Archive for category science
Science class a real blast
Making your own erupting volcano is a classic experiment to do at home or in science class. Some, such as the ammonium dichromate one in the video, should not be done without strict supervision and safety precautions.
However, the standard experimental volcano with vinegar and baking soda generally does not cause much harm; that is, until an overzealous mom in India took it to a new level with a blast that injured 59. Fortunately, as reported here, the two students who went to hospital came out intact. Perhaps a non-working volcano might be advised in future.
Fascination for pendulums piqued by Foucault’s in France
Posted by mark in science, Uncategorized on June 26, 2018
Earlier this month I visited the Pantheon in Paris where I observed this attendant recalibrating Foucault’s pendulum.
This French scientist’s elegant scientific demonstration of earth’s rotation has delighted observers like me since 1851. For more on this story read this Ask Smithsonian blog. Unfortunately, one morning in 1998, the cable on the 52-foot long pendulum at Smithsonian’s National Museum of Natural History (originally History and Technology when opened in 1964) snapped, nearly ‘clocking’ a staffer with its wayward 240-pound brass bob. This Foucault device being unAmerican and dangerous, it was removed in favor of the Star-Spangled Banner Preservation Project, thus eliminated a favored place for folks to gather.
By the way, I am now reading The Discoverers by The Librarian of Congress, Daniel Boorstin—the first in his wonderful Knowledge Trilogy. There, coincidentally, I learned that Galileo—only 19-years old at the time (1583) and bored by a church service in Pisa—became distracted by the swinging of a chandelier. By timing his pulse, he observed the time of a pendulum being independent of its arc length—an important discovery of a property called isochronism. This simple discovery, as pointed out by Boorstin, began a new age where science developed from observation and measurement rather than pure speculation.
Unearthly Stats on Spaced-Out Tesla Roadster
Spaceman calmly motoring over Earth in his Tesla Roadster
Powered by the most powerful booster since NASA’s Saturn V, the SpaceX Falcon Heavy Rocket lifted off earlier this month with a Tesla Roadster as its payload. The FHR’s two side boosters stuck their simultaneous landing as you can see and hear (double sonic booms!) here. Unfortunately, the rocket’s main booster missed its landing on an offshore drone ship. Elon Musk, CEO of SpaceX, attributed this failure to a shortfall of ignition fluid, for which the “fix is fairly obvious.”
Starman’s Tesla Roadster will be a very high-mileage car by the time it crashes back into the earth, or perhaps Venus or maybe the sun, after about 10 million years. (As detailed here the calculations remain very uncertain.) If you wonder where Starman might be, go to this website. As of today, he’s over 3 million miles away from earth, moving at a rate of 7,463 miles per hour. It’s good that Starman is a dummy because otherwise he would suffer from the worst earworms ever, having already listened to David Bowie’s “Space Oddity” 5000 times in one ear and the singer’s Life on Mars in the other ear nearly 7000 times.
Models responsible for whacky weather
Posted by mark in Basic stats & math, pop, science on August 14, 2016
Watching Brazilian supermodel Gisele Bundchen sashay across the Olympic stadium in Rio reminded me that, while these fashion plates are really dishy to view, they can be very dippy when it comes to forecasting. Every time one of our local weather gurus says that their models are disagreeing, I wonder why they would ask someone like Gisele. What does she and her like know about meteorology?
There really is a connection of fashion and statistical models—the random walk. However, this movement would be more like that of a drunken man than a fashionably-calculated stroll down the catwalk. For example, see this video by an MIT professor showing 7 willy-nilly paths from a single point.
Anyways, I am wandering all over the place with this blog. Mainly I wanted to draw your attention to the Monte Carlo method for forecasting. I used this for my MBA thesis in 1980, burning up many minutes of very expensive main-frame computer time in the late ‘70s. What got me going on this whole Monte Carlo meander is this article from yesterday’s Wall Street Journal. Check out how the European models did better than the Americans on predicting the path of Hurricane Sandy. Evidently the Euros are on to something as detailed in this Scientific American report at the end of last year’s hurricane season.
I have a random thought for improving the American models—ask Cindy Crawford. She graduated as valedictorian of her high school in Illinois and earned a scholarship for chemical engineering at Northwestern University. Cindy has all the talents to create a convergence of fashion and statistical models. That would be really sweet.
Hold on a second—the lords of time elect to extend the year of 2016
The controllers of clocks at the International Earth Rotation and Reference Systems Service (IERS) decided recently that 2016 ought to leap an extra second to stay in synch with Earth’s rotation. This will create a great deal of consternation for computers, thus IERS is giving six months’ notice for IT people to prepare themselves. Despite that lead time, about 10 percent of networks around the world are expected to fail, e.g.; a worldwide airline booking system that went down in 2012 for several hours when its computers’ internal clocks could not reconcile the discrepancy with outside systems. (I suggest you stock up on water, food stuffs and toilet paper.)
Here are some stats I gleaned from reports on this astronomical happening by New Scientist and National Geographic:
- Clocks will read 23:59:60 on the 31st of December (I am doubtful this will work on my timepieces)
- 86,400 seconds tick off every day on the master atomic clock for Coordinated Universal Time (UTC), however; the push and pull of the Moon causes the Earths massively heavy oceans to slosh around, which decelerates the spin between 1.5 and two milliseconds every 24 hours, on average.
- Gauging by sightlines from far off galaxies, IERS monitors changes to Earth’s spin. When it goes off by more than 0.9 seconds plus or minus, they mandate a 1 second adjustment.
- In 1972, when the adjustments began, the world got 10 extra seconds to make up for lost time. Since then 16 more seconds have been added—the last one on June 30, 2015. IERS have never removed a second. (If you are a rocket scientist, please compute how long it will it be until the Earth stops and let me know so I have plenty of time to begin packing up my things.)
Since antiquity the Earth’s rotation has provided us with our timescale – it is the Earth’s rotation that gives us our most basic unit of time, the solar day.
— Rory McEvoy, Curator of Horology, Royal Observatory Greenwich
American Statistical Association (ASA) defends itself against P-shooters
With the fundamental statistic of P value coming under severe attack, e.g., it being banned in early 2015 by the Basic and Applied Social Psychology (BASP) journal, the ASA has been compelled to issue an unprecedented press release with guidelines for avoiding misuse of hypothesis testing by scientists claiming significant experimental results.* “The ASA statement is intended to steer research into a ‘post p<0.05 era,’” said Ron Wasserstein, the ASA’s executive director.
“To pounce on tiny P values and ignore the larger question is to fall prey to the ‘seductive certainty of significance.’”
– Geoff Cumming, emeritus psychologist, La Trobe University, Melbourne, Australia
The ASA statement on “Statistical Significance and P-Values” can be seen here. It includes 6 guidelines on proper use of this essential tool for assessing research data, beginning with the assertion that “P-values can indicate how incompatible the data are with a specified statistical model.”
*See, for example, this Nature article that claims P values, the ‘gold standard’ of statistical validity, are not as reliable as many scientists assume.
Technology advanced beyond any hope for healthy curiosity
I am watching the Syfy’s series “Childhood’s End” this week. It is based on a science fiction novel by British author Arthur C. Clarke, one of my favorites growing up. One of the main characters is a very bright boy who at the end of the premier episode last night becomes an astrophysicist, despite this scientific profession being made entirely superfluous by the advanced technology of the alien Overlords.
This morning Robert Scherrer, the chairman of the department of physics and astronomy at Vanderbilt University, lamented in an editorial* for Wall Street Journal that children no longer have any reason to be interested in science, mainly because most of our household gadgets fall into the category of magic—alluding to Clarke’s observation that “any sufficiently advanced technology is indistinguishable from magic.”
“The world’s now placid, featureless, and culturally dead: nothing really new has been created since the Overlords came. The reason’s obvious. There’s nothing left to struggle for, and there are too many distractions and entertainments.”
― Arthur C. Clarke, Childhood’s End
Crater Experiment Makes a Big Impact
Posted by mark in design of experiments, science on June 25, 2015
Craters are crazy and cool. One that is quite amazing was created by the Barringer Meteorite that crashed into Arizona about 50,000 years ago with an explosion equal to 2.5 megatons of TNT. Based on this detailing of what a 2 MT bomb would do I figure that Barringer would have completely wiped out my home town of Stillwater, Minnesota and its 20,000 or so residents, plus far more beyond us. The picture my son Hank took of the 1 mile wide 570 foot deep crater does not do justice to its scale. You really need to go see it for yourself
as the two of us did.
Because of my enthusiasm for craters, making these rates number on my list of fun science projects in DOE It Yourself. As noted there, members the Salt Lake Astronomical Society wanted to drop bowling balls from very high altitudes onto the salt flats of Utah, but workers in the target area from the U.S. Bureau of Land Management objected to the experiment.
Kudos to science educator Andrew Temme for leading students through a far more manageable experiment shown in this video. In reply to me asking for permission for providing a link to his fantastic impact movies Andrew gave me this heads-up. “I attended a NASA workshop to get certified to handle real moon rocks and meteorites at the NJ State Museum in Trenton. This lab in the educator guide suggested mixing up your own lunar powder and throwing objects to simulate impact craters. When I got home I ran the lab with a few of my classes and then made the video. I used a Sony handheld camera that had a slow motion setting (300 fps).” Awesome!
The other day I went up to the 9th floor of my condo building in Florida and tossed a football down on to the parking lot. I am warming up to heaving a 15 pound mushroom anchor over on the beach side from atop one of the far pricier high rises along the Gulf. However, I have to wait until the turtle nesting season is over.
Believe it or not–sweet statistics prove that you can lose weight by eating chocolate
A very happy lady munching on a huge candy bar caught my eye in The Times of India on Friday, May 25. Not the lady—the chocolate.
After tasting a variety of delectable darks from a chocolatier in Belgium many years ago, I became hooked. However, I never imagined this addiction would provide a side benefit of weight loss. It turns out that a clinical trial set up by journalist John Bohannon and two colleagues came up with this finding and showed it to be statistically significant. This made headlines worldwide.
Unfortunately, at least so far as I’m concerned, the whole study was a hoax based on deliberate application of junk science done to expose phony claims made by the diet industry.
It turns out to be very easy to generate false positive results that favor a dietary supplement. Simply measure a large number of things on a small group of people. Something surely will emerge that out of this context tests significantly significant. What this will be, whether a reduction in blood pressure, or loss in weight, etc., is completely random.
Read the whole amazing story here.
My thinking is while Bohannan’s study did not prove that eating chocolate leads to weight loss, the subjects did in fact shed pounds faster than the controls. That is good enough for me. Any other studies showing just the opposite results have become irrelevant now—I will pay no attention to them.
Now, having returned from my travel to India, I am going back to dip into my horde of dark chocolate.
Null hypothesis significance testing procedure (NHTSP) psyched out
My colleague Brooks Henderson alerted me to this new policy by the editors of the Basic and Applied Psychology (BASP) journal to ban the NHSTP. According to the editorial in their Feb 2015 issue, authors must remove all p-values and the like and not refer to “significant” differences. They also banned confidence intervals, which really makes this new policy onerous, in my opinion.
I do see the sense of focusing on effect sizes and allowing the readers, presumably subject matter experts, to judge their importance. However, although they do “encourage the the use of larger sample sizes”, it makes no sense, I feel, to disregard the impact of small studies on the uncertainty of the results.
Blaming the misuse of NHTSP and p-values in particular for bad science is like letting a bad guy go by saying the gun is at fault.