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DR. IFFIC LECTURE #1: THE NATURE OF STUFF, THE FOUR FORCES, AND THE MYSTERY OF THE NON-COLLIDING PARTICLES.
Greetings, seekers of knowledge and Internet time wasters! Welcome to the Dr. Iffic lecture series. I am Dr. Tyr Iffic, professor of New Clear Physics at the Online University of New Reykjavik. This is my assistant, Dmitri AlekseyevichDemokritov. Hello. In these lectures, I and the rest of the world’s greatest scientific minds will be answering your questions about why stuff behaves the way it does, and fails to behave in other ways. Questions and offers of lucrative speaking fees and book deals can be sent to firstname.lastname@example.org. Please make sure questions are related to science topics. (Speaking fees and book deals can be on any topic.)
Now, let us address the nature of stuff. First of all, if you are new to this cosmos, you should be aware that we have four really excellent fundamental forces: Gravity, Electromagnetism, Nuclear Strong, and Nuclear Weak. - - GRAVITY + + - ELECTROMAGNETISM + Q Q Q Q Q + Q Q Q Q + Q Q Q Q Q Q + Q Q - Q NUCLEAR STRONG NUCLEAR WEAK Dr. Iffic, can you remind me how these forces work?
Certainly. Gravity pulls stuff together, and is pathetically weak like a little girl.
However, gravity is also super long distance, so if you get a lot of stuff together like a planet or a star, it can actually be pretty formidable, like an army of little girls with nunchuks. But gravity isn’t what makes nunchucks formidable.
A good point, which brings us to Electromagnetism, or EM. EM only works on things that have charge. Things can have positive charge, negative charge, or be neutral, with no charge. EM pulls things together when they have opposite charge, and pushes them apart when they have the same charge. - - + + - +
What charge donunchucks have? Nunchuks have no charge, unless they are electrified tazer nunchuks, which will be the topic of a future lecture. You probably know that all material things are made out of atoms. Atoms have positive charge in the middle and negative charge on the outside, and in most atoms – including nunchuk atoms – this cancels out overall. - - - + - + BUT … the negative charge on the outside prevents the nunchuk from passing through other objects that have a negative charge on the outside, like your ribcage. - -
So when objects bump into each other, that’s really EM? Yes, EM is responsible for lightning, toasters, compass needles, and stuff not passing through other stuff. It can also make stuff emit radiation such as light, radio waves, microwaves, gamma rays – it’s a biggie. It’s also much stronger than gravity, but here’s the catch: because most atoms are neutral, EM usually doesn’t make any difference at long range. Typically, it’s gotta be right in your face do do any good, just like a nunchuck.
What about the Nuclear Strong and Nuclear Weak forces? Nuclear Strong is super strong and super short range. It keeps the protons and neutrons in the middle of your atoms from flying apart from each other, and from breaking into smaller pieces called quarks, which would be embarrassing as well as inconvenient. Or, if you are a giganormous sphere of gas like the Sun, it releases tremendous energy as gravity crushes your atoms together. Q Q Q + Q Q Q Q Q Q + Q Q Q
And Nuclear Weak? Nuclear Weak is a little weird. It’s not about pushing things together or pulling them apart. It causes quarks to change their status, and that can turn a neutron into a proton that spits out an electron and a very odd little particle called a neutrino. But this force can be very relevant to us, because it is what causes some materials to be radioactive. Q Q Q - + Q Q Q
So that’s it – only four forces. - - GRAVITY + + - ELECTROMAGNETISM + Q Q Q - + Q Q Q Q Q Q + Q Q Q Q Q Q + Q Q Q NUCLEAR STRONG NUCLEAR WEAK Yes, and everything that happens in the physical world is because of them. Now, Dmitri Alekseyevich, I understand you have a question for me about these forces.
Yes, Doctor. I think I understand what each force does. But I am confused about one thing. You mentioned that atoms have positive charge in the middle and negative charge on the outside. Yes, because in the middle you have protons and neutrons – protons are positive and neutrons are neutral. So that’s why they’re called neutrons. Yes, in those days scientists were very busy and couldn’t be bothered to think of creative names, so when they discovered a particle they pretty much just stuck “-on” onto the first word that came into their head. It wasn’t until later that they stayed up all night coming up with tripped-out crazy names like Charm Quark. I am very pleased to the announce the discovery of the … (drat, I’m already late for lunch) … of the “thingon.”
So atoms are positive in the middle, and on the outside they’re negative … Because there you have electrons, which are negative, and they go zipping around extremely fast, making a sort of blurry cloud of negative charge. - Cartoon Atom More Realistic Atom - - + + - + + negative
EM keeps the electrons orbiting the protons, instead of just flying through space. Yes, their charges are opposite, so they’re attracted to each other. - + + And that’s my question. Why don’t the electrons crash into the protons? Ah, I see. EM is pulling them together, but only up to a point. So you are thinking, what keeps them apart? ? -
It doesn’t seem to fit any of the forces. Yes, EM should pull them together … - Gravity should pull them together … + Q Q Q + Q Q Q Q Q Q + Q Q Q … and it doesn’t seem like Strong or Weak would care one way or the other. Q Q Q + Q Q Q -
Maybe the protons push back on the electrons because they’re in a committed relationship with the neutrons. + ? -
I don’t think that’s… Yes, maybe the electron comes up to the proton and is all like, “let’s get together” … I’m pretty sure… … and the proton says, “Look, I think you’re a really great particle and everything, but Neutron and I are very happy together, so … you know … let’s just stick with the orbiting.” I’m pretty sure that those sorts of relationships are limited to multi-atomic beings.
Dmitri Alekseyevich, I have returned. Would you kindly bring me a bucket of ice water for my swollen, fevered brain? I take it the answer was tripped-out crazy?
Yes indeed, because it has to do with the tripped-out crazy world of quantum mechanics. I see. Can you give me a summary that will not cause my brain to swell? Well, as you know, quantum mechanics has to do with the behavior of astonishingly small things like protons and electrons, and that behavior is very different indeed from the behavior of large things like bowling balls. + Even though the large things are made up of small things? ? -
Yes. Even though this is true, physics simply has a different set of rules for quantum-scale things than for larger things. Are there different forces for quantum things? - There are the same four forces, but at the quantum level those forces generate tripped-out crazy rules we don’t see at larger scales, like the Pauli Exclusion Principle and the Heisenberg Uncertainty Principle. + + Q Q Q + Q Q Q Q Q Q + Q Q Q - I think my brain is starting to swell … Q Q Q + Q Q Q ? - ? ? ? ?
OK, calm down. Take deep breaths and think of bowling. First, let us discuss what would happen if an electron did collide with a proton: it would bounce off and go right back to orbiting. For two things to stick together, they have to turn their movement energy into some other form of energy. For example, let me throw this bowling ball at your nonbranded subcompact car. No! My nonbranded subcompact car!
There! The energy that was moving the bowling ball has been transformed into the energy needed to make a large dent in the hood, and both objects are now at rest. But electrons and protons can’t make dents in each other. Electrons are undentable because they’re fundamental: they’re not made of smaller things that can rearrange their shape. - Protons are made of smaller things: quarks. But quarks are held together by the Strong Force, and that makes protons pretty tough. There’s a reason we didn’t name it the Lame Force. Q Q + Q So an electron-proton collision wouldn’t be very dramatic.
Not unless the electron had its energy level pumped way into the crazy zone by something like a particle accelerator. In that case, it would blast the quarks apart, which is how we discovered quarks in the first place. Q - Q Q
So do natural electron-proton collisions happen all the time? No, and that is where we start to get a little quantum mechanical. All you need to know for now is that electrons are not just particles. They are also waves. I know this is a brain-swelling concept, but it is one of the fundamental insights of quantum mechanics. Now, for an electron that is zipping around a proton to pull in towards the proton, its orbit would have to shrink. And because the electron is also a wave, a smaller orbit means a smaller wavelength. Larger Size More Energy But waves increase in energy when their wavelengths get smaller. So as the electron gets closer to the proton, its energy increases, and pretty soon it’s moving so energetically that it zips back out again. It’s as if the electron has a minimum speed, and the minimum speed is too fast to let it spiral in to the proton. Orbiting is the closest it can get. So the electron can never ever collide with the proton?
Well … never ever is a tricky concept in quantum mechanics. At the quantum level, the laws of physics are not really laws. They’re more like really high probabilities. There’s a really high probability that an electron will be where the laws of physics say it should be. But there’s a really low probability that it will turn up somewhere else. So the electron we’re talking about might actually be inside my left nostril? Or in the core of Jupiter. But the chances that it is in either place are really, really low. You have no idea how low – it’s a brain-swellingly small number. probably somewhere in here not here or here
I do feel a little brain-swollen. This quantum stuff is hard to picture. It’s totally alien to how we perceive the world at our large-scale sizes. But the predictions of quantum theory have been tested in the lab quite a bit, and they just keep succeeding. The Universe is one tripped-out crazy place. Let us rest our swollen brains for now. Would you care to go bowling? Can you promise me that my bowling ball won’t end up inside my left nostril? Almost certainly.