Tuesday 13 March 2012

Public Experiments with Light



On 8th March, the first event of newcastle sciencefest was something that I organised at the Star & Shadow. Which means it was shambolic and amateur as is my style, but definitely participatory and I had a really good day - think the others did too! Here's a write-up before I forget we did it, using some photos lent me by Camille.


The idea began with the aurora borealis that was widely seen across Northumberland in February. I raced out to dark Northumberland hoping to see it, and didn't, but it still planted a seed of thinking, and so I started re-reading a book by Arthur Zajonc which had fascinating elements but REALLY annoyed me - his writing style, his inaccuracies, pomposity etc.. So the first time I had left it half way through and that is often the best way to keep a read in your head. In fact I have two comics and one classic novel that I have deliberately left unfinished because I just loved the place I was at with them and didn't want to lose it by gaining the 'closure' that comes from finishing the last page. This time I ripped out the pages as I went, keeping the intriguing ones and using a few of them for the flyer/poster/dada-mentalist-zine I made for the sciencefest event.





Then I borrowed the camcorder from work, decided I would learn how to do video editing, and made an educational science video with the help of my old schoolfriend Simon (a positron physicist). An out-take from the filming features a huge trout or salmon freaking us out. As it turns out, no-one who turned up on the 8th had even watched the video, but it was good fun to make and think about anyway. I am no scientist, in fact I am one of those people who starts to get a headache as soon as complicated maths or scientific theories get talked about. So this too was a good and challenging process for me. I believe in always doing something new, always attempting, branching out, refusing elitism and learning throughout life. So the ethos of the 8th march experiments was very much about having a go. As the Star & Shadow website had it: "Do not expect professional razmatazz. The experiments may fail. This is a part of experimental science and the way that new discoveries are found."

For the detail of the historical experiments we tried to recreate you must watch the video. I thought I might video on the day too but was too busy & involved. I'm anyhow quite happy to leave it there, and have this blog post as the conclusion.


(pic - camille cocaud)

Experiment 1: Alhazen's camera obscura with candles!

Everyone got stuck in with cardboard boxes and masking tape to bodge our own attempt at making not just one candle flame, but several, appear through a camera obscura hole and thus disprove two ancient theories of light. At first it didn't seem very promising, but we tweaked the holes and the distance and I was personally thrilled when it actually worked and we could move our candles around on one side of the box, and see them inverted and moving the opposite direction on the cinema screen!


(pic - camille cocaud)


One participant had even brought his own opaque plastic device (probably once from a wedding cake stand) that had its own mind-bending effect: instead of turning images upside down, like the small hole does, it switched left to right. So if you stood next to your friend and were watched by a third party, they would see you standing on the opposite side of each other. I literally CANNOT GET MY HEAD AROUND THIS and am quite impressed that our brains manage to cope with it on a daily basis without freaking out. I mean, the world's UPSIDE DOWN for cripe's sake, and I don't know why, but our brain quietly puts it the right way up for to soothe us. It's more science fiction than your average arthur c.clarke novel and beats the matrix for having a secret universe all around us that no one talks about...

Experiment 2:
Brunelleschi's perspective illusion, making light geometric etc.. (see video for what and why!) had everyone drawing with felt tips outside the cinema, but I think we have to mark this one down as an 'unfinished' experiment - no one seemed especially proud to show off their efforts! Let me know if you fancy having another go with me another day.




(pic - camille cocaud)

Experiments 3 & 4: Prisms and Beams


(pic - camille cocaud)

An appeal sent out on facebook had got me a prism and some lenses, which we then combined with some of the spot lights in the bar to get some rainbows out of white light and play about with what Newton and Goethe disagreed about. One participant (who came straight from the city library after seeing the event on the website) was able to link this to current thinking and disputes about photography and digital cameras and how green is replacing blue as the basis for light replication? Again, I don't really understand this, but it was great to have this kinda thing talked about and brought the historical past-ness of my thinking into the present day.


(pic - camille cocaud)

Colour shadows are not really, objectively, there. The red shadow in the picture (below) yes, because there is a red light shining from one side, and a white from the other. But the eye tells us that the other shadow is greenish (a bit clearer to the eye than to the camera) when it is not 'really' - we see colour as an intelligent, interpreted process - in this case because red is the dominant colour, our mind supplies the 'green'. As Zajonc put it, "The human visual organisation accommodates to the dominant colour, [in this case red], then it responds by 'seeing' white as green, which is the colour complementary to red."


(pic - camille cocaud)

Not convinced? Well we tested it, changed the filter to blue, and sure enough we saw the shadow as yellow/orange, the complementary colour to blue.


(pic - camille cocaud)

Finally, thankyou to the group of people who came, who were a diverse bunch of genuinely inquisitive, patient and practical folk, most of whom were entirely new to me, and who happily worked together to get round my failings and try, communally, to get our heads round the mind-bending, light-bending realities of sight and light.


(pic - camille cocaud)

On the morning of the experiments, the news was reporting unusually strong sunspot activity and the likelihood of more aurora visibility, which was a really nice circularity to the day. And so what if I didn't see the aurora this time either - the fact that it is happening and that electricity and light and charged particles and wave activity and all that is going on is WONDERFUL. Science and stars, the cinema salutes you!

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