Flat earthers are crazy

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o make some product work. Be good rather than get by.

Only if there are enough people around prepared to buy what you can do well . I've got what looks like a nice design for a low-distortion audio-frequen cy sine wave oscillator, but essentially no customers. The motivation for t urning it int something I could sell is correspondingly weak.

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to make some product work. Be good rather than get by.

I never ran into an application engineer who was good enough to hire.

I met a couple who were masters of presentation, which isn't all that usefu l when you want to build something that works. Jim Williams was impressive, but his application notes do include rather more bad ideas - recognised as such - than you'd like in an employee. The fact that he could recognise wh en his ideas were bad is a definite plus. You may have that ability, but yo u don't tell us about it.

Do you? It MEANT: The Romans soldiers could walk up and slap you hard, across the cheek. If you reacted, they had 'the right' to cut off your head.

It doesn't require it although such events might play their part. I'm a bit sceptical of these recent claims - seems to me like ordinary supernova will make sufficient of the heavy elements on their own.

Quick point - the capture cross section for a Schwarzchild black hole is around 3r across rather than the r sized billiard ball you imagine. Anything that passes too close end up inside in finite time.

Geological processes that select by density, volatility and solubility for the most part.

It is a good geological heuristic that very old rocks and very young ones tend to be rich in useful minerals. Middle aged rocks are boring.

Not really since the stuff stays soluble in molten iron and vulcanism provides enough churn at the surface to keep plenty in play.

A lot of it is in the core, but enough meteoric stuff gets added, vulcanism and mountains eroded over time to concentrate the more interesting and inert minerals. Uranium is surprisingly common there is about 2ppm in almost everything but decent uranium ores are rare.

When the Earth's chemistry switched from being a reducing atmosphere to having free oxygen various metals were forced out of the sea relatively quickly. Notably iron which is highly soluble as green FeII and quite insoluble as FeIII (rust). Very old red sandstones and iron ores result.

Same with uranium when the chemistry of the oceans and lakes altered it precipitated out (though in this case most probably as the carbonate). Back then there was a much higher proportion of U235 since the material was 4bn years younger than it is today.

Gold tends to get concentrated by erosion of huge mountains and gravity in streambeds - it doesn't indulge in much by way of chemical reactions.

Many of the sulphide ores occur as a result of vulcanism.