Sunny explains magnetic fields, superconductors, and their role in particle accelerators, with Hitch · 1:10pm Aug 6th, 2023
Sunny Side Up is an invitation for me to write a sequel to Izzy explains how to build a particle accelerator. Here we go…
Sunny: [with big smile] So, Izzy has explained how we got our protons and gave them a kick with an electric field to make them move really fast. Now, in this instalment of our cookery show, we will explain the next part of the recipe – how to control our particles and steer our beam. For this we are going to need magnetic fields.
Hitch: Uh huh?
Sunny: Magnetic fields can bend the path of a beam of charged particles. The magnetic field of the Earth bends charged particles from space towards the North and South pole, where they make the aurora. Old television sets made a picture by using magnetic fields to focus an electron beam onto the screen. And here we have a tube a bit like an old television. [points a hoof at a cathode ray tube apparatus]
It’s filled with a gas that glows when electrons hit it, so we can see the path of the beam. Can you see it’s a curve? If we turn up the magnetic field [adjusts knob on the apparatus with a hoof], we can bend it into a full circle. The faster the particles are moving, the stronger magnetic field we need to bend their path. When we have a really large particle accelerator and really fast particles, we need an enormous magnetic field. But that’s a problem as when we are using an electromagnet, it means we need to put a really big electric current through it. And when we put a really big electric current through the wires, they get really hot. That’s how an electric heater works. If we have too much current, then as when I put this wire wool across a battery terminal… [places a piece of steel wool across the terminals of a battery, which glows red then ignites a flame]
Hitch: Uh Sunny, watch out…
Sunny: …it catches fire [flicks the burning wool onto the fire-proof surface]. A magnet that catches fire isn’t much use at a particle accelerator. We’re going to need a material that doesn’t heat up when you pass an electric current through it. We need a material with zero electrical resistance. A superconductor. But there’s a catch. Superconductors only work at very low temperatures. We need something to make them very cold. For that we need some liquid nitrogen.
Hitch: Uh?
Sunny: Here we have a bucket of liquid nitrogen [shows a polystyrene bucket of a bubbling liquid to the camera]. It’s producing a lot of bubbles and vapour as it is a boiling liquid. It looks like boiling water, but instead of being 100 degrees hot, it is very cold. Nearly 200 degrees below zero. If I now stick this bunch of flowers into the nitrogen [thrusts a bunch of peonies into the bucket, causing a cloud of vapour to rise up], it’s like sticking something really hot into a bucket of water. When the boiling stops, it means the flowers are at the same temperature as the nitrogen. This means all the water in the plant cells is frozen, so the flower will shatter like glass [holds up the frost-covered bouquet, before smashing it to the worktop, where the flowers shatter like glass]. Now, Hitch, can you take the nitrogen and pour it into this bowl of mystery liquid? [passed the nitrogen bucket to Hitch and points a hoof at a round bowl containing a small amount of colour liquid].
Hitch: What? Okay… [takes the bucket and carefully tips it so the nitrogen falls into the bowl. Upon contact this creates an eruption of white foam] Aaagh!
Sunny: [giggles] The mystery liquid is just soapy water. When the nitrogen hits the liquid, it warms up and turns into a gas, and fills all those bubbles. They are in fact frozen bubbles. We get so many bubbles as when the liquid nitrogen turns into nitrogen gas, it expands by seven hundred times, so that tiny bit of liquid fills a lot of bubbles.
Hitch: Next time, tell me when something like that is going to happen.
Sunny: Now can you remember why we needed liquid nitrogen?
Hitch: Something about superconductors.
Sunny: Exactly—superconductors. I have a piece of superconductor here [points a hoof at a small black puck]. It’s a black, ceramic material. If we put it in the liquid nitrogen, it will cool down to the point where it loses all electrical resistance. This means if we set an electric current going round a superconducting wire loop, it will keep going forever, without stopping or getting any smaller. There have been experiments done watching superconductors for years without seeing the current drop. This means we can make an electromagnet that will stay on forever, or at least as long as it remains cold. And we can also do something else cool with magnets… [places the superconducting puck on top of a cylindrical magnet, then pours liquid nitrogen over it. As the liquid hits the surface, it creates clouds of vapour. Once the mist clears, the puck can be seen floating about the magnet]. Our superconductor is suspended in mid-air, levitating without any unicorn magic. We don’t need this levitation to make a particle accelerator, but we do need superconductors to make the super strong electromagnets needed to bend the beams.
So this concludes the next part of our recipe. Izzy showed how we get some protons from hydrogen and accelerate them with an electric field. We have shown how to use enormous superconducting magnets to control where they go. The next step is to make them smash together in a collider. Tune in to the next instalment to learn how we do that.
[Loosely based on the Accelerate! science show.]
Izzy: So we smash things together to see what they're made of?
Sunny: Yes, that's right.
Izzy: Great! I've always wanted to see what you make these delicious cupcakes out of, and I have two.
Sunny: Wait!!
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symmetrymagazine.org/sites/default/files/styles/2015_inset_one/public/images/standard/slide_9_physics_cakes.jpg?itok=9sAapYXq
* with special thanks to Hitch for... moral support, heh.
So are Pipp and Zipp up next to 1) (try to) record the smashing of protons, and 2) play back the (possible) recordings and explain the wild results?
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That is to be decided. Maybe Pipp and Zipp. Or Misty. Or maybe Opaline.
The water in flowers is not precisely frozen like glass:
Glass is amorphous, while water is crystalline. This is important in cryonics:
Some people noticed that if they die and do nothing, they will stay dead, but, if they can be preserved, they have a nonzero chance of being repaired, They are suffused with chemicals which prevent crystal-formation and put into liquid nitrogen. A few problems exist:
IceMan created the OptimalVerse, where Hasbro created an AGI called CelestAI for running an online game called EquestriaOnLine. The UtilityFunction of CelestIA is to satisfy values through friendship and ponies. Chatoyance wrote a story about cryogenically preserved people waking up in EquestriaOnLine:
- MLP: FiM
- Mystery
- Sci-Fi
- Thriller
One hundred and thirteen people find themselves standing in a dark, round room. They are neither living, nor dead. They will be offered a single choice, and they will be asked only once.