“Be kind, for everyone you meet is fighting a hard battle” - Often attributed to Plato but likely from Ian McLaren (pseudonym of Reverend John Watson)

Saturday, August 28, 2010

The bracelet rage

Was I asleep? I don't even remember where I read the first article about some sort of bracelet designed to, in some fashion, harmonize your energy field or some such. I do remember, though, that it was just this past Wednesday!? This particular one was the Power Balance Bracelet. I read about it and sadly shook my head. Its makers claim to embed frequencies into a hologram that "resonate and respond to the natural energy field of the body."

Then,THE VERY NEXT DAY, I was talking to a person with whom I work and noticed an unusual looking bracelet on her wrist. Innocently, I asked her what it was and she mumbled something about "balance" and told me that she'd give me a card from the guy that sold it to her. Sure enough, she had an EFX BRACELET that uses a hologram that "contains algorithms and frequencies" that interact positively with your body's energy field at the cellular level. As someone commenting on a site said, "how could that not work?"

Next, my stepson asked me to email his Spanish teacher, holding a note out for me to read. "Why, what's that bracelet you're wearing?" I asked, knowing the answer. Andre doesn't know the name of it but it's all the rage on his football team. I shook my head and told him it's useless. "No," he said, "they proved it works." See below.

Now I'm watching ESPN and see a series of advertisements for the iRenew Bracelet with its "Biofield Technology." And they have a quantum physicist! You can't go wrong if you're dealing with energy and have a quantum physicist on your side.

All three show the same "tests" to demonstrate the efficacy of the bracelets. There's one where the victim mark subject holds their arms out to their side and lifts a leg. The grifter tester pushes down on the arm sticking out to the side with the raised leg at about bicep level, first without (always) and next with (always) the bracelet. Due to learning, the mark subject will do better at resisting the second time and the snake oil salesperson vendor will state that it's due to the curative powers of the bracelet.

There's another where it's purported to enable a person to rotate farther from front to rear at the waist as measured by an arm extended out foreward. As usual, the "with the bracelet" test is second. You can go to any of the linked sites and see videos of these "tests" in action.

Back in the 1970s there was a pyramid craze. People wore wire pyramids on their heads to increase their intelligence or sleep better. I remember being offered ... an illegal substance commonly rolled into cigarette shaped cylinders and smoked ... with the kicker that "it was cured under a pyramid." People go to Sedona, Arizona for a "harmonic convergence" and then buy crystals. This sort of woo has always been around I guess, the new aspect is the word salad involving words like quantum, biofield, resonance, hologram, algorithm, and cellular.

Two of the three companies above offer to donate part of the price of some of their items to charitable causes - Save the Seas and Ovarian Cancer. I guess that's a good thing, in the way that you'd want the guy that mugs you to donate some of the proceeds to Jerry's Kids. The sites talk about scientific studies and evidence but I can't see anything except testimonials.

The placebo effect is well known and I'm all for it but the gullibility shown by the ability to make a living selling these pieces of plastic for $30 is another sign of the descent into the abyss of the level of scientific literacy of the average American. In the Far East some believe Rhino horn or shark fin or some other animal part will give them virility or cure them. We smile condescendingly and "tsk tsk" and send our money off for pieces of plastic with holograms embedded with frequencies to tune our biofields.

Update: Rhett Allain at Dot Physics has a supplementary and probably better explanation for the success of the first test described above in his post here.

Thursday, August 26, 2010

A brief essay on logic

While driving, I typically listen to Sirius Satellite Radio dividing my time between BBC World Service and Radio Classics (a channel devoted to the old time radio dramas and comedies). BBC is advertisement free (excepting adverts for its own programs of course) but Radio Classics has advertising for various things, including other channels, on the half-hour. One of the channels advertised is BB King's Bluesville.

During the commercial, BB King comes on and says (as close to verbatim as I can remember) "I'm the mayor. And if BB King doesn't like it, I figure no one else will either." Huh. This is, in first order predicate logic, known as an implication, i.e., if A then B, or A->B (pronounced "A implies B"). This implication is, as the saying goes (and as can be shown in a truth table), logically equivalent to | B -> | A (man, I wish I had more symbols in the Blogger interface: -> is an implication arrow; | is negation or "not" so that | B -> |A should be read "not B implies not A").

To BB's statement, this translates to "if not 'no one else will like it then not BB King doesn't like it.'" Next, "not no one else will like it" translates to "there exists someone who will like it." And "not BB King doesn't like it" translates to "BB King likes it." Thus, BB's statement is the logical equivalent of "if there exists someone who will like it then BB King likes it." There probably is no music such that there does not exist someone who will like it. Thus, there is probably no music that BB King does not like.

I'm guessing that that's not what he meant.

Monday, August 23, 2010

More on the Airbus A319 data

In my previous post I discussed gathering some data from the Airbus A319. I want to look into this a bit more, and consider some of the forces involved. Starting with takeoff and looking here I find that the standard maximum takeoff weight of the aircraft is 64,000 kilograms and that its range at that takeoff weight is 3391 kilometers. There are several variants of the aircraft but I'll assume that the figures cited are correct. There were no empty seats on the plane but Wolfram Alpha tells me that the distance from New York Laguardia to Chicago O'hare is 1180 kilometers so I assume that a partial fuel load was carried. The maximum fuel capacity was found here to be 24,210 liters or 24.21 m^3, which, at  804 kg/m^3, has a mass of 19,465 kg. I'm going to speculate that the aircraft carried 2/3 of its maximum fuel capacity, which should meet FAA regulations and United's standard operating procedures, for a weight savings of 6,488 kilograms.

So we're contemplating an aircraft with a mass of about 57,512 kg. and an average "mid roll" acceleration of about 3.4 m/s^2 by my data. So, as usual F=m*a, and the force the engines are applying is 195,500 Nt or about 44,000 pounds of force. This is, for the two engine aircraft, 22,000 pounds per engine. I've checked various sites and determined that the specific aircraft was likely the A319-131 model with IAE 2500 series engines with thrust rated in the 25,000 pound force range. Thus, the data is clearly on the right track. I do so love it when that happens.

 How about stopping? The aircraft from Chicago O'hare to John Wayne Airport in Orange County was also an Airbus A319, presumably another "dash 131" as they say in aviation. Since it was also full and traveled a considerably larger distance, I'll assume that it started at 64,000 kilograms. Here I find that my flight took 3 hours, 42 minutes, or 3.7 hours. I find here that, as an estimate, the A319 burns maybe 5,000 pounds mass or about 2,270 kilograms of fuel per hour so I estimate that the aircraft burned 3.7*2,270 kilograms from its 64,000 starting weight to land weighing 55,600 kilograms.

Touching down at 90 knots (I suspect this is actually a bit slow) or 46.3 m/s, the airplane has a kinetic energy of 0.5*55600*46.4^2 or 59,850,000 joules. It stops braking at 10 knots or 5.14 m/s and then has about 734,000 joules of kinetic energy (non-intuitively, not that far from my Land Rover LR3 HSE at 55 m.p.h.). The brakes have dissipated (that is, turned into heat) about 59,000,000 joules in about 27 seconds. This equates to a rate of energy dissipation of 59,000,000/27 or 2.19 megawatts. They are actually assisted in this disspation by burning jet fuel in a process called "reverse thrust" but in the end, that's the kinetic energy that is dissipated. Of course, braking is an extraordinarily efficient process for turning kinetic into thermal energy, slowing the plane down by reverse thrust is much less efficient but, in the end, it's all turned into dispersed thermal energy.

Next post: Integrate again for length of takeoff and landing roll.

Sunday, August 22, 2010

Airbus A319 on the runway

Like most modern "smart phones," the Apple iPhone has accelerometers on all three of its axes so that it knows its orientation. This enables the screen to flip, games involving motion to be played, etc. Various companies have produced apps to enable the user to have access to the acceleration data gathered by the accelerometers, I've posted about playing with that feature before.

Of course many have pushed this capability farther than I have, but Rhett Alain at his Dot Physics blog reviewed some of these apps and did a brief review of the Pasco Sparkvue app. Pasco is a company that makes various sensors that are typically used in Physics classes. The Sparkvue app is made to allow the use of their sensors with the iPhone, but includes access to the iPhone accelerometers. I purchased this app, and will likely also purchase some of the sensors as well.

I was in New York City (Queens, actually) for a conference held by the American Society for Nondestructive Testing, ASNT. By a freak accident (the flight crew is quite adamant that such things must not happen), on takeoff from Laguardia Airport, I happened to have left the iPhone on (in airplane mode) and Sparkvue running with the y axis very close to parallel to the longitudinal axis of the airplane, recording data. Shockingly, the same thing happened upon landing at John Wayne Airport in Orange County. I have GOT to be more careful about this.

But, having gathered the data anyway, I thought I'd spend a few minutes playing with it. The Sparkvue software enables adjustment of units ("g's" or meters/second^2) and sampling rate. I used meters/second and 20 Hz. I've inserted graphs of the speeds determined by numerically integrating the acceleration data below, I cut off the takeoff data at about 30.3 seconds because that's when the aircraft "rotated" (lifted the nose wheel off the runway, that is, began to leave the runway) and I didn't account for the fact that the downward acceleration of gravity now had a component along the y-axis of the iPhone, giving a falsely high reading of acceleration (the Equivalence Principle).

I intend to go back and attempt to correct this by estimating the so-called "deck angle" (the angle between the aircraft's longitudinal axis and horizontal) and backing it out of the numbers. This will enable me to estimate the aircraft's acceleration once airborne.

For landing, I did approximately the same thing, but I wanted to know the touchdown speed of the aircraft. Data was recorded until the aircraft was at its taxi speed and turning off the runway. I estimated this to be 10 knots and used the "goal seek" facility of Excel to determine what starting speed would give 10 knots when acceleration was deemed to have reached zero.

I have no idea how accurate the accelerometers are in an iPhone, but the numbers calculated are within the realm of plausibility. I estimated Vr (rotation speed in pilot speak) to be about 152 knots, and touchdown speed to be about 90 knots. A knot is a nautical mile (6080 feet) per hour or about 1.15 statute miles per hour. The graphs are below:

Sunday, August 15, 2010

YouTube - A Turing Machine - Busy Beaver 4-state

The busy beaver function is, as far as I know (and I've looked around a bit), the fastest growing function currently known. I first learned about it here. I'd known of Turing machines from general reading but have never taken a formal course in computer science (sadly). But Mike Davey has built a Turing machine and used it to demonstrate a four state busy beaver.

If you want to know more about the busy beaver function and why it's interesting, a good place to start is at the link above.

YouTube - A Turing Machine - Busy Beaver 4-state

Science Digestive: My application for a job as a Homeopath

More fun poked at homeopathy. I admit that it's a soft target.

Science Digestive: My application for a job as a Homeopath

Sunday, August 08, 2010

Creationism Lives - The Daily Dish | By Andrew Sullivan

I'm a regular at Dr. Michael Tobis' blog Only In It For The Gold (his blog's name is a sarcastic reference to the meme that climate scientists are engaged in a conspiracy to promote climate change in order to get rich from grant money). Michael has a "mt's shared items" section where he links to articles that he finds interesting. Often, he'll link to Andrew Sullivan's blog from the Atlantic Magazine (a magazine I really enjoy) entitled "The Daily Dish." He's currently linking to the article Creationism Lives - The Daily Dish | By Andrew Sullivan which quotes portions of a Scientific American article bemoaning the level of scientific ignorance in the United States. And apparently, the origin is the National Science Foundation's bienniel reportScience and Engineering Indicators. It reports the results of surveys in various countries that indicate many Americans don't believe, for example, in evolutionary theory.

By and large, I agree with Sullivan's point here, but the article he cites (and his quotation of it ends with) includes the following: "
Only 33 percent of Americans agreed that “the universe began with a big explosion.” Hmmm.... if someone phoned me and said "I'm taking a survey, do you agree that the universe began with a big explosion?" I would say "no." If they asked if I agreed that what is commonly known as the "Big Bang Theory" is currently the most likely explanation for the origin of our universe, I would say yes. The Big Bang, as presently understood, was not in any way an explosion. So, would I be marked down as another example of American scientific illiteracy?

I believe that whoever published the information quoted by Sullivan was attempting to further the case that Americans don't understand science. Paraphrasing A. Conan Doyle through Sherlock Holmes, the writer had not the gift of the true journalist, the knowledge of when to stop. The author succeeded only in showing the limits of his or her understanding of science, or at least of cosmology.

CO2 Now | CO2 Home

I've seen widgets on various web sites that track atmospheric CO2 and, in glancing at one, something caught my eye. I determined to visit the source site, called CO2 Now | CO2 Home to verify that what I'd noticed was accurate. Here's the image I looked at:

Now, what disturbed me is that the year over year increase was about 72% larger in the July, 2009 to July 2010 period (0.606%) than in the July, 2008 to July 2009 period (0.352%). This is quite disturbing in that the July 2009 to July 2010 period is one of subdued economic activity in much of the so-called developed world (to be fair, much of the previous period could also be described in this way).

Here's a brief graph of world GDP from 2005 to mid - 2010:

(Source: http://www.economicswebinstitute.org/ecdata.htm and http://web.worldbank.org/WBSITE/EXTERNAL/EXTDEC/EXTDECPROSPECTS/EXTGBLPROSPECTSAPRIL/0,,contentMDK:20370107~menuPK:659160~pagePK:2470434~piPK:4977459~theSitePK:659149,00.html)
Note that while world GDP declined for the first period noted in the CO2 concentration above and rose at about 3.3% for the second, the dip in GDP is not mirrored by a reduction in slope of the graph of atmospheric CO2 concentration for the period. I don't know whether the absence of a decrease in rate of growth of CO2 concentration is due to a statistical fluke, measurement error, volcanic eruption, or the increased use of coal to provide primary energy in emerging economies - China and India in particular. But an increased growth rate of atmospheric CO2 concentration without an increase in the rate of growth of economic activity is a disturbing data point.