Friday, September 29, 2006

What's in a name?

Has this ever happened to you?

I dwell online often in various online chat group, including the #physics channel on the Undernet server. Occassionally, we get a rather amusing incident that, while it is funny, it is also rather sad and pathetic. What typically happen is this: a user, whose nickname we have never seen before, would come into our IRC channel and asks for a "reading". This has happened a few times and most of us already know what this means. This person mistook "physics" for "psychic".

Being a smarty pant myself, I usually play along with this person and would say something like "Oh, let me see... I see some images..... hum. I can see that spelling is not one of your strong suit. In fact, you hate spelling when you were in school".

Inevitably, this person would express astonishment on how right on I was! After being led on by a few other people for several minutes, this person finally caught on that he/she was taken for a ride and left. However, a few of them actually did stay on and in fact, express their puzzlement on why physics is not the same as psychic since ".. don't they both try to understand our universe and predict the future?"

Of course, this was there things get ugly.

I often find it ironic that people who misspell "psychic" would get "physics" instead, since physics is a complete opposite of psychic, the latter being a pseudoscience at best, and crackpottery at worst.


Monday, September 25, 2006

Why is Quantum Mechanics SO Difficult?

Strangely enough, QM's formalism isn't any more difficult than other areas of physics. The mathematics of the "standard" QM isn't any worse than, let's say, electromagnetism. Yet, to many people, especially non-physicists, QM presents a very daunting effort to understand.

I strongly believe that it all comes down to how we understand things and how we expand our knowledge. Typically, when we teach students new things, what we do is build upon their existing understanding. We hope that a student already has a foundation of knowledge in certain areas, such as basic mathematics, etc., so that we can use that to teach them about forces, motion, energy, and other fun stuff in intro physics. Then, after they understand the basic ideas, we show them the same thing, but with more complications added to it.

The same thing occurs when we try to help a student doing a homework problem. We always try to ask what the student know already, such as the basic principle being tested in that question. Does the student know where to start? What about the most general form of the equation that is relevant to the problem? Once we know a starting point, we then build on that to tackle that problem.

The common thread in both cases is that there exists a STARTING point as a reference foundation on which, other "new" stuff are built upon. We learn new and unknown subject based upon what we have already understood. This is something crucial to keep in mind because in the study of QM, this part is missing! I am certain that for most non-physicists, this is the most common reason why QM is puzzling, and why quacks and other people who are trying to use QM into other areas such as "metaphysics" or mysticism, are using it in a completely hilarious fashion.

There is a complete disconnect between our "existing" understanding of the universe based on classical understanding, and QM. There is nothing about our understanding of classical mechanics that we can build on to understand QM. We use the identical words such as particle, wave, spin, energy, position, momentum, etc... but in QM, they attain a very different nature. You can't explain these using existing classical concepts. The line between these two is not continuous, at least, not as of now. How does one use classical idea of a "spin" to explain a spin 1/2 particle in which one only regains the identical symmetry only upon two complete revolutions? We simply have to accept that we use the same word, but to ONLY mean that it produces a magnetic moment. It has nothing to do with anything that's spinning classically. We can't build the understanding of the QM spin using existing classical spin that we have already understood.

Now interestingly enough, the MATHEMATICAL FORMULATION of QM is quite familiar! The time-dependent Schrodinger equation has the same structure as a standard wave equation. We call the energy operator as the Hamiltonian not for nothing since it looks very familiar with the hamiltonian approach to classical mechanics. The matrix formulation also isn't anything new. What this means is that while the conceptual foundation of QM is completely disconnected with our traditional conceptual understanding, the mathematical formulation of QM completely follows from our existing understanding! Mathematically, there is no discontinuity. We build the formalism of QM based on our existing understanding!

This is why, in a previous thread in PF, that I disagree that we should teach students the concepts of QM FIRST, rather than the mathematical formulation straightaway. There is nothing to "build on" in terms of conceptual understanding. We end up telling the students what they are out of thin air. The postulates of QM did not come out of our classical understanding of our world. Instead, the mathematical formalism is the only thing that saves us from dangling in mid air. It is the only thing in which our existing understanding can be built on.

What this implies clearly is that, if one lacks the understanding of the mathematical formalism of QM, one really hasn't understood QM at all! One ends up with all these weird, unexplained, unfamiliar, and frankly, rather strange ideas on how the world works. These conceptual description QM may even appear "mystical". It is not surprising that such connections are being made between QM and various forms of mysticism. One lacks any connection with the existing reality that one has understood. So somehow, since QM can do this, it seems as if it's a licence to simply invent stuff weely neely.

The mathematical formalism of QM is what defines the QM description. The "conceptual description" is secondary, and is only present because we desire some physical description based on what we already have classically. It is why people can disagree on the interpretation of QM, yet they all agree on the source, the mathematical formalism of QM.

This, however, does not mean that QM is nothing more than "just mathematics". This is no more true than saying the musical notes on a sheet of paper are just scribbles. The notes are not the important object. Rather, it is the sound that it represents that's the main point. The musical notes are simply a means to convey that point clearly and unambiguously. Similarly, the mathematics that is inherent in QM and in all of physics, is a means to convey an idea or principle. It is a form of communication, and so far it is the ONLY form of communication accurate and unambiguous enough to describe our universe. It reflects completely our understanding of a phenomena. So a mathematical formulation isn't "just math".

You cannot use your existing understanding of the universe to try to understand the various concepts of QM. There is a discontinuity between the two. It is only via the mathematical continuity of the description can there be a smooth transition to build upon. Without this, QM will not make "sense".


Wednesday, September 20, 2006

The most influential physicist

If you ask a bunch of people on who is the most influential physicist of, let's say, since the beginning of 1900, you would get the usual answers: Einstein, Feynman, Bohr, Heisenberg, Dirac, etc... all the big names. However, consider this: there is only ONE person who has won the Nobel Prize for Physics twice; this person is a co-inventor of the most important device that is now the foundation of our modern society that we use everyday; and this person is not on that list above.

Ladies and Gentlemen, let me introduce you to John Bardeen!

(Who? WHO?)

In my book, John Bardeen is the physicist that has the MOST direct influence on all of our lives. His first Nobel Prize was awarded for the invention of the transistor along with William Shockley and Walter Brattain. To say that the transistor has revolutionized our world would be almost an understatement, unless one has no clue what a transistor is and why it is useful.

That invention alone would have been sufficient to put him at the top of this list, but nooooo.... His second Nobel Prize in Physics pushed him way over the top. He is the "B" in the BCS Theory of Superconductivity, along with Leon Cooper and Robert Shrieffer. The BCS theory is considered to be one of the most successful and highly verified theories in all of physics. Till 1986, it was thought that the BCS theory has explained everything there is to know about all of superconductivity. However, the significance of the BCS theory goes way beyond just explaining a single phenomena. It marked one of the earliest sucesses of the application of quantum field theory in the emerging field that is now known as condensed matter physics. This sparked further refinement of the field theoretic methods in the study of materials, something that we now are reaping the rewards from. So the impact of this theory transcends beyond just what it describes.

But why isn't he more well known?

He is one of those rare breed of physicist that isn't eccentric, is not loud, profoundly understated, and intensely private. While the general public may not even know of his existence, those of us in physics, and especially in condensed matter physics, have nothing but the utmost respect and admiration for him as a person, and his body of work.

I highly recommend the biography of Bardeen written by Lillian Hoddeson, Daitch Vicki, Vicki Daitch titled "True Genius: The Life and Science of John Bardeen" (National Academies Press, 2002). This could be the most fascinating and important person that you have never known.


Tuesday, September 19, 2006

I learned how to bake bread because of Physics

One of the requirements I had to go through while in graduate school was an oral comprehensive exam. In this exam, you present a half-hour talk on a subject within the area of physics that you are going to specialize and do research in. Then your exam committee will have another 15 to 30 minutes in which they can ask you about ANYTHING they wish in physics, whether it is related to what you had just presented or not.

As you can guess, preparing for this exam can be quite a nerve-wrecking experience. I remember that for the week leading up to the exam, I was having trouble sleeping, waking up in the middle of the night anticipating another question that might be asked. I've scoped as much as I can the background of all the committee members and their areas of expertise so that I could anticipate what kinds of questions I might be asked. Still, I was a nervous wreck that whole week.

I was maybe 3 or 4 days before the exams when I almost reach the breaking point. I had way too much nervous energy that I simply had to do something, or I would go nuts. I wanted so badly just to go out and walk around the neighborhood towards the lake, but it was in the middle in winter! I ended up pacing around the house trying to figure out what to do. The TV was on, and there was this cooking show (I watch cooking shows religiously) featuring an Italian woman kneading dough for a bread. As she was pounding the dough into submission, she kept saying that she didn't need to go to a psychiatrist, because she got rid of all her aggression and troubles by making and baking bread all the time.

Well I certainly didn't need to be smacked on the head with a rolling pin to realize that, wait a minute, I can also try and make bread by hand! I mean, I'm a good cook (it's a hobby), but I've never done a lot of baking, and certainly have never baked bread from scratch, other than putting everything into an automatic bread machine that I got for christmas.

So I looked up a few of the cookbooks that I had, and found a rather simple recipe for a version of the french baguette. I had some yeast, flour, and everything I would need. So I dove right in! I had to make space on my kitchen counter to knead the dough, but other than that, there were no other obstacles. The only problem was, one had be patient when making bread. This one required at least 2 risings, each lasting an hour or more. The dough can't be hurried if you want the full flavor and texture.

In any case, I finally got to the point where it was ready to be baked. This is where I ran into some problems. I didn't have a baking stone for my oven to bake the dough on. And I certain did not also have a steam oven, which is what most bread bakers use. So after making do with putting the dough on a cookie sheet, I armed myself with a water squirt bottle and sprayed the inside of the oven with a mist of water (I could have sworn I remember seeing Julia Child doing something like this in one of her cooking shows). I did this several times during the baking.

Finally, it was time for the bread to come out. I must tell you that while it was baking, the smell coming out of the kitchen was HEAVENLY! My first bread was..... er.... well, how shall I put it.... rather odd. It certainly wasn't the typical, long baguette (would not fit the oven). It was a bit tough, and the crust didn't develop as well as I would like, but man, it was one of the best things I've ever done! There is no doubt that even mediocre home-made bread tastes better than the ones in the supermarket, AND, has no preservatives!

Since then, I've improved my skills at making bread. I'm the type of person who, if I want to do something, I tend to go all out and try doing it as best as I can (why waste time doing something half-heartedly?). I bought myself a set of baking tiles, bread cookbooks, and other accesories. I no longer buy bread anymore. I make a bunch of dinner rolls and freeze them, so that I always have some on hand whenever I want them. I often make what I would call rustic italian country breads. These are hearty breads with thick, delicious crust and a distinct, yeasty flavor. This is a favorite whenever I have dinner parties. I also make pizza and pizza dough. The result is a flavorful pizza crust that does not taste like a cardboard.

The unfortunate (or fortunate?) side effect here is that I have since become a bread snob! I can no longer tolerate breads from supermarkets, only breads from real bakeries will do. I pay utmost attention to bread ingredients (no bleached flour, only stone-ground, only organic, etc.). After discovering how good it can taste, I find that I have no reason to tolerate mediocre bread, and certainly not bread that is full of chemicals just simply to make it lasts longer on the shelf. Once you have opened your eyes to how good it can be, I guess you can no longer settle for anything less.

And oh, my oral exam? I passed! I've gone on to do other, better things. But I still make my breads by hand.


Sunday, September 17, 2006

An ominous problem in physics today

This article by Michael Riordan in Physics Today basically sums up my current object to how String Theory is being practiced by those in this field, and how it is being sold to the general public.

Also read his gem of a reply to one of the response to his article.

A highly-recommended reading.


Friday, September 15, 2006

This is the best open physics forums, bar none.



I needed a place to store all my links, thought, resources, and other rumblings regarding Physics and Physicists. I often have to keep looking for many common links and papers, especially when trying to refer to them for posting on various forums. Having them here might make it more convenient.

Thanks for visiting. I look forward to hearing your comments.