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For over a decade, University of Maryland geophysicist Dr. Dan Lathrop has been on a quest to construct and run tests on spherical models that simulate the physics of the Earth’s magnetic field. Now completing work on the fourth model, his academic group is close to their biggest feat yet: filling the rotating sphere with sodium to create a self-generating magnetic field. These tests will contribute to our understanding of the inner workings of the Earth’s core, which in turn alters our approach to dealing with the effects of solar radiation. Black and White talks with Dr. Lathrop about his work and influences.
Welcome to Black and White. I appreciate you taking the time to do the interview.
LATHROP: I’m happy to help you.
You are a geophysicist at the department at the University of Maryland?
LATHROP: I actually am faculty in two different departments, physics and geology, although the research I do, at least half of it is geophysics. There’s no proper department with that name.
This project is designed to help identify how the earth’s magnetic field is generated?
LATHROP: Yes. In particular, we’d like to understand how it’s generated and use the experiments to help build a science of the earth’s magnetic field because there is no current way to predict where the earth’s field is headed and going to forecast right now.
I’m going to come back to the project itself in a second, but I want to talk to you about your background first. What made you want to become a geophysicist? How old were you when you made that decision to enter that field? What influenced you?
LATHROP: There is not a short answer to those questions. I grew up in a family where my father was an engineer and the family often spent time outdoors, actually doing some rock hunting. So I grew up in a situation of being interested in the earth. And I started out in college as a mineral engineer, to start with, at UC Berkeley, but then nearly switched to geology, and in the end, finally switched to being a physicist, although under somewhat strange influences. The course that convinced me to become a physicist was a geology course. It was taught by Walter Alvarez, a professor at Berkeley in geology who was the son of Luis Alvarez, who was a Nobel Prize winning physicist at Berkeley. But the way that Walter taught his geology class interested me quite a bit in physics in the end. So I went on to get undergraduate degrees in physics, and then a PhD in Physics from UT Austin, mostly studying turbulent flood flow. But when it came time to become a faculty member, I was looking for different projects that I might set out on my own to do. And I learned about the possibility of doing experiments to understand the earth’s magnetic field and that was very attractive to me. Ed Bolton, who is a geophysicist at Yale, was the first to suggested it to me, when I was a post doctorate at Yale at the time. And just over lunch one day, he and I were brainstorming about what it is I should do as a young faculty member, if I could get a position. And that was one of the projects that he said he thought was possible but challenging, and I guess I liked that part of it.
Was there a key person at that time in your developing professional career who may have influenced you to become a geophysicist?
LATHROP: Well, the pivotal character that caused me to almost go into geology and, in the end, into physics was Walter Alvarez when I was an undergraduate. So, with faculty in physics and also faculty in geology, I have quite a bit of leeway as to the different areas I could work in. And those early influences then steered me towards geophysics. Another major influence was Harry Swinney, my Ph.D. adviser at the University of Texas. He taught me how one might design experiments such that they might yield unexpected results. This has been especially important in my work through the years.
When you were young, what were you interested in?
LATHROP: Oh, I guess, as a kid I was definitely prone toward tinkering. And so my father would often give me things to take apart. And I would take them all apart and save some of the parts and then combine parts together into other devices. I think more or less, I was raised to be an engineer. I think my father really had that vision in mind. I think he was a little bit surprised by the change of direction, but he got used to it.
Still in the lab, now, when we build these things, we’re designing things from scratch and putting them together and debugging them as such. There’s definitely a tinkerer’s aspect to being an experimental physicist.
This is your third sphere that you’ve built?
LATHROP: The fourth, actually. Well, the first one was not spherical, but it’s the fourth of the line as experiments of this sort, the fourth sodium experiment.
How long have you been working on this project?
LATHROP: Oh, goodness. I’m going to feel old talking about it. Well, the first idea was probably around in ’93, maybe spring, ’94. And then I became an assistant professor in faculty that — later that year in ’94. I didn’t start sodium experiments probably until ’96. So it’s probably been about 12 years now working on sodium experiments, all of them with the same set of goals in mind, to understand the earth’s magnetic field.
What have you learned? What progress has led to this latest one?
LATHROP: Well, in each case we’ve taken steps toward larger experiments with higher input power. And in each stage along the way, we have seen in experiments that have not generated their own magnetic field, but would respond to an external magnetic field and to the rotation to give magnetic fields and to give the sort of fluid motion inside that have pointed the way toward more earth-like models.
So the first several didn’t generate the magnetic field, but they responded to outside magnetic fields?
LATHROP: Right. For those first experiments, if you applied an external magnetic field, ones from the outside, they would then respond by generating a magnetic field of their own, but only while that outside field was present. They weren’t– and believe me when I use this– they weren’t dynamos by themselves, but they would induce magnetic fields from an outside source. But if you spoke to them, they would speak back. But they wouldn’t just start chattering on their own.
12 responses so far.
Slomow - Jul 10, 2008 at 12:42 pm
Spinning sphere’s filled with sodium. Life size no doubt, all in an effort to understand magnetic fields. This sounds like big bucks. While the reasoning stated is to prepare for a future reversal of the poles and the affects of it on space entry, satellites, etc. it would nice to see some more immediate matters.
What else can this research be used for and when? There is so much written about medicine and the benefits of magnets. Any ideas there?
alex - Aug 18, 2008 at 1:17 pm
I’ve read some contrasting info on other sites. Some explain the reversal as the physical reversal of the north and south poles, examples given would be Greenland is now in the southern hemisphere. Other sites are thinking the field switch would leave life vulnerable to possible harmful effects from the sun for relatively a short period of time. One more interesting observation is the alignment of the Earth, Sun and center of Milky Way in 2012 causes a rare wobble effect causing the liquids in the Earth to shift. So many different theories, from rouge planets to Aliens, this topic is hard to love and if anyone knows of more sites to check out with similar topics please reply.
Beau - Sep 19, 2008 at 11:48 am
I was noticing how the charts that outline tectonic plates and their movements mirror the magnetic field fluctuations and their movements. Any thoughts on the fact that superheated molten iron, while expanding and contracting (possibly due to rapid cooling) could release flux lines???
jordan - Feb 17, 2009 at 10:02 pm
what would earth do if earth didn’t have magnetic field
Dustin - Mar 22, 2009 at 10:08 pm
We have wobbled befor and we all know it now ,the question is when will it happen again, my calulation is it happens every 3,649,200 rotations, This answers the question about noahs ark, and the signs where oceans have move very quickly. Just maby we all have a front row seat.
brandy - Jun 7, 2009 at 7:00 am
What unit of energy do you use to calulate the strength the magnetic field of the earth?
pat duning - Jul 30, 2009 at 9:29 am
have mercy and email me moreon this,please
Eric Diaz - Nov 30, 2009 at 11:34 pm
Magnetic Field is made by a layer oxygen atoms in the atmosphere and oxygen goes to the Earth’s core ( that time was before the discovery of fossil fuel or gasoline ) now the ozone layer has weakened. Oxygen tames the heat and pressure in the Earth’s and may even controls the tectonic movements of our continents.
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Dave - Dec 16, 2009 at 9:32 am
Earth’s magnetic field
The magnetic field of the Earth can be quite easily explained but we have to backtrack 100 years to an experiment done by one JJ Thomson at Cambridge. In this experiment he was trying to find the provenance of cathode rays and in his Nobel Prize speech, this is what he said ; ‘ The results of the determination of the value of e/m by this method ( his experiment), are very interesting for it is found that however the cathode rays are produced we always get the same value for e/m ‘. He then goes on in the speech to describe all the things he changed to obtain this fact. And then he made the fateful decision which has more or less condemned 20th century Physics to the back water it is. He then said that not only were cathode rays particles
( which is correct), but that they were all the same particle – the electron, an exclusive particle ( which is incorrect). You see he obtained the same e/m value for all his experimental particles, because every particle in the Universe has the same e/m value, and this is because as I wrote in an article to Nature several years ago ; ‘ Every particle in the Universe has electric charge proportional to its mass’. In other words electric charge being proportional to mass, then this will always give you the same e/m value. So once we know this, we can imagine the Earth as a ball of Electric charge rotating about a central axis and therefore producing a magnetic field through that axis. Venus, in many ways similar to the earth, and does not rotate, has virtually no magnetic field to speak of.
SIMPLE
Ernie DeLugo - Jan 7, 2010 at 4:58 am
Two Questions:
1-Are Plasmas generated at the Earth’s core?
2-What is the magnitude of the electric currents at the Earth’s core?
Thank you,
Ernie DeLugo
evgeniy - Mar 6, 2010 at 6:06 am
I offer other mechanism of formation of a magnetic field of the Earth. The analogy between a magnetic field and gravitational can be used. I.e. it is necessary to replace an origin of a magnetic field of the Earth, this rotation of the Earth, and a charge of the Earth with its weight. It has a deep substantiation with use of the general theory of a relativity. Thus for sphere in the size 2m, weight 10^5kg with speed of rotation 2pi/sec, intensity of a field on a pole 10 ^ (-6) А/м turns out. You received a question, what sizes at measurement of a magnetic field of such system. If your parametres differ, specify them please.
John - Mar 16, 2011 at 2:42 pm
Twenty years ago, high pressure diamond anvil experiments on iron crystals discovered serendipitously, when a vacuum seal ruptured, that hydrogen moved quickly into the iron lattice forming a layered structure (FeH) which resembled certain superconductors. As a result , I suggested that 1) the unexplained density of the solid core of the Earth, lower than pure iron, is due to its composition of FeH and 2) that the geomagnetic field is the result of a superconducting current within the solid core, which has been noted seismically to have structure. In this model the ponderously slow swirling in the liquid outer core is responsible for the very gradual deviations from an ideal dipole which we measure at the surface. This supercurrent is pumped up by sudden waves of positively and negatively charged particles from CMEs the effects of which (by Faraday induction and Lenz Law) are additive because the positive and negative particles spiral into into the poles in opposite directions.
I believe there was a ‘law’ stating that the dynamo effect, based on the idea currently in vogue, could not produce a perfectly symmetric magnetic dipole field. The last I heard Cassini has found a nearly perfect dipole magnetic field around Saturn. If true, the ‘law’ will have to be revised, or the notion that the field is generated by superconductive currents in the solid core might have to be considered.
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