Showing posts with label Richard Feynman. Show all posts
Showing posts with label Richard Feynman. Show all posts

Friday, July 27, 2012

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).

Friday, May 25, 2012

Transpersonal psychology & quantum weirdness


Re-reading Ken Wilber’s Spectrum of Consciousness again, now when a little older, a little wiser (one hopes) has helped me better appreciate the significance of Wilber’s 1977 book. This is specially the case as I’ve been brushing up on the strange world of the quantum in the last couple of years.

Wilber attempts to integrate transpersonal psychology into a comprehensive new world view drawing on vast variety of areas and disciplines, ranging from psychology, anthropology, sociology, mythology, and comparative religion, through linguistics, philosophy, and history, to cosmology, quantum-relativistic physics, biology, evolutionary theory, and systems theory.

Transpersonal psychology is concerned with the study of humanity's highest potential, and with the recognition, understanding, and realization of unitive, spiritual, and transcendent states of consciousness.



Quantum theory has been said may help us understand consciousness and, more so, perception of the objective world, and the meaning of reality. A small example is the original work undertaken by Scully and Drühl that shook the physics community when it was first published in 1982. Essentially they demonstrated the possibility of simultaneously observing both particle-like and wave-like behavior of a quantum via quantum entanglement. The which-path or both-path information of a quantum can be erased or marked by its entangled twin even after the registration of the quantum.

This is weird because, in simple terms, an electron [somehow knows] that in the future the information about which slit it went through will be erased, and decides to act differently in the present moment.

From the double-slit experiment we know that when a particle is observed it behaves like a ball of matter since two bands are formed on the back screen. However, if we remove this information by making it uncertain again an interference pattern reappears (this is because an observer does not know through which slit the particle went when information about the path it took is removed). Amazingly an interference patterns appears even when the which-slit information is removed in the far future! It is as if the electron knows that in the future the information about which slit it went through will be erased, and decides to act differently in the present moment.

The great Richard Feynman was fond of saying that all of quantum mechanics can be gleaned from carefully thinking through the implications of the double-slit experiment.