作为一个对绝大部分超自然现象表示怀疑的科学工作者和一个对人感兴趣的心理学家，一个时期以来我总感到奇怪，为什么对超自然的信仰如此普遍。经过调查，我发现这源自两个方面：大众宣传媒介和个人经验。本文只涉及后者。我要考察一下为什么超自然信仰在人们只凭直觉经验时显得那么逼真，使人非信不可；为什么在形成这类信仰时，直觉经验会使人陷入歧途。为了检查学生的直觉洞察力，我曾在课堂上要求他们不做实验而回答下列问题：
1，是什么使得岛屿浮在海洋上？
2，当玻璃杯子放在桌面上时，杯内水面与桌面呈平行(见图1(A))。但如果将玻璃杯如(图1(B))那样搁置（杯底平面与桌面成45°倾角）时，杯内水面与桌面的夹角是多少度？
3，月亮看起来是从哪一个方向或哪几个方向升上夜空的？
4，在左图中，一个4磅（约合1.8千克）的物体和一个2磅（约合0.9千克）的物体从离地16英尺（约合4.9米）的高度同时下落，它们各需要多少秒才能到达地面？
5，妇女的平均月经周期是多少天？
6，交通灯垂直排列时，绿灯是在顶部，还是在底部？
7，想一想和你最要好的同性朋友的眼睛是什么颜色的？
8，在一个有30名学生的班级里，至少有2人生日相同的概率是多少？（可以用奇数或0和1之间的数表示）
答案：
1，岛屿并不是浮在海上。因为岩石和泥土不会在水上漂浮。岛屿是浸在海中的山、礁石或大块陆地的顶部。许多学生都不注意这一事实，他们认定岛屿比海水轻，从而被海流托浮在水面上。
2，零度，因为静水水面总是呈水平状态的。大多数男生（但不是全部）懂得这个基本的自然现象。然而，女生只有半数知道这个现象。你不妨在杯子里倒一些水，再把杯子朝多个方向慢慢倾斜。这样你就能明白无误了。
3，象所有其它天体一样，月亮总是从东边升起，沿西边落下，但只有少数学生注意到这个事实。可能是因为许多学生有时在白天看到过月亮的模糊轮廓，以为月亮不象太阳那样有升有落，而总是悬挂在空中，只是要到天黑下来才看得清。
4，两个物体同时落地，落地时间需要1秒钟。但许多学生以为重物体的下落要比轻物体快。做自由落体实验很容易，譬如在一个标准高度上让一个纸夹子和一本笔记本同时落下来，观察它们的落地时间。这两样东西会同时落地。除非某个物体重量太轻，例如一片羽毛，因受到的空气阻力过大，才会慢慢地飘落。
5，妇女的平均月经周期是28天。大多数女生清楚地知道这一事实。多数男生猜想妇女的平均月经周期是30天。就我测验的情况看，男生对妇女平均月经周期的猜测从5天到30天不等。
6，绿灯总是在底部。少数学生（象我一样）对这个事实经常搞不清或搞错了。
7，你可能会一下子说不出来。当我捂住脸，要求学生们写出我的眼睛颜色时，最普遍的回答是蓝色。其实，我的眼睛是绿色的。
8，一个30人的班级里至少有两个人是同一天生日的可能性是十分之七；说得精确些，概率是0.71。但几乎每个学生都估计这种可能性很小，不超过千分之一。
在上述问题中，学生很少能够得到理想的分数，而且常常为自己成绩欠佳而气恼。然而，学生碰到的情况对我们每个人来说都是如此。我们几乎每天都看见月亮升起，倾斜的玻璃杯里保持着水平状态的水，交通灯的排列，和最亲密的朋友眼睛的颜色。但这些对我们每个人来说似乎是无须注意并记住的事情，虽然司空见惯却没有意识到。出现这种情况并不是因为我们愚蠢，而是人类的一个特性——无系统观察的结果。拿我自己来说，每次进行上述测验时都不得不看一下笔记上关于交通灯排列的正确答案；连自己眼睛的颜色都几乎想不起，更不用说别人的了。假如我要求你在接受测验之前，先作一些有关的系统观察，那么正确的回答就不会有什么困难了。要发现静止的水总是水平的，只须做5秒钟的实验，把一杯水倾斜一下即可；要知道你朋友眼睛的颜色，只须一次有意识的观察等等。系统观察是科学的特性，这说明了为什么与无系统的直觉相比，科学常常是现实的最佳鉴定者。
这种观点怎样用于解释超自然现象呢？引起一些关于飞碟（UFO）报道的，是某些不明确的物体，例如发光体或发光球体。这些东西常被看作是几英里以外运动极快的大型物体。然而，这类物体经常被证明是几百英里以外的流星或是缓慢飘过汽车玻璃窗的雨点反射光。这没什么可惊奇的，因为心理研究表明人们的大脑经常在感性方面欺骗自己。对人们观察能力的测验表明，人是自然环境的天生拙劣观察者，有时几乎不能辨清方向。
人们不注意无意识中观察的那些屡见不鲜、但通常又不是很重要的事情，犹如预兆性的梦。但人们如梦见至亲好友快要死去，或梦见其他一些后来与事实相符的灾祸，又会觉得自己在梦中得到了预兆。也许因为梦是如此隐晦和神秘，才使这种巧合带有令人畏惧的信服感。声称得到过梦兆的人断言，这样的梦并非偶然应验，而是每次必应。但对观察力测验的结果表明，他们以前曾做过数百次类似的梦，但是只要这些梦并未兑现，也就不加注意，随后遗忘了。
事实上，所有的人都要做梦，人们每晚睡眠中都有大约2小时做梦，伴随着眼球迅速转动。而大多数梦的基调都是消极的。如果我们一发现睡眠者眼球转动，即做梦时就把他唤醒，那么他就会说，刚才做的梦乱七八糟，有事故、死亡或迫在眉睫的危机。换言之，我们每夜都要做整整1小时左右的恶梦，其中大部分我们都忘记了。因为现实生活中充斥着死亡、税捐和灾难，恶梦的一小部分肯定会成为现实。当现实生活中的灾难真的临头，而我们前不久又做过一个“预兆性”的梦时，我们就会自然而然地把梦与现实的巧合错误地看作是不平常的事件。我不是在论证根本就不存在预兆性的梦。我论证的是，我们显然不能靠日常的观察和对自己经历的解释来推断预示未来的能力；只有采用系统的客观的方法，才有可能得到有关这些经历的合理看法。
研究表明，所有的人，包括训练有素的科学家，在估计可能性时都容易产生某种可预知的偏见。如果把一枚硬币连续向上抛掷5次，将结果列为第一组；重复进行6次，得到6组不同的结果。记下每组前4次抛掷的结果（正面或反面）为：
1 正正反正__ 4 正反反反__
2 反反反反__ 5 正正正正__
3 正反反正__ 6 正正反反__
那么最后一次抛掷结果是正面还是反面的可能性均为百分之五十。然而，大多数人总是根据前面的结果作出自己的猜测，人们一般会推测第2、4组的答案是“正”，第5组的答案是“反”。但这种猜法从统计学上讲却是不正确的。
特别是罕见事件在数学上的可能性常常与直觉背道而驰，但正确的恰恰是数学而不是人们的直觉。例如，假设一位桥牌手得到一手同花色的牌，他可能会认为这是件不平常的事，值得惊叹。虽然出现一手牌全是梅花的先验可能性很小（低于百亿分之一），得到其它特定的一手牌也同样不太可能，然而毕竟还是有其可能性，而这种不同寻常的特性并不在于事情本身。
人们还倾向于低估罕见事件的实际发生率，例如得到一手特定的牌。假设在任何指定的试验中，事件发生的可能性仅占千分之一。然而从长远来看，在1000次试验中，事件至少发生1次（扫校者注：此次原文为11次，当为错印。应当是1次，大家可自己计算一下）的概率是0.63，或者说，比十分之六稍强。如果从更长远来看，比方说，在1万次试验中，这样的事实际上是肯定要发生的（概率为0.99995）。同样，梦与真实事件的偶然一致也许是罕见的；不过从长远来看，在人的一生中，梦与真实事件戏剧性的一致肯定会仍然发生几次。
因此，从这个估计可能性的简单心理观察中得出的结论是，大多数人都极不善于估计偶发事件的概率，不善于评定巧合事件。常有人告诉我，一连串的特殊事件一定含有心理上的力量，因为这不太可能仅仅是巧合。或象有时所说的，“这事太巧了”。巧合的意思是指两个偶发事件以恰好给人们留下戏剧性印象的方式在时间或空间上结合在一起。不过我们刚才已经讲了，多数人判断可能性的能力很差，很可能往往会在平时发生的一些事情之间添上一层戏剧性的色彩。要证明某两件事并非是巧合，但又不做认真的统计分析，这是不可能的。
例如，假设你在从幼儿园到高中的各个班上都发现至少有两个人的生日是在同一天，这一事实在你看来可能很奇怪，但根据几率这并非是出乎意料的事，甚至是”注定的”。因为我们知道这种事在每个班出现的可能性都是十分之七，而且任何一个班的出现率都不会减少其它班的出现几率。再如，多数人的婚姻并不是罗曼蒂克式恋爱的结果，而通常有着许多实用的动机。假设一位通灵人或“能猜出别人心思的人”把你的手表拿在手里，说“这块表是你的亲爱者所赠”——他并不需要有什么超自然的能力。因为很少有人给自己买手表，而手表常作为礼物送人。再说，因为手表通常很贵，所以一般只能由亲爱者而不是泛泛之交的朋友所赠。在这种情况下，通灵人只是一位比你要善于判断几率的人。
阿莫斯·特维斯基和丹尼尔·卡尼曼是两位心理学家，他们最近调查了可能性推理问题中出现的常见谬误。其中之一叫做“典型谬误”，我认为这种谬误对形成错误的超自然看法要比其它任何因素的作用都大。假如，有一位三十多岁的男子，身材细长，视力较差，生性腼腆，喜欢读书，那么这个人可能是个图书馆管理员还是个农民呢？多数人立即就会答道：“图书馆管理员。”然而，这并不是最好的猜测。说他是图书馆管理员，显然是因为人物的外表符合或“代表”了人们心目中男性图书馆管理员的模式，而肯定不符合所谓农民的模式。然而，这里的错误在于只考虑了一件事情在规定范围中的典型性，而没有考虑到这件事在可选择的范围中的几率，即我们没有考虑到这一事实：农民要比图书馆管理员多得多。做一个合乎情理的估计，假设5个图书馆管理员中有一个符合这种外表，再假设这个国家有5万名图书馆管理员，而100名农民中仅有一位符合这种外表，但这个国家却有500多万人是农民。这样，与符合这种外表的1万名图书馆管理员相对应的有5万个农民。换言之，符合这种外表的人是农民的可能性是图书馆管理员的5倍。
虽然“典型谬误”的概念似乎稍微复杂一点，但它有助于搞清楚人们形成超自然说的原因。我认为，人们很容易立刻将神秘事件与神秘原因联系起来，而容易忽略普通起因。事实上，普遍原因可能有许多机会以看来不太可能的方式综合起来，从而导致神秘的事件。如果我们有系统地思考一下这类事件，往往就能认识到这点。
再举一个例子，假设发现中型方帆双桅船“玛丽·塞莱斯特号”泊在被称为百慕大三角区的海面上。船上一切完好，厨房里剩着吃了一半的饭菜，几个星期以来天气一直良好。这是怎么回事呢？我们可以设想，船员们是被来自大西洋的死光突然杀死的，或是被飞碟掠走的，或者被百慕大三角区产生的磁性旋涡吸走了。即便承认这些超自然的假设似乎不太可能成立，但是我们至少倾向于否定其它普通起因，因为这个事件不象是由普通原因产生的。
但是请等一等，让我们来考虑一下，与超自然原因相比，普通原因引起这类事件的可能性有多大。普遍原因是什么呢？也许船上的全体人员在船边游泳时，碰上了旋涡或遭到鲨鱼的进攻；也许船上的粮食发霉产生麦角酸，致使船员饭吃到一半就集体发作了狂想型精神病，从船上跳入海中或弃船而去。这种情况估计多长时间发生一次呢？几率当然极小。作为不无道理的推测，也许一艘船每100万次航行中只发生一次。但是，如果每年大约有400万艘船进入百慕大三角区，那么就会出现每年有4艘船被弃的几率。这样看来，玛丽·塞莱斯特事件更可能来自自然原因而不是超自然原因。
我并不想竭力使这个例子成为百慕大三角区实际事件的解释，我想要说明的是，当人们把神秘事件归结于超自然的原因，而且不考虑普通原因造成这些事件的机会时，推理中复杂而普遍的偏见——“典型谬误”，可以很容易地使人们陷入困境。
影响人们准确领悟的是人们过于重视巧合、并把巧合与事实混为一谈的倾向。巧合是指两个事件偶然同时发生，而没有因果关系和其他联系，但观察者却从主观上把这两个事件放在一起来领悟。巧合常使人们感到富有戏剧性、奇怪和迷惑，但这些感觉并不意味着两个巧合的事件本身有什么值得奇怪或需要解释的地方。没有什么事情真正“需要解释”，需要解释的仅仅是观察者主观的要求。不过，强烈的要求有时会诱使人们相信，巧合确实有某种神秘的地方。
譬如，有一位叫布雷德的青年人正躺在床上思恋一位多年杳无音信的姑娘，并后悔当初的分手。突然那位姑娘打来长途电话，告诉布雷德，她恰好也在想他，要求见见面。第二天，布雷德冲进办公室告诉我这个情节，他提高嗓门问：“您怎么解释这件事呢？”那意思是“哈哈，这回我可抓住您了！除非认为这是超自然事件以外，您没有别的解释。”其实，这件事恰恰正是偶发事件。如果布雷德告诉我，他每次躺在床上，想到一位旧友时，这位朋友就会立刻给他打来电话，我会非常感兴趣。但是对于一次孤立事件——我没有兴趣。在我看来，这件事需要解释的倒是布雷德对解释该事件的内心要求。
我和其他调查这类事件的心理学家都认为，与个人有关的重大事件发生时，人们由此产生印象并思索可能的潜在原因，这都是必要的，以利今后更好地预知和控制这类事件。当我们的一位祖先在夜晚远离山洞篝火而看到一只剑齿虎，受到惊吓后，他会对此印象深刻，想到黑夜与猛兽出现之间的可能联系，这是正常的。但一旦这类涉及个人的事件偶然同时发生时，就会使人们陷入困境。从理性的或客观的角度讲，只有当这类事件按照可以预知的规律发生时，我们才应为之所动。
人们认为自己的不管什么样的结论都合理并为之辩护的执拗性，加剧了他们贸然下结论的弊病。心理实验表明，在要求人们对某些猜测判断是对是错时，会有如下倾向：
1，立刻作出一个假设，并且专门寻找证实该假设的例子，而不去寻找反驳他们假设的证据。尽管这种方法实际上会极力把一切与该假设对立的证据弃之不顾。
2，如果在猜测过程中答案被偷偷地改变了，他们对改变曾经正确而突然成为错误的假设是非常缓慢的。
3，如果一个假设与事实非常符合，他们便坚持这一假设，而不再寻找可能更符合事实的其他假设。
4，如果提供的情况过于复杂，他们就采用过于简单的假设和解决的办法，而忽略一切与之对立的证据。
5，如果本来就没有答案，人们会就所知情况中自己认为存在的因果关系作出各种各样的假设，并且坚信自己的假设绝对正确。即使不存在因果关系，他们也一定要把它找出未。
在现实世界中，成年人常常显得比鸽子或儿童更善于解决问题，这不是因为成年人无偏见，而是因为他们理解力较高，富有经验，能够更为抽象地思维，并且已经逐步得出了解决问题和形成概念的有效方法。这种方法包括考虑一切可能的假设来解释令人困惑的事件；按照可能性大小的顺序排列各种假设；试着寻找与某些假设相矛盾的证据来否定这些假设；最后，判断剩下的假设中哪一个可能性最大，从而作为最好的选择。同时，新出现的证据又可能会使原来的想法转变。
这种方法看来很合理，人们也都很熟悉。譬如，医生在诊断和治疗时，就常采用这种方法来分析病人的诉述。警探在侦破或刑事法庭在裁定时，也使用这种方法。这同样也是科学上采用的一般方法。但是，除了象科学、法律、警务以及医学等一些紧要问题外，我认为人们一般还是倾向于不使用这种方法。因为正如上面心理研究所表明的那样，人们不容易或不会自然而然地想到这套方法。
为了说明偏见是如何在考虑超自然现象中引起麻烦的，我想先用一个比拟。假设我断言月亮是用乳酪做的，我用什么证据呢？月亮是淡黄色的，很象陈年的干乳酪；月亮上有各种各样的大小暗点，看上去象这种干乳酪上的孔；月亮是圆的，很象我们看到在市场上挂着的进口干乳酪球；外空间的真空和刺骨寒冷把这乳酪完好地保存了千年之久。此外，月亮是个乳酪球的说法古已有之。你当然会说：“登月宇航员看到的一切不就是灰土和岩石吗！”“哈哈！”我反击道，“这有什么！这样大的乳酪在漫长的时间里难道不会从流星雨中获得大量的灰土和岩石吗？”还有，据宇航员留在月亮上的地震记录仪的报道，月动特性曲线不象地球上岩石的振动，而是一个巨大乳酪球所特有的振动特性曲线。只要我狡辩得体，你很可能会相信月亮的食用性。
除了月亮象乳酪这种论点外，还有另一种假设，即月亮是由岩石和金属组成的类似于地球的球体——这一假说具有更强有力的证据，而我忽略了这个假说而倾向于荒谬的论点。从广义上讲，只要不顾对立的假说，我可以为任何一种观点提供一种看上去令人信服的例证。譬如，艾森豪威尔总统是共产主义者；地球和地球上的生命是仅仅在一万年前天神心血来潮创造出来的；太阳是空心的；等等。同样，如果你愿意为“一群古代宇航员开创了我们的文明世界”搞出一个例证，你只需要简单地翻阅一下有插图的考古学课本，找出几十例古代技术的奇迹和看上去很象宇宙飞船的原始图画。这种理论既无法被证明是错误的，也找不到可以肯定它的证据，但它是荒谬的、武断的、有偏见的、凭空编造的。与之相对的理论，即“文明世界是社会进化过程的结果，是有机地逐渐发展而成的”，却有无数足以佐证的论据。我们往往倾向于赞同自己最满意的假设，而忽略更合理的其它选择，从而使自己陷入困境——必须谨防犯这样的错误。
在倾向于忽略合理的其它选择方面，最令人震惊的一个例子就是观察“通灵人”的方式与观察魔术师的方式之间存在的差别。也就是说，当一个所谓的通灵人看出别人的心思、用意念弄弯一小块金属物体、使灰烬非物质化、或遥控指南针时，我们许多人都会因这种显而易见的通灵能力而激动，并产生深刻的印象。但是如果一位魔术师做了这些相同的惊人表演，人们就会认为表演是乏味的老把戏。假若我们形成某些看法是完全有理智和有条理的，我们就会仔细观察通灵人的表演，并询问魔术师能做这种表演吗？如果能，那么这个表演实际上会不会是变魔术呢？但是，也许因为对通灵能力的看法太令人激动，而且我们需要证实这些看法，所以我们常常只用倾向于证实自己看法的方式观察通灵人的表演。
最近，我和几位同事做了这样一个实验。我们请一位名叫克雷格的学生给学院的一些班级表演了标准的魔术节目。在表演中，他完全蒙住眼睛，用自己的手指读出一些三位数；在一位志愿者的手上，不加外力而使灰烬移动；用食指轻轻敲打一根较粗的黄铜棍，使之弯曲。其实，所有这些戏法都很简单，是标准业余性的，只要几分钟就可以学会，甚至可以在儿童魔术书里找到。
在表演过程中，克雷格从未说自己是通灵人或魔术师，他只是表演。克雷格在学院六个不同的班级里做了表演。在第三个班上，教授向学生们介绍说克雷格自称是通灵人，尽管这些教授自己也有怀疑。在其它班上，教授们详细地解释说克雷格是位业余魔术师，他将利用简单的舞台花招来模仿通灵表演。在这些班上，教授们要求学生记录并解释这段开场白，以确保学生们听到并理解了。克雷格结束表演之后，要求学生们写下他们的任何反应。
我们分析了学生的反应表，首先确证他们认为克雷格是什么人。在被告知克雷格自称是通灵人的那些班上，大约80%的学生也都明确地认为他是通灵人，只有少数学生对此表示怀疑。事先我们虽然料到相信的百分比会很高，但是我们仍对笃信的强烈程度感到吃惊：在整个表演过程中，许多学生喘息着，小声惊呼着，明显地受到了震动。许多学生在反应表上写下了这样的评语：“难以置信！如果不是亲眼所见，我是不会相信的。每个人都能培养出这种能力吗？”大约有12名学生变得心烦意乱或非常惊恐，他们在表上写满了驱邪用的咒语，或警告克雷格不要与魔鬼来往。我们对如此轻易地引起这样强烈的反应感到不安。次日，我们全体回到那些班上，向学生们解释说表演是假的。
在被告知克雷格是位业余魔术师的那些班级上，我们发现了两个有趣的情况。第一，相信克雷格是通灵人的学生大约比被告知克雷格是通灵人的那些班级少三分之一。虽然这些学生看到的表演和其他班看到的完全一样，但是这些学生常常评论说：“真漂亮的把戏！”而不说“你是怎样培养出这种能力的呢？！”这些班级的一些学生对如何变这套戏法所做的一些猜测，有时还是正确的。第二，即使这些班级对通灵人的相信程度较低，但仍有百分之五十以上的学生相信克雷格是通灵人，其中某些学生甚至评论说，克雷格的表演根本不可能是舞台魔术。
总之，心理调查告诉我们，在人们的日常推理过程中存在着严重的缺陷，他们是拙劣的自然环境观察者和归纳者。人们经常低估可能性，并发现要准确地推论这些可能性是很困难的，人们把神秘事件过于轻易地归结于神秘的原因，还过于轻易地把对这些事件的感受混同于事实。人们在面对问题时，往往不是考虑所有可能的假设，而是选择一个自以为是的假说，然后只寻找支持这一假说的证据。
科学方法可能会因其涉及的数学、术语和技术设备而令人生畏，但它基本上不过是一种审慎建立起来从而弥补人们天生的推理缺陷的实用而又系统的推理方法。因此，科学方法不允许把感觉和愿望与解释混为一谈，要求认真系统地观察环境，尽可能使用仪器而不是单纯的直观或者利用数学来论证正确的可能性，并考虑一切可以选择的其它假设，同时尤其要认真分析与所主张的假设相对立的证据，而不是武断地一概否定。在认识世界的过程中，凭藉科学取得的成就要比单靠人直觉取得的多得多，这并非因为科学是一种非凡的体系——科学并不是不犯错误，而是因为单靠直觉太容易出错了。
在许多科学与直觉相抵触时，人们会明智地认识到科学是正确的，直觉是错误的。因此，尽管直觉使我们感到地球是处于静止状态，而太阳是每24小时绕地球一周，但人们仍相信地球在绕地轴自转的同时绕太阳公转；尽管凭直觉看来椅子是实心的，但人们相信椅子是由原子组成的，而从这个意义上讲，椅子几乎是空洞洞的空间。然而，当科学家告诉人们，占星术或超感官知觉的看法不合逻辑，也没有证据时，人们却认为科学家是错误的。这是怎么回事呢？
科学并非总是比直觉的认识要强，科学也不是一贯正确的。不过，最显著的科学进展是以科学超越或否定人们的普通知觉和直觉为特征的。过去，科学经常清楚地证明它强于直觉，因此，在超自然现象的直觉经验与科学观点相抵触时，我们就应当仔细考虑我们的推论，看看自己是否被作为人类天性一部分的偏见所蒙骗。诚如弗兰西斯·培根指出的那样，“当一种见解一经提出之后……人的理解力便会强使其他的一切来支持和证实这种见解。……容易被肯定的而不是被否定的观点所影响和激动，这是人的理解力的一种奇特的和永存的错误。”
Thursday, December 28, 2006
Tuesday, December 26, 2006
The new 100 most useful sites
Applications
Why have an application to run in your browser? Because for tasks shared between people at different locations, it makes sense to access password-protected sets of work. 37signals offers Backpack (note the domain is backpackit) for simple tasks and the bigger Basecamp for grown-up projects. Tadalist is simpler, being just to-dos (but isn't that what it's about?), while Google's Documents & Spreadsheets requires a Google account (they're free) and doesn't try to compete with Microsoft Office. Wikicalc is a free online spreadsheet, and developing smartly.
Blogs: reading
There are millions of blogs out there; you need to pick the best. Step forward RSS (aka web feeds) and blog search engines to simplify things. Technorati is occasionally flaky, but generally a reliable indicator of what's being blogged about. Icerocket runs it close. And you'll need an online aggregator to keep abreast of the feeds you're most interested in: Newsgator and Google Reader are good choices. Bloglines is an excellent alternative feed reader.
Blogs: writing
To do it rather than read it, you need a good set of tools. The open-source and free software project Wordpress has risen to prominence, elbowing aside many rivals with its blog creation, management and (importantly) spam-beating tools. Wordpress.org is the free software; wordpress.com offers paid-for, managed versions of the free package. Blogger is the best of the rest; Vox is neat, easy and free, and plugs into lots of social applications. Statcounter counts, well, statistics for your site; the free Google Analytics (if you can get an account) is good too.
Google's Gmail has become the web-based email system of choice for those who can get access. Its main drawback is that it's still an invitation-only system in the UK. However, Yahoo's free email service is a decent competitor, and Microsoft has Live Mail. Unlike Microsoft's old Hotmail service, none will delete all your old emails if you fail to log on every 30 days. Among the dozens of free alternatives, Bluebottle is a decent option for its focus on spam filtering. The free version offers 250MB of storage and supports the POP3 and SMTP standards, so you can use a proper email program as well as web access. There's also TempInbox, which provides free, temporary, throwaway email accounts with no registration.
Gaming
There are far too many videogame news sites on the internet today; you need an aggregator like Gametab to filter through to the best. Pocketgamer specialises in handheld games, while Gamasutra is absolutely unmissable. Gamesfaqs has FAQs and walkthroughs (plus cheats, reviews and previews) for loads of games. And the ESRB lets you search by age rating.
Maps
Maps matter, but once you're past Google's maps and satellite detail, everyone's thrown back on the Ordnance Survey's data, which means there's little to choose between them. Ordnance Survey has improved its site, and can at least now tell you which map to buy for an area; its placename search is nifty. Meanwhile, the New Popular Edition site shows how the country looked in the 1940s. Delightful.
News: mainstream
The BBC marches on, adding more media forms while also letting users add their comments. The New York Times site is vast (though it has shut off some of its content behind a "paywall"). Both sites' (short) RSS feeds can be read on a mobile at bbcriver.com and nytimesriver.com. Google News extends its reach, though the top headline is still whichever site last updated rather than the one which is most accurate. Nowpublic is a US rival to OhMyNews and claims 52,000 (and counting) "mojos" - amateur journalists with mobile phones whose location can be figured out from GPS or phone triangulation.
News: recommendation
One thing that Web 2.0 is really good at is letting lots of people vote on things. It can be (and is) abused, but generally the system works. That's seen the rise of sites which let people vote stories up, or which news stories (and how) bloggers are talking about (at memoerandum).The biggest is Digg, which overtook Slashdot earlier this year. Reddit was recently bought by Wired magazine. Findory is slightly different, learning what you like the more you use it.
Offbeat
Snopes checks out unbelievable tales, scams and urban legends and debunks (or confirms) them. Slightly less useful is the 100-strong webring of Unusual Museums of the Internet. These include the Virtual Toilet Paper Museum, the Old Calculators Web Museum and Signalfan's museum of traffic control signals. You can find links to lots of other offbeat sites via the Weird Site's Other Weird Links page. The Onion is the web's leading satire magazine, though with an American bias. Otherwise, for five minutes of fun, try browsing B3ta. This UK site sends out a weekly newsletter of cool links and runs a message board where people post amusingly manipulated pictures. But be warned: it's often offensive - that's part of the point - and most definitely rated NSFW (Not Safe For Work).
Politics
The MySociety team remains unbeatable for turning Hansard inside out with Theyworkforyou and Publicwhip, but bloggers have begun to expose the unwritten workings of politicians to greater public scrutiny too. Guido Fawkes' blog has the inside gossip from Westminster, while NO2ID agitates on arguably the most important political and technological issue around, while NHS 23 is a wiki outlining the problems with the political, technological and medical drama of the NHS computer- isation programme.
Public action
Now, it's time to bug someone in power. The idea that the web can make a difference is growing; politicians are on the web and there's an online petition site at No.10. Pledgebank and HearfromyourMP are both part of the excellent MySociety (mysociety.org) family of sites enabling citizens to connect to decision-makers - and, one would hope, vice versa. Netaction includes The Virtual Activist, a manual for anyone looking to build and promote a cause online. Those interested in helping out in their area might try Timebank, which finds organisations to which to donate spare time.
Radio
Radio now travels over wires, at least to our homes. The BBC dominates here, but there are thousands of stations to choose from. AOL's Shoutcast is interesting: find whatever's on right now (you can tune in via iTunes or any internet radio-enabled player.) Radio-locator and Live-radio list broadcasters worldwide, so you can find something new to listen to. Reciva does the same, but if you buy its internet radio you can add your own favourites online and they show on the gadget; or just listen online.
Recommendation: music
Another new category: being able to find stuff that's similar to music you like is increasingly important, both to listeners and to record companies trying to profit from niches. Last.fm requires an application that runs on your machine, and shows what other people with the same music like. Pandora says you need a US postcode; so give it one, then enjoy its expert-chosen stations. Liveplasma can search relationships in films as well as music. Tuneglue is a relatively new venture between last.fm and EMI, using data from Amazon and last.fm. Goombah requires a small download and only works on music in an iTunes library, but has been at it for some time.
Reference
Wikipedia now dominates the reference side of the web, partly because its pages are ranked so highly in Google. User-written, it's not always reliable, but is usually a good place to start. It competes with the Encyclopedia Britannica, which isn't free. However, another traditional alternative is the HighBeam Encyclopedia, which searches more than 57,000 articles from the Columbia Encyclopedia. Otherwise Jim Martindale's Reference Desk, started in 1994, provides an astonishing collection of links to reference sources. For words, try Onelook, which indexes more than 7.5m words in 931 dictionaries. It also has a reverse lookup to find words from their meanings. Finally, Teldir (on the infobel site) has links to the world's online phone books.
Science
Alphagalileo gives a view of public-facing science in Europe and is a counterpart to eurekalert, the American Association for the Advancement of Science's press announcements forum. Space.com remains fascinating for all things spacey. Nasa contains a wealth of information. The growing importance of climate change makes the RealClimate blog written by climate change scientists important.
Search
Google continues to tighten its grip on our hunt for information (it now gets half of all searches) but that doesn't necessarily mean it's the best. Search can now encompass your hard drive, blogs (a separate category - see above), images, peer-to-peer and even what used to be out there. Blinkx remains unique with its focus on video, while Ask (now without Jeeves) has made great strides recently, though it only gets a tiny portion of searches.
Social software
The browser has grown up: now it's the path to meeting people of similar interests and creating your own personal space online in a shared area. Social networks have become a cliche, but that hasn't stopped MySpace becoming the biggest site online. Bebo is popular, Habbo is more tuned to the kids, while Friendster and LinkedIn will appeal to the older user.
Video
The crowds are all over at YouTube, the poster child of online video (a category too niche to merit mention two years ago; YouTube was founded in February 2005). But it's not the only place to find video. Revver offers a revenue-sharing system (people pay to watch your video, you get some cash). You can also start your own TV station at brightcove and currenttv. And Videojug has demonstrations of how to do lots of possibly useful tasks.
Virtual worlds
The key distinction from social sites like MySpace is that virtual worlds give you an avatar - your representation of yourself in the online world. The advent of broadband allied to faster machines has made them usable. When the BBC held a concert in Second Life, it seemed like an anomaly; then IBM's chief executive got an avatar, and suddenly everyone's there. Habbo Hotel is booming with teens. World of Warcraft has millions of users; Everquest, its own culture. Or you can play the Sims online. Whether an influx of new users will make these worlds more antisocial remains open.
eqplayers.station.sony.com/index.vm
Zeitgeist
It's what everyone's talking about. Some of these sites appear above because they're the places to go to find out whatthe webworld is thinking. Watch them whizz by, but don't forget to breathe. YouTube is the moving picture of the web; Flickr the static one. Google Trends shows what the world's looking for; Digg, what it's found. And Technorati shows what it's writing about. youtube.com flickr.com google.com/trends digg.com technorati.com
Readers' suggestions
VideoJug (videojug.com). Videos on how to do everyday stuff such as tying a tie etc. (HiddenAway)
Slideshare (slideshare.net) . For sharing presentations; Best Tech Videos (bestechvideos.com). Very techie tutorial videos; TechXtra (techxtra.ac.uk). Has a long enough 'tail' to answer real queries. (RoddyM)
Online apps and desktops: Zoho (zoho.com); Cosmopod (cosmopod.com); eyeOS (eyeos.org). Online video editing: jumpcut.com. (hakluytbean)
Reevoo (reevoo.com) is a very handy site for people looking for honest feedback on products, as it only publishes reviews known to come from customers. (TechMonkey)
Friday, December 22, 2006
One Backstreet Boy Is Gay
We are on fire,
We have desires,
But one is that way,
One backstreet boy is gay.
But we don’t want to
Be mean,
Since now he’s a queen,
Don’t ask me,
Which backstreet boy is gay?
Tell me who,
(They’re saying that it’s AJ)
Tell me who,
(They’re saying that it’s Howie)
Tell me who,
I never wanna hear you say,
Which backstreet boy is gay?
Now I can see him,
He’s in women’s clothes,
But he don’t need an IUD…yeah
He likes village people
He’s playing croquet,
His dog is a Pekinese.
He’s on fire,
His back perspires,
Won’t say (won’t say, won’t say, won’t say, won’t saaaaay)
He’s always saying
Ain’t nothing but a butt ache,
Ain’t nothing but a fruitcake,
I never wanna hear you say (I never wanna hear you say)
Which one of us is gay?
Tell me who,
(They’re saying that it’s Brian)
Tell me who,
(They’re saying Nick or Kevin)
Tell me who,
He’s baking up a soufflé,
Which backstreet boy is gay?
Ok, we’re all gay…
Wednesday, December 20, 2006
M I N D_I n t r o d u c t i o n t o C og n i t ive S c i e n c e
Cognitive science is the interdisciplinary study of mind and intelligence,
embracing philosophy, psychology, artificial intelligence, neuroscience,
linguistics, and anthropology. Its intellectual origins are in the mid-1950s
when researchers in several fields began to develop theories of mind based
on complex representations and computational procedures. Its organizational
origins are in the mid-1970s when the Cognitive Science Society was
formed and the journal Cognitive Science began. Since then, more than sixty
universities in North America and Europe have established cognitive
science programs and many others have instituted courses in cognitive
science.
Teaching an interdisciplinary course in cognitive science is difficult
because students come to it with very different backgrounds. Since 1993,
I have been teaching a popular course at the University of Waterloo called
Introduction to Cognitive Science. On the one hand, the course attracts
computationally sophisticated students from computer science and engineering
who know little psychology or philosophy; on the other, it attracts
students with good backgrounds in psychology or philosophy but who
know little about computation. This text is part of an attempt to construct
a course that presupposes no special preparation in any of the fields of cognitive
science. It is intended to enable students with an interest in mind
and intelligence to see that there are many complementary approaches to
the investigation of mind.
There are at least three different ways to introduce cognitive science to
a multidisciplinary audience. The first is to concentrate on the different
fields of psychology, artificial intelligence, and so on. The second is to organize
the discussion by different functions of mind, such as problem
solving, memory, learning, and language. I have chosen a third pproach,
systematically describing and evaluating the main theories of mental representation that have been advocated by cognitive scientists, including
logic, rules, concepts, analogies, images, and connections (artificial neural
networks). Discussing these fundamental theoretical approaches provides
a unified way of presenting the accomplishments of the different fields of
cognitive science to understanding various important mental functions.
My goal in writing this book is to make it accessible to all students likely
to enroll in an introduction to cognitive science. Accomplishing this goal
requires, for example, explaining logic in a way accessible to psychology
students, computer algorithms in a way accessible to English students,
and philosophical controversies in a way accessible to computer science
students.
Although this book is intended for undergraduates, it should also be
useful for graduate students and faculty who want to see how their own
fields fit into the general enterprise of cognitive science. I have not written
an encyclopedia. Since the whole point of this exercise is to provide an
integrated introduction, I have kept the book relatively short and to the
point, highlighting the forest rather than the trees. Viewing cognitive
science as the intersection rather than as the union of all the relevant fields,
I have omitted many topics that are standard in introductions to artificial
intelligence, cognitive psychology, philosophy of mind, and so on. Each
chapter concludes with a summary and suggestions for further reading.
The book is written with great enthusiasm for what theories of mental
representation and computation have contributed to the understanding of
mind, but also with awareness that cognitive science has a long way to go.
The second part of the book discusses extensions to the basic assumptions
of cognitive science and suggests directions for future interdisciplinary
work.
I have been grateful for the reception of the first edition of this book,
especially its translation into Italian, German, Czech, Portuguese, Japanese,
Korean, and two variants of Chinese. For this second edition, I have
brought part I up to date and substantially revised part II, adding new chapters
on brains, emotions, and consciousness. Other additions include a list
of relevant Web sites at the end of each chapter, and a glossary at the end
of the book. My anthology, Mind Readings: Introductory Selections on Cognitive
Science (MIT Press, 1998) remains a useful accompaniment.
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GETTING TO YES
The authors of this book have been working together since 1977.
Roger Fisher teaches negotiation at Harvard Law School, where he is Williston Professor
of Law and Director of the Harvard Negotiation Project. Raised in Illinois, he served in World
War II with the U.S. Army Air Force, in Paris with the Marshall Plan, and in Washington, D.C.,
with the Department of Justice. He has also practiced law in Washington and served as a
consultant to the Department of Defense. He was the originator and executive editor of the
award-winning series The Advocates. He consults widely with governments, corporations, and
individuals through Conflict Management, Inc., and the Conflict Management Group.
William Ury, consultant, writer, and lecturer on negotiation and mediation, is Director of
the Negotiation Network at Harvard University and Associate Director of the Harvard
Negotiation Project. He has served as a consultant and third party in disputes ranging from the
Palestinian-Israeli conflict to U.S.-Soviet arms control to intracorporate conflicts to labormanagement
conflict at a Kentucky coal mine. Currently, he is working on ethnic conflict in the
Soviet Union and on teacher-contract negotiations in a large urban setting. Educated in
Switzerland, he has degrees from Yale in Linguistics and Harvard in anthropology.
Bruce Patton, Deputy Director of the Harvard Negotiation Project, is the Thaddeus R. Beal
Lecturer on Law at Harvard Law School, where he teaches negotiation. A lawyer, he teaches
negotiation to diplomats and corporate executives around the world and works as a negotiation
consultant and mediator in international, corporate, labor-management, and family settings.
Associated with the Conflict Management organizations, which he co founded in 1984, he has
both graduate and undergraduate degrees from Harvard.
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Investment Madness
WARNING: Allowing emotion to invade your investment decisions can be hazardous to your wealth.
* Think about your investments more clearly
* How overconfident investors trade too much, take too many risks, and earn lower returns
* The investment impact of your self-image
* Why avoiding feelings of regret now will cause you even greater regrets later
* Yesterday's trade, today's emotions, tomorrow's mistake
* Placing your recent investment experiences in realistic perspective
* The devil you know versus the devil you don't
* Familiarity breeds investment—but not necessarily profit
* Is your memory playing tricks with you?
* You're not alone. We'll tell you what to do about it
* Not all information is alike
* Avoiding herd mentality: your chat room, your brother-in-law, and other temptations. Remember when dotcoms were going to end business as we know it?
How your psychology reduces your profits and increases your risks-and what to do about it!
* Why'd you fall for that Internet stock?
* Why'd you keep money in cash when it could've earned far better returns elsewhere?
* Why haven't you fully funded your retirement plan when you know you should?
* Why do you always seem to buy high and sell low?
* Why does it look like everyone else is getting rich but you?
It's your psychology. It's your emotions. As an investor, they're your biggest obstacles. They cut your returns, and raise your risks. It's about time you did something about it. Investment Madness will show you how. Drawing on the new science of behavioral finance, Dr. John Nofsinger shows you how to:
* See through the "illusion of control" that makes you overconfident about your investments
* Objectively evaluate the stocks and financial instruments you've inherited
* Recognize the feelings of pride, regret, and herd behavior that lead to disaster
* Improve your "mental accounting"—and your portfolio's diversification
With today's instantaneous Internet-based trading, your psychological biases have become more dangerous than ever. Investment Madness delivers expert techniques and mental strategies that will empower you with true self-control—the decisive factor in investment success.
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The Age of the Earth
by Chris Stassen
Copyright © 1996-2005
Overview
- How old is the Earth, and how do we know?
- Common creationist "dating methods"
- Common creationist criticisms of mainstream dating methods
- Suggested further reading
- References
How Old Is The Earth, And How Do We Know?
The generally accepted age for the Earth and the rest of the solar system is about 4.55 billion years (plus or minus about 1%). This value is derived from several different lines of evidence.
Unfortunately, the age cannot be computed directly from material that is solely from the Earth. There is evidence that energy from the Earth's accumulation caused the surface to be molten. Further, the processes of erosion and crustal recycling have apparently destroyed all of the earliest surface.
The oldest rocks which have been found so far (on the Earth) date to about 3.8 to 3.9 billion years ago (by several radiometric dating methods). Some of these rocks are sedimentary, and include minerals which are themselves as old as 4.1 to 4.2 billion years. Rocks of this age are relatively rare, however rocks that are at least 3.5 billion years in age have been found on North America, Greenland, Australia, Africa, and Asia.
While these values do not compute an age for the Earth, they do establish a lower limit (the Earth must be at least as old as any formation on it). This lower limit is at least concordant with the independently derived figure of 4.55 billion years for the Earth's actual age.
The most direct means for calculating the Earth's age is a Pb/Pb isochron age, derived from samples of the Earth and meteorites. This involves measurement of three isotopes of lead (Pb-206, Pb-207, and either Pb-208 or Pb-204). A plot is constructed of Pb-206/Pb-204 versus Pb-207/Pb-204.
If the solar system formed from a common pool of matter, which was uniformly distributed in terms of Pb isotope ratios, then the initial plots for all objects from that pool of matter would fall on a single point.
Over time, the amounts of Pb-206 and Pb-207 will change in some samples, as these isotopes are decay end-products of uranium decay (U-238 decays to Pb-206, and U-235 decays to Pb-207). This causes the data points to separate from each other. The higher the uranium-to-lead ratio of a rock, the more the Pb-206/Pb-204 and Pb-207/Pb-204 values will change with time.
If the source of the solar system was also uniformly distributed with respect to uranium isotope ratios, then the data points will always fall on a single line. And from the slope of the line we can compute the amount of time which has passed since the pool of matter became separated into individual objects. See the Isochron Dating FAQ or Faure (1986, chapter 18) for technical detail.
A young-Earther would object to all of the "assumptions" listed above. However, the test for these assumptions is the plot of the data itself. The actual underlying assumption is that, if those requirements have not been met, there is no reason for the data points to fall on a line.
The resulting plot has data points for each of five meteorites that contain varying levels of uranium, a single data point for all meteorites that do not, and one (solid circle) data point for modern terrestrial sediments. It looks like this:
 |
Most of the other measurements for the age of the Earth rest upon calculating an age for the solar system by dating objects which are expected to have formed with the planets but are not geologically active (and therefore cannot erase evidence of their formation), such as meteorites. Below is a table of radiometric ages derived from groups of meteorites:
| | |||
| Type | Number Dated | Method | Age (billions of years) |
|---|---|---|---|
| | |||
| Chondrites (CM, CV, H, L, LL, E) | 13 | Sm-Nd | 4.21 +/- 0.76 |
| Carbonaceous chondrites | 4 | Rb-Sr | 4.37 +/- 0.34 |
| Chondrites (undisturbed H, LL, E) | 38 | Rb-Sr | 4.50 +/- 0.02 |
| Chondrites (H, L, LL, E) | 50 | Rb-Sr | 4.43 +/- 0.04 |
| H Chondrites (undisturbed) | 17 | Rb-Sr | 4.52 +/- 0.04 |
| H Chondrites | 15 | Rb-Sr | 4.59 +/- 0.06 |
| L Chondrites (relatively undisturbed) | 6 | Rb-Sr | 4.44 +/- 0.12 |
| L Chondrites | 5 | Rb-Sr | 4.38 +/- 0.12 |
| LL Chondrites (undisturbed) | 13 | Rb-Sr | 4.49 +/- 0.02 |
| LL Chondrites | 10 | Rb-Sr | 4.46 +/- 0.06 |
| E Chondrites (undisturbed) | 8 | Rb-Sr | 4.51 +/- 0.04 |
| E Chondrites | 8 | Rb-Sr | 4.44 +/- 0.13 |
| Eucrites (polymict) | 23 | Rb-Sr | 4.53 +/- 0.19 |
| Eucrites | 11 | Rb-Sr | 4.44 +/- 0.30 |
| Eucrites | 13 | Lu-Hf | 4.57 +/- 0.19 |
| Diogenites | 5 | Rb-Sr | 4.45 +/- 0.18 |
| Iron (plus iron from St. Severin) | 8 | Re-Os | 4.57 +/- 0.21 |
| | |||
| After Dalrymple (1991, p. 291); duplicate studies on identical meteorite types omitted. | |||
As shown in the table, there is excellent agreement on about 4.5 billion years, between several meteorites and by several different dating methods. Note that young-Earthers cannot accuse us of selective use of data -- the above table includes a significant fraction of all meteorites on which isotope dating has been attempted. According to Dalrymple (1991, p. 286) , less than 100 meteorites have been subjected to isotope dating, and of those about 70 yield ages with low analytical error.
Further, the oldest age determinations of individual meteorites generally give concordant ages by multiple radiometric means, or multiple tests across different samples. For example:
| | |||
| Meteorite | Dated | Method | Age (billions of years) |
|---|---|---|---|
| | |||
| Allende | whole rock | Ar-Ar | 4.52 +/- 0.02 |
| | whole rock | Ar-Ar | 4.53 +/- 0.02 |
| | whole rock | Ar-Ar | 4.48 +/- 0.02 |
| | whole rock | Ar-Ar | 4.55 +/- 0.03 |
| | whole rock | Ar-Ar | 4.55 +/- 0.03 |
| | whole rock | Ar-Ar | 4.57 +/- 0.03 |
| | whole rock | Ar-Ar | 4.50 +/- 0.02 |
| | whole rock | Ar-Ar | 4.56 +/- 0.05 |
| | |||
| Guarena | whole rock | Ar-Ar | 4.44 +/- 0.06 |
| | 13 samples | Rb-Sr | 4.46 +/- 0.08 |
| | |||
| Shaw | whole rock | Ar-Ar | 4.43 +/- 0.06 |
| | whole rock | Ar-Ar | 4.40 +/- 0.06 |
| | whole rock | Ar-Ar | 4.29 +/- 0.06 |
| | |||
| Olivenza | 18 samples | Rb-Sr | 4.53 +/- 0.16 |
| | whole rock | Ar-Ar | 4.49 +/- 0.06 |
| | |||
| Saint Severin | 4 samples | Sm-Nd | 4.55 +/- 0.33 |
| | 10 samples | Rb-Sr | 4.51 +/- 0.15 |
| | whole rock | Ar-Ar | 4.43 +/- 0.04 |
| | whole rock | Ar-Ar | 4.38 +/- 0.04 |
| | whole rock | Ar-Ar | 4.42 +/- 0.04 |
| | |||
| Indarch | 9 samples | Rb-Sr | 4.46 +/- 0.08 |
| | 12 samples | Rb-Sr | 4.39 +/- 0.04 |
| | |||
| Juvinas | 5 samples | Sm-Nd | 4.56 +/- 0.08 |
| | 5 samples | Rb-Sr | 4.50 +/- 0.07 |
| | |||
| Moama | 3 samples | Sm-Nd | 4.46 +/- 0.03 |
| | 4 samples | Sm-Nd | 4.52 +/- 0.05 |
| | |||
| Y-75011 | 9 samples | Rb-Sr | 4.50 +/- 0.05 |
| | 7 samples | Sm-Nd | 4.52 +/- 0.16 |
| | 5 samples | Rb-Sr | 4.46 +/- 0.06 |
| | 4 samples | Sm-Nd | 4.52 +/- 0.33 |
| | |||
| Angra dos Reis | 7 samples | Sm-Nd | 4.55 +/- 0.04 |
| | 3 samples | Sm-Nd | 4.56 +/- 0.04 |
| | |||
| Mundrabrilla | silicates | Ar-Ar | 4.50 +/- 0.06 |
| | silicates | Ar-Ar | 4.57 +/- 0.06 |
| | olivine | Ar-Ar | 4.54 +/- 0.04 |
| | plagioclase | Ar-Ar | 4.50 +/- 0.04 |
| | |||
| Weekeroo Station | 4 samples | Rb-Sr | 4.39 +/- 0.07 |
| | silicates | Ar-Ar | 4.54 +/- 0.03 |
| | |||
| After Dalrymple (1991, p. 286); meteorites dated by only a single means omitted. | |||
Also note that the meteorite ages (both when dated mainly by Rb-Sr dating in groups, and by multiple means individually) are in exact agreement with the solar system "model lead age" produced earlier.
Common Young-Earth "Dating Methods"
Young-Earthers have several methods which they claim to give "upper limits" to the age of the Earth, much lower than the age calculated above (usually in the thousands of years). Those which appear the most frequently in talk.origins are reproduced below:
- Accumulation of helium in the atmosphere
- Decay of the Earth's magnetic field
- Accumulation of meteoritic dust on the Moon
- Accumulation of metals into the oceans
Note that these aren't necessarily the "best" or most difficult to refute of young-Earth arguments. However, they are quite popular in modern creation-"science" literature (even though they should not be!) and they are historically the ones posted to talk.origins more than any others.
1. Accumulation of Helium in the atmosphere
The young-Earth argument goes something like this: helium-4 is created by radioactive decay (alpha particles are helium nuclei) and is constantly added to the atmosphere. Helium is not light enough to escape the Earth's gravity (unlike hydrogen), and it will therefore accumulate over time. The current level of helium in the atmosphere would accumulate in less than two hundred thousand years, therefore the Earth is young. (I believe this argument was originally put forth by Mormon young-Earther Melvin Cook, in a letter to the editor which was published in Nature.)
But helium can and does escape from the atmosphere, at rates calculated to be nearly identical to rates of production. In order to obtain a young age from their calculations, young-Earthers handwave away mechanisms by which helium can escape. For example, Henry Morris says:
"There is no evidence at all that Helium 4 either does, or can, escape from the exosphere in significant amounts." ( Morris 1974, p. 151 )
But Morris is wrong. Surely one cannot "invent" a good dating mechanism by simply ignoring processes which work in the opposite direction of the process which the date is based upon. Dalrymple says:
"Banks and Holzer (12) have shown that the polar wind can account for an escape of (2 to 4) x 106 ions/cm2 /sec of 4He, which is nearly identical to the estimated production flux of (2.5 +/- 1.5) x 106 atoms/cm2/sec. Calculations for 3He lead to similar results, i.e., a rate virtually identical to the estimated production flux. Another possible escape mechanism is direct interaction of the solar wind with the upper atmosphere during the short periods of lower magnetic-field intensity while the field is reversing. Sheldon and Kern (112) estimated that 20 geomagnetic-field reversals over the past 3.5 million years would have assured a balance between helium production and loss." ( Dalrymple 1984, p. 112 )
Dalrymple's references:
- (12) Banks, P. M. & T. E. Holzer. 1969. "High-latitude plasma transport: the polar wind" in Journal of Geophysical Research 74, pp. 6317-6332.
- (112) Sheldon, W. R. & J. W. Kern. 1972. "Atmospheric helium and geomagnetic field reversals" in Journal of Geophysical Research 77, pp. 6194-6201.
This argument also appears in the following creationist literature:
Brown (1989, pp. 16 and 52)
Jansma (1985, p. 61)
Whitcomb and Morris (1961, pp. 384-385)
Wysong (1976, pp. 161-163)
2. Decay of the Earth's magnetic field
The young-Earth argument: the dipole component of the magnetic field has decreased slightly over the time that it has been measured. Assuming the generally accepted "dynamo theory" for the existence of the Earth's magnetic field is wrong, the mechanism might instead be an initially created field which has been losing strength ever since the creation event. An exponential fit (assuming a half-life of 1400 years on 130 years' worth of measurements) yields an impossibly high magnetic field even 8000 years ago, therefore the Earth must be young. The main proponent of this argument was Thomas Barnes.
There are several things wrong with this "dating" mechanism. It's hard to just list them all. The primary four are:
- While there is no complete model to the geodynamo (certain key properties of the core are unknown), there are reasonable starts and there are no good reasons for rejecting such an entity out of hand. If it is possible for energy to be added to the field, then the extrapolation is useless.
- There is overwhelming evidence that the magnetic field has reversed itself, rendering any unidirectional extrapolation on total energy useless. Even some young-Earthers admit to that these days -- e.g., Humphreys (1988).
- Much of the energy in the field is almost certainly not even visible external to the core. This means that the extrapolation rests on the assumption that fluctuations in the observable portion of the field accurately represent fluctuations in its total energy.
- Barnes' extrapolation completely ignores the nondipole component of the field. Even if we grant that it is permissible to ignore portions of the field that are internal to the core, Barnes' extrapolation also ignores portions of the field which are visible and instead rests on extrapolation of a theoretical entity.
That last part is more important than it may sound. The Earth's magnetic field is often split in two components when measured. The "dipole" component is the part which approximates a theoretically perfect field around a single magnet, and the "nondipole" components are the ("messy") remainder. A study in the 1960s showed that the decrease in the dipole component since the turn of the century had been nearly completely compensated by an increase in the strength of the nondipole components of the field. (In other words, the measurements show that the field has been diverging from the shape that would be expected of a theoretical ideal magnet, more than the amount of energy has actually been changing.) Barnes' extrapolation therefore does not really rest on the change in energy of the field.
For information, see Dalrymple (1984, pp. 106-108) or Strahler (1987, pp. 150-155) .
This argument also appears in the following creationist literature:
Brown (1989, pp. 17 and 53)
Jackson (1989, pp. 37-38)
Jansma (1985, pp. 61-62)
Morris (1974, pp. 157-158)
Wysong (1976, pp. 160-161)
3. Accumulation of meteoritic dust on the Moon
The most common form of this young-Earth argument is based on a single measurement of the rate of meteoritic dust influx to the Earth gave a value in the millions of tons per year. While this is negligible compared to the processes of erosion on the Earth (about a shoebox-full of dust per acre per year), there are no such processes on the Moon. Young-Earthers claim that the Moon must receive a similar amount of dust (perhaps 25% as much per unit surface area due to its lesser gravity), and there should be a very large dust layer (about a hundred feet thick) if the Moon is several billion years old.
Morris says, regarding the dust influx rate:
"The best measurements have been made by Hans Pettersson, who obtained the figure of 14 million tons per year1."
Morris (1974, p. 152) [italic emphasis added -CS]
Pettersson stood on a mountain top and collected dust there with a device intended for measuring smog levels. He measured the amount of nickel collected, and published calculations based on the assumption that all nickel that he collected was meteoritic in origin. That assumption was wrong and caused his published figures to be a vast overestimate.
Pettersson's calculation resulted in the a figure of about 15 million tons per year. In the very same paper, he indicated that he believed that value to be a "generous" over-estimate, and said that 5 million tons per year was a more likely figure.
Several measurements of higher precision were available from many sources by the time Morris wrote Scientific Creationism. These measurements give the value (for influx rate to the Earth) of about 20,000 to 40,000 tons per year. Multiple measurements (chemical signature of ocean sediments, satellite penetration detectors, microcratering rate of objects left exposed on the lunar surface) all agree on approximately the same value -- nearly three orders of magnitude lower than the value which Morris chose to use.
Morris chose to pick obsolete data with known problems, and call it the "best" measurement available. With the proper values, the expected depth of meteoritic dust on the Moon is less than one foot.
For further information, see Dalrymple (1984, pp. 108-111) or Strahler (1987, pp. 143-144) .
Addendum: "loose dust" vs. "meteoritic material"
Some folks in talk.origins occasionally sow further confusion by discussing the thickness of the "lunar soil" as if it represented the entire quantity of meteoritic material on the lunar surface. The lunar soil is a very thin layer (usually an inch or less) of loose powder present on the surface of the Moon.
However, the lunar soil is not the only meteoritic material on the lunar surface. The "soil" is merely the portion of powdery material which is kept loose by micrometeorite impacts. Below it is the regolith, which is a mixture of rock fragments and packed powdery material. The regolith averages about five meters deep on the lunar maria and ten meters on the lunar highlands.
In addition, lunar rocks are broken down by various processes (such as micrometeorite impacts and radiation). Quite a bit of the powdered material (even the loose portion) is not meteoritic in origin.
Addendum: Creationists disown the "Moon dust" argument
There is a recent creationist technical paper on this topic which admits that the depth of dust on the Moon is concordant with the mainstream age and history of the solar system. In the Abstract, Snelling and Rush (1993) conclude with:
"It thus appears that the amount of meteoritic dust and meteorite debris in the lunar regolith and surface dust layer, even taking into account the postulated early intense bombardment, does not contradict the evolutionists' multi-billion year timescale (while not proving it). Unfortunately, attempted counter-responses by creationists have so far failed because of spurious arguments or faulty calculations. Thus, until new evidence is forthcoming, creationists should not continue to use the dust on the moon as evidence against an old age for the moon and the solar system."
Snelling and Rush's paper also refutes the oft-posted creationist "myth" about the expectation of a thick dust layer during to the Apollo mission. The Apollo mission had been preceded by several unmanned landings -- the Soviet Luna (six landers), American Ranger (five landers) and Surveyor (seven landers) series. The physical properties of the lunar surface were well-known years before man set foot on it.
Further, even prior to the unmanned landings mentioned above, Snelling and Rush document that there was no clear consensus in the astronomical community on the depth of dust to expect. So those making the argument do not even have the excuse that such an consensus existed prior to the unmanned landings.
Even though the creationists themselves have refuted this argument, (and refutations from the mainstream community have been around for ten to twenty years longer than that), the "Moon dust" argument continues to be propagated in their "popular" literature, and continues to appear in talk.origins on a regular basis:
Brown (1989, pp. 17 and 53)
Jackson (1989, pp. 40-41)
Jansma (1985, pp. 62-63)
Whitcomb and Morris (1961, pp. 379-380)
Wysong (1976, pp. 166-168)
See the talkorigins.org archived feedback for February and April 1997, for additional examples.
4. Accumulation of metals into the oceans
In 1965, Chemical Oceanography published a list of some metals' "residency times" in the ocean. This calculation was performed by dividing the amount of various metals in the oceans by the rate at which rivers bring the metals into the oceans.
Several creationists have reproduced this table of numbers, claiming that these numbers gave "upper limits" for the age of the oceans (therefore the Earth) because the numbers represented the amount of time that it would take for the oceans to "fill up" to their present level of these various metals from zero.
First, let us examine the results of this "dating method." Most creationist works do not produce all of the numbers, only the ones whose values are "convenient." The following list is more complete:
| | ||
| | ||
| Al - 100 years | Ni - 9,000 years | Sb - 350,000 years |
| Fe - 140 years | Co - 18,000 years | Mo - 500,000 years |
| Ti - 160 years | Hg - 42,000 years | Au - 560,000 years |
| Cr - 350 years | Bi - 45,000 years | Ag - 2,100,000 years |
| Th - 350 years | Cu - 50,000 years | K - 11,000,000 years |
| Mn - 1,400 years | Ba - 84,000 years | Sr - 19,000,000 years |
| W - 1,000 years | Sn - 100,000 years | Li - 20,000,000 years |
| Pb - 2,000 years | Zn - 180,000 years | Mg - 45,000,000 years |
| Si - 8,000 years | Rb - 270,000 years | Na - 260,000,000 years |
| | ||
Now, let us critically examine this method as a method of finding an age for the Earth.
- The method ignores known mechanisms which remove metals from the oceans:
- Many of the listed metals are in fact known to be at or near equilibrium; that is, the rates for their entering and leaving the ocean are the same to within uncertainty of measurement. (Some of the chemistry of the ocean floor is not well-understood, which unfortunately leaves a fairly large uncertainty.) One cannot derive a date from a process where equilibrium is within the range of uncertainty -- it could go on forever without changing concentration of the ocean.
- Even the metals which are not known to be at equilibrium are known to be relatively close to it. I have seen a similar calculation on uranium, failing to note that the uncertainty in the efflux estimate is larger than its distance from equilibrium. To calculate a true upper limit, we must calculate the maximum upper limit, using all values at the appropriate extreme of their measurement uncertainty. We must perform the calculations on the highest possible efflux rate, and the lowest possible influx rate. If equilibrium is within reach of those values, no upper limit on age can be derived.
- In addition, even if we knew exactly the rates at which metals were removed from the oceans, and even if these rates did not match the influx rates, these numbers are still wrong. It would probably require solving a differential equation, and any reasonable approximation must "figure in" the efflux rate. Any creationist who presents these values as an "upper limit" has missed this factor entirely. These published values are only "upper limits" when the efflux rate is zero (which is known to be false for all the metals). Any efflux decreases the rate at which the metals build up, invalidating the alleged "limit."
- Many of the listed metals are in fact known to be at or near equilibrium; that is, the rates for their entering and leaving the ocean are the same to within uncertainty of measurement. (Some of the chemistry of the ocean floor is not well-understood, which unfortunately leaves a fairly large uncertainty.) One cannot derive a date from a process where equilibrium is within the range of uncertainty -- it could go on forever without changing concentration of the ocean.
- The method simply does not work. Ignoring the three problems above, the results are scattered randomly (five are under 1,000 years; five are 1,000-9,999 years; five are 10,000-99,999 years; six are 100,000-999,999 years; and six are 1,000,000 years or above). Also, the only two results that agree are 350 years, and Aluminum gives 100 years. If this is a valid method, then the age of the Earth must be less than the lowest "upper limit" in the table. Nobody in the debate would agree on a 100-year-old Earth.
- These "dating methods" do not actually date anything, which prevents independent confirmation. (Is a 19 million year "limit" [Sr] a "confirmation" of a 42,000 year "limit" [Hg]?) Independent confirmation is very important for dating methods -- scientists generally do not place much confidence in a date that is only computed from a single measurement.
- These methods depend on uniformity of a process which is almost certainly not uniform. There is no reason to believe that influx rates have been constant throughout time. There is reason to expect that, due to a relatively large amount of exposed land, today's erosion (and therefore influx) rates are higher than typical past rates.
- There is no "check" built into these methods. There is no way to tell if the calculated result is good or not. The best methods used by geologists to perform dating have a built-in check which identifies undatable samples. The only way a creationist can "tell" which of these methods produce bad values is to throw out the results that he doesn't like.
One might wonder why creationist authors have found it worthy of publishing. Yet, it is quite common. This argument also appears in the following creationist literature:
Brown (1989, p. 16)
Morris (1974, pp. 153-156)
Morris & Parker (1987, pp. 284-284 and 290-291)
Wysong (1976, pp. 162, 163)
Conclusion
Obviously, these are a pretty popular set of "dating" mechanisms; they appear frequently in creationist literature from the 1960s through the late 1980s (and can be found on many creationist web sites even today). They appear in talk.origins more often than any other young-Earth arguments. They are all built upon a distortion of the data.
A curious and unbiased observer could quite reasonably refuse to even listen to the creationists until they "clean house" and stop pushing these arguments. If I found "Piltdown Man" in a modern biology text as evidence for human evolution, I'd throw the book away. (If I applied the same standards to the fairly large collection of creationist materials that I own, none would remain.)
Common Creationist Criticisms of Mainstream Dating Methods
Most creationist criticisms of radiometric dating can be categorized into a few groups. These include:
- Reference to a case where the given method did not work .
- Claims that the assumptions of a method may be violated :
1. Reference to a case where the given method did not work
This is perhaps the most common objection of all. Creationists point to instances where a given method produced a result that is clearly wrong, and then argue that therefore all such dates may be ignored. Such an argument fails on two counts:
- First, an instance where a method fails to work does not imply that it does not ever work. The question is not whether there are "undatable" objects, but rather whether or not all objects cannot be dated by a given method. The fact that one wristwatch has failed to keep time properly cannot be used as a justification for discarding all watches.
How many creationists would see the same time on five different clocks and then feel free to ignore it? Yet, when five radiometric dating methods agree on the age of one of the Earth's oldest rock formations ( Dalrymple 1986, p. 44 ), it is dismissed without a thought.
- Second, these arguments fail to address the fact that radiometric dating produces results in line with "evolutionary" expectations about 95% of the time (Dalrymple 1992, personal correspondence). The claim that the methods produce bad results essentially at random does not explain why these "bad results" are so consistently in line with mainstream science.
2. Claims that the assumptions of a method may be violated
Certain requirements are involved with all radiometric dating methods. These generally include constancy of decay rate and lack of contamination (gain or loss of parent or daughter isotope). Creationists often attack these requirements as "unjustified assumptions," though they are really neither "unjustified" nor "assumptions" in most cases.
2.1 Constancy of radioactive decay rates.
Rates of radiometric decay (the ones relevant to radiometric dating) are thought to be based on rather fundamental properties of matter, such as the probability per unit time that a certain particle can "tunnel" out of the nucleus of the atom. The nucleus is well-insulated and therefore is relatively immune to larger-scale effects such as pressure or temperature.
Significant changes to rates of radiometric decay of isotopes relevant to geological dating have never been observed under any conditions. Emery (1972) is a comprehensive survey of experimental results and theoretical limits on variation of decay rates. Note that the largest changes reported by Emery are both irrelevant (they do not involve isotopes or modes of decay used for this FAQ), and minuscule (decay rate changed by of order 1%) compared to the change needed to compress the apparent age of the Earth into the young-Earthers' timescale.
A short digression on mechanisms for radioactive decay, taken from USEnet article <CK47LK.E2J@ucdavis.edu> by Steve Carlip (subsequently edited in response to Steve's request):
For the case of alpha decay, [...] the simple underlying mechanism is quantum mechanical tunneling through a potential barrier. You will find a simple explanation in any elementary quantum mechanics textbook; for example, Ohanion's Principles of Quantum Mechanics has a nice example of alpha decay on page 89. The fact that the process is probabilistic, and the exponential dependence on time, are straightforward consequences of quantum mechanics. (The time dependence is a case of "Fermi's golden rule" --- see, for example, page 292 of Ohanion.)
An exact computation of decay rates is, of course, much more complicated, since it requires a detailed understanding of the shape of the potential barrier. In principle, this is computable from quantum chromodynamics, but in practice the computation is much too complex to be done in the near future. There are, however, reliable approximations available, and in addition the shape of the potential can be measured experimentally.
For beta decay, the underlying fundamental theory is different; one begins with electroweak theory (for which Glashow, Weinberg and Salam won their Nobel prize) rather than quantum chromodynamics.
As described above, the process of radioactive decay is predicated on rather fundamental properties of matter. In order to explain old isotopic ages on a young Earth by means of accelerated decay, an increase of six to ten orders of magnitude in rates of decay would be needed (depending on whether the acceleration was spread out over the entire pre-Flood period, or accomplished entirely during the Flood).
Such a huge change in fundamental properties would have plenty of noticeable effects on processes other than radioactive decay (taken from <16381@ucdavis.ucdavis.edu> by Steve Carlip):
So there has been a lot of creative work on how to look for evidence of such changes.
A nice (technical) summary is given by Sisterna and Vucetich (1991) . Among the phenomena they look at are:
- searches for changes in the radius of Mercury, the Moon, and Mars (these would change because of changes in the strength of interactions within the materials that they are formed from);
- searches for long term ("secular") changes in the orbits of the Moon and the Earth --- measured by looking at such diverse phenomena as ancient solar eclipses and coral growth patterns;
- ranging data for the distance from Earth to Mars, using the Viking spacecraft;
- data on the orbital motion of a binary pulsar PSR 1913+16;
- observations of long-lived isotopes that decay by beta decay (Re 187, K 40, Rb 87) and comparisons to isotopes that decay by different mechanisms;
- the Oklo natural nuclear reactor (mentioned in another posting);
- experimental searches for differences in gravitational attraction between different elements (Eotvos-type experiments);
- absorption lines of quasars (fine structure and hyperfine splittings);
- laboratory searches for changes in the mass difference between the K0 meson and its antiparticle.
While it is not obvious, each of these observations is sensitive to changes in the physical constants that control radioactive decay. For example, a change in the strength of weak interactions (which govern beta decay) would have different effects on the binding energy, and therefore the gravitational attraction, of different elements. Similarly, such changes in binding energy would affect orbital motion, while (more directly) changes in interaction strengths would affect the spectra we observe in distant stars.
The observations are a mixture of very sensitive laboratory tests, which do not go very far back in time but are able to detect extremely small changes, and astronomical observations, which are somewhat less precise but which look back in time. (Remember that processes we observe in a star a million light years away are telling us about physics a million years ago.) While any single observation is subject to debate about methodology, the combined results of such a large number of independent tests are hard to argue with.
The overall result is that no one has found any evidence of changes in fundamental constants, to an accuracy of about one part in 1011 per year.
To summarize: both experimental evidence and theoretical considerations preclude significant changes to rates of radioactive decay. The limits placed are somewhere between ten and twenty orders of magnitude below the changes which would be necessary to accommodate the apparent age of the Earth within the young-Earth timescale (by means of accelerated decay).
2.2 Contamination may have occurred.
This is addressed in the most detail in the Isochron Dating FAQ , for all of the methods discussed in the "age of the Earth" part of this FAQ are isochron (or equivalent) methods, which have a check built in that detect most forms of contamination.
It is true that some dating methods (e.g., K-Ar and carbon-14) do not have a built-in check for contamination, and if there has been contamination these methods will produce a meaningless age. For this reason, the results of such dating methods are not treated with as much confidence.
Also, similarly to item (1) above, pleas to contamination do not address the fact that radiometric results are nearly always in agreement with old-Earth expectations. If the methods were producing completely "haywire" results essentially at random, such a pattern of concordant results would not be expected.
Suggested Further Reading
An excellent, detailed exposition of the means by which the Earth's age is known, as well as the history of attempts to estimate that value, is given in Dalrymple (1991) . This book is a must-read for anyone who wishes to critique mainstream methods for dating the Earth. A review of this book in the young-Earth creationist journal Origins ( Brown 1992 ) includes the following text:
"Dalrymple makes a good case for an age of about 4.5 billion years for the material of which the Earth, Moon, and meteorites are composed. [...] His treatment in The Age of the Earth has made it much more difficult to plausibly explain radiometric data on the basis of a creation of the entire Solar System, or the physical matter in planet Earth, within the last few thousand years. In my opinion, the defense of such a position is a losing battle."
(Note: R.H. Brown believes life on Earth and the geological column to be young, but argues that a proper reading of Genesis allows the Earth itself to be much older.)
For those who wish to develop more than a layman's understanding of radiometric dating, Faure (1986) is the prime textbook/handbook on the topic.
There are several shorter works which describe creationist "dating" methods and/or creationist challenges to mainstream dating methods. The best in my opinion is Dalrymple (1986) . Brush (1982) and Dalrymple (1984) are also very good.
Writings by old-Earth creationists demonstrate that argument for an old Earth is quite possible without "assumption of evolution." The best few are Stoner (1992) , Wonderly (1987) , and Young (1982) . In addition, Wonderly (1981) , Newman & Eckelmann (1977) , and Wonderly (1977) are also good.
And, of course Strahler (1987) covers the entire creation/evolution controversy (including all of the topics discussed here) in a reasonable level of detail and with lots of references.
References
Baker, Sylvia, 1976. Evolution: Bone of Contention, New Jersey, Evangelical Press. 35 pp. ISBN 0-85234-226-8
Back to Helium , Magnetic decay , Moon dust , or Metals in oceans .
Brown, Robert H., 1992. "An Age-Old Question -- Review of The Age of the Earth by Brent Dalrymple" in Origins Volume 19, No. 2, pp. 87-90. ( http://www.grisda.org/origins/19087.htm - Editor)
Back to reference to this book review .
Brown, Walter T., Jr., 1989. In The Beginning..., Arizona, Center for Scientific Creation. 122 pp.
Back to Helium , Magnetic decay , Moon dust , or Metals in oceans .
Brush, Steven G., 1982, "Finding the age of the Earth by physics or by faith?" in Journal of Geological Education 30, pp. 34-58.
Back to reference to this work .
Dalrymple, G. Brent, 1991. The Age of the Earth, California, Stanford University Press. 474 pp. ISBN 0-8047-1569-6
Back to meteorites (oldest or multiple dating methods ) or further reading .
Dalrymple, G. Brent, 1986. Radiometric Dating, Geologic Time, And The Age Of The Earth: A Reply To "Scientific" Creationism, U.S. Geological Survey Open-File Report 86-110. 76 pp.
Back to model lead age , multiple dating methods , or further reading .
Dalrymple, G. Brent, 1984. "How Old Is the Earth? A Reply to ``Scientific Creationism''", in Proceedings of the 63rd Annual Meeting of the Pacific Division, AAAS 1, Part 3, California, AAAS. pp. 66-131. [Editor's note (January 12, 2006): This article is now online at http://www.talkorigins.org/faqs/dalrymple/how_old_earth.html.]
Back to Helium , Magnetic decay , Moon dust , or further reading .
Emery, G. T., 1972. "Perturbation of nuclear decay rates" in Annual Reviews of Nuclear Science 22 , pp. 165-202.
Back to reference to this work .
Faure, Gunter, 1986. Principles of Isotope Geology 2nd edition, New York, John Wiley & Sons. 589 pp. ISBN 0-471-86412-9
Back to isochron dating , or further reading .
Humphreys, D. Russell, 1988. "Has the Earth's magnetic field ever flipped?" in Creation Research Society Quarterly 25, No. 3, pp. 130-137.
Back to reference to this work .
Jackson, Wayne, 1989. Creation, Evolution, and the Age of the Earth, California, Courier Publications. 57 pp.
Back to Magnetic decay or Moon dust .
Jansma, Sidney J., Jr., 1985. Six Days, Michigan, Jansma.
Back to Helium , Magnetic decay , or Moon dust .
Morris, Henry, and Gary Parker, 1987. What is Creation Science?, California, Master Books. 336 pp. ISBN 0-89051-081-4
Back to reference to this work .
Morris, Henry, 1974. Scientific Creationism, California, Creation- Life Publishers. 217 pp. ISBN 0-89051-001-6
Back to Helium , Magnetic decay , Moon dust , or Metals in oceans .
Murthy, V. R., and C. C. Patterson, 1962. "Primary isochron of zero age for meteorites and the Earth" in Journal of Geophysical Research 67, p. 1161.
Back to reference to this work .
Newman, Robert C., and Herman J. Eckelmann, Jr., 1977. Genesis One and the Origin of the Earth , Pennsylvania, IBRI. 154 pp. ISBN 0-944788-97-1
Back to reference to this work .
Sisterna, P., and H. Vucetich, 1990. "Time variation of fundamental constants: Bounds from geophysical and astronomical data" in Physical Review D (Particles and Fields) 41, no. 4, pp. 1034-1046.
Back to reference to this work .
Snelling, Andrew A., and David E. Rush, 1993. "Moon Dust and the Age of the Solar System" in Creation Ex Nihilo Technical Journal 7, No. 1, pp. 2-42. http://www.answersingenesis.org/tj/v7/i1/moondust.asp
Back to reference to this work .
Stoner, Don, 1992. A New Look at an Old Earth: What the Creation Institutes Are Not Telling You about Genesis, California, Schroeder Publishing. 192 pp. ISBN 1-881446-00-X.
Back to reference to this work .
Strahler, Arthur N., 1987. Science and Earth History: The Creation/Evolution Controversy , New York, Prometheus. 552 pp. ISBN 0-87975-414-1
Back to Magnetic decay , Moon dust , or further reading .
Whitcomb, John C., and Henry M. Morris, 1961. The Genesis Flood, New Jersey, Presbyterian and Reformed Publishing Company. 518 pp. ISBN 0-87552-338-2
Back to Helium or Moon dust .
Wonderly, Daniel E., 1987. Neglect of Geologic Data: Sedimentary Strata Compared with Young-Earth Creationist Writings, Pennsylvania, IBRI. 130 pp. ISBN 0-944788-00-9
Back to reference to this work .
Wonderly, Daniel E., 1981. Coral Reefs and Related Carbonate Structures as Indicators of Great Age, Pennsylvania, IBRI. 19 pp.
Back to reference to this work .
Wonderly, Daniel E., 1977. God's Time-Records in Ancient Sediments, Michigan, Crystal Press. 258 pp. ISBN 0-930402-01-4
Back to reference to this work .
Wysong, R. L., 1976. The Creation-Evolution Controversy, Michigan, Inquiry Press. 455 pp. ISBN 0-918112-01-X
Back to Helium , Magnetic decay , Moon dust , or Metals in oceans .
York, D., and R. M. Farquhar, 1972. The Earth's Age and Geochronology, Oxford: Pergamon Press, 178 pp.
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Young, Davis A., 1982. Christianity and the Age of the Earth, California, Artisan. 188 pp. ISBN 0-934666-27-X
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