Monday, 22 April 2013

The End Of The World As We Know It (Again?)

Have i already used that title?

Anyway, for some reason i don't understand, there are a number of peculiar things on the GCSE chemistry syllabus.  Either that or i've made a mistake.  If i have, it's OK because it is at least on some kind of GCSE science syllabus somewhere, and since i think no-one's following the videos i might as well stick it in anyway.

So here's today's:

Click to tweet: .  Continental drift was initially a hypothesis proposed by Alfred Wegener in 1912.  At the time, although some evidence was available it was not widely accepted, partly because there was no apparent mechanism whereby it could occur - Polflucht was the name of the process he proposed, which was a centrifugal effect caused by the planet's rotation which he saw as pulling the continents away from the poles.

There are nowadays quite a few pieces of evidence that continental drift takes place.  Firstly, as i observed in 1976 shortly before being shut in a cupboard for four months (not as bad as it sounds incidentally), the coastlines of Africa and South America fit together quite well, and similar fits can be observed elsewhere, such as between the southern coast of Australia and part of the coast of Antarctica.  The fit is better if the shallow seas around continents are taken into consideration.  There are also a number of fossils which are found on widely separated continents, such as Glossopteris, Cynognathus and Lystrosaurus.  This used to be explained by the idea of land bridges like the one between North and South America, across which plants and animals could spread, and this explanation was maintained up until the middle of the last century.  Eventually, however, more evidence and also a mechanism emerged.  It seemed that the mantle of the planet has swirling currents which act like a conveyor belt to drive landmasses along.  The ocean beds contain ridges from which the surface seems to spread - changes in the magnetic field of Earth are frozen in the rocks and are symmetrical either side of these ridges, from which lava constantly wells up.  Finally, there are mineral deposits and sometimes other geological features which match up well if the continents are pieced together.  It is now thought that there is a cycle of a few hundred million years, during which the continents form a single giant landmass which then breaks up.  Pangea is the most recent.

From outside the viewpoint of the content of the theory, Wegener's continental drift is a good example of how science changes.  I would personally link it to Thomas Kuhn's quasi-Marxist analysis of scientific change, where entrenched opinions are gradually dislodged by social forces, although clearly the evidence would have to be there.  I'd like to go into this in greater depth but unfortunately the limitations of GCSE science mean i can't really do more than mention it here.

OK.  Um, i didn't mark the two grossth video because i realise people tend to see other number bases as less significant than decimal, and i feel a little uncomfortable commenting on the three hundredth.  It might be an idea to take stock at this point and decide which videos work, which don't and what i mean by "work".  I recently made my most popular video ever on the main channel - the mpreg hoax vid, enough to spin off another channel on its strength.  It would of course make sense, in a way, to split the subjects into different channels, but i can't do that because all the subs and views are on the main one.

Here's the all-time performance for this channel in terms of views:

(I hope that fits).  My eye, but probably nobody else's, can see the rain video, Christmas series, Thatcher's death and the mpreg hoax on that graph.  Thatcher doesn't show up underneath because she's topical, and a number of other topical videos are also absent from the list for the same reason.  Liz's wee video is still at the top of course.  The two top videos date from before the kink in the views in April 2011.  What most of the videos have in common is demonstrable kinkiness.  The mpreg vid is the fastest climber and also, i think, the steadiest grower, which is oddly appropriate.  It's also, of course, physically the most difficult video to make.  So, sex sells.