Words That Survive
Editor,
Regarding Words That Survive by Sheldon Greaves (The Citizen Scientist, 5 January 2007), I have often wondered the same thing, and it was interesting to read of efforts to preserve our writings. I think random probability (luck) will preserve quite a bit of our history. I remember digging at Tel el-Hesi in the Negev Desert and we found cow thigh bones that had been inscribed with Akkadian. (They turned out to be orders for grain and oil and other commodities.) The bones were terribly old and probably should not have survived at all, but with care they were recovered. (The dry climate helped, but only enough to preserve those bones.)
[The preservation of writings] also depends on how a civilization came to its end. The Early Bronze portion of the city at Tel el-Hesi had a destruction layer that showed evidence of raiders. They were only interested in pillage and so did not damage a lot of potential artifacts. Whereas, a lot of good information has been forever lost because of conquerors like the Moslems and others who made a specific goal of destroying an existing culture.
As a result, a lot of an archaeologist's interest is in the trash of an ancient society. It makes one wonder what future archaeologists will believe about us based on our trash.
As far as ideas for saving information I wonder if there are any long-lived plastics to write on for the future generations? Perhaps some sort of ceramic coated cloth?
Maybe the key is proper storage, like storing modern optical media and a reader in a container that is designed to preserve it well. This would be like the stone jars that held the Dead Sea Scrolls, except that if they had been well sealed they might have been able to preserve the documents even in a wet environment.
Thank you for your thought provoking article.
Tim Kraemer
Editor,
Allan Rydberg asked in Backscatter: "The FAA has standardized many tests relating to flying. In the test that is given to prospective private pilots there is a section on a acronym called “ANDS.” This acronym stands for accelerate north decelerate south . It means that when a plane is flying in a east-west direction then the magnetic compass will move in response to acceleration or deceleration. The direction of the motion is given by the acronym. My question is why does this effect place? Is there any explanation for it?"
This effect is easier to understand than to explain, but I will take a shot at it. First remember that a compass seeks neither geographical north nor geomagnetic north but rather follows the magnetic lines of force emanating from the north magnetic pole deep beneath the surface of the earth. (Is my north hemisphere chauvinism showing?).
Because these lines of force tend to dip into the earth, this phenomenon is called magnetic dip, and it increases in magnitude as we near the magnetic poles. A compass card, however, is constrained to rotate in a plane normal to the local gravity vector (normally the horizontal plane). In this situation the north seeking pole of the compass seeks the point directly above the north magnetic pole on the horizon. That is exactly what we want.
The compass is pointing north, or at least something close to north, for most commonly visited locations. However, when we accelerate or decelerate, we add an inertial vector to the gravity vector and the resultant vector is no longer vertical.
To illustrate this, imagine tying a weight on a string to your rear view mirror. This weight will shift backward as you accelerate and forward as you brake, and the string will no longer be vertical. When accelerating, the compass card is still constrained to rotate about this new apparent gravity vector, which is no longer vertical. In this case, the card pointing to the magnetic pole is free to read some portion of the dip which you read as a pointing error.
Again, for the purposes of illustration, imagine you contrived a means to constrain a compass card to rotate in the vertical plane. Now take your new instrument and align it such that the plane of rotation includes the vertical as well as the direction of the north magnetic pole. The reading you get will be the local magnetic dip. Your acceleration error is something between the two, depending on factors like rate of acceleration, heading, location etc. BTW, the instrument you have just invented is called the magnetic dip meter. Too bad you were a few hundred years too late.
This web page illustrates this and the other common compass bugaboo that we all studied in ground school, the turning error which arises for similar reasons. Hope this helps.
John Green
The ULAO Project
ulao@earthlink.net
Editor,
Re. http://www.sas.org/tcs/weeklyIssues_2007/2007-01-05/backscatter/index.html, I always fed my pill bug collection on slightly moist sawdust obtained from a lumberyard. The sawdust must be slightly coarse, so it does not get too dense for the little beasts.
Paul Sagi
Part of my SAS membership is being a part of the amateur network. I have a question that I would like to have answered and I am not sure if it would be better to post it on that network or in the Backscatter. (I'm not even certain whether that is one of the purposes of Backscatter.) What I am looking for is information on locating infectious diseases for simple organized animals such as Hydra, Pill Bugs, etc. I would like to do a few experiments with an agent that seems to leave organized tissues alone while inhibiting the life of single cells. I'm not sure where to ask.
Also, I finally obtained a copy of Glenn Knoll's book on radiation measurement that you and Shawn suggested to me. Thanks again. SAS is always very useful and helpful.
Tim Kraemer
Some science ideas:
1. Not sure how I'd present or promote this, but do you think it would be possible to study the structure of the other planets with dual orbiting satellites that act like a virtual CAT scan machine? X-rays
might not be good enough, so perhaps a particle beam or other high-energy beam might be used. The satellites would be in exact opposition around a planet, and one would shoot a beam through the planet
to the satellite on the other side. Wouldn't it be interesting to see what's going on inside? The trouble is that it would not be real time by any means, since several passes would be needed to
reconstruct an image, and the outer planets would change too much due to high rotation rates and gaseous composition. But it might still shed much meaningful info.
2. Marine mammals must surface frequently. The change in pressure is significant. Might it be possible to make an electronic tag, not unlike the small transmitters in your Radio Shack engineering notebooks, that harvest energy by harnessing this frequent pressure change? There's an inventor who made a "perpetual" clock that runs off air pressure changes: http://www.uh.edu/engines/epi527.htm
3. This one most likely applies to the Citizen Scientist. Using UV LEDs it may be possible to study mating and other behavior in jumping spiders: http://www.msnbc.msn.com/id/16810841/
Mark Valentine
Mark, these are all interesting ideas. Readers, what do you think? Please send comments to Backscatter or begin a thread at the SAS Community. Editor.
Editor,
Re. the contrail photos at http://www.sas.org/tcstest/weeklyIssues_2005/2005-12-09/gallery/index.html, I suggest the contrail may have been twisted by the wake vortex of an aircraft, possibly the very same aircraft that produced the contrail.
Paul Sagi
Editor,
Bacteria have limited morphology but specific physiology or pathogenicity. Plankton are classified by morphology; thus, two similar-appearing organisms may differ greatly in physiology and ecology. It is therefore proposed that plankton of current interest be described by both physiology and morphology. Plankton of potential utility in the Pacific Northwest have common physiology; but slight differences in morphology and size. All grow in water near the freezing point. The marine species are killed by fresh water, and the reverse is also true. All four species that I am studying are killed by polyethylene or the plasticizer in it and are inhibited by borosilicate glass. They are cultured using food-grade glass or food or beverage containers. All four species pass though paper filters. They bare are green, capsule shaped and measure approximately 1 x 2 microns. One is freshwater, and the others are marine. These species are not caught with nets. They are collected by enriching seawater samples with garden fertilizer at 1 gram/gallon and aerating in light with a water bath to prevent freezing. Fresh water with plankton is enriched with 1 gram/gallon garden fertilizer containing 5% calcium nitrate and 5% magnesium sulfate
Glen Hemerick
Editor,
Fire ants cause lots of troubles when they infest electrical equipment. Research that elucidates causes and prevention may be a boon.
Years ago I found black carpenter ants congregating beneath a fluorescent desk lamp in the vicinity of the choke (ballast). I don't know whether it was an electrical field, magnetic field, sound or heat that was attractive. All can be tested as attract-ants (pun intended).
I found this on a French site: "Thresholds for ant response to electricity were 5.0 V and 0.83 mA."
Whoopee!! 5.0V is logic level 1 in TTL circuits, and TTL can source/sink 0.83 mA. Just for fun, it should be possible to use ants as TTL state indicators or even try to use ants as logic elements.
Paul Sagi
Editor,
I have a favorite web site to share. http://sunearthday.nasa.gov There are podcasts and other educational activities.
Anna Hillier
Editor,
The article about temperature conversions sounds really familiar. Below is a copy of my algorithm that I sent to a teachers web site about 6 months ago. I found the 9/5, 5/9 part of the official conversion unwieldy, also, and preferred 1.8, because you loose the division step. Less steps means easier math. My algorithm is based on 2 just like yours except I just tell them to move the decimal and subtract their answer (explained below). This method works perfectly for the Celsius to Fahrenheit conversion.
100 x 2 = 200 - 20 = 180 + 32 = 212
The reverse is more difficult using this method.
212 - 32 = 180 / 2 = 90 + 9 = 99 + .9 = 99.9 + .09 = 99.99 + .009 = 99.999 etc. You should always go to at least 3 decimal points using this method. You loose accuracy going from F to C because you end up having to round to get the actual answer.
Joe Metheny
Editor,
One problem faced by the media, general public and courts is knowing if a digital image is genuine or "doctored".
I suggest experimenting to determine if the Image J software at http://rsb.info.nih.gov/ij/ can be used to authenticate digital images.
For example, if a digital image has been altered using Photoshop, or similar software, can that be detected?
I suggest beginning with an image having a checker board pattern, before trying the software on an image with subtler features.
Paul Sagi
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