Many are familiar with the idea of magnetic poles flipping every 200,000 years or more, (if not have a look at my previous blog). Evidence for this was found in the 1960’s when scans by aircraft looking for submarines showed some strange anomalies in the strength of the magnetic field at different locations. It was later realised that basalt, a volcanic rock containing magnetite, fixes the current magnetic orientation of the earth’s magnetic field as it cools down. The younger the rock the closer it aligns to the current magnetic north, older basalt rock shows evidence of previous magnetic fields and that the magnetic poles flip so north becomes south. This can be seen when taking magnetic readings of the basalt rock emanating from the mid Atlantic ridge where the tectonic plates are being forced apart as volcanic rock pushes up from the upper mantle. The process of millions of years of new rock being pushed out, like the rings of a cut tree, show lines indicating different polarities of earths history. The image below shows the magnetic striping of the sea bed of the mid Atlantic ridge, the darker tone, the closer it is to out current North / South orientation, the lighter tone shows the opposite polarity. In effect the sea bed is like a tape recording of the earths magnetic past, as the theory was accepted a new area of plate tectonics was born called Magnetostratigraphy.
Further anomaly’s have since been mapped by NOAA, this image shows more subtle variations in the earths magnetic field strength.
Another big subject: how magnets have infiltrated our daily lives. It’s remarkable to think how magnet based technology has shaped our lives over the last century to the point of utter dependency.
Without magnets we wouldn’t have electricity, thanks to Michael Faraday who showed that electricity, magnetism and motion are all linked. Electric generators can be powered by wind, water, coal, oil, gas, petrol, diesel or nuclear power, without magnets they would just be producing heat.
Magnets are integral to computers, smart phones, speakers not to mention scientific instruments which help us discover more about our world such as MRI scanners or Large Hadron Collider the largest magnetic instrument on the planet working at the quantum physics level.
Thousands of “lattice magnets” on the LHC at CERNbend and tighten the particles’ trajectory. They are responsible for keeping the beams stable, and aligned so they don’t touch the sides of the accelerator as they reach near the speed of light . 1232 main Dipole magnets are arranged along the 27 km length of the collider each 15 metres long and weighing in at 35 tonnes (click to see the film).
At the other end of the scale magnetic nano sensors are being developed for many research applications and one area of interest which is gathering pace are those used in neuroscience. As magnets get stronger they can also get smaller and therefore more affordable, opening up research possibilities like Magnetoencephalogram (MEG) headset technology. I mentioned this in a previous blog which use quantum sensors (SQUIDS) to measure the weak magnetic fields produced by the brains electrical activity.
Periodic table Number :26 / known as element “Fe” (from latin Ferrum)
Iron is the most common element on earth by mass, it’s found in rocks and living things. It’s in our blood which is why its red in colour due the reaction with oxygen when transferred from our lungs into the haemoglobin. But how did it get there in the first place? To understand this we need to take a big step back in time, 1.8 billion years ago, when atoms of iron were floating around in the oceans. Bacteria capable of photosynthesis releasing oxygen into the sea enabled iron to be converted into hematite and magnetite minerals which sank to the sea floor. This was fundamental to the geological process in forming iron deposits which were later covered by other minerals and compressed into rock over millions of years.
Iron ore was first used in the near east and spread around the Mediterranean in all directions expanding populations as a result of more efficient tools and the ‘iron age’ began. The end of the bronze age around 1200BC was heralded by the development of iron smelting (heating iron ore with coal) which in turn lead to the birth to the industrial revolution in Northern Europe changing societies rapidly with mass production methods.
Skyscrapers rely on steel (99% iron 1% carbon) to give the structure enough strength to build as high as the Burj Khalifain Dubai at 828 meters, all thanks to bacteria
Today we can see chemotrophic bacteria which get their energy by oxidising molecules of iron and therefore thrive in areas rich in iron deposits so the bacterial cycle continues. . When you see orange coloured stream beds you are seeing the specialised iron oxidising bacteria at work.
Humans need iron or we become anaemic (tired and lacking vitality) and we get this by eating food containing iron. Humans are 10% bacteria (by mass) and those bacteria too need iron and they have specialised ways of harvesting the iron they need from their human host. “Iron is the single most important micronutrient bacteria need to survive,” (Doyle, 2008) and without bacteria humans can’t survive. This is one of the many symbiotic relationships animals and humans have with bacteria.
Doyle, 2008: Journal of Bacteriology (volume 190, issue 16) published by the American Society for Microbiology. https://www.sciencedaily.com/releases/2008/07/080731140223.htm
It’s amazing to me that the brain also generates magnetic fields outside of our heads. Perhaps this is what some people call the ‘aura’ of a person but I’ll leave that for another day. Proof of these magnetic fields are evidenced in the use of very sensitive magnetic sensors which are placed on the head, usually by neuroscientists conducting experiments, which pick up electrical wave lengths via the magnetic fields they produce. Neuroscientists can look at the graph produced by the EEG (electroencephalogram) and make diagnoses like epilepsy or sleep disorders. Magnetoencephalogram (MEG) headset technology is able to detect magnetism deeper in the brain (without any ill effects on the subject) and can give a more detailed picture of the cognitive processes in different areas in the brain whilst performing different activities.
Magnetoencephalogram (MEG) 3D printed headset developed by Nottingham University.
Without the magnetic field generated by the earths liquid iron core two thousand miles beneath our feet we wouldn’t have the spectacle of the Northern Lights.
This is a phenomena whereby the magnetic field producing the North and South Poles at either end of the earth have the strongest magnetic pull. Charged particles emitted from the sun during increased sunspot activity, also known as coronal mass ejections, create radiation also known as ‘solar wind’ which is dragged toward the North and South poles.
The magnetosphere is a magnetic shield that protects us from the majority of this solar radiation but the charged particles which do get though do so during increased activity during the suns 11 year cycle.
Here’s a video I posted on Vimeo showing the magnetic field lines of the Sun observed over a 4 year period. The different colours correspond to the distance the field lines travel away from the surface.
The bright colours are generated when the charged electrons and protons collide with the gases in the earths atmosphere and are converted into photon energy that lucky observers can see when near the poles at night during increased sun spot activity. Oxygen in the upper atmosphere emits green or orange-red, depending on the amount of energy absorbed. Nitrogen emits blue or red; blue if the atom regains an electron after it has been ionized, red if returning to ground state from an excited state.
Scientists have discovered how the Earth’s magnetic field fluctuates, but also weakens and reverses dramatically every 200,000 years or more. The next flip is overdue and scientists have observed significant weakening of the magnetic field over the last 100 years decreasing in strength about 5 percent per decade and some believe this is the beginning of a polarity reversal. During this event the earth’s magnetic shield is reduced and the charged particles would hit the earth everywhere on the side facing the sun, creating an Aurora spectacle for everyone to see. The downside is that there would be a corresponding increase in cancer rates as we are bombarded with harmful radiation we are currently protected from by our magnetic field.
This image shows a computer generated model of the Earth’s fluctuating magnetic field thousands of years ago based on data from lava samples which have fixed the earths magnetic field in the rock as they cooled down.
In the piecing together of the moving magnetic field over 100’s, 1000′ s and millions of years brings together unlikely disciplines analysing navigational maritime charts, ancient pottery and geo magnetic core samples.
Over a series of posts I’d like to talk about lots of different aspects of this Natural force of Nature.From Geomagnetism to the Magnetosphere and from historic Navigational compasses to Magneto-reception in animals. But first I’d like to talk about the biggest magnet on earth : Planet Earth.
The earths North and South poles exist as a result of molten iron swirling miles beneath our feet.This liquid outer core at the centre of the earth is very active and flows in random patterns a bit like our weather.What generates this continuous movement, is the spin of the earth in space, which is 1000 miles per hour at the equator.Because of the spinning, a motor like effect is produced and in turn electrical currents are generated by the swirling iron.It’s these electrical currents which are responsible for creating the magnetic fields which polarise the Earth into a giant magnet with a North and a South pole.
NOAA has a very cool website about declination and this page shows where the north pole has moved over the last 400 years which was painstakingly generated from shipping logs collected from hundreds of historic journeys. This illustration shows the movement of magnetic north over the last 100 years. https://maps.ngdc.noaa.gov/viewers/historical_declination/
Here’s a video I posted on Vimeo showing the movement of the magnetic North Pole over the last 300 years.
As well as orienting the earth’s magnetic field lines from north to south, the magnetic field also extends out beyond the earths atmosphere creating the Magnetosphere. Without the Magnetosphere, life on earth wouldn’t have evolved as we know it today because it shields us from the suns harmful radiation as this illustration shows.
This is also the reason we get the Northern Lights, more on this in the next post. I’ll leave you with this rather understated quote:
“I happen to have discovered a direct relation between magnetism and light, also electricity and light, and the field it opens is so large and I think rich.” — Michael Faraday (1899)
It’s proven that many animals possess a sense that make them aware of the earths magnetic field, mice, rats, flies, bees, birds, whales, dolphins, turtles, dogs, deer, cows, snails, foxes, bats, eels and so on, have all been scientifically proven to have ‘magnetoreception’. This magneto sense is a precision instrument like hearing or eyesight and is sensitive to minute variations in magnetism which is why many animals have been shown to be affected by man made magnetism, namely electricity. As Michael Faraday showed us 200 years ago, magnetism is an integral part of electricity. Cows naturally align themselves along the north-south magnetic field as do Roe Deer but both display random alignment when in the vicinity of electricity cables carried by pylons across fields (Burda et al., 2009) see article.
In red foxes it has been proven that interference with the natural magnetic field by humans via electric cables can have a detrimental effect on it’s hunting behaviour. Red fox align themselves in a particular direction before pouncing on rodents underground, they are more successful in a north east direction (Cˇ erveny ́ et al., 2011).
It has also been demonstrated that the reason dogs often spin in circles whilst trying to defecate is because they may not get a good sense the earths natural magnetic field, perhaps because of electromagnetism produced in underground cables. (article)
Radar, has proliferated the natural environment across the globe which produces electromagnetic magnetic waves travelling long distances through the earth, the sea and air. Radar is used in ship navigation, mobile phone, radio and tv, air traffic control, weather monitoring and satellite technology. There are WHO guidelines for it’s safe use in humans (article) but we are less sensitive than birds for example where it has been shown that radar does affect migratory behaviour (article).
The question that arises is to what degree are animals with magneto reception, in the air, on the ground and in the sea, being affected by the electromagnetic noise we humans emit all over the earth? Just because we humans have an almost extinct magneto sense should we not be protecting the depleting wild biomass left on the earth ? (article)
Burda, H., Begall, S., Cˇ erveny ́, J., Neef, J., & Neˇmec, P. (2009). Extremely low-frequency electromagnetic fields disrupt magnetic alignment of ruminants. Proceedings of the National Academy of Sciences of the United States of America, 106, 5708–5713.
Cˇ erveny ́, J., Begall, S., Koubek, P., Nova ́kova ́, P., & Burda, H. (2011). Directional prefer- ence may enhance hunting accuracy in foraging foxes. Biology Letters, 7, 355–357. Cook, C. M., Thomas, A. W., & Prato, F. S. (2002). Human electrophysiological and cognitive effects of exposure to ELF magnetic and ELF modulated RF and microwave fields: a review of recent studies. Bioelectromagnetics, 23, 144–157.
Eleanor Sheridan, Jacquelyn Randolet, Travis Lee DeVault, Thomas Walter Seamans, Bradley Fields Blackwell, & Esteban Fernández-Juricic. (2015). The effects of radar on avian behavior: Implications for wildlife management at airports. Applied Animal Behaviour Science 171, 241–252. DOI: 10.1016/j.applanim.2015.08.001.
I’m fascinated by this subject. For hundreds of years humans have known of animal migration, at least seasonally animals appeared and disappeared, the mechanics of which have been a mystery until recently. Science has discovered that most animals have a sense which can detect the earths magnetic field, in short they instinctively know which way is north and south. This is a young area of science and we are still finding out to what degree this sense plays a part in the migration patterns of animals.
The animals which have been studied and proven to have a magnetic sense are: pigeons, salmon, trout, dolphins, whales, squid, octopus, fruit flies (of course), mice (of course), moles, bats, red fox, roe deer, red deer, eels, robins, turtles, dogs, geese, in fact most migratory birds – and the list goes on. However, it is apparently a difficult sense to study compared to the other senses which is why we don’t have a comprehensive list. Humans on the other hand don’t seem to demonstrate a clear magnetic sense at all, although there have been studies which claim to show that we do have this magneto-receptive ability.
Here Joe Kirschvink (Human Frontier Science Program, California) wearing an EEG monitor inside a faraday cage (which neutralises the earths magnetic field and induces a new field in any direction). Kirschvink, a respected geophysicist, suggests that human Magnetoreception is a primal sense which we may have lost but is still doing experimental work in this area with colleges in Japan.
This of raises the question as to whether Humans have lost their sense of direction both literally but also metaphorically when we consider the state of the planet in ecological terms and socio equality. If we have lost this Magnetoreception then when in our evolutionary history did it become genetically deselected and why? Could it have been as a result of our move from hunting & gathering to farming when we first put down roots as a species around 10,000 years ago? Perhaps we’ll never know but for me this is a rich area of postulation that will, no doubt, migrate into my own work.
magnets, iron filings, magnetic canvas (rusted) by richard paton 2017
The earliest basic magnetic compass, like many of humanity’s important technological breakthroughs, owes its development to the necessities brought on by warfare. Emperor Hoang-ti (2700 B.C.) used a magical stone hung on horse drawn wagons in pursuit of his enemies giving a tactical advantage.
Lodestone is the name given to this iron rich mineral magnetite which orientated itself along the magnetic field lines. As a consequence of its seemingly magical property became highly prized and worth its equivalent weight in silver. The magnetic stone was either suspended by a thread or placed on a piece of floating wood (sometimes sculpted into the shape of a boat) on the surface of a bowl of water and by eliminating friction the stone naturally oriented itself along the North & South poles.
Later the Chinese found that they could magnetise an iron wire (or needle) by touching it to a lodestone. The needle would then become magnetised for a short time and could be stuck in a piece of straw or cork to float and likewise orientate North & South. To maintain the magnetism of this early compass it was necessary to frequently slide the stone along the needle, a process known as “feeding the needle.”
Sailors in Europe became aware of this crude compass via the Arabs around 1000 A.D. and began developing it for use in Maritime exploration.
However, floating a magnetized needle on a liquid surface was not easy, especially in a rolling sea, so a pivot pin was developed onto which the magnetised needle could be mounted to rotate freely. This technological innovation was followed by the introduction of a compass “card,” which later became the “compass rose” showing North, South, East & West, and subdivided into 32 points. North was traditionally indicated on the card by a fleur-de-lis, probably because of the early use of marine compasses by the seamen from the ancient Aquitaine region of France, (according to Norie & Wilson in 1889 ).
Over the ensuing 1000 years the compass as we know it today has changed very little but was used during that time to generate increasingly accurate maps that enabled a cumulative knowledge of the physical world.
The maps became a precious resource for explorers, merchants, politicians and their Navy’s. Maps represented a tool for power and expansion, without the compass may not have been possible. The compass was without doubt a key technology that shaped the world we live in today. For hundreds of years the compass and the exploration it honed has been a fascination for many artists, perhaps because of the horizon of possibilities it represents.
For Vermeer it was something of an obsession. Next I’ll look at more contemporary artists who have used the compass, maps or navigation as a means to produce artwork.