In my previous blog, I had talked about several things, namely, Copenhagen interpretation of the Quantum Theory, Schrödinger's cat paradox, the famous Einstein quote "God does not play dice" and the collapse of the wave function. Frankly speaking, until recently this Einstein's quote was over and above my head although I kept saying the quote several times to myself just because it sounded "high funda" (I know it had something to do with the probability but nothing more!). Similarly, the Schrödinger's cat paradox was no paradox to me - just some strange words beyond the scope of my understanding. By this time, I guess I don't need to say anything about my ignorance of the wave function collapse or the Copenhagen interpretation. But when I managed to sneak into the world of Quantum Mechanics (QM), some of the things were clear as a crystal - especially the Einstein quote and our cat. Of course, there are several things that are still hazy and they are bound to be. Even the great practitioner of QM, Richard Feynman had said "No body really understands Quantum Mechanics". I will discuss later in what spirit he had said that but in the meantime, in the series of blogs to continue, I want to discuss QM. The idea behind writing these series of blogs are two fold:
1. To share the joy and excitement that I have had so far had in my little understanding of this amazing world.
2. To travel more closer to this world and have a 'aerial look' of the much nicer things that are abound.
I was careful when I said 'aerial look'. I will not land into this world to look at the landscapes and sunrises. That job is for the experts. They are specifically for the people who go by the Feynman words "just shut up and calculate" and I am positive that these people will have a nicer (and a closer) look of the beauties that escape the aerial survey. Having said that, by aerial survey, I don't mean the philosophical speculation of the QM alone. Although any thought out QM discussion is bound to contain quite an amount of philosophy (I am tempted to say QM itself is a philosophy, but let me not go into that right now), I don't want to ignore the beautiful white clouds of mathematics (especially, the infinite dimensional Hilbert space theory) that envelope the rich quantum world. So, without any more ado let me begin my journey. Oh and by the way, by QM I mean the traditional way (or Copenhagen interpretation) as it is typically understood.
At the heart of QM lies this famous experiment called the double-slit experiment. It is one of the most amazing and a remarkable experiment in the history of physics. In September 2002, it was voted as the "most beautiful experiment" by readers of the Physics World. It is indeed. Quite fairly one can say that this one experiment shaped the modern theory of Quantum Mechanics and still keeps baffling physicists. The philosophical implications of this experiment are abound. Feynman had remarked that this single experiment contains everything that one needs to know about Quantum Mechanics. I will briefly describe the experiment here and give the statistical interpretation (or postulates) of Quantum Mechanics completely based on this. This is the crux of the Copenhagen interpretation that I had mentioned in this blog and the Schrödinger's cat paradox is the outcome of this interpretation.
The Double-Slit Experiment
The origin of this experiment dates back to 1801 when Thomas Young wanted to study the behavior of the light and determine whether the light is a wave or a particle. The experiment is quite simple. There is a machine gun which can spray either bullets or electrons, a barrier with two slits and a wall (or a detector) which can record the place where the bullets or electron hits the wall. Something like the one shown in the figure. We now conduct three experiments.
Experiment 1: We spray the bullets from the gun and record the pattern on the wall.
Experiment 2: Instead of the gun, we keep a candle and record the pattern on the wall.
Experiment 3: We spray electrons instead of bullets and record the pattern on the wall.
To be continued...
3 comments:
While we're on the topic, have you heard of quantum entanglement?
I think that's at work here. I was joblessly sifting through my own blog's archives and saw you had commented on my very first one (and no more, I think). And I was at a talk yesterday about the Copenhagen interpretation. And now your post. Quite unnerving, that.
So, I assume you're a Ph.D?
Hi Anand,
Welcome. Since I have one visitor now, it will inspire me to write more focused. Yeah, quantum entanglement is definitely at work here since its not even a couple of hours since I had written the blog after years of my slumber (baring a couple of blogs I had just written). And yes, I recently completed my degree in Computer Science and venturing into the world of Quanta. What do u do?
Heh, one visitor who came just as you woke up from slumber. Entanglement maaax only. Me, 4th year, ChemE, IITM. You were in IIT-M too, or some other IIT? And when?
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