Experiments with magnets and our surroundings


Magnets and biology

This is a fascinating field of study, and still very new with a lot more to learn.   I am not an expert in this area, so I will refer you to some links and articles where you can start a search of your own.

Do magnetic fields affect biological organisms?

Here are some references that can start you out.  Science fair demonstrations in this field is not easy, and requires several months to grow and observe plants or animals. 

Science News Online, Jan 10, 1998, EMF's Biological Influences, Janet Raloff
http://www.spor4u.com/post/doc.html   Bioelectromagnetics Applications in Medicine
http://grants.nih.gov/grants/guide/rfa-files/RFA-ES-94-001.html   Cellular Effects of Low Frequency Electromagnetic Fields
http://www.biophysj.org/cgi/content/full/78/2/707

Biomagnetic therapy

Many people claim that wearing innersoles in their shoes containing a magnet, or bracelets made of copper with small magnets on the ends, or other magnetic therapy helps to relieve them of some pains or reduce depression.  I don't know.  Perhaps some of this is real, perhaps most of this is imaginary.  Some therapists define North magnetic poles opposite to what is accepted by the engineers who fabricate the magnets.  This makes you wonder if the promoters of these therapeutic magnetic devices know what they are talking about.  However, for you to start checking into this yourself, here are a few links to start you out:
http://www.magnetman.com
http://skepdic.com/magnetic.html
http://www.quackwatch.org/04ConsumerEducation/QA/magnet.html
http://www.holcombhealthcare.com/reports/pub-bio.html
http://www.cbsnews.com/stories/2003/09/16/earlyshow/contributors/emilysenay/main573628.shtml
http://www.hinduonnet.com/thehindu/mp/2002/11/11/stories/2002111101030300.htm
http://www.painrelief.org.uk/
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=155398
http://www.csicop.org/si/9807/magnet2.html
http://www.findarticles.com/cf_0/m0HKL/5_7/66918308/p1/article.jhtml?term=Atheletes+attracted+to+magnets
http://www.garynull.com/Documents/magnets.htm

I have also heard of some who have made the statement that you should only cook with non-magnetic pots and pans.  This usually means stainless steel.  However, there are some stainless steels that are slightly magnetic.  It depends on the amount of impurities making the alloy, and the processing of the steel.  Cold rolled versus hot rolled have an affect on this property.  All of these change the crystalline structure, that in turn can change the magnetic properties.  I have not seen any study that can show how the magnetic property of a pot or pan can affect the leeching of impurities into the food you prepare in those pots.  Sounds like a gimmick to sell something expensive.  

Navigating with magnets

According to Tim Taylor of Home Improvement, men have magnetic boogers in their noses, allowing them to sense which direction is north.  That is why men don't need to ask for directions!  Ha, ha!

Seriously, what do we know?

First, magnets have been used to determine which direction is north.   However, because the geomagnetic north pole is always moving and is not located where the geographic north pole is located, navigators have needed to maintain a chart of deviations between true north and magnetic north, depending on where they are located on the surface of the earth. 
http://antwrp.gsfc.nasa.gov/apod/ap001203.html   (be sure to check out all the related links - very useful information!)

Also, since ships have been made with iron, that affects the compass located on the deck of the ship.  Often you see two grapefruit-sized iron balls, located on either side of the ship's compass.  They were used to null the effects of the iron in the ship, so the compass readings would be true.

What about biological compasses?

Here are some links you may wish to use as starting points in your research.   I'd like to express my thanks to Professor John Buntin at UW-Milwaukee for these references.

1: Biosystems 1981;13(3):181-201
Biogenic magnetite as a basis for magnetic field detection in animals.
Kirschvink JL, Gould JL

Bacteria, sharks, honey bees, and homing pigeons as well as other organisms seem
to detect the direction of the earth's magnetic field. Indirect but reproducible
evidence suggests that the bees and birds can also respond to very minute
changes in its intensity. The mechanisms behind this sensitivity are not known.
Naturally magnetic, biologically precipitated magnetite (Fe3O4) has been found
in chitons, magnetotactic bacteria, honey bees, homing pigeons, and dolphins.
Its mineralization in localized areas may be associated with the ability of
these animals to respond to the direction and intensity of the earth's magnetic
field. The presence of large numbers (approximately 10(8)) of superparamagnetic
magnetite crystals in honey bees and similar numbers of single-domain magnetite
grains in pigeons suggests that there may be at least two basic types of
ferrimagnetic magnetoreceptive organelles. Theoretical calculations show that
ferrimagnetic organs using either type of grain when integrated by the nervous
system are capable of accounting for even the most extreme magnetic field
sensitivities reported. Indirect evidence suggests that organic magnetite may be
a common biological component, and may account for the results of numerous high
field and electromagnetic experiments on animals.

PMID: 7213948, UI: 81161405

 

2: J Exp Biol 1988 Jan;134:27-41
Homing of magnetized and demagnetized pigeons.
Walcott C, Gould JL, Lednor AJ
Laboratory of Ornithology, Cornell University, Ithaca, NY 14850.

Homing pigeons appear to use the earth's magnetic field as a compass and perhaps
as part of their position-finding system or 'map'. The sensory system they use
to detect magnetic fields is unknown, but two current possibilities are some
mode of response by the pineal organ or by the visual system, or it may be based
on the magnetite crystals found in their heads. Three series of experiments to
test the involvement of magnetite are reported here. The alignment of the
permanent magnetic domains in the birds heads was altered by (a) demagnetizing
the birds, (b) magnetizing them with a strong magnetic field and (c) exposing
the birds to a strong magnetic gradient. None of these treatments had a marked
effect on the pigeon's orientation or homing under sunny skies, but a few
results obtained under overcast skies suggest that demagnetizing the birds may
have increased the scatter of their vanishing bearings. Perhaps pigeons use one
magnetic sensor for their magnetic compass and another for some component of the
map.

PMID: 3356963, UI: 88187587

 

P.S. Here's another cool thing you can do with magnets: if you have an
aquarium full of shrimp with a sandy substrate, the shrimp will
incorporate sand grains into their statocysts, which are sensory organs
of balance and equilibrium very similar to our semicircular canals. The
sand grains move around in a fluid filled sac as the animal moves,
tilts, etc., and in the process, the grains bend sensory hairs which
provide information about the animal's position in space. There is a
famous anecdotal story about an Austrian scientist by the name of Kreidl
who, in the late 1800s, dramatically demonstrated how the statocyst
worked by removing all the sand in the bottom of an aquarium filled with
shrimp. Shortly before the animals molted (which is the time that normal
animals acquire new sand grains for their statocysts) he replaced the
sand with iron filings. The shrimp incorporated the filings into their
statocysts instead of sand, and Professor Kreidl then had hours of fun
making the shrimp assume all sorts of bizarre postures and orientations
by making the filings move in various ways by dragging a magnet around
on the bottom of the aquarium.

I've never tried it but it sounds interesting and fun!

See also:  
Nature 400, 324 - 325 (1999) Macmillan Publishers Ltd. (Nature magazine, July22, 1999, p324)
Extraocular magnetic compass in newts
M. E. DEUTSCHLANDER, S. C. BORLAND & J. B. PHILLIPS

Geomagnetic orientation is widespread among organisms, but the mechanism(s) of
magnetoreception has not been identified convincingly in any animal. In agreement
with biophysical models proposing that the geomagnetic field interacts with
photo-receptors, changes in the wavelength of light have been shown to influence
magnetic compass orientation in an amphibian, an insect and several species of birds
(reviewed in ref. 5). We find that light-dependent magnetic orientation in the eastern
red-spotted newt, Notophthalmus viridescens, is mediated by extraocular
photoreceptors, probably located in the pineal complex or deeper in the brain
(perhaps the hypothalamus).

 

Nature 390, 371 - 376 (1997) Macmillan Publishers Ltd.
Structure and function of the vertebrate magnetic sense
MICHAEL M. WALKER, CAROL E. DIEBEL, CORDULA V. HAUGH, PATRICIA M. PANKHURST,
JOHN C. MONTGOMERY & COLIN R. GREEN

Some vertebrates can navigate over long distances using the Earth's magnetic field, but the
sensory system that they use to do so has remained a mystery. Here we describe the key
components of a magnetic sense underpinning this navigational ability in a single species, the
rainbow trout ( Oncorhynchus mykiss). We report behavioral and electrophysiological
responses to magnetic fields and identify an area in the nose of the trout where candidate
magnetoreceptor cells are located. We have tracked the sensory pathway from these newly
identified candidate magnetoreceptor cells to the brain and associated the system with a
learned response to magnetic fields.

Experiments  expt.gif (888 bytes)

What kinds of experiments can we do to learn more?
1.    Try growing peas with a strong magnet located under the roots.   Try a south pole and a north pole.
2.    Try growing peas within a Helmholtz coil assembly with a constant (dc) magnetic field.
3.    Try growing peas within a Helmholtz coil assembly with an ac magnetic field
(Remember to have a control for the experiment where there is not a magnetic field at all, except for the earth's natural one.)
4.    Do you have other ideas?

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