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The_Magick_of_Matter363 karma

Thank you!

OK, here are a couple I've had some success with.

  1. Get a plasma ball (perhaps borrow one off someone in 1993) and hold a strip light near it. The light lights up without any wires. Hold it at the end furthest from the ball. Then slide your finger along the light from your hand towards the ball, and the light goes out up to your finger. It's very lightsaber-like.
  2. Harder to source, but I once saw someone get a tank of xenon and float a paper boat in it. That's really astounding to see. The xenon is invisible, and unlike helium it's heavier than air. The person I saw then breathed the xenon in and showed their voice got deeper rather than lighter. But they did this standing on their head, because while helium will float out of your lungs, xenon will get stuck and potentially suffocate you. So be careful! I mentioned this one in the book.

The_Magick_of_Matter320 karma

Definitely -- they're also freely available online:

https://www.feynmanlectures.caltech.edu/

The_Magick_of_Matter297 karma

I'd say they should read this book, for sale on the internet, which contains only the latter!
I've tried to make it clear that 'magic', in the sense I use it in the book, is simply the ability of the world to inspire. That is of course not only compatible with science, but is the essence of why we study it.

The_Magick_of_Matter173 karma

Condensation usually means, say, water appearing on a window when it's cold. Gaseous water (water vapour) is turning into liquid water, because the interactions between water molecules cause them to stick together. The 'condensed' bit of condensed matter is a generalisation of this idea. We can say that solids are a condensed form of liquids, for example. In general we might say that condensed matter is the whole which is more than the sum of the parts: to describe liquid or solid water as individual molecules is to miss something important out of the description (the interactions, and therefore the familiar behaviour of water).

So in answer to your question, condensed milk has had some of the water evaporated off so as to become more viscous (sticky), as a result of the stronger interactions between what remains. Strictly milk and condensed milk are colloids (solid particles suspended in a liquid) rather than true liquids.

The_Magick_of_Matter161 karma

That's a great (and difficult) question! The modern explanation is in terms of Feynman diagrams (he begins, to the 5 year old...). They describe all forces as being conveyed by particles. In the case of the attraction between opposite charges, the force (electromagnetism) is carried by photons. At the simplest level, one charge can emit a photon and the other catches it, receiving momentum and energy. So that's a simple answer.

But the photon itself has a probability to turn into an electron-positron pair along the way, before recombining into a photon. And there are other such processes which must be accounted for.

A dimension is really a 'degree of freedom'. For example, an ant essentially lives in two dimensions, rather than three, as it can't jump. It can move left or right (one degree of freedom), backwards or forwards (a second degree of freedom), but it can't move up and down. We can move in three dimensions.

You're quite right, though: quasicrystals are materials which are often said to display properties only possible in more than three dimensions. That's a bit misleading, though: the properties would only be possible for crystals in more than three dimensions, but they aren't crystals. So that's the trick.