• Question: What is your favourite experiment? :) xx

    Asked by emmaharvey to Alastair, Emma, Hywel, Keith, Vicki on 15 Jun 2010 in Categories: .
    • Photo: Alastair Sloan

      Alastair Sloan answered on 15 Jun 2010:

      Hi Emma

      That’s a difficult one. If I have one favourite experiment in my field then it would be really classical tissue combination experiments which are used in developmental biology to help us understand what controls how our organs and tissues form. If you take the outer part of a developing tooth and put it together with the inner part of the developing skin you get skin forming. BUT if you take the inner part of the developing tooth and put it together with the outer surface part of the developing skin you get a tooth forming!

      But my fave experiment has to be the effect of dropping a mentos sweet into a bottle of diet coke! It creates a major eruption of coke shooting out of the top of the bottle. Do YOU know why? Have you tried it?

    • Photo: Keith Brain

      Keith Brain answered on 15 Jun 2010:

      I have several, but here are a couple:

      William Harvey, back in the 17th century, had a wonderful demonstration on the direction of blood flow in the veins of the arm. For about 2000 years people had followed the teaching of ancient Greek natural philosophers arguing that blood flowed only away from the heart (they didn’t know that it circulates, but assumed that it was created in the chest and flowed outwards). Harvey showed very simply that you could occlude veins in forearm, empty them of blood, and then see the flow returning from the periphery back towards the heart – contrary to 2000 years of teaching.

      I also like an experiment by Michelson and Morley (called, rather unsurprisingly, the Michelson-Morley experiment) in the late 19th century. They were testing the idea (the “hypothesis”) that light traveled through a substance called ‘aether’ that filled the universe. If this was really the case, then when sending light beams in different directions they should travel at different speeds (the “prediction”), because the earth is moving through space and hence through the aether. They were able send beams of light in different directions (the “experiment”) and used a phenomenon called interference to show that the light traveling at the same speed in all directions (the “result”). The result contradicted the prediction so the hypothesis was discarded – the concept of aether was in the dustbin, and this key conclusion was central to Einstein’s special theory of relativity just a few years later. That theory changed our ideas about the very nature of space and time.

      From a personal point of view, I like these two experiments because I’ve been able to do them myself – the first one I can do on my own forearm, and the second one I did while studying Physics at University. I have favorite experiments of my own design, but I think I’m trumped … for now!

    • Photo: Vicki Stevenson

      Vicki Stevenson answered on 15 Jun 2010:

      I love the mentos and diet coke experiment too! Another one I like is how to tell the difference between a raw egg and a hard boiled egg. If you spin the egg then gently put your hand on it and lift your hand away, the boiled egg will stop dead, but the raw egg will start turning again. This is because the raw egg yolk keeps spinning inside the egg and has enough momentum to start it turning again. Be careful if you try this though! I was doing it as a demonstration and the raw egg span away from me, when i tried to catch it I ended up smashing the raw egg on the desk – very messy!

    • Photo: Hywel Vaughan

      Hywel Vaughan answered on 15 Jun 2010:

      The one experiment I always enjoy doing is one involving Coke and Menthos. We do this a lot to explain how thrust can be used to propel a vehicle – very similar to the way that our rocket will be pushing our car forward. It is great fun, and creates an amazing reaction… it does get messy though!

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