A canna’ change the laws of physics

Scotty, The Naked Time, stardate 1704.3, Episode 7

Why science is important to me

Posted by apgaylard on December 30, 2008

simpsons-avatar-1Back in October I was surprised, and to be honest a little suspicious, to receive an invitation from Alom Shaha to contribute to, “a “collective blog” where scientists, “Science communicators” and “ordinary” people, leave their thoughts on why science is important.” 

Anyway, after making sure that I wasn’t having my leg-pulled (If he has Simon Singh and Susan Blackmore, I wondered, why me?) I put something together.  It’s a personal account, and perhaps, a little sentimental.  Anyway, I’ve decided not to be embarrassed about it.  So, as part of my end-of-year virtual desk clearing here’s the link

There are some really interesting contributions on the site; it’s well worth a browse.  It did make me a little envious of the chemists (they always have such pretty demonstrations),  cartoonists and the photogenic. 

During my somewhat autobiographical rambling I talk about an undergraduate lab experiment, making the point that my expectations influenced the way I took data.  Putting the piece together prompted this memory and led me back to my lab notebooks.  So, here is the passage [links added] together with a graph reconstructed from the original data. 

na_experiment
Determination of the numerical aperture of an optical fibre (black line and symmbols) 22 October 1984

“In one memorable lab I was required to determine the numerical aperture of an optical fibre (this is a number that describes the range of angles over which an optical system can accept or emit light).  The experimental apparatus was crude:  an optical fibre connected at one end to a device for measuring the intensity of light that it had captured; at the other sat a light source pointing at the bare end of the fibre, along with a crude system for measuring the angle between the two. 

I remember that I had pretty clear expectations of the result: with the light source shining straight down the fibre – their axes parallel – it is pretty obvious that the maximum amount of light would be captured by the fibre.  Increase the angle and this will fall away.  The resulting curve of intensity versus angle, I expected, would be symmetrical about the “straight down its throat position” and have a nice “bell shape“. 

Even with a crude experiment and a light intensity reading that didn’t really settle for each reading: that is exactly what I got.  I don’t think there was any conscious dishonesty at work, and neither did my lecturer: as far as I was concerned I was just setting angles and reading numbers off a digital voltmeter.  The symmetry and orderliness was all natures doing! 

In reality I saw what I wanted to see; what I was expecting to find.  Later I learned about a French physicist called Blondlot who did something similar.  He convinced himself that he could see the effect of a new form of radiation – ‘N Rays‘.  When he was visited by a sceptical scientist called R. W. Wood it all unravelled: Wood removed a key piece of his experiment, without him knowing.  Without this component in place there was no way he could see these ‘N rays’ if they were real.  He continued to see them – they did not exist outside his mind.” 

A good lesson learnt.  One that continues to be useful and underpins a good deal of what I’ve ended up discussing on this blog.

2 Responses to “Why science is important to me”

  1. dvnutrix said

    Due homage to Blackmore and Singh – Barack Obama is listed as one of your fellow contributors…I’m awestruck.

    Very nice piece – congratulations.

  2. apgaylard said

    dvnutrix: Thanks for the kind words. It’s odd, but the mention of the usual luminaries nearly put me off; until I realised that worker drones were welcome as well!

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