Particles and waves

I could have studied Physics. Really. As Ernest Rutherford is said to have said: “All science is either physics or stamp collecting”.

As with many other subjects, I deeply enjoy being an amateur; and that’s why I cannot understand why journalists and TV people think they have to embellish or enrich their stories. The truth, the real world, is astounding. Be it cuneiform script, jazz music, lawn mowing or quantum mechanics.

I’ve been trying to understand quantum mechanics. For years. As an example, right now I’m reading The God Particle, by Leon Lederman (interesting, but not so good, so far). But I think I haven’t quite understood what’s going on yet.

One could argue that nobody really understands quantum mechanics; that subatomic world is counterintuitive, and that you cannot really aspire to understand it. After all, Richard P. Feynman, one of the greatest scientists of the 20th century, the co-author of one of the most succesful theories in the history of physics (quantum electrodynamics) and an excellent teacher, is often quoted as having said things like these:

– I think I can safely say that nobody understands Quantum Mechanics.

– If I could explain it to the average person, I wouldn’t have been worth the Nobel Prize.

– Things on a very small scale [like electrons] behave like nothing that you have any direct experience about. They do not behave like waves, they do not behave like particles, they do not behave like clouds, or billiard balls, or weights on springs, or like anything that you have ever seen.

So… do you have to give up?

I don’t think so.

I still believe that, given a proper explanation, given the right one for you, you can understand everything. After all, Ernest Rutherford said as well: “An alleged scientific discovery has no merit unless it can be explained to a barmaid”.

Today, I’ve just read a sentence that I absolutely have to record here. The problem is: I can’t tell whether it’s absolutely correct or not (and, according to Feynman, it isn’t). But at least it says something, and I understand it. It mentions a doubt I have, and it says something clarifying. Actually, I knew everything it says; but I hadn’t seen these ideas put together, in such a simple and elegant way.

So, be it correct or not, I make a note of it.

How can something be both a particle and a wave at the same time? For one thing, it is incorrect to think of light as a stream of particles moving up and down in a wavelike manner. Actually, light and matter exist as particles; what behaves like a wave is the probability of where that particle will be.

Thank you so much, Todd Stedl.

Other sentences by Todd Stedl:

atomic particles possess an intrinsic angular momentum, or spin, and that this spin is quantized (that is, it can only have certain discrete values). Spin is a completely quantum mechanical property of a particle and cannot be explained in any way by classical physics. It is important to realize that the spin of an atomic particle is not a measure of how it is spinning! In fact, it is impossible to tell whether something as small as an electron is spinning at all! The word ‘spin’ is just a convenient way of talking about the intrinsic angular momentum of a particle.

And these were written by Stephen Jenkins:

wave phenomena, such as diffraction, are generally only important when waves interact with objects of a size comparable to their wavelength. Fortunately for the theory, the wavelength of everyday objects moving at everyday speeds turns out to be incredibly small.



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