據(jù)國(guó)外媒體報(bào)道,，多年前世界末日預(yù)言者曾預(yù)言,，稱(chēng)一顆未探測(cè)到的同伴恒星將周期性地向地球釋放彗星，像宇宙時(shí)鐘一樣周期性地導(dǎo)致地球物種大滅絕,。目前,，一位天文學(xué)家已掌握確鑿證據(jù)，并聲稱(chēng)彗星或者小行星周期性變遷并不存在,。
在最新一項(xiàng)研究中,，研究人員指出叫做“涅墨西斯”或者死亡之星的一顆黑暗同伴星體將于2012年碰撞地球,，帶來(lái)毀滅性災(zāi)難。像其它神秘的2012災(zāi)難論,，涅墨西斯假設(shè)論具有一定的科學(xué)研究支持：1984年,，古生物學(xué)家提議每間隔2700萬(wàn)年天外星體將對(duì)地球構(gòu)成毀滅性災(zāi)難。最初認(rèn)為一顆褐矮星或者紅矮星在太陽(yáng)系邊境破壞彗星軌道,，并將彗星噴射釋放至地球方向,。
“涅墨西斯”具有X行星假設(shè)——它有一顆未探測(cè)到的行星潛在碰撞地球，同時(shí),，這種假設(shè)也與古代瑪雅日歷上的預(yù)言相符,。但顯然這種擔(dān)憂性完全是臆造的，瑪雅人“長(zhǎng)期計(jì)算”的預(yù)言?xún)H是一個(gè)日歷而已,，當(dāng)時(shí)并沒(méi)有任何科學(xué)工具進(jìn)行計(jì)算分析,。
2010年，研究人員報(bào)道稱(chēng),，如果鄰近太陽(yáng)系不遠(yuǎn)的“涅墨西斯”的確存在,，那么它并不一定環(huán)繞一個(gè)2700萬(wàn)年的精密運(yùn)行周期。這項(xiàng)研究發(fā)表在《皇家天文學(xué)會(huì)快報(bào)》上,，并對(duì)涅墨西斯假設(shè)論描述為“最后的棺材釘”,，但研究人員仍不能解釋為什么地球物種滅絕周期為2700萬(wàn)年。美國(guó)堪薩斯大學(xué)物理學(xué)家艾德里安-米勞特稱(chēng),，對(duì)我而言,，”這是一個(gè)非常棘手的問(wèn)題“。
目前,，德國(guó)馬克思-普朗克天文學(xué)會(huì)研究員哥倫-巴勒-瓊斯稱(chēng),，米勞特應(yīng)當(dāng)不必對(duì)此感到頭疼。他發(fā)表在《皇家天文學(xué)會(huì)月刊》的分析文章指出,，所謂“涅墨西斯”星體周期性釋放彗星可能僅是一個(gè)模型,，除非是經(jīng)過(guò)統(tǒng)計(jì)學(xué)人工計(jì)算得出該結(jié)論。
瓊斯在馬克斯-普朗克學(xué)會(huì)的報(bào)道中指出,，人們傾向于發(fā)現(xiàn)并不存在的自然現(xiàn)象,，但不幸的是，一些確鑿的統(tǒng)計(jì)分析數(shù)據(jù)顯示出它的弱點(diǎn),。他觀測(cè)了歷史時(shí)期地球成坑比率,，使用一種替代性方法評(píng)估了貝葉斯統(tǒng)計(jì)分析法的可能性。貝葉斯統(tǒng)計(jì)分析法提供了統(tǒng)計(jì)學(xué)的真實(shí)性檢測(cè),，該分析排除了簡(jiǎn)單的周期性變化,。相反，統(tǒng)計(jì)分析數(shù)據(jù)顯示在過(guò)去2.5億年以來(lái)地球隕坑成坑率逐漸增大。（生物谷 Bioon.com）
doi:10.1111/j.1365-2966.2011.19112.x
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PMID:
Bayesian time series analysis of terrestrial impact cratering
Bailer‐Jones, C. A. L.
Keywords:methods: data analysis;methods: statistical;Earth;meteorites, meteors, meteoroids;planets and satellites: surfacesABSTRACTGiant impacts by comets and asteroids have probably had an important influence on terrestrial biological evolution. We know of around 180 high‐velocity impact craters on the Earth with ages up to 2400 Myr and diameters up to 300 km. Some studies have identified a periodicity in their age distribution, with periods ranging from 13 to 50 Myr. It has further been claimed that such periods may be causally linked to a periodic motion of the Solar system through the Galactic plane. However, many of these studies suffer from methodological problems, for example misinterpretation of p‐values, overestimation of significance in the periodogram or a failure to consider plausible alternative models. Here I develop a Bayesian method for this problem in which impacts are treated as a stochastic phenomenon. Models for the time variation of the impact probability are defined and the evidence for them in the geological record is compared using Bayes factors. This probabilistic approach obviates the need for ad hoc statistics, and also makes explicit use of the age uncertainties. I find strong evidence for a monotonic decrease in the recorded impact rate going back in time over the past 250 Myr for craters larger than 5 km. The same is found for the past 150 Myr when craters with upper age limits are included. This is consistent with a crater preservation/discovery bias modulating an otherwise constant impact rate. The set of craters larger than 35 km (so less affected by erosion and infilling) and younger than 400 Myr is best explained by a constant impact probability model. A periodic variation in the cratering rate is strongly disfavoured in all data sets. There is also no evidence for a periodicity superimposed on a constant rate or trend, although this more complex signal would be harder to distinguish.
