Tired of the war? Not sufficiently scared by the spread of SARS? Want something different, more dramatic, and larger scale to worry about? How about the running down of the nuclear reactor supposedly at the Earth's core?
Geophysicist J. Marvin Herndon argues that the core of the Earth is really a 5 mile (or 8 kilometer) uranium ball that operates as a natural nuclear reactor. He says some day the reactor will exhaust its supply of radioactive material and that when it does the Earth's magnetic field will collapse with disastrous consequences.
SAN DIEGO, March 27 (UPI) -- New government laboratory test results are fueling a controversial contention that a giant natural nuclear reactor at the center of the Earth powers the planet's life-protecting magnetic field -- but it might be running out of gas, scientists told United Press International.
Herndon happens also to have served as a technical consultant for the new disaster movie "The Core" which is based on the idea that the Earth's core will stop spinning.
J. Marvin Herndon of Transdyne Corp. in San Diego, who worked as an advisor to Paramount Pictures in the creation of the new science thriller, maintains that a nuclear "georeactor" provides most of the heat in the Earth's spinning core
Unfortunately its probably impossible for real life terranauts to travel down to the Earth's core and fix it if the core starts running out of nuclear fuel.
A new research paper published in the Proceedings of the National Academy of Sciences provides supporting evidence for the theory.
Computer simulations of a nuclear reactor in the Earth's core, conducted at the prestigious Oak Ridge National Laboratory, reveal evidence, in the form of helium fission products, which indicates that the end of the georeactor lifetime may be approaching.
Dr. Fred Vine laid the foundations for many of Herndon's theories in the 1970s. Vine, however, believes that the Earth's core stops spinning every 400,000 years.
The August 2002 issue of Discover has a fairly lengthy write-up of Herndon's theory.
In Herndon's view, these polarity flip-flops make no sense if the magnetic field is powered, as traditionalists contend, by heat from the crystallization of molten iron and nickel from the fluid core or from the decay of isolated radioactive isotopes. "Those are both gradual, one-way processes," he says. But if the field's energy results from a mass of uranium and plutonium acting like a natural nuclear reactor, Herndon says, such variations in the field's strength would be almost mandatory.
"It's a self-sustaining critical reaction," said nuclear engineer Daniel F. Hollenbach of Oak Ridge National Laboratory, a longtime collaborator of Herndon's until the two parted ways last year. "Depending on how much it fissions, that's the power."
There are a few separate issues here. One is whether the Earth's core is a large nuclear reactor that drives the Earth's magnetic field. There is no consensus among geophysicists that this is the case. Herndon is definitely in a small minority with his theory. However, there is also the widely accepted theory that every few hundred thousand years the Earth's core stops spinning, the magnetic field collapses, and then the core starts spinning again and the magnetic field reverses. So a magnetic field collapse could still happen as part of the process of periodic magnetic field collapse even if Herndon's theory is wrong.
This leads to the important question: Could the Earth's magnetic field reverse today? The British Geological Survey weighs in on the odds of the possibility.
Measurements have been made of the Earth's magnetic field more or less continuously since about 1840. Some measurements even go back to the 1500s, for example at Greenwich in London. If we look at the trend in the strength of the magnetic field over this time (for example the so-called 'dipole moment' shown in the graph below) we can see a downward trend. Indeed projecting this forward in time would suggest zero dipole moment in about 1500-1600 years time. This is one reason why some people believe the field may be in the early stages of a reversal. We also know from studies of the magnetisation of minerals in ancient clay pots that the Earth's magnetic field was approximately twice as strong in Roman times as it is now.
Even so, the current strength of the magnetic field is as high as it has been in the last 50,000 years, even if it is nearly 800,000 years since the last reversal. Also, bearing in mind what we said about 'excursions' above, and knowing what we do about the properties of mathematical models of the magnetic field, it is far from clear we can easily extrapolate to 1500 years hence.
The British Geological Survey does not see a big threat to human life if an Earth's magnetic field reversal should start happening in earnest today.
Is there any danger to life?
Almost certainly not. The Earth's magnetic field is contained within a region of space, known as the magnetosphere, by the action of the solar wind. The magnetosphere deflects many, but not all, of the high-energy particles that flow from the Sun in the solar wind and from other sources in the galaxy. Sometimes the Sun is particularly active, for example when there are many sunspots, and it may send clouds of high-energy particles in the direction of the Earth. During such solar 'flares' and 'coronal mass ejections', astronauts in Earth orbit may need extra shelter to avoid higher doses of radiation. Therefore we know that the Earth's magnetic field offers only some, rather than complete, resistance to particle radiation from space. Indeed high-energy particles can actually be accelerated within the magnetosphere.
At the Earth's surface, the atmosphere acts as an extra blanket to stop all but the most energetic of the solar and galactic radiation. In the absence of a magnetic field, the atmosphere would still stop most of the radiation. Indeed the atmosphere shields us from high-energy radiation as effectively as a concrete layer some 13 feet thick.
Human beings have been on the Earth for a number of million years, during which there have been many reversals, and there is no obvious correlation between human development and reversals. Similarly, reversal patterns do not match patterns in species extinction during geological history.
The fact that Earth's atmosphere provides as much protection from radiation as 13 feet of concrete has interesting ramifications for space exploration and planet colonization. The ability to create a thick atmosphere on Mars would be enormously valuable not just for allowing people to go out and breath the atmosphere. It also greatly reduce the amount of radiation Mars colonists would be exposed to.
You can read more about Herndon's nuclear core theory and its ramifications on the NuclearPlanet website.
|Share |||Randall Parker, 2003 March 28 02:09 PM Dangers Natural General|