A Misunderstood Word

Regarding our conversation about time, or the lack of it. On thinking
about it, my opinion is that it's a very great trap laid by a culture that
envies geniuses. What a narrow, one-dimensional portrayal of genius, that
he/she has to accomplish everything at a young age! I think we should all
be kinder to ourselves, with regards to time. That means taking things
easy and enjoying life when I can! (That's my plan.)

Ian:
What you wrote seems very reasonable. It does seem likely that my ideas
about age and about what it means to be successful in physics (or life) are
somewhat ingrained in me because of cultural impositions. I've thought about
this a lot since I was in high school. And, actually, this has led me to
think more about what the purpose of all of this really is.

That is, what is the purpose of studying physics? The trivial answer is that
it's interesting, we like to understand nature, and so on. But that doesn't
seem to answer the more fundamental question. We're interested...so what?
What is our purpose, what are we doing this for??
And then, talking with a friend about this, he made me realize that perhaps
the problem wasn't what the purpose of all of this is, but better, what one
understands by purpose. I've thought about this last thing quite a bit. But
I would still like to know what this means to you, what is your feeling
about this.

I love the way you rephrased the question. In so many ways, it is a better question because of it. It is better because I think the original question: what is the purpose of learning physics (which might as well be: what is the purpose of learning sociology, or what is the purpose of life, in general) is a very great hoax. When people search for a standardized answer to the purpose of life, they fall victim to “mind viruses” (not my words, but I thought they fit) such as religion.

This recurrent theme in all major religions (that it has to answer this hoax of a question) reflects a very large void in the masses that has to be filled. Some psychologists believe that people are native teleologists. Teleology is the assignment of purpose to everything. I have not met an intelligent person who has not wondered about his/her purpose. Maybe there is really some truth in the claims of these psychologists.

My feeling is that there is no standardized purpose to life, or learning physics, or physics itself. Even the word ‘purpose’ is misleading. It implies that life could not exist without purpose. But in fact, we know from Darwin that it can. The same word implies that learning physics is impossible without a purpose (obviously wrong). Some people claim that the purpose of law in nature is to allow life (this answer is of course very ego-centric), which brings us back to the first question. These are the unanswerable questions that leave me sick to the stomach when people try to ask me about them. They are just ill-posed questions.

If we discard the word ‘purpose’, I think we should be talking about ‘directions’ in life. Life can exist with or without direction, but a directed person will find fulfillment, whereas one who is aimless will go nowhere. One can learn physics with or without direction, but as you say, intellectual curiosity is a very poor stand-alone reason to commit a lifetime of effort to the study of physics.

My direction in physics has always been simple. I want to help people. This may surprise you, but before I found my intellectual passion for physics, I recognized that I was good in physics, and if there was anything substantial I could do, I thought surely it must be in this field, and the passion came after this decision. Later on, my simplistic view is to take on some hard knocks, but my resolve to stick to my direction is as strong.

I believe it is the search for clarity of this direction that makes each individual person unique. There should be no standardized direction, because we are too different! It’s impossible. Any answer that claims to apply to all is part of that same great hoax.

The search for clarity of direction is not just a very personal voyage. I think it defines who you are, it defines your life, everything about you.

We are aided in our search by external ideas, images, words that resonate through us. We find what is admirable about the life stories of other people and tuck them in the back of our head, to take seed. We create the idea of an ideal person, which could not be a single person that has already existed, because that would be extreme idolatry. Instead this ideal person must be an amalgamation of many, many influences, so that it is impossible to identify one dominant influence. I am left with no choice but to admit that YES this ideal person is unique, because no such other person has ever existed. With experience comes greater wisdom, and the ideal person may evolve in my fertile imagination, but always I strive to reach that ideal which is mine, mine only.

That, in short, is what I understand about purpose (possibly the most misunderstood word in the world).

Round 2

Broke's Unexplainable Farewell Floorball Extravaganza (TM)

Time: 19th, Saturday, 12pm, latecomers are welcome, but inform me if you intend to come very late, ie after 3pm. Time to leave: anytime you want to.

Food and Drinks: provided. If anybody has an itch to cook or bake, please tell me. But tell me only if you're good of course. Modesty shalt be cast out and ne'er seen again. Interesting drink combination ideas are very welcome.

Place: Mine. 23 Grange Road. Grange Heights. Swimming pool.
If you're driving, enter a small side road called St. Thomas Walk from either River Valley Road or Killiney Road, then drive till you find Grange Heights. Call if lost. There is no shame in being lost.
If you're taking the mrt, go to somerset and give me a call once you're there. I'll pick you up.
If you already know the way to my place, just be there. Don't call me. Unless you get lost.

Activities:
Floorball
Swimming
Skateboarding
Eating and drinking (for non-sports enthusiasts)
(but seriously, give all of the activities a shot, some people may even call them fun)
(actually, I take it back. it would actually be UNACCEPTABLE for you to not have fun.)

Bring:
Sports shoes
Extra change of clothes (you will perspire, profusely)
Soap and towel if you want to shower at my place
Swimming attire
Water for keeping alive

My number: 98778851 (I don't have caller id or voice message, so if I don't pick up, keep calling, or leave an sms.)

If it rains: we wait for it to stop.

As a way for me to keep track of who's seen this blog post and who hasn't, kindly leave a comment under this post, with your name.
I look forward to seeing you then.

Why Infrared

Dear Mr. Malone

When we met some time back, you asked me why the human body emits infrared radiation. I gave you an answer that was my intelligent guess, and a very unsatisfactory explanation (at least, I thought so). The intelligent guess turned out to be the correct answer. After having spent time leisurely reading in the summer (of which half that time is spent on physics), I have understood more concepts related to this question, and I feel I can attempt a more satisfying explanation. Some parts of the explanation require me to qualitatively explain the mathematics, but this is far from a ‘dumbed-down’ explanation, because in as much as mathematics can be translated to words, I believe that the translation is mostly correct. I am not sure whether it’s possible to try to explain this to your class, but I thought you may be interested intellectually. So here goes.

(In the following, I may use the terms ‘light’ and ‘electromagnetic radiation’ interchangeably.)

First, I will introduce the concept of a blackbody. A blackbody absorbs all light that falls upon it. Once the light is absorbed, it will bounce around inside the blackbody. Light will be continually absorbed and re-emitted by the atoms inside the blackbody. Because the light cannot escape and is eventually absorbed/re-emitted by ALL the atoms, there is a continual exchange of energy between all the atoms. Any net flow of energy stops, on average, when the entire blackbody is in thermal equilibrium, i.e. we can define the blackbody to have an exact temperature.

A perfect blackbody is sure to achieve thermal equilibrium, if we give it some time. But we cannot expect that the human body is a perfect blackbody, because we only absorb some of the light that falls on us. Hence, the human body is not exactly in thermal equilibrium, but we shall make the approximation that in fact, it is! 310K, which is about the normal temperature you see when you use a thermometer on yourself. Of course, we know that the temperature of our liver is probably slightly higher than that of our earlobes, but I make no apologies about the blatant approximation, because we usually need them to make any prediction at all. Most dense, opaque objects can be approximated as blackbodies, because the light interacts strongly with the atoms in this objects, and the exchange of energy through light also results in an approximate thermal equilibrium.

Second, I must introduce the concept of the simple harmonic oscillator (SHO), as applied to electromagnetic fields. The classic example of a SHO is a mass on a spring, or a pendulum. As you probably already know, the energy of the system, which depends on two variables (position and momentum), will oscillate between kinetic and potential energy.

Any electromagnetic field in a cavity/object/blackbody can be described in the following manner: at an infinite set of points (or locations) inside the cavity, we measure the electric (E) and magnetic (B) fields in the x,y,z directions for each point. In a sense, this is the most obvious way to describe the e-m field. However, the mathematics offers us another equivalent way of looking at the problem. The alternative description is that the field is really a sum of an infinite number of standing waves which vibrate at different frequencies. The following may sound familiar to you: a string clamped at both ends, any arbitrary deformation of the string can be alternatively described as a sum of many standing waves of different wavelengths, and vibrating at different frequencies. The technique I have described for the string is called Fourier decomposition, and the mathematics is simpler but not unlike that for the electromagnetic field.

Depending on the nature of the e-m field, standing waves of certain frequencies may have a stronger “presence” or amplitude of oscillation, as compared to other frequencies. We quantify the strength of each standing wave by a number N. Since we have an infinite number of standing waves, we really have an infinite number of N’s. Now it’s pretty amazing, but each N obeys an equation that is identical to that of a simple harmonic oscillator. The same equation that describes how the position of the mass/pendulum evolves with time, also describes N. This means that the e-m field is mathematically equivalent to a set of independent harmonic oscillators. In the case of the mass/pendulum, the total energy oscillates between kinetic and potential energy (at a certain time, the kinetic may be higher than the potential, but at all times the total energy is constant); in the case of the e-m field, the total energy sloshes between energy stored in the electric and the magnetic fields.

We need quantum mechanics to quantize these harmonic oscillators. In effect, we are allowing the energy of each harmonic oscillator to assume only certain values that occur at discretely-spaced levels. No longer do we have a continuous spread of energies.

Now suppose this harmonic oscillator is in thermal equilibrium at temperature 310K. The temperature tells us, on average, what the energy of the oscillator would be. We expect that at higher temperatures, the oscillator has more energy.

After we sum the average energies of all the harmonic oscillators in the human body, we find that the total energy is spread out among all the possible frequencies. Again, at certain frequencies, the electromagnetic energy is “stronger” than at other frequencies. When we actually plot it out (for 310K), the energy spread peaks at the infrared. And that is why the human body emits light in the infrared. It is more accurate to say that it emits light at all frequencies, but mostly in the infrared. Incidentally, using the same analysis on the sun (which has a surface temperature of 5800K), the energy spread peaks nicely in the region of visible light, hence we earthlings see only in the visible spectrum. The most perfect blackbody known to man is the entire universe (during a time, billions of years ago, when it was still opaque), and the Cosmic Microwave Background presents the most exact fit to this blackbody model.

I hope this explanation was more satisfying. It is certainly very mathematical, in the sense that you could not intuit the arguments here by simple physical principles, but that can’t be helped (for now). The math does not lie, and we do our best in interpreting it. Tell me if you want a greater depth of understanding for any of the ideas I wrote about. I wish you well.