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为什么磁极逆转不是更有害的生活?

这个问题与下面的问题,有两个部分。

火星阻碍了大约40%的太阳辐射(每平方米)的地球。已经声称火星是人类生活不可持续,部分由于太阳风粒子辐射,这样四年往返火星可能会导致癌症和/或基因组等永久性损伤。为什么一个磁极逆转,这通常需要1000年,没有一段时间的辐射是生命无法忍受?
候鸟不仅需要的磁极方向,某些细菌和藻类在海洋兴衰正确。如果磁极逆转不是很快,为什么鸟迁徙不会歪斜的主要数据。(注:我有点怀疑学习景观建议中发现的相关问题——有证据采取类似的横向道路鸟,,证明他们是认识风景吗?景观和功能在距离变化很快。如果是的话,那么磁场方向感觉真的帮助迁移吗?时扭转,如果磁场是一个关键的组件知道方向,然后不会倾向于把他们在相反的方向,所以即使一个快速的最后阶段的逆转可能导致大量失踪的鸟。)同时,微生物生物食物链崩溃时为什么不使用时开始更深入去表面的磁罗盘?

回答

有几个因素需要考虑。主要的一个是大气(特别是如果你想比较火星与地球的磁场逆转)。地球的大气层是一个强大的防御太阳风和宇宙辐射。每种类型的辐射有不同的渗透,但总的来说每种类型的辐射相关的辐射剂量衰减指数较低海拔地区。例如对电离辐射的关系是$ E (z) = E_0 \离开(0.21 E ^ {-1.649 z} + 0.79 E ^ {-0.4528 z} \右)E是剂量美元,美元E_0美元是剂量吃海平面和z是高度([引用][1])。下图说明辐射剂量较低海拔下降。但如果你这条曲线扩展到100公里你就能掌握多少的入射辐射是由大气层过滤。[![在这里输入图像描述][2]][2]图:宇宙辐射的函数高度,北纬50°,来自欧洲核能协会[3]。因此,即使在没有磁场的情况下,只有一小部分的辐射会让它浮出水面。 And note that reversals only means a weakening of the magnetic field, not a complete disappearance. What can disappear is the dipole component of the magnetic field, not the magnetic field as a whole. It is important to note also that the magnetic field is very important to prevent atmospheric erosion. Therefore, a permanent lack of magnetic field can generate the loss of the atmosphere (likely what happened to Mars). Conversely, Earth's magnetic field is one of the reasons we have a very thick atmosphere compared to Mars, and during the brief periods of magnetic field weakening (due to pole reversals), our thick atmosphere still provided a quite effective protection. The fact that space radiation doesn't penetrate much can be observed in many different ways, one of them is noting that [auroras][4] (a.k.a. northern lights) usually never happen below 90 km of elevation. Moreover, the reason why auroras happen only at high latitudes (i.e. near the poles), is due to the "geomagnetic latitude effect" that describe how radiations dose rates are minimal at the equator and maximal at the geomagnetic poles. Nevertheless, the atmosphere absorbs most of that extra radiation and life thrives in the arctic forest without any problems. Also, the atmosphere would not be just a passive filter, it could create its own magnetic field as some studies suggest. Such studies argue that as long as we have atmosphere, the solar wind can induced a magnetic field around the Earth even in the absence of internal magnetic field ([reference][5]) The other important point is: Would the paleontologic record of migratory birds populations and magnetic-dependant microbial life be good enough to detect a catastrophic population reduction on migratory birds and some microbial life that happened 780,000 years ago? I'm not an expert but I would be skeptical. In fact, 780,000 years seems to be enough time for the evolution whole new species and the rise of the migratory behaviour from scratch. More recent reversal events like the [Laschamp event][6] 41,000 years ago were much quicker than 1,000 years, and even so, I wonder how well we could reconstruct migratory birds populations that far back (considering that we have trouble reconstructing human populations back then). Regarding migratory birds, you say that after the reversal the birds would migrate in the wrong direction. And that is quite questionable. In the lack of any point of reference, using an improvised compass to know the north-south direction is easy, but figuring out which side is north and which is south is much more difficult. Therefore, maybe birds use other means to figure that out which side of their compasses is north, means that don't depend on the magnetic field. For example, the side at which sunrise happen or something like that. Finally, microbes evolve and adapt very quickly, so even assuming that some (or many) of them would die during reversals, I'm sure others would take their place. At the end the ocean microbiota is nutrient-limited, and all the nutrients not used by the dying species will be used by other species that can thrive with a weaker magnetic field. So I wouldn't be so quick to think that such event would lead to a food chain collapse. [1]: http://www.unscear.org/docs/reports/2008/09-86753_Report_2008_Annex_B.pdf [2]: https://i.stack.imgur.com/mGzAk.png [3]: https://www.euronuclear.org/info/encyclopedia/r/radiation-exposure-cosmic.htm [4]: https://en.wikipedia.org/wiki/Aurora [5]: https://arxiv.org/abs/astro-ph/0404580 [6]: https://en.wikipedia.org/wiki/Laschamp_event

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\ begingroup美元我记得微生物进入u / g讲座。可观的少数“走错了路”在一个磁场(隐性基因是我的猜测,或频繁突变)。也许多达10%。因此一个重要的人口将生存——当然,微生物的寿命相比是非常小极性逆转——甚至进化能够跟上。至于鸟类——磁场是只有一个感觉,他们使用。例如许多可以用星星来导航。 \ endgroup美元
- - - - - -winwaed
2018年8月10日
\ begingroup美元当你说“辐射”,你具体指的是什么?地球磁场影响带电粒子,如电子和质子和东西来自太阳。另一种形式的辐射是电磁辐射,紫外线。这是不同的。 \ endgroup美元
- - - - - -Gimelist
2018年8月11日,在32
\ begingroup美元 @Gimelist时辐射可以产生突变,它包含所有这一切,在地球上最常见的是中子,μ介子,质子,π介子,电子和高能光子。在大多数情况下影响生活表面上也没有什么粒子/电磁辐射直接来自太空的副产品大气中一连串的碰撞。 \ endgroup美元
- - - - - -卡米洛·Rada
2018年8月11日14:26

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