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Posted: 08-07-2002 19:16 Post subject: The Earth's Core

A new theory says that the centre of the Earth is actually a huge nuclear reactor.

The idea seems to make sense, and it could also explain why the Earth's magnetic poles 'flip' every few thousand years.

(Better not tell CND or other anti-nuclear types, though!)

Posted: 08-07-2002 21:17 Post subject:

Hmm !

Could they not just pop a Giger counter down the 7.5 mile hole they commented on and see if the radiation tat far down is worthy of comment. I know it is a tiny hole on the scale of things but if the radiation is higher at 7mi then it is at 5 mi then they could be onto something.

then again I guess the chance of anything significant at theat depth is hardly gonna be likely

So ignore me (too much red wine)

Posted: 08-07-2002 22:16 Post subject:

Rather appropriate that my email notifications tonight from FT had one about "Underground", and beneath that "The Earth's Core"...!

Posted: 08-07-2002 22:40 Post subject:

Some quick calculations. Assuming that the radiation from the earth's core obeys a 1/r^2 law, and that the contribution from extraterrestrial sources is tiny, then we find that the intensity of radiation at a depth of 10 km is going to be ~0.3% greater than that at the surface.

However:
a) the radiation from a putative reactor at the core is unlikely to obey the 1/r^2 law. Scattering and absorption phenomena will scupper that idea. (Lots and lots of rock to interact with.) In addition, un-bound neutrons (i.e. those emitted by a nuclear reaction) have a half-life of ~10 mins (if I remember correctly), so most of those will have decayed into other "stuff".
b) a significant source of radiation at the earth's surface is from extraterrestrial sources. (Ye olde cosmic rays.)

But, the previous estimate probably gives a rough order of magnitude estimate as to the maximum change in the radiation intensity that might be observed. Smile

Posted: 08-07-2002 22:53 Post subject:

Posted: 09-07-2002 01:15 Post subject:

Posted: 09-07-2002 06:37 Post subject:

When a bit of lead and a few yards of concrete are considered enough protection from a Nuclear Power Station, I guess several thousand miles of rock and mantle would make it nearly impossible to detect the radiation from the Earth's core.

Presumably now the idea is out in the open various experts will think on't and come up with more subtle ways to prove or disprove this theory.

But it surprises me that no-one seems to have suggested this before - it's long been known that uranium is the heaviest element, so would have settled to the centre of the planet, and there has even been one case of a natural reactor than ran in a uranium deposit somewhere in Africa, I think.

Posted: 09-07-2002 13:58 Post subject:

Actually, rynner, J Marvin Herndon published "Nuclear Fission Reactors as Energy Sources for the Giant Outer Planets" in the journal Naturwissenschaften in 1992. The silence was deafening.

The case you speak of was in Gabon, Africa. In 1972 scientists found fission-produced isotopes of neodymium and samarium in a seam of uranium. No one said much about that, either.

God, I love my subscription to "Discover"!

Posted: 09-07-2002 14:12 Post subject: nife

I used to enjoy 'Call MyBluff' and learned many new words from it.
One was 'nife', pronounced 'niffee'. This is apparently what the centre of the earth is composed of: nickel and iron, the word being a combination of their abbreviations.

So it should really be 'NiFe', I suppose. Hmmm.

Posted: 09-07-2002 18:14 Post subject:

Posted: 09-07-2002 21:51 Post subject:

Hmmm.... if I may just add my own lack of knowledge here (never stopped me before!).

Uranium would surely be extremely rare in the universe, compared to say iron or aluminium, because it is so heavy. Assuming this is correct, than there simply wouldn't be enough of this element to account for all the planets (and moons, asteroids, etc) in our solar system, let alone elsewhere. This doesn't mean of course that some planets don't have uranium cores, but I'm not convinced that Earth is one of them.

I seem to recall from Earth Sciences studies that the Earth's inner core is believed to be either solid iron or a mixture of iron & nickel - this is inferred from the behaviour of seismic waves (S & P waves) and also from studies of volcanic rocks (some of which originated in the inner core). Evidence from meterorites, which may be the failed remains of planet formation, also bears out this theory.

A liquid iron outer core sloshing around above this solid ball accounts for the Earth's magnetic fields.

I say "fields" rather than "field" because there is more than one, and the interference patterns between these different fields is sufficient to explain the shifting of the magnetic poles over time, and even their occasional apparent complete disappearence and "flip".

Having said all that, there's a lot of "infers" and "may bes" in the accepted version and any new theory that challenges the status quo is fine by me. If it can answer puzzles not addressed by the existing theories then it will be accepted, grudgingly, in time... possibly not in our lifetime, but eventually.

Jane.

Posted: 11-07-2002 20:15 Post subject:

Someone once explained to me, when I was at University, that Geology is a very faddish science, and that theories about planetary formation and the internal structure of the Earth tend to change on a regular basis. This is largely because of the problems mentioned: that we haven't been able to look at it directly. That being said, I see a few problems with the theory as stated.

1. A ball of Uranium 5 miles wide is a lot of Uranium. As mentioned, Uranium is only formed as a by-product of supernovae (on current theories). That's a lot of supernovae.

2. The other planets mentioned (IE: those with the "unexplained" energy output) are gas giants, not terrestial planets. Gas giants could be expected to have a radically different structure (as is evidenced by the size of their atmospheres) to a planet like the Earth. So, even if it were true for gas giants (which I'm not convinced, see point one above), that's not enough to make it likely for Earth.

3. While we haven't been able to drill down terribly far into the core, we have been able to probe it with radar. The last I heard, this had given geologists a fairly good idea of what it looks like, if not exactly what it's made of.

4. We know how dense the Earth is (we know how much it weighs, and we know how big it is). Surely the difference between a large lump of Uranium at the core and a large lump of nickel/iron would be noticeable?

If we wanted to check, couldn't we just ask the people at the bottom of the hole the Russians drilled into Hell? Surely someone down there would have an idea? (Unless of course they're too busy being tortured.)

Posted: 11-07-2002 21:10 Post subject:

But surely the earth's hollow?:p

As a person with a totally non-scientific brain, might it not be possible that there is a completely new element or elements at the earth's core? I'm probably showing my abject ignorance here. Have all the elements that exist been discovered? How do we know whether or not they've all been discovered?

Carole

Posted: 11-07-2002 21:32 Post subject:

Posted: 11-07-2002 21:42 Post subject:

When I took geology A level ( 20 years ago ! Eek Eek

) I remember being taught the Earth's inner core was a reactor and the temperature of the interior of the Earth was actually rising due to these reactions . I think we were taught this to disprove the long held theory that the Earth was originally molten and was slowly cooling down .
As for natural radioactivity , I live in an area so naturally radioactive the houses need special vents built into them to release it ! All payed for by the government .