Jan 302009

I’m reading a 40-year old book, Methods of Thermodynamics by Howard Reiss. I think I bought it after reading a recommendation on Amazon.com, describing this book as one of the few that takes the idea of axiomatic thermodynamics seriously, and treats it without mixing in concepts from statistical physics or quantum mechanics.

It is a very good book. Not only does it deliver on its promise, it also raises some issues that would not have occurred to me otherwise. For instance, the idea that a so-called equation of state does not fully describe the state of a material, even an ideal gas. You cannot derive U = CvT from the equation of state. You cannot that the internal energy U is a linear function of the temperature T, it has to be postulated.

One thing you can derive from the ideal gas equation of state alone is that an adiabatic expansion must be isothermal. As an ideal gas expands and its volume increases while its pressure decreases, its temperature remains constant. It also made me think again about the cosmological equation of state… cosmologists often play with idealized cases (e.g., dust-filled universe, radiation-filled universe) but until now, I never considered the possibility that even in these idealized cases, the equations of state do not full describe the stuff that they supposedly represent.

 Posted by at 1:30 pm
Jan 302009

Our paper about the thermal analysis of Pioneer 10 and 11 was accepted for publication by Physical Review and it is now on ArXiv.

I think it is an interesting paper. First, it derives from basic principles equations of the thermal recoil force. This is not usually in heat transfer textbooks, as those are more concerned about energy exchange than about momentum. We also derive the infamous factor of 2/3 for a Lambertian (diffuse) surface.

More notably, we make a direct connection between the thermal power of heat sources and the recoil force. The thermal power of heat sources within a spacecraft is usually known very well, and may also be telemetered. So, if a simple formalism exists that gives the recoil force as a function of thermal power, we have a very meaningful way to connect telemetry and trajectory analysis. This is indeed what my “homebrew” orbit determination code does, using Pioneer telemetry and Doppler data together.

No results yet… the paper uses simulated Pioneer 10 data, precisely to avoid jumping to a premature conclusion. We can jump to conclusions once we’re done analyzing all the data using methods that include what’s in this paper… until then, we have to keep an open mind.

 Posted by at 1:25 am
Jan 292009

In two days, I got two notices of papers being accepted, among them our paper about the possible relationship between modified gravity and the origin of inertia. I am most pleased, because the journal accepting it (MNRAS Letters) is quite prestigious and the paper was a potentially controversial one. The other paper is about Pioneer, and was accepted by Physical Review D. Needless to say, I am pleased.

 Posted by at 3:58 am
Jan 272009

Long before blogs, long before the Web even, there was an Internet and people communicated via public forums (fora?), Usenet foremost among them.

Yet I stopped using Usenet about a decade ago. Here is a good example as to why. Excerpts from an exchange:

You will have more success on Usenet if you learn and follow the normal Usenet posting conventions.

About posting conventions: where did I stray from them? I do indeed want to respect the list rules.

Have a look at <http://cfaj.freeshell.org/google/>

Got it: thanks.

You failed to appropriately quote the message that you are responding to. See the FAQ and the more detailed explanation of posting style that it links to. Then, if the explanation provided is not sufficiently clear, ask for clarification.

I am afraid that you have not yet ‘got it’. You have gone from not quoting the message you are responding to, to top-posting and failing to appropriately trim the material that you are quoting.

If you had been told what you did wrong, that would, hopefully, eliminate one class of error from your future posts. You were told where to read about conventions, which *should* eliminate *all* of the well-known errors.

You are forgiven if you thought that the thread from which I excerpted these snotty remarks was about Usenet’s “netiquette”. But it wasn’t. It was all in response to a very polite and sensible question about ways to implement a destructor in JavaScript.

I guess my views are rather clear on the question as to which people harm Usenet more: those who stray from flawless “netiquette”, or those who feel obliged to lecture them. I have yet to understand why it is proper “netiquette” to flood a topic with such lectures  instead of limiting responses to the topic at hand, and responding only when one actually knows the answer. I guess that would be too helpful, and helping other people without scolding them is not proper “netiquette”?

 Posted by at 1:31 pm
Jan 272009

I’ve read a lot about the coming “digital dark age”, when much of the written record produced by our digital society will no longer be readable due to changing data formats, obsolete hardware, or deteriorating media.

But perhaps, just perhaps, the opposite is happening. Material that is worth preserving may in fact be more likely to survive, simply because it’ll exist in so many copies.

For instance, I was recently citing two books in a paper: one by d’Alembert, written in 1743, and another by Mach, from 1883. Is it pretentious to cite books that you cannot find at any library within a 500-mile radius?

Not anymore, thanks, in this case, to Google Books:

Jean Le Rond d’ Alembert: Traité de dynamique
Ernst Mach: Die Mechanik in ihrer Entwickelung

And now, extra copies of these books exist on my server, as I downloaded and I am preserving the PDFs. Others may do the same, and the books may survive so long as computers exist, as copies are being made and reproduced all the time.

Sometimes, it’s really nice to live in the digital world.

 Posted by at 3:51 am
Jan 262009

The other day, I put my latest (well, I actually did it last summer, but it’s the latest that has seen the light of day) Pioneer paper on ArXiv.org; it is not about new results (yet), just a confirmation of the Pioneer anomaly using independently developed code, and a demonstration that a jerk term may be present in the data.

 Posted by at 3:30 am
Jan 252009

Often, I wondered: who designed the graphical elements, like the fonts and icons that appear on my computer screen?

Finally, I know the name of one of these people. She is Susan Kare, and her work appeared in the original Macintosh, Windows 3.0, OS/2, even Facebook. I came across her name as I was reading about the 25th anniversary of the Macintosh and clicked a link that took me to a 12-year old article from The New York Times that Ms. Kare has on her Web site.

 Posted by at 3:04 pm
Jan 242009

Once again, I am studying classical thermodynamics. Axiomatic thermodynamics to be precise, none of this statistical physics business (which is interesting on its own right, but it is quite a different topic.)

The more I learn about it, the more I find thermodynamics incredibly fascinating. Why is it so different from other areas of physics? Perhaps I now have an answer that may be trivial to some, but eluded me until now.

Most of physics is described by functions of coordinates and time. This is true even in the case of general relativity, even as the coordinate system itself may be curved, the curvature (the metric) is described as a function of space-time coordinates.

In contrast, there are no coordinates in axiomatic thermodynamics, only states. States are decribed by state variables, and usually you have these in excess. For instance, the state of one mole of an ideal gas is described by any two of the three variables p (pressure), V (volume) and T (temperature); once two of these are known, the third is given by the ideal gas equation of state, pV = KT, where K is a constant.

Notice that there is no independent variable. The variables p, V, and T are not written as functions of time. Nor should they be, since axiomatic thermodynamics is really equilibrium thermodynamics, and when a system is in equilibrium, it is not changing, its state is constant.

So why is it not called thermostatics? What does dynamics have to do with stationary states? As it turns out, thermodynamics is the science of fitting a square peg in a round hole, as having just established that it’s a science of static states, it nevertheless goes on to explain how states can change… so long as all the intermediate states can exist as static states on their own right, such as when you’re heating a gas slowly enough so that its temperature is more or less uniform at all times, and its state is well approximated by thermodynamic variables.

The zeroeth law states that an empirical temperature exists that is associative: systems that have the same temperature form equivalence classes.

The first law defines the (infinitesimal) quantity of heat dQ as the sum of changes in internal energy (dU) and mechanical work (p dV). An important thing about dQ is that there may not be a Q; in the jargon of differential forms, dQ is a Pfaffian that may not be exact.

The second law uses the assumption of irreversibility and Carathéodory’s theorem to show that there is an integrating denominator T and a function S such that dQ = T dS. (Presto, we have entropy.) Further, T is uniquely determined up to a multiplicative constant.

Combined, the two laws can be written in the form dU = T dSp dV. After that, much of what is in the textbooks about classical thermodynamics can be written compactly in the form of the Jacobian determinant  ∂(T, S)/∂(p, V) = 1.

Given that I know all this, why do I still find myself occasionally baffled by the simplest thermodynamic problems, such as convincing myself that when an isolated system of ideal gas expands, its temperature remains constant? (It does, the math says so, textbooks say so, but still…) There is something uniquely non-trivial about axiomatic thermodynamics.

 Posted by at 3:15 pm
Jan 222009

The other day, arXiv.org split a popular category, astro-ph, into six subcategories. This is convenient… astro-ph, the astrophysics archive, was getting rather large, and the split into sub-categories makes it easier to find papers that are relevant to one’s specialization.

On the other hand… it also means that one is less likely to read papers that are not directly relevant to one’s specialization, but may be interesting, eye-opening, and may help to broaden one’s horizons. Is this a good thing?

There are no easy answers of course… the number of papers just on arXiv.org is mind-boggling (they proudly announced that they’ve passed the half million paper milestone on October, with thousands of new papers added every month) and no one has the time to read them all. Hmmm, perhaps I should have spent more time applauding a recent initiative by Physical Review, their This Week in Physics newsletter and associated Web site.

 Posted by at 12:42 pm
Jan 202009

While we were celebrating President Obama, the Bank of Canada made its move: the Canadian prime rate is now lower than ever, at 1%. The expectation is that the economy will not fare well in coming months.

Being the holder of a variable rate mortgage, I have no reason to complain. Still, it’s an unsettling development.

 Posted by at 11:37 pm
Jan 192009

There is ceasefire in Gaza. Perhaps it will hold for a while.

It may have been precipitated by Israel’s desire to wrap up its military operations before Obama is inaugurated, anticipating that the new administration in Washington will be a lot less sympathetic toward, well, if not necessarily Israel’s cause then certainly the methods that Israel chooses to advance its cause.

It may have been the result of rising doubt and anger among Israelis themselves, those who realize that the history of the Gaza strip did not begin with the Qassam rockets.

Or perhaps they began asking questions like that asked by Time Magazine: Can Israel survive its assault on Gaza?

Or maybe it was compassion. The other day, the assault on Gaza turned from an abstract litany of numbers (last I heard, over 1,100 killed, more than 4,000 wounded, many of them civilians) into something personal, as an Israeli-trained Palestinian doctor, peace activist to boot, who regularly reported on Israeli television via cell phone, was reporting the shelling of his own house and the loss of three of his daughters on live TV.

The biggest irony of any “war on terror” (not just that of Bush, not just that of Olmert) is how, contrary to the stated intent of the war’s leaders, such a war flawlessly serves the terrorists’ interests. Such wars are based on the blatant ignorance of their leaders, leaders who believe that the terrorist is motivated by hatred and a desire to kill. While they are not free of hatred and bloodlust, they are motivated by something else altogether: by a desire to change the political course through their acts of terror. When our leaders declare a “war on terror” in response, they accomplish precisely what the terrorist wants… which is why Bush and Olmert ended harming the interests of their own countries to an extent far greater than anything the terrorists could have accomplished by themselves.

Gavrilo Princip knew this. When he assassinated the arch-duke of Austria-Hungary in 1914, his hatred of a despised leader was outweighed by his the hope that the assassination will change the existing world order and free Serbia from Austrian rule. Princip became one of the most influential (and most successful!) persons of history, not so much as a result of his own actions, but as a result of the predictably stupid reaction of Vienna’s fossilized political leadership. Why are we—the U.S., the Western world, Israel—so bent on repeating that mistake?

 Posted by at 2:10 pm
Jan 182009

“John Moffat is not crazy.” These are the opening words of Dan Falk’s new review of John’s book, Reinventing Gravity, which (the review, that is) appeared in the Globe and Mail today. It is an excellent review, and it was a pleasure to see that the sales rank of John’s book immediately went up on amazon.ca. As to the opening sentence… does that mean that I am not crazy either, having worked with John on his gravity theory?

 Posted by at 3:58 am
Jan 162009

My uncle, my mother’s younger brother, is dead this morning I am told.

His name was József Sztojka, although I remember him from my childhood as Jóska bácsi, or uncle Jóska. I have many, many, many fond memories of him. He has been suffering from illness for a long time, so his death is not altogether a surprise, but I am saddened nevertheless.

Some random memories.

  • I have a copy of volume 3 of a Hungarian language physics book, Mechanics by Tibor Cholnoky, which was the first book I ever owned that explained in detail how the laws of orbital mechanics can be derived from Newton’s law of gravitation. This book was a gift from Jóska bácsi. I saw it on his bookshelf when I was around 10 or so, and sat down reading it, forgetting about the world. That’s how he found me and that’s when he gave the book to me. Thank you for helping to steer my life in this direction.
  • I loved playing with my cousins, his two children (later three), at Jóska bácsi‘s place. It was the selfishness of childhood (I was no more than 6 or 7 at the time), as it wasn’t family ties but my cousin’s toys that I found the most interesting. But what is most memorable is how Jóska bácsi played with us. He helped us build toy castles and helped us destroy them with toy weapons. He helped us build elaborate tracks for Matchbox cars (oh, how I envied my cousin’s amazing Matchbox car collection!) and helped us race them. Though I never understood why he seemed so offended by my childish attempt at poetry. When one of the Matchbox cars kept oscillating left and right as it went down the track, I attempted to describe this in rhyme with words that may be best translated into English as “wiggled its fanny”. He angrily told me not to say such things again.
  • A relative of my father visited us once from Romania. His family name was Fogas, a word that means, among other things, (coat)hanger in Hungarian. Together with this relative, we went to the flat of Jóska bácsi one day, a flat that was under major renovation at the time. So we rang the doorbell, Jóska bácsi opened the door, and as he never met our distant relative, introductions began. “Fogas,” said our relative, thrusting his right hand out for a handshake, while holding his coat in his left. “We don’t have those yet,” apologized Jóska bácsi
  • I first heard the record At the Speed of Sound by Paul McCartney and the Wings at Jóska bácsi. I also first heard Jeff Wayne’s musical experiment, The War of the Worlds, at his place. I still enjoy listening to both records from time to time, and when I do, I often remember Jóska bácsi.
  • Shortly before I left Hungary, I visited Jóska (by this time, I often omitted the bácsi part) at his cottage north of Budapest. He was already in the habit of spending much of his time alone, like a hermit, in this cottage. I spent a whole evening with him before heading back to town, and we had a long, long conversation about life, universe, and everything. He was a sad man by this time, and I listened to him with the infinite wisdom of youth, certain that I had all the answers, certain that if he only heeded my advice, all would be well.

Well, Jóska bácsi is no more. Only the memories remain.

 Posted by at 2:26 pm
Jan 152009

I suppose “brace for impact” are not exactly the words you’re hoping to hear from the pilot when you’re a passenger on board a commercial flight:

US Airways 1549

US Airways 1549

They say the airplane may have struck a bird. Apparantely, everyone got out and from the looks of it, if it doesn’t sink the airplane may be salvagable, too, which would be phenomenal.

 Posted by at 9:16 pm
Jan 152009

When I was learning to fly, one of the first things I was taught was the use of checklists. Checklists contain trivial things that are supposedly self-evident. Stuff like this, for the Cessna 172 that I used to fly:

Aircraft position INTO WIND
Flight controls FREE & CORRECT
Fuel selector valve BOTH
Elevator trim TAKEOFF

So who in his right mind would forget to close the doors, you might ask, or open a fuel valve? But the fact is, people do, and people died as a result. Pilots, gung-ho folks that they are, were nevertheless humble enough to realize this, and the use of checklists has been common practice pretty much since the dawn of flying.

Unfortunately, the same cannot be said for hospital operating rooms. It seems that surgical death rates can be cut by up to one third through the simple use of a checklist… so why hasn’t this been done before? Is it ignorance, arrogance by the medical community, or a combination of both?

In any case, introducing checklists in operating rooms is a no-cost improvement that can save billions of dollars a year not to mention a number of lives.

 Posted by at 6:09 pm
Jan 152009

Not quite the twin towers, but sights like this will likely evoke similar feelings of anger in many Arabs and non-Arabs alike:

Gaza burning

Gaza burning

Israel says that the attack on a UN compound was an accident. Israel says that the attack on this building, housing news organizations, was an accident. Israel says that the killing of hundreds of civilians was just accidental, “collateral damage”. Yes, I believe in the tooth fairy, too.

But even if I did believe them… why is it that as soon as you make civilized noises about it, and use euphemisms like “collateral damage”, suddenly mass murder becomes acceptable?

Meanwhile, the BBC showed pictures of the wife of Syrian president al-Assad touring a Palestinian refugree camp… with her head pointedly not covered by a scarf or other headwear. This was seen as an indication that even Syria is now worried about the rise of Islamic fundamentalism in response to Israel’s attack on Gaza. Which raises the same question that was raised by Bush’s attack on Iraq, which boosted Iran’s influence in the region: just how STUPID are we, using our military in such braindead ways that the ones who benefit the most are our deadliest enemies? What exactly do Bush and the Israeli leadership really want, the rise of the Caliphate? Presently, they’re doing more to realize that dream than all the ayatollahs and all the bin Ladens combined.

 Posted by at 2:32 pm
Jan 152009

This is what Windows Vista’s weather gadget told me this morning:

Slightly exaggerated

Slightly exaggerated

Fortunately, it is lying. It’s only -29 outside, not -35. Still, it made me remember fondly the good ole’ days when there was still some global warming…

 Posted by at 2:21 pm
Jan 152009

The union of OC Transpo drivers threatened to picket the city’s Para Transpo service if the city brought in additional drivers to deal with increased demand. Para Transpo is not part of OC Transpo. It is a service for the really needy, disabled people for whom walking is not an option, not even when it’s not -30 below, like this morning. By threatening to picket, the union makes once again crystal clear a point that has been obvious since the beginning: their utmost contempt towards the residents of Ottawa. It is for this reason that I support the city’s unwavering position. The drivers had other options, like work-to-rule. By choosing to go on strike in the middle of winter, by choosing to picket sites such as city hall that have nothing to do with transportation, they’ve made their feelings clear towards the nearly one million residents of the city… if we don’t feel compassionate towards their supposedly just cause, they only have themselves to blame.

 Posted by at 2:13 pm
Jan 142009

Wow. Look at this temperature gradient between Ottawa and Montreal:

Arctic cold front

Arctic cold front

And while these are wind chill temperatures, the real thing is soon to follow: some stations forecast a temperature of -33 Centigrade Friday morning. Needless to say, global warming is not exactly high on the list of priorities of most people I know.

 Posted by at 5:09 am
Jan 122009

I asked a New York friend today, what will they do on Times Square on New Year’s Eve, December 31, 2010?

In the 2000’s, every other person on attending the New Year’s Eve celebrations at Times Square was wearing a pair of 2oox party eyeglasses, with the two zeroes in the middle forming the pair. The same thing worked in the 1990’s (the upper halves of the two 9’s serving the same purpose) and even in the 1980’s (again, the upper halves of the 9 and the 8 doing the same thing.) I have no idea about the 1970’s… that was before my time, I came to North America in 1987.

It’ll still work at the end of this year, because 2010 has two zeroes. But… what will happen at the end of 2010? How will they use the number 2011 to create a pair of New Year’s eyeglasses? That’s what I asked my friend.

He asked me in return why I am worried about such things. “I am worried about the future,” I told him, “aren’t you?” “No,” he replied, “not that badly…”

 Posted by at 10:34 pm