Exeter Science Centre - #GlobalScienceShow October 2020

Hi I’m Natalie, and I’m Alice, and we’re the founders of the Exeter Science Centre. We’re trying to create a STEAMM discovery centre in Exeter where STEAMM stands for science, technology, engineering, art, maths and medicine. We want to create an amazing place where people of all ages and backgrounds can learn about and engage with science. There are no general science discovery centres in this region and we want to fill that gap. We love the South West and all it has to offer and we often feel that as a region it’s misunderstood - yes we are a fantastic holiday destination but we are also globally recognised in various areas of STEMM research and industry and we want to find a way to connect people up with those incredible STEMM practitioners and researchers working all over our region, through the means of an amazing hands-on science centre.

In doing so we want to help 00:59 - everybody to understand the science behind global challenges so we can work together to tackle them. We want to start having an impact right now whilst we raise the awareness and funding for the physical centre, so although we don’t have an amazing building full of exhibits for you to visit just yet, we’d still like to share with you some information on our research and our favourite demos - over to you Alice! Thanks Nat! I did my PhD in Astrophysics at Durham University looking at how stars form in very distant galaxies, in particular looking at the chemistry of the gas and the dust in those galaxies. But to do that, the problem is that dusty galaxies block the light from the stars forming so you can’t see them with an optical telescope, you have to study them at every different wavelength in the spectrum which means looking at all the different types of light that are emitted by that galaxy, so that’s radio waves, X-rays, ultraviolet light, infrared light, and infrared is a really particularly important one so if something is shining behind that dust you should be able to see it with an infrared telescope. This leads me nicely on to one of my favourite demos, so I love demos that you can do with at-home stuff so this one just uses your remote control for your television. I’m gonna need to dim the lights - okay so the lights are dimmed, I’ve got my remote, the first thing I’m going to do is just look at the end of it and I can see a little LED there (there’s a little LED) and if I press the button and point it at myself I still can’t see anything, but if I point it at you hopefully you can see a little flashing LED.

02:40 - So you can’t see infrared light but your digital camera can, it has some sensitivity in the infrared range of the spectrum and it can convert it then in the camera into something you can then see in this video, so that’s a really really cool little demonstration of how useful other parts of the electromagnetic spectrum are, and how we can’t fully understand the world around us and the universe without understanding how things give out light at every wavelength, and how this indeed talks to your television through a little flash of infrared light. That’s so cool! I think you can see it here too. My research was pretty different - I was looking at sending waves through magnets in the form of spin waves. Now these spin waves aren’t sound waves, they’re not electrical waves, they are magnetic waves, and they come about because the atoms in a magnet behave like little tiny magnets, they have a North pole and a South pole and they can send a wave through the material by the North poles pushing and pulling on their neighbours and the same with the South poles, and that can send a wave through the material. I was looking at controlling the way that these waves travel through the material by changing the refractive index, because I was trying to make a spin wave lens.

Now a refractive index is a really important concept in pretty much all areas 04:13 - of wave physics and you’re already really familiar with it, because if we look at this very typical demonstration of a pen being bent in a glass of water, you can see that there appears to be a little bending at the interface that’s because the light has gone through the glass through the water and bent as it comes out of the glass water interface into the air and it bends differently as it moves through the air because the air and the water have a different refractive index. The refractive index really just determines how fast a wave travels through a medium. What we can do if we play around with the refractive index is we can get some really interesting effects - so here I have two pyrex bowls you can see the edge of this bowl inside the other bowl because we have air between them and because air has a different refractive index to pyrex. However, vegetable oil has a different refractive index to air but coincidentally it has the same refractive index as pyrex. So here I have two bowls both filled with oil and you should see that you can’t actually detect where the edge of the inner bowl is, because the refractive index of oil and pyrex is the same! Now that’s one of my favourite demonstrations and you can do it at home but it’s really messy, you tend to get completely covered in oil, but we make these kind of sacrifices for science! I’m gonna go and get cleaned up and Alice has another amazing demonstration to show you.

06:03 - Okay another demo which is just awesome and has no particular link to my research at all but I just love it - it’s plasma balls. They are generally just one of the coolest toys and are packed full of physics they may be a bit 80s but then so am I, so here goes - at the centre of the ball is an electrode which builds up a high voltage and has a high frequency alternating current, this means that it has an oscillating electric field which changes direction constantly. As electrons leave the electrode in the middle, they are accelerated along the electric field and sometimes they crash into other atoms and molecules in the gas. If they bash the atoms hard enough they can knock other electrons off the atoms or molecules and this is called ionisation, and when these collisions occur energy is transferred and the excess energy is given off as a packet of light called a photon. When you touch the surface you are connected to the ground, so you make a nice path for the charge to go down to the ground.

Now for the bit I 07:10 - absolutely love - when you bring a fluorescent strip light near the plasma ball, this happens: it lights up! It’s not even touching the ball but it’s lighting up, it’s amazing! The light is full of gas some of the gas is mercury atoms in a vapour and the electrons in that gas really get excited by the oscillating electric field and they crash into atoms in the vapour, causing them to give out some light. A lot of this light is ultraviolet light which again we can’t see but which interacts with the fluorescent coating on the inner surface of the bulb and causes it to give out visible light. So it’s complicated physics but it’s just awesome and hopefully you can see that the closer I get to the ball the brighter the light is and that’s a really nice demonstration of how an electric field gets weaker as you get further away. Anyway, that’s all for now, we hope you’ve enjoyed our contribution to the Global Science Show! Check out our website at exetersciencecentre.org and follow us on social media to keep updated with our progress. Thanks for watching! .