It’s a funny thing, when you think about it, that if you owned a stock in the market and the value went up 50%, and then went down 50%, that it wouldn’t end up at what it started.

Another way to look at it, is if you owned something worth 100 and it lost 50%, it’d be worth 50. To get back to being worth 100 you’d then need a 100% gain. 

Asymmetry of returns

The clarity of the night sky. A low number means clear, black and amazing stars. Higher numbers mean gradually more urban environments with increasing light pollution. At 9 you’ll barely spot a star being pretty much in Piccadilly Circus or Times Square.

More detail needed? John Bortle, Light Pollution And Astronomy: The Bortle Dark-Sky Scale, Sky and Telescope, July 18 2006.

Bortle Scale

What is the difference between venomous and poisonous?

Venomous animals inject venom through bites, stings and the like. Think snakes, spiders, stingrays…

Poisonous animals poison you if you absorb - perhaps by touching the skin of a poisonous frog - consume - perhaps by eating a poisonous animal - or inhale the poison - perhaps by breathing in some poisonous spores. Think amphibians, plants, fungi…

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Venomous, poisonous - what’s the difference