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* Posts by Dave

3 publicly visible posts • joined 16 Jan 2008

Is the earth getting warmer, or cooler?

Dave
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Even worse maths

The appeal to probability against the likelihood of the changes to the graph seems rather poorly thought out, and even more poorly argued.

The odds of flipping a coin 70 times and getting 55 heads would actually be (unless probability has changed in the many years since I did GCSE maths):

Combinatorial (55, 70) / 2^70

or about 1 in 1.6 million, so about 6 orders of magnitude more likely than claimed. Not sure where the 2^40 figure came from. However, this all relies on each result being independent. The keyword appears in the article itself, 'systematic', and therefore the changes are not independent and the probability cannot be calculated in this way. In fact we can draw no conclusion at all from this argument without fully understanding what changes were made to the graph and why.

The probability argument is therefore moot. This sort of poor, superficially attractive, but completely worthless argument is unfortunately common on both sides of the 'debate'. A more interesting question is why the different data sets do not agree, but the writer already knows the answer to that without needing to consider it: NASA bias of course!

Come on Reg, we expect better.

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Boffins: Antimatter comes from black holes, neutron stars

Dave

@Mark

"The charges on atomic/subatomic particles are not the same as magnetism... a magnetically neutral element could not be held in a magnetic field"

- until the charged particle starts moving relative to the magnetic field, which it must in this case due to gravity if nothing else. This being the principle behind the generation of aurora on Earth and the electric motor.

This used to be taught at GCSE as the left hand rule, but obviously physics education isn't what it used to be.

Of course the magnetic field around a black hole may not do anything other than concentrate the particles at the 'poles', as with the Earth's field. But initially at least positively and negatively charged particles would experience forces in opposite directions.

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Dave

Separating -ve and +ve

As black holes (probably) have very strong magnetic fields and may be rapidly spinning, that would be enough to send positrons and electrons escaping at the event horizon in opposite directions. If the density of matter nearby is low enough, a significant proportion might make it far enough away to form clouds of particles?

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