Isotopic analysis is necessary to determine if a material is from Earth or another world." http://www.openminds.tv/test-confirms-roswell-debris-733/
...really? Here is the data they found.
Isotope | Measured | Background
--------+----------+------------
Mg-24: | 79.1±0.5 | 78.6
Mg-25: | 10.1±0.5 | 10.1
Mg-26: | 10.8±0.5 | 11.3
You will note that the natural background concentrations fall within the error bars of the measurements. Meaning no significant difference.
When you plot it on a graph with no error bars, it looks like the measurement is really anomalous. When you notice that the error bars are as large as they are and the measurement errors are in opposite directions, it becomes quite obvious why that measurement falls so far from the line he plotted. Consider that the error bars are 0.5% in either direction, and the graph is only 1% on a side. That means you would expect a measurement of a sample from Earth to fall... somewhere on the graph. Not any more specific than that though.
It is things like this that make us skeptical of supernatural claims. If the aluminum compound actually came from space, we would expect a much higher concentration of Al-26 (extremely high levels, in fact, whereas material on Earth has effectively none), and that would constitute much stronger evidence than slightly anomalous but not significant differences in Magnesium isotope ratio. It's not that there are no observations that could persuade us, it's that we don't see any persuasive observations. If they had found high concentrations of Al-26, that would have been news (in fact, since Al-26 has a half-life of 720,000 years, anyone who wanted to could see if they could find any Al-26 at the Roswell site even now, and if they could, that would be strong evidence that the craft was extraterrestrial in origin).
In fact, you could go now and perform those tests. But you already know what the result would be. You're already making excuses in your mind for why you won't find any Al-26 at the site, like any alien craft would be shielded (in which case, why would the Magnesium concentrations be off). You believe that you believe in aliens, but your real-world predictions don't match the aliens hypothesis.
And if I'm wrong, and there actually are significant concentrations of Al-26 in the metal fragments at the Roswell crash site (fragments that are dug up and immediately tested so as to remove the possibility of someone irradiating before testing), I will significantly update my beliefs toward whatever landed at Roswell being extraterrestrial in origin. But I don't expect to have to update my beliefs. Do you expect that I would?
Al-26 (the only semi-stable isotope of Aluminum besides the stable Al-28) has a half-life of approximately 720,000 years. Seeing as it's been several billion years since the formation of the Earth, it's reasonable to say that all of the Al-26 you see comes from high-energy collisions and artificial
Recently I've been struck with a belief in Aliens being present on this Earth. It happened after I watched this documenary (and subsequently several others). My feeling of belief is not particular interesting in itself - I could be lunatic or otherwise psychological dysfunctional. What I'm interested in knowing is to what extend other people, who consider themselves rationalists, feel belief in the existence of aliens on this earth, after watching this documentary. Is anyone willing to try and watch it and then report back?
Another question arising in this matter is how to treat evidence of extraordinary things. Should one require 'extraordinary evidence for extraordinary claims'? I somehow feel that this notion is misguided - it discriminates evidence prior to observation. That is not the right time to start discriminating. At most we should ascribe a prior probability of zero and then do some Bayesian updating to get a posterior. Hmm, if no one has seen a black swan and some bayesian thinking person then sees a black swan a) in the distance or b) up front, what will his a posterior probability of the existence of black swans then be?