheter reported that a sigma of 4.9 equals a certainty of 99.99994%, which obviously isn’t true, simply because p(D|H0 ) is not the same as p(H0|D) meaning p-value represents the conditional probability of getting the data given that the null hypothesis is true. Nothing more, and it surely doesn’t give the probability for the alternative hypothesis being true, Ala the “certainty” that something has been found that’s not a random fluctuation.

Can you keep a secret

Recently much has been written about the physical and psychological consequences of secrecy. We know for example, that some of us can be trusted with other’s private matters, while some of us are less capable of keeping our mouths shut.

A diagnostic tool called the Self-Concealment Score gauges how secretive we are on a scale of ten (very open) to 50 (bank vault). Most of it turns out fall somewhere near the middle, which is the healthy range.

Generally, people with high-self concealment scores are those who tend to keep their thoughts and feelings bottled up and can be correlated with a host of emotional and physical issues, including stress, depression and have low self esteem.

Secrecy, it turns out, is taxing. Studies suggest that exercising the kind of self control required to deliberately conceal information is psychologically and even physically tiring, which sheds light on why secrecy can sabotage our health and well-being. It may also help explain why, for instance, it’s harder to diet during times of stress—because restraint depletes the same physical and emotional reserves as do stress and exhaustion.

God and the Delayed Choice Quantum Eraser – he may never be able to see the wave-like nature of reality.

In the last few months pretty much all the available time I have – I’ve been thinking about the implications of the Delayed Choice Quantum Eraser. All my life I understood the double-slit experiment to need ran observer in order to collapse the wave-like nature of reality. I have, as perhaps others, never grasped the deeper, the more subtle implication – the idea that:-

If we can know the path the entangled photon takes, that in itself is enough to bring about a collapse.

In quantum mechanics, the quantum eraser experiment is a double-slit experiment that demonstrates several fundamental aspects of the quantum theory, including quantum entanglement and complementarity. Brian Greene describes the experiment in his recent book The Fabric of the Universe. Consider

“A simple version of the quantum eraser experiment makes use of the double-slit set up, modified in the following way. A tagging device is placed in front of each slit; it marks any passing photon so that when the photon is examined later, you can tell through which slit it passed…when this double-slit-tagging experiment is run, the photons do not build up an interference pattern.

What if just before the photon hits the detection screen, you eliminate the possibility of determining through which slit it passed by erasing the mark imprinted by the tagging device?

As we know, it turns out, that the interference pattern shows up again. Which, is unexpected, counter initiative and strange to say the least.  But again it gets even stranger with the delayed-choice quantum eraser. Greene describes it thus,

It begins with [the set-up of the quantum eraser], modified by inserting two so-called down-converters, one on each pathway. Down-converters are devices that take one photon as input and produce two photons as output, each with half the energy (“down converted”) of the signal. One of the photons (called the signal photon) is directed along the path that the original would have followed toward the detector screen. The other photon produced by the down-converter (called the idler photon) is sent in a different direction altogether. On each run of the experiment we can determine which oath a signal photon takes to the screen by observing which down-converter spits out the idler photon partner. And once again, the ability to gleen which-path information about the signal photons– even though it is totally indirect, since we are not interacting with any signal photons at all– has the effect of preventing an interference pattern from forming.

So all we know about the signal photon we learn by observing the idler photon. But even so, we get the photons acting like particles. Greene again

What if we manipulate the experiment so as to make it impossible to determine from which down-converter a given idler photon emerged? What if, that is, we erase the which-path information embodied by the idler photon? Well, something amazing happens: even though we’ve done nothing directly to the signal photons, by erasing which-path information carried by their idler partners we can recover an interference pattern from the signal photons.

The implication here is the fact that we can know which slit the photon exits is exactly what causes the interference pattern to collapse. In the double slit experiment it isn’t the detector (the measurement) that collapsing the waveform. It is that fact that we can know that collapses the wave.

Now if a God can always knows which-path information a photon is to pass, he/she can therefore never see the interference pattern, the wave like nature of reality will be hidden from such a God.

Gender bias when using the internet

Some years ago the Pew Research Center published findings of a wide-ranging look at the way American women and men use the Internet.  At the time they suggested that men pursued many internet activities, more intensively than women, and that men were the first to try the latest technologies.

An interesting insight from that work reveled that women were framing their online experience with a greater emphasis on deepening connections with people.

Now, according to Medical New Today (MNT) Psychologists from the Department of Psychology at the University of Bath, England, have discovered that the difference between how men and women use the Internet has become even more significant in the last 10 years.

While surfing the Internet, men were more likely to visit entertainment, games and music websites. Women, on the other hand, were more apt to check out social networking sites.

After the introduction of Facebook, Twitter, and MySpace, women started to focus most of their time surfing on these types of sites. While some men are still interested in social networking online, women spent considerably more time on these sites than men.