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First off, a definition of gravitational acceleration from the perspective of a geologist or geophysicist. Imagine a 50 cm tall cylinder with all the air drawn out. A small ball is held in place at the top of the cylinder. The device is firmly fixed to the surface of the Earth and the ball is released. Timing how long it takes for the ball to fall to the ...


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Neutrinos are produced in the atmosphere all the time as a consequence of cosmic ray interactions, and they mostly then fly right through the planet. So there is no problem with a source. In fact the "flying right through" bit is one of the problems: even the full diameter of a planet simply doesn't intercept a large enough fraction of the beam to make ...


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Another possible reason for gravitational anomalies. But, as you ask in your comments: Could this explain why thousands of people disappear each year? No. And it would only affect those areas of the world covered by ice to a significant depth in the past. Lower than Average Gravity A new satellite survey may have solved the mystery behind one of the ...


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Yep, it is possible to measure this deviation from mean surface gravity from both the earth and space. Take a look at this article on io9: http://io9.com/new-high-res-maps-of-earth-s-surprisingly-inconsistent-1171851670 There are three main things that cause this. 1) Distance from the centre of the earth. As you get higher, gravitational force becomes ...


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You have exactly the right idea. The decay products are only useful in as much as we can compare a previous isotopic ratio to the current (measured) ratio. How this is done differs from dating method to dating method. As an example, C14 dating originally came about with the idea that atmospheric and therefore living plants have a near-constant ratio that ...


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One needs to account for lead that was formed as lead, rather than by radioactive decay. Wikipedia has a discussion. Lead-204 is not formed by decay, so if you know the primordial distribution of the isotopes, you can compute the primordial amount of each of the others. The rest comes from decay.


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I'll approach this slightly differently. The abundance of Li in the solar system and in the Earth's crust is low compared with elements like carbon, oxygen, silicon and iron. The solar system lithium is created partly (only 10%) by primordial nucleosynthesis, a bit by spallation reactions of cosmic rays on nuclei in the interstellar medium, but mainly in ...



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