In recent years there has been an upsurge in the discussion of so-called delayed-choice experiments, as exemplified in the interferometer experiment discussed by Wheeler [1]. In commenting on this experiment Bohm et al. [2] claim that their quantum potential interpretation gives results entirely compatible with Bohr's views on wholeness and complementarity. It seems to me, however, that this discussion to a large extent completely misses the fundamental point in Bohr's argumentation as given in his famour answer [3] to Einstein, Podolsky and Rosen as well as in his paper on his discussions with Einstein [4]. Expressing it a bit paradoxically one might say that in the examples discussed the experiments are not sufficiently delayed. I shall therefore here discuss a different thought experiment, much closer to Bohr's own examples, which brings out this point.
The intellectual adventure story of the "double-slit" experiment, showing how a sunbeam split into two paths first challenged our understanding of light and then the nature of reality itself--and continues to almost 200 years later.Many of the greatest scientific minds have grappled with this experiment. Thomas Young devised it in the early 1800s to show that light behaves like a wave, and in doing so opposed Isaac Newton's view that light is made of particles. But then Albert Einstein showed that light comes in quanta, or particles. Quantum mechanics was born. This led to a fierce debate between Einstein and Niels Bohr over the nature of reality--subatomic bits of matter and its interaction with light--again as revealed by the double-slit experiment. Richard Feynman held that it embodies the central mystery of the quantum world. Decade after decade, hypothesis after hypothesis, scientists have returned to this ingenious experiment to help them answer deeper and deeper questions about the fabric of the universe.How can a single particle behave both like a particle and a wave? Does a particle, or indeed reality, exist before we look at it, or does looking create reality, as the textbook "Copenhagen interpretation" of quantum mechanics seems to suggest? How can particles influence each other faster than the speed of light? Is there a place where the quantum world ends and the familiar classical world of our daily lives begins, and if so, can we find it? And if there's no such place, then does the universe split into two each time a particle goes through the double-slit?Through Two Doors at Once celebrates the elegant simplicity of an iconic experiment and its profound reach. With his extraordinarily gifted eloquence, Anil Ananthaswamy travels around the world, through history and down to the smallest scales of physical reality we have yet fathomed. It is the most fantastic voyage you can take.
To explain Young’s Double Slit Experiment Niels Bohr postulated his Complementarity Principle according to which if the observation is for interference pattern the particle will change to wave. Albert Einstein had objected: how can inanimate particle know what the observation is about? Experiments have confirmed Bohr’s Complementarity Principle. Upon investigation, the author was able to explain all experiments without invoking Complementarity Principle, using only coherence and alignment considerations. This research recently culminated in revolutionary finding by the author, that particle always remains particle and its wave function always remains wave, no mysterious change from particle to wave or vice-versa and published a paper in the Journal of High Energy Physics and Cosmology (JHEPGC), 9, 596 – 601, widely acclaimed by readership and reviewers. It restores objectivity to science and opens new vistas of research developing new concepts, advancing science.