Oceans charge up new theory of magnetism
2009 06 28
By Jonathan Leake | timesonline.co.uk
A radical new idea may revolutionise our understanding of one of the most vital forces on Earth
Earth's magnetic field, long thought to be generated by molten metals swirling around its core, may instead be linked to ocean currents, according to controversial new research published this week.
It suggests that the movements of such volumes of salt water around the world have been seriously underestimated by scientists as a source of magnetism.
If proven, the research would revolutionise geophysics, the study of the Earth’s physical properties and behaviour, in which the idea that magnetism originates in a molten core is a central tenet.
Earth’s magnetic field is vital for life, extending tens of thousands of miles into space and protecting the planet against radiation that would otherwise burn away the atmosphere and oceans.
However, its origin was a mystery until early last century when Albert Einstein said understanding the phenomenon was one of science’s most important tasks. This provoked a debate which concluded with scientists agreeing that magnetism must originate in the Earth’s core.
“Everyone accepted this, but in reality there has never been any proof,” said Gregory Ryskin, associate professor of chemical and biological engineering at Northwestern University in Illinois. “It is just an idea we have accepted for a long time without questioning it enough.”
His research suggests that Earth’s magnetism is actually linked to ocean movements. The salt in seawater allows it to conduct electricity, meaning it generates electrical and magnetic fields as it moves.
The findings, published by Britain’s Institute of Physics’s New Journal of Physics, will cause a fierce scientific debate.
Existing theories explain Earth’s magnetism by suggesting that the centre of the planet comprises a white-hot solid iron ball about 1,500 miles in diameter, surrounded by an outer shell of liquid metal a further 1,400 miles thick.
As the liquid iron in that shell is heated by the inner core it becomes less dense and rises upwards, to be replaced by cooler material from above.
The resulting swirls of molten metal create electric currents that in turn produce the planet’s magnetic field, the conventional theory suggests.
The big problem with this idea is that it is almost impossible to obtain experimental evidence because the Earth’s core is so inaccessible. Indirect approaches, such as computer modelling, have thrown up many inconsistencies.
Ryskin approached the problem differently, by looking at the way Earth’s magnetic field undergoes constant changes, growing stronger in some regions and weaker in others. This phenomenon, known as variation, also sees gradual shifts in the locations of the north and south magnetic poles.
Scientists have always linked variation with turbulence in the outer core, but Ryskin suggests it actually correlates with changes in ocean circulation. In the north Atlantic, for example, changes in the strength of currents were matched by sharp changes in magnetic fields.
One idea is that changes in ocean circulation may explain the curious reversals shown by Earth’s magnetic field, in which the north and south magnetic poles suddenly flip over. This last happened 780,000 years ago.
This could also be linked to tectonic plate movements that have shifted the world’s land masses around the globe, forcing ocean currents to adopt entirely new routes.
If Ryskin is right, then climate change, predicted to alter the strength and course of ocean currents, could also alter the planet's magnetic field.
Ryskin emphasises that such suggestions need much more research, but some other physicists have been quick to recognise its implications. Raymond Shaw, professor of atmospheric physics at Michigan Technological University, said it could make “the ruling paradigm of geophysics irrelevant”.
Others are sceptical. Andrew Jackson, professor of geophysics at the Federal Institute of Technology in Zürich, Switzerland, and an expert in planetary magnetism, said the magnetic fields generated by moving seawater would be thousands of times smaller than what is observed. “I think the calculations are wrong,” he said.
Kathy Whaler, professor of geophysics at Edinburgh University, would not comment directly on Ryskin’s work as she had not read it.
However, she said the idea that the Earth’s molten core produced its magnetic field was “well founded”. She said: “We know from seismology what the Earth’s structure is, and that it is likely to contain molten iron at high temperatures flowing around a solid core.”
Article from: timesonline.co.uk
Magnetic Portals Connect Sun and Earth
Earth's Magnetic Field Is Fading Fast
A Bird's Eye View Of Magnetic Earth
Magnetic energy? Perhaps
Earth’s Weakening Magnetic Field Contributes to Extreme Weather
Latest Scientific Study Demonstrates Magnetic Influence on Humans
Magnetic field found to stimulate brain cells
Latest News from our Front Page
If Someone Secretly Controlled What You Say, Would Anyone Notice?
2014 10 01
The subject enters a room in which a 12-year-old boy is seated. A 20-minute conversation ensues. The subject quizzes the boy about current events and other topics to get a sense of his intelligence and personality. But the boy is not what he appears to be.
Unbeknownst to the subject, the boy is wearing a radio receiver in his ear, and ...
Obama has had accurate intelligence about ISIS since BEFORE the 2012 election, says administration insider
2014 10 01
‘President Barack Obama’s intelligence briefings have provided him with specific information since before he won re-election in 2012 about the growing threat of the terror group now known alternatively as ISIS and ISIL, an administration insider told MailOnline on Monday.
‘Unless someone very senior has been shredding the president’s daily briefings and telling him that the dog ate them, highly accurate ...
Can holding a magnet against your head help defeat depression?
2014 10 01
Former GP Sue Mildred suffered from crippling depression and anxiety for 20 years.
On two occasions it was so severe that she ended up in hospital, and for 15 years she was unable to work.
Sue, 51, has tried antidepressants, talking therapies and, out of desperation, even ECT (electro-convulsive therapy), where an electric current is passed through the brain.
This did ...
Extremists to have Facebook and Twitter vetted by anti-terror police
2014 09 30
Theresa May to announce new Extremist Disruption Orders to strengthen counter-terrorism if the Tories win the next general election
Extremists will have to get posts on Facebook and Twitter approved in advance by the police under sweeping rules planned by the Conservatives.
They will also be barred from speaking at public events if they represent a threat to “the functioning of democracy”, ...
Scottish Independence: Protesters demand revote
2014 09 30
Pro-independence campaigners gathered outside the Scottish Parliament for the second day in a row, this time to demand a revote of the September 18 referendum.
While yesterday’s “Rally For A Revote” saw the return of Saltires and Yes banners to Holyrood, it did not match the turnout for the “Voice Of The People” rally held on Saturday, when up 3000 people ...
|More News » |