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  1. #21
    Ole
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    Wayne, please do the search yourself before spreading pseudoscience.

    Except for the fact that the magnetic field is weakening very slowly which may or may not presage a flip, everything you have referred to is balderdash to put it nicely.
    -- Ole Tjugen, Luddite Elitist
    Norway

  2. #22
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    Acutally, the magnetic field of the earth is weakening, and also it 'bends' the solar wind around the earth while creating a band of particles circling the earth. This band is the Van Allen belt. So, in a sense, the magnetic field does shield the Earth. At the same time, the UV is blocked by the Ozone layer which is decaying and the UV is the major contributor to skin cancers. Cosmic radiation is weakly blocked by the magnetic field and also by the atmosphere.

    It is believed that the magnetic poles have shifted every several hundred thousand years, and this has been extensively discussed in science journals but due to the lack of positive evidence it is a theory at this point with reasonably good backing.

    The earth and any planet with a metallic core or a molten magnetic core has a magentic field with a strong influence on solar wind. Thus, Earth and Jupiter have strong fields due to iron and metallic hydrogen respectively. Mars has virtually no field and is weakly shielded from solar (and cosmic) radiation. The solar wind is considered to be a contributor to the conditions on both Mars and Venus.

    The sun has a huge magnetic field itself, and in addition there is a 'sphere' around the entire solar system which limits the extent of the size of the solar wind. The reflection of the solar wind from this sphere was recently detected as a signal by an astronomy team working with the Pioneer sattelites. They have named the field and its reflection or limiting ability in a recent article. It is approximately 10 - 20 Billion miles in radius.

    There is a distinction between cosmic rays and solar wind, although both are made up of ionizing radiation to some extent. Cosmic rays are directed at us from all directions at about the same intensity, whereas the solar wind is unidirectional and shaped like a teardrop as it strikes the earth's magnetic field and is deflected.

    You guys should read "Science News" and watch "The Universe" and "The Planets" on the Science Channel and Discovery.

    PE

  3. #23
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    Back in the dark ages when I was in high school, I attempted a science project to detect background radiation, or more specifically, radioactive fallout from nuclear testing (this was in the early 60s) using photographic film. A friend helped me select a high-speed black and white film (Ansco Super Hypan) that I cut into small pieces, wrapped in black plastic and then left outdoors for several days before processing. The hypothesis in this "research" was that fallout particles would result in pinpoint exposure of the film that would show up after processing. That was my first experience with processing film (in the bathroom using a monobath), and while it probably helped form my current interest in photography, was a failure as a science project.

    Incidentally, I heard a presentation a few months ago by a physician who has some association with NASA who pointed out that astronauts are carefully monitored for exposure to background radiation. The duration of time in space has traditionally been limited to minimize exposure. It is known that radiation exposure can, over time, lead to various forms of cancer. So far, one astronaut has died of leukemia, but it isn't known if that was an anomaly or a consequence of exposure during space flight, and the other members of the astronaut fleet are monitored very carefully for any signs of problem.

    She also noted that one of the concerns in any future longer duration space flights (eg, Mars) is that the astronauts will be exposed to much more radiation than on orbiter or moon flights, and that as a result, it is likely that the individuals who are finally selected for these journeys will be much older than traditional astronauts partly to minimize the risk that they could eventually develop cancer as a consequence of that exposure.
    Louie

  4. #24
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    After the first nuclear tests in the US, Kodak observed an increase in fog in many products. Tests found that it was due to fallout being brought in on shoes. At that point, Kodak installed shoe washers at all entry points into Kodak Park buildings in which emulsions were made or in which coatings were made. The only exceptions, AFAIK, were the research labs buildings (at that time, B-3 and B-59) and the new research buildings also lacked these devices.

    PE

  5. #25

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    Quote Originally Posted by keithwms View Post
    ...What really annoys me are the neutral kaons. I am quite certain that somebody is directing a beam of them at my brain lately, causing me to think strange thoughts.
    Kaons are strange virtual particles, AFAIK, so you could be right about that. I'm not sure about a beam though, they don't travel a great distance and exist for some small fraction of a millisecond during decay interactions. But then there are those quantum uncertainties - 'spooky action from a distance'.
    "Pictures are not incidental frills to a text; they are essences of our distinctive way of knowing." Stephen J. Gould

  6. #26
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    Concerning the pole movement and reversal, let me refer everyone to a wonderful article in Sci. Am. coauthored by Peter Olson from Johns Hopkins, who I was fortunate to entice to my department as a colloquium speaker some time ago.

    http://webusers.astro.umn.edu/~larry...ciAmerican.pdf

    The geodynamo is very interesting, to say the least. Several things surprised me, in particular: (1) the poles are wobbling and always have been; (2) satellite data show substantial movement of regions of flux reversal over a ~20 yr period of observation; (3) we don't know when a flip is due; they have happened at odd periods and scientists are only just now beginning to do realistic models of this behavior. And most fun of all (4) when a flip does happen, there will be, who knows, ~5-10 kyr of magnetic chaos characterized by many flux reversal patches moving all over the globe. So it's not like there will be a fast flip and that's it.

    Oh there was one other thing that I learned from Peter's talk that was a surprise to me, namely that ancient mariners knew about flux reversal patches long ago and constructed very detailed correction maps by reconciling star data with compass measurements.

    I asked Peter to speculate on what effect the preflipping movement may have on weather (after all, the van Allen belt will be less able to screen us from ionizing solar radiation during this period), but he politely and wisely declined to comment on this on the record, noting that we just don't have the models and the experimental evidence to even begin to speculate. I think I did get him to agree that it is "possible" that the geodynamo affects weather indirectly.
    Last edited by keithwms; 05-30-2008 at 03:43 PM. Click to view previous post history. Reason: sp
    "Only dead fish follow the stream"

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