Jun
14
Posted by jns on
June 14, 2007
From a recent Physics News Update comes this half-science, half-technology report about a device that uses heat to make electricity, with sound as an intermediary.
The story is interesting enough by itself, but it is also a useful illustration that sometimes there are new ideas in science and technology that are not as inscrutable as general relativity or string theory, but are nevertheless pretty startling and understandable.
There’s really nothing in this report that requires much in the way of deep technical or scientific understanding, although it might help if I describe the idea of the piezoelectric effect a little. There are some substances, largely ceramics but also some naturally occurring crystals that exhibit this property: applying stress to them (e.g., squeezing them) creates an electrostatic charge, i.e., a voltage across the crystal. Sometimes this property is used in reverse: put a voltage across a piezoelectric substance and it expands by a tiny amount. Piezoelectric devices are often used, therefore, to make precision actuators, devices that move things closer together or further apart depending on an applied voltage.
TURNING HEAT INTO ELECTRICITY THROUGH SOUND has been demonstrated by the University of Utah group of physicist Orest Symko. The group has built devices that can create electricity from the heat that would otherwise be wasted in objects such as computer chips. The devices might potentially make extra electricity from the heat of nuclear power plant towers, or remove extra heat from military electronics.
At last week’s meeting of the Acoustical Society of America in Salt Lake City, five of Symko’s students demonstrated the latest versions of the devices, which they have been developing for a few years. The devices first convert heat into sound, and then sound waves into electricity. Typically, each device is a palm-sized cylinder containing a stack of materials such as plastic or metal or fiberglass. Applying a heat source, such as a blowtorch, to one end of the stack creates a movement of air which then travels down the cylindrical tube. This warm, moving air sets up a sound wave in the tube, similar to the way in which blowing air into a flute creates sound. The pitch, or frequency, of the sound wave depends on the dimensions of the tube; current designs blast audible sound, but smaller devices would create ultrasound. The sound wave then strikes a piezoelectric crystal, a commercially available material that converts sound into electricity when the sound waves put pressure on the crystal.
Symko says a ballpark range of 10-25% of the heat gets converted into sound in typical situations. The piezoelectric crystals then convert about 80-90% of the sound energy into electrical energy. Symko expects the devices to be used in real-world applications within two years, and may provide a better alternative to photovoltaic solar cells in some situations. (Session 5aPA at meeting; also see University of Utah press release at http://www.unews.utah.edu/p/?r=053007-1)
[Phillip F. Schewe and Ben Stein, Physics News Update: The American Institute of Physics Bulletin of Physics News, Number 828, 13 June 2007.]
Jun
05
Posted by jns on
June 5, 2007
I know there are people who can’t sleep at night worrying about the impending explosion of the sun or the heat-death of the universe. Global warming is no doubt adding to their insomnia. Now it turns out that the consequences of global warming are even worse than we thought:
WARM THE WORLD, SHRINK THE DAY.
Global warming is expected to raise ocean levels and thereby effectively shift some ocean water from currently deep areas into shallower continental shelves, including a net transfer of water mass from the southern to the northern hemisphere. This in turn will bring just so much water closer to the Earth’s rotational axis, and this — like a figure skater speeding up as she folds her limbs inward — will shorten the diurnal period [i.e., the length of the day]. Not by much, though. According to Felix Landerer, Johann Jungclaus, and Jochem Marotzke, scientists at the Max Planck Institute for Meteorology in Hamburg, the day should shorten by 0.12 milliseconds [0.00012 seconds] over the next two centuries. (Recent issue of Geophysical Review Letters.)
[Phillip F. Schewe and Ben Stein, "Physics News Update: The American Institute of Physics Bulletin of Physics News", Number 826, 30 May 2007.]
Jun
03
Posted by jns on
June 3, 2007
This week Bob Park (What’s New for 1 June 2007) revisits presidential candidate Sam Brownback’s positive response when asked during a debate whether he was one who did not “believe” in evolution:
BELIEFS: BROWNBACK DEFENDS SCIENTIFIC ILLITERACY BY EXAMPLE.
A month ago at the Republican Presidential debate, there was a show of hands of those who don’t believe in evolution. One who raised his hand, Sam Brownback, was moved to explain why in yesterday’s New York Times: “I believe wholeheartedly that there cannot be any contradiction between faith and reason.” Which faith does he have in mind? Different faiths are often at war with each other, but no wars are fought over science. Science relies on Nature as the sole arbiter. There was much more, all in the language of the intelligent design movement, including the substitution of “materialism” for “naturalism.”
The op-ed in question is “What I Think About Evolution” (Sam Brownback, New York Times, 31 May 2007). In it he, apparently, tries to soften his position and find a way to say that he doesn’t not believe in evolution, mostly by trying to deny most of what evolution is and is all about, and then claiming that he doesn’t not believe in that. It’s not a successful tactic.
In matters of conflict between science and theology, there is a famous aphorism of the late John-Paul II: “Truth cannot contradict truth”, which is to say that if there is an apparent conflict between theological truth and scientific truth, it must be apparent only and due to incomplete understanding, because “truth cannot contradict truth”. Not so long ago I wrote an essay on the matter (“Evolution and the Vatican“), in which I ended up tracing the “truth cannot contradict truth” idea back to Pope Leo XIII, and then following forward papal writings and attitudes about evolution. In the context of mature Catholic theology it makes clear sense. Once again, it reminds me of my feeling that a mature theology like that of the Catholic church makes what passes for fundamentalist theology seem juvenile and exceedingly simple-minded by comparison.
Unfortunately, Mr. Brownback misunderstands and perverts the deep significance of “truth cannot contradict truth” — quite knowingly, I suspect — by offering in his op-ed “clarification” this updated fundamentalist version:
The heart of the issue is that we cannot drive a wedge between faith and reason. I believe wholeheartedly that there cannot be any contradiction between the two.
In other words: “faith cannot contradict reason”. Or, I suspect, he’d prefer “reason cannot contradict faith”, because he goes on to say that “Faith seeks to purify reason…”, which does not indicate a comparison of equals. He seems to assert that reason and faith are equally reliable except when there’s a contradiction, then faith wins — of course.
“Faith” is not interchangeable with a concept like “theological truth”. Faith, claimed as a revelation by the faithful, has virtually no connection to theological debate — debate is not necessary — and no connection to the use of reason which, in the context of a mature theology, is a God-given faculty provided to assist in the discovery of “truth”. “Faith” is a personal matter, but hardly the foundation of doctrine or theology.
Is this a naive misinterpretation of the John-Paul II aphorism, or a willful bending to suit Brownback’s own purposes? Either one is deplorable and neither does much to bolster Brownback’s claim that he doesn’t reject evolution, well, not reject entirely. In my opinion Brownback has only dug his hole deeper, but I’m sure his supporters will have faith that it brings him closer to heaven.