METATOYs and Aeolipiles – ultimately frustrating……

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In science you can sometimes build up a lot of frustration. Sometimes a reaction doesn’t happen the way you expect, or some of your equipment is faulty so it has to be repaired before you can continue, or even a case of trying and trying again from different angles and approaches to make an experiment work only for it to result in the same outcome – failure.

I experienced it first hand during my honours project at university, which was all about metamaterials for rays (or METATOYS as we liked to call them). My task was simple in principle, to construct a window in which if you placed an object on the other side, say a chess piece, then what you would see through the window would be an unusual image – e.g. the chess piece has flipped, or sometimes even disappeared completely. It was all to do with refraction of light, and to make the window all that was needed were some lenticular arrays – the plastic front to 3D post cards. Put two sheets back to back, and do likewise with another set, then rotate one at an angle to the other and through it you would start to see some unusual images. However it turned out to be not as simple as that.

When placed back to back each lenticular lens had to be lined up perfectly with its opposite on the other array, so this involved sticking both arrays on a mount each, and delicately pushing them closer together millimetres at a time, before making even more adjustments up, down, left and right until you could see a clear picture of the chess piece. Ditto for the second window. Now unfortunately the thing about mounts is that they are quite thick, and you couldn’t actually bring the two windows close enough together to get a clear picture. Therefore some ingenuity was required.

The view through one window
The view through one window
The view through the METATOY
The view through the entire METATOY

It was decided to take what we were seeing through one window and image it onto the other window. So then I tried a giant lens to project the image from one window and into the other, I had to take into account the focal length of the lens and the angle at which it would sit compared to each window, before bolting down everything just in case the table was knocked. However the mirror idea turned out to not be very good, as there wasn’t that clear an image through the second window. A plan B was required. Unbolt everything, get rid of the mirror and replace it with a mirror. By this time I had been working on my project a few months, and finally saw some light at the end of the tunnel, when a quick rejig of my set up actually provided a good enough image of the chess piece through the METATOY to actually start experimenting.

Plan A, which didnt work so well........
Plan A, which didnt work so well…….. on to plan B!
……so on to plan B!

When I started to rotate one window it looked promising, the image of the chess piece was beginning to rotate as expected. However, as the angle of the window increased the more the image became distorted to the point where the chess piece was just replaced with a square blob of light. Loads of tinkering happened over the following months, but ultimately time ran out for me, and even though I got some good images, I didn’t get the consistent result I was looking for. Frustrating.

(My report is here for anyone interested: METATOYS Honours Project)

Today I have a similar feeling of frustration. You may recall that in January I started a new section to Sincy Science, in which I would film live experiments either in my flat or in the science centre, and present them to you for your own entertainment. It started well, with a simple floating egg experiment, followed by a hydrogen balloon, both of which you can see in the experiments page. There was another idea I had at the time though, which was another simple experiment that I could perform in my flat. Or so I thought. I’ll give you a bit of background first though.

In the first century, there lived an inventor name Hero, which is a name verging quite high on the arrogance scale I think. He was sometimes known as Hero of Alexandria, as he lived in that city in Roman occupied Egypt. He created many things, including a vending machine and syringes, but is most well-known for his Aeolipile, the first recorded steam engine. In the middle of the Aeolipile would lay an enclosed basin of water with two pipes attached on either end. The basin would be heated, and the water would gradually evaporate into water vapour, flow down each pipe and out into the atmosphere. It was at this point that the water vapour condensed into steam, and the resulting propulsions allowed the basin to start spinning, eventually reaching quite a high speed. Hero built this for children’s entertainment, but the exact same principle is used in our power generation today. Instead of spinning basins though, today the steam is used to spin giant turbines to generate our electricity.

Hero of Alexandria
Hero of Alexandria
An illistration of Hero's Aeolipile
An illustration of Hero’s Aeolipile

A simpler version can be done just using a can and a heat source, and this is what I wanted to recreate.  However no matter where I put the two holes in the can, or how close I held the can over a flame, or how long I held the can over the flame, all it did was disapprovingly spit boiling hot water at me every now and then or try to catch fire. So once again after months of effort and ideas I am left frustrated, but at least it’s not counting toward my degree this time!

My failed attempt.....
My failed attempt…..

Luckily though we live in a world of technology, and finding a successful Aeolipile experiment is a mere google search away……Enjoy!


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