< p >是的,大意是正确的:同位素半衰期相对较短,通过数量略微分钟到可检测,然后只有在被别的东西:产生一些长寿的同位素的衰变产物或宇宙射线轰击。< / p > < p >例如< a href = " https://en.wikipedia.org/wiki/Isotopes_of_gadolinium " rel = " nofollow noreferrer " >钆- 150 < / >。这个半衰期约为180万年,我认为根本不自然发生。钆- 152,半衰期约<跨类= " math-container " > 10美元^ {14}< / span >年,美元自然发生。< / p > < p >不管原始钆- 150有了(在40亿年,你会得到一个减少的因素类< span = " math-container " > 10美元^ {669}$ < / span >:地球周围包含<跨类= " math-container " > 10美元^ {50}$ < / span >原子,所以有机会< span class = " math-container " > 1/10美元^ {619}< / span >美元的地球上发现一个原子)。不幸的是要知道有多少你需要详细了解超新星核合成(钆比铁更重,所以部分或全部来自超新星),和我不喜欢。但我认为这是安全的说他们可能至少部分,理由是任何我们做的粒子撞击方式使同位素(我们做了<跨类= " math-container " > $ ^ {150} \ mathrm {Gd} $ < / span >)超新星也做,除了很多很多。如果我们假设地球只有一百万岁,然后对<跨类= " math-container " > < / span > \ % 68美元的原始类< span = " math-container " > $ ^ {150} \ mathrm {Gd} < / span >美元仍将是:我们会找到它的。< / p > < p >当然,这里有两个捕获:< / p > < ul > <李>也许< span class = " math-container " > $ ^ {150} \ mathrm {Gd} $ < / span >所有已经秘密的地方,我们找不到它,李< / > <李>这一切取决于超新星核合成的概念。< /李> < / ul > < p >所以回答第一:如果这是真的,那将是完全与众不同。特别是我们花了大量的时间(真的很多时间)试图隔离不同同位素的元素:人们去真正巨大的努力区分不同同位素铀的实例。这是你可以做化学,因为不同的同位素具有相同的化学性质。 Instead you have to do things like spin them in very high-speed centrifuges, or use mass spectrometers. These things just don't exist naturally on Earth, so, since we do find other isotopes of gadolinium (including ${}{150}\mathrm{Gd}$, which is not stable), how come we don't find this one? Well, we don't find it because it's not there, of course. The second problem is perhaps more severe: people who believe the Earth is a million years old probably have no truck with supernovae at all, or are happy to just argue that, well, supernovae don't produce some isotopes because they just don't. I don't think there's a useful argument against that.