The Skeptical Teacher

Musings of a science teacher & skeptic in an age of woo.

Posts Tagged ‘tidal force’

More Media Fail and Silliness: Lunar Effect Babies

Posted by mattusmaximus on August 17, 2011

This week there’s been a story going around the media about a supposedly huge jump in births in a Sacramento hospital where “45 babies were delivered in 48 hours.”  Now that may or may not sound very unusual (it ends up it isn’t that strange – read on), but the really weird aspect of this is the claim made by the hospital officials with nary a skeptical thought:

“The human body is 80 percent water, after all. And, given that both menstruation and ovulation roughly follow a lunar cycle – occurring on a monthly basis – it doesn’t seem too far off to think that the moon could have a say in childbirth as well,” hospital officials said.

And, of course, the supposed mechanism for this “lunar effect”, as espoused by the hospital spokesman, is gravitational in nature:
According to the news release, the moon’s gravitational pull “can control a woman’s body” the same way the moon’s gravity controls tides.
*Cue spooky music…
Image courtesy of Nineplanets.org

First of all, the fact that 45 babies were born in 48 hours is not that significant.  Note the article states that there have been a total of 325,000 babies delivered at the hospital since 1937.  If you do the math, then this comes out to an average of about 12 babies per day – compared to the claim in the article (which basically averages out to about 22 or 23 babies in one day), this seems not very extraordinary because it shows that there was a weekend where the hospital had only double the average number of births!  100 times the average number of births would be statistically significant, but not 2 times the average.

Then there’s the stupid claim about the “lunar effect”.  Not only is this a bogus claim – click here to see why not – but it is also implausible from the standpoint of basic physics.  The hospital spokesman makes a common claim about the “lunar effect” being gravitational in nature, like the tidal effects on the Earth’s oceans.  However, if one takes a moment to work through the mathematics, this arguments falls apart pretty quickly.  For example, I perform the calculations for the tidal effects of the moon (whether it is full or not is irrelevant) on a person in my physics classes, and it ends up the tidal forces that act upon a person are stupendously small – about one-billionth the weight of a paperclip!  So whether or not you decide to wear a hat or use hair gel on any given day has more gravitational influence on you than does the tides from the moon!

That’s because the strength of the tidal forces that act on an object are proportional to the size of that object.  In the case of a large planet, like the Earth, the relative difference between gravity from one side of the planet to the other (this difference is the tide itself) is pretty big since the Earth is big.  But humans are so small on this size scale that the difference in gravity (tide) on us is miniscule.

So the next time you gaze upwards and see the full moon, appreciate it for all its beauty and wonder.  But don’t worry about it making you crazy; the failure of the media to accurately report science is a bigger threat of making you nuts 😉

Posted in astrology, mathematics, media woo, physics denial/woo | Tagged: , , , , , , , , , , , , , , , , , , , | 1 Comment »

Double-Whammy of Stupid Regarding the Japanese Earthquake

Posted by mattusmaximus on March 25, 2011

I’ve been sitting on this a bit, but I can’t take it anymore.  Beyond the idiocy being bantered about much of the media concerning the Fukushima nuclear power plant in Japan, there is an entire other layer of stupid superimposed atop that: it’s about what caused the earthquake in the first place and future effects (i.e. “mega”-quakes) resulting from the Japanese quake.

The first bit of pseudoscientific flummery comes from various physics cranks & astrological weirdos who seem to have been going on and on about something called the “Supermoon”.  Here’s a great Bad Astronomy article (written March 11th, 2011) taking down why this Supermoon nonsense is Super-Stupid…

No, the “supermoon” didn’t cause the Japanese earthquake

… The idea of the Moon affecting us on Earth isn’t total nonsense, but it cannot be behind this earthquake, and almost certainly won’t have any actual, measurable effect on us on March 19, when the full Moon is at its closest.

So, how can I be so sure?

The gravity of the situation

Here’s the deal. The Moon orbits the Earth in an ellipse, so sometimes it’s closer to us and sometimes farther away. At perigee (closest point) it can be as close as 354,000 km (220,000 miles). At apogee, it can be as far as 410,000 km (254,000 miles). Since the Moon orbits the Earth every month or so, it goes between these two extremes every two weeks. So if, say, it’s at apogee on the first of the month, it’ll be at perigee in the middle of the month, two weeks later.

The strength of gravity depends on distance, so the gravitational effects of the Moon on the Earth are strongest at perigee.

However, the Moon is nowhere near perigee right now! [Note: This article was written on March 11th, the same date as the Japanese earthquake]

The Moon was at apogee on March 6, and will be at perigee on March 19. When the earthquake in Japan hit last night, the Moon was about 400,000 km (240,000 miles) away. So not only was it not at its closest point, it was actually farther away than it usually is on average.

So again, this earthquake in Japan had nothing to do with the Moon…

The second bit of nonsense which is making the rounds on the Internet is an article published in Newsweek magazine stating that the Japanese earthquake makes it more likely there will be a super-duper “mega-quake” which will, among other things, flatten California & the west coast of the United States.  Sadly, this is yet another example of media fail on a scientific topic, because had the writer (supposedly a “journalist”, but actually someone who doesn’t deserve that title) of the Newsweek article taken just a little time to check his facts, he would have seen that such an idea is nonsense.  LiveScience.com has a great take down of this fiasco…

Bogus Claim: Japan Earthquake Won’t Trigger a California Quake

An unfounded scientific assertion by a nonscientist has swept across the Web like a tsunami over the past few days. In an article in Newsweek, writer Simon Winchester claimed that the 9.0-magnitude Japan earthquake, following close on the heels of recent quakes in New Zealand and Chile, has ratcheted up the chances of a catastrophic seismic event striking in California.

In his article, “The Scariest Earthquake Is Yet to Come,” Winchester pointed out that all three of those recent earthquakes occurred along faults on the edge of the Pacific Plate — the giant tectonic puzzle piece under the Pacific Ocean — and that this also butts up against the North American plate along the San Andreas Fault.

“[A] significant event on one side of a major tectonic plate is often … followed some weeks or months later by another on the plate’s far side,” he wrote. “Now there have been catastrophic events at three corners of the Pacific Plate — one in the northwest, on Friday; one in the southwest, last month; one in the southeast, last year. That leaves just one corner unaffected — the northeast. And the fault line in the northeast of the Pacific Plate is the San Andreas Fault, underpinning the city of San Francisco.” …

Of course, the actual journalists (not the hacks who seem to pump out useless bilge called “science reporting” at Newsweek) at LiveScience.com check with real scientists on the question, and here’s what they found:

… “There is no evidence for a connection between all of the Pacific Rim earthquakes,” Nathan Bangs, a geophysicist who studies tectonic processes at the University of Texas Institute for Geophysics, told Life’s Little Mysteries. “I don’t know what the basis is for the statements and implications in the Newsweek article, but there is no evidence that there is a link.”

U.S. Geological Survey (USGS) earthquake geologist David Schwartz, who heads the San Francisco Bay Area Earthquake Hazards Project, concurred. “Simon Winchester is a popular science writer, not a scientist,” Schwartz said. “I’m not saying we won’t have an earthquake here in California at some point in the future, but there really is no physical connection between these earthquakes.” …

… Rich Briggs, a USGS geologist whose work focuses on how earthquakes happen, explained another way in which earthquakes can cascade. “The other way earthquakes affect their neighbors is that when a fault ruptures, it sends out seismic waves that in the case of large earthquakes can even circle the globe. In some cases, this ‘dynamic stress transfer’ increases seismicity,” Briggs told Life’s Little Mysteries. “But that only happens as waves go by, in the minutes that it takes the waves to travel out from the fault zone.” …

… So when will a major earthquake strike California? “Based on models taking into account the long-term rate of slip on the San Andreas fault and the amount of offset that occurred on the fault in 1906, the best guess is that 1906-type earthquakes occur at intervals of about 200 years,” Robert Williams, USGS seismologist, wrote in an email. “Because of the time needed to accumulate slip equal to a 20-foot offset, there is only a small chance (about 2 percent) that such an earthquake could occur in the next 30 years.” …

The Japanese earthquake, subsequent tsunami, and all the related pain, suffering, and death is a horrible tragedy that the world will no doubt be grappling with for many years to come.  However, in order for us to deal with these inevitable & uncontrollable tragedies, we must use the best tools at our disposal.  These tools include addressing things from a careful, rational, scientific, and fact-based view, not by appealing to our more primitive notions of superstition & fear-mongering.  One works, the other doesn’t: take a guess which is which.

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