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The Selfish Gene, by Richard Dawkins
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MikeAlx



Joined: 17 Nov 2008
Posts: 2104


Location: Seaford, East Sussex

PostPosted: Tue Apr 21, 2009 11:32 pm    Post subject:  Reply with quote

I hear that Stephen Hawking is expected to make a full recovery.

Caro, calculus may be 'made up', but it is part of mathematics rather than science per se, and is a useful tool for science because it's rather good at predicting quantitatively how things will behave, given Newton's laws. It's entirely testable by measurement. Integration tells us, for example, that the volume of a sphere is 4/3 * PI * r cubed. Dunk a sphere in a measuring vessel full of water, and whaddya know?

String theory, however, is entirely speculation and has yet to produce a single prediction testable with current technology. Some in the physics community are starting to challenge its dominance.

As to Himadri's spooky spoon, I suspect some sort of springboard effect, probably on the part of the draining board.

I've seen one 'hidden camera' study showing a very direct connection between poltergeist activity and a teenage girl. A connection of the most unmysterious kind!



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Caro



Joined: 22 Nov 2008
Posts: 2915


Location: Owaka, New Zealand

PostPosted: Tue Apr 21, 2009 11:42 pm    Post subject: Reply with quote

Quite a number of them turn out to be right - and then ones that seem to have evidence turn out to be wrong.  I think speculative scientific ideas do need to be talked about so people can look for things to prove or disprove them.  I presume there is some sort of evidence for people to consider them.  Scientists do not speculate on the possibility of angels dancing on a pin for instance.  Or flying pigs. Or earthquakes being caused by falling stars.  

Yes, Simon it was that book I was meaning.  

And Himadri (and Mike) I hope you are better at explaining calculus than my 6th form (first year) teacher was.  I feel a bit cheated since I was quite good at maths till then.  All I remember - all I ever knew - was dx by dy.  No idea what that meant though.  Or what it was supposed to do. I know more from my grandmother's teachings.  She used to say, a propos of water and volume, "When a body is immersed in a liquid it loses weight and the        of the weight lost equals the            ."  (The gaps are the bits I have forgotten!)

There must be a way I could use this knowledge to fool the doctor about my weight.  

Cheers, Caro.


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TheRejectAmidHair



Joined: 19 Nov 2008
Posts: 3864


Location: Staines, Middlesex

PostPosted: Wed Apr 22, 2009 2:57 pm    Post subject: Reply with quote

MikeAlx wrote:
As to Himadri's spooky spoon, I suspect some sort of springboard effect, probably on the part of the draining board.


Well, you're no fun, are you?  Very Happy


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MikeAlx



Joined: 17 Nov 2008
Posts: 2104


Location: Seaford, East Sussex

PostPosted: Wed Apr 22, 2009 4:10 pm    Post subject: Reply with quote

Wouldn't get a job at Hammer films, would I?  Wink

Seriously though, I speak as someone frequently woken in the middle of the night and ordered to patrol the house because 'I'm sure I heard a noise'.  Smile



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MikeAlx



Joined: 17 Nov 2008
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Location: Seaford, East Sussex

PostPosted: Wed Apr 22, 2009 4:22 pm    Post subject: Reply with quote

Caro wrote:
All I remember - all I ever knew - was dx by dy.  No idea what that meant though.

More usually dy by dx - which is the rate of change of y with respect to x, or, if you have a graph, the gradient (slope) of the graph at any given point.

Finding dy/dx is called differentiation; its inverse is called integration, which is useful for calculating areas and volumes and doing anything else that involves summing large numbers of infinitely narrow shapes.

Well, aren't I just the life and soul of the party today...  Wink



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Caro



Joined: 22 Nov 2008
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Location: Owaka, New Zealand

PostPosted: Wed Apr 22, 2009 9:06 pm    Post subject: Reply with quote

Hmmm, thank you, I think...

I'm dismayed about dy by dx though - for 40 years I have thought we talked about dx by dy and now you've thrown that into disarray with one sentence.  I wonder if I can remember differentiation and integration long enough to work that into a conversation.  
Quote:
summing large numbers of infinitely narrow shapes.
is not quite a phrase I can get my mind round.  "Adding up lots and lots of tiny numbers"?  How can shapes be infinitely narrow?  I don't like 'infinite' - it confuses me and I like to avoid it.

Cheers, Caro.


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MikeAlx



Joined: 17 Nov 2008
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Location: Seaford, East Sussex

PostPosted: Wed Apr 22, 2009 9:18 pm    Post subject: Reply with quote

dx by dy is equally valid; it's just that dy by dx is more common (because of the way round we normally draw graphs). I just depends which way round you hold your graph-paper, really!

Calculus is all about infinitely small bits - it calculates things to do with curves by pretending they're made up of lots of points joined by straight lines, then seeing what happens when you add more and more points and the spaces between them get smaller and smaller (in the jargon, "tending to zero"). Very clever really - and to think Newton & Leibniz worked all this out 300 years ago!

All of which is a long way from the original topic of this thread!  Embarassed



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Caro



Joined: 22 Nov 2008
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Location: Owaka, New Zealand

PostPosted: Wed Apr 22, 2009 9:34 pm    Post subject: Reply with quote

My fault, sorry.  

People could work this out, yet no one could understand there were bacteria causing illnesses.  I find this very odd. (No, I am NOT diverting this to a new discussion on biology!)

Cheers, Caro.



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