On Many Worlds

I don’t know where Sean Carroll stands on the Everett Many-Words Interpretation of quantum mechanics, but in an (otherwise unrelated) piece of writing, I thought this was quite a neat way of putting it:

In quantum mechanics, any particular system is potentially described by an infinite number of distinct wave functions; again, it is only when different branches of such a wave function are labeled as “universes” that one starts to hear objections, even if the mathematical description of the wave function itself hasn’t grown any more complicated.

― Sean Carroll, “Does the Universe Need God?

(Emphasis mine.) In the passage, he’s actually discussing Kolmogorov complexity, but I think the principle is the same when applied to people’s gut reaction when they hear “many worlds”.

Posted in Physics | 2 Comments

Ultra Happy Game Jam

I spent this past weekend at the Melbourne site for the IGDA Global Game Jam. The premise: 48 hours to build a game.

Subsisting on minimal sleep[1] and large quantities of caffeine, sugar and complex carbohydrates, the team I was on (called Team Broficiency for fairly obscure reasons) produced Ultra Happy Death Virus HD. It looks something like this:

A screenshot of Ultra Happy Death Virus HD in action

Despite exceptional competition, we were lucky enough to tie for the Participants’ Favourite award (with The Last Flight of the Bumblebee), and were awarded Best Game. You can get a copy of Ultra Happy Death Virus HD from the Global Game Jam website[2]. You can also get all the other games that were built over the weekend, all of which are of truly impressive quality.

Anyway, wow, that was a lot of fun. Score one for spur of the moment decisions, and thanks to the organisers and all the other participants!

[1] On sleep: what I did not do this weekend was get very much of it. I did manage to get a few hours on Friday night on the delightfully hard floors of the computer lab, and another hour or two in strategically placed sneaky blocks on Sunday, at times when I thought I would otherwise pass out.

[2] You will notice it is 80 MB. There are a number of reasons for this, but in short, they all boil down to not enough time. All things considered, there were a number of… approximations to good software engineering due to that constraint.

Posted in Games, Programming | 3 Comments

Bicycle Tyre

Found in my bicycle tyre:
A chunk of glass in my bicycle tyre

Poking through the inside:
A chunk of glass in my bicycle tyre, view from inside the tyre
That chunk punctured the tube in no fewer than five separate places. It now sits proudly on my desk, and I will no doubt lose track of it and later find it in a sock.

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Electricity I: Magic

This is part 6 of my series of posts Introduction to Physics.

My original intention when planning the Introduction to Physics series was to follow the semi-standard path of introducing electricity and magnetism together. However, I’ve changed my mind, and we’re going to instead look at electricity, then special relativity, then we’ll loop back and discuss magnetism. (Those who’ve already done Special Relativity and E&M will know why I’m doing it this way, but for everyone else, my evil pedagogical plans will soon become apparent.)

Anyway, electricity. Since we don’t really have enough words to develop theories of electricity rigorously, I will instead assert things to be true, and you will (I assert) believe me.

There exists something called electrical charge. Charge comes in two types, which we call positive and negative. Here’s where something slightly special seems to happen: if you take something with a positive charge, something with a negative charge, and then put them near each other, they will be attracted to each other (i.e., move towards each other). (Hence the aphorism, opposites attract.) Likewise, if you take two positive charges (or two negative charges), they’ll repel each other.

Now, to some extent, this is freaky, magical action at a distance. What sorcery makes it all happen? To be honest, I don’t really know, and when one thinks about it, it might not even be an answerable―after all, if told you that something made electrical attraction work, you could just as well ask what made that work, ad infinitum. (Apparently, despite this, particle physicists have an explanation. Shows what I know.)

However, this magic isn’t quite as magical as it might first appear: it’s really a consequence of the environment we learnt what “normal” is. We don’t see it as odd that pushing something makes it move: there’s some intuition that if you’re touching something, it’s not unreasonable for you to be able to push, pull and otherwise alter the position, velocity and so forth of that object.

It turns out that, on a microscopic scale, all that intuitively-reasonable pushing and pulling we do is, in fact, a consequence of this force from electricity (and its closely related sibling, magnetism). You may recall that matter is made of atoms, which are in turn made up of positively charged protons (in the nucleus) and electrons (spinning around the nucleus).

In another of my famous gross oversimplifications of what’s really going on, I’m going to say that between electrons and protons making up atoms, electromagnetism can explain why everything works. (I’m ignoring, among other things, molecules, nuclear reactions, gravity and chemistry in general.) As we established above: like charges (such as the negative charges from the electrons in the atoms) repel each other: so pushing things works.

(In fact, according to the modern conception of physics, there are only four fundamental forces. Gravity we’re (somewhat) familiar with, and electromagnetism we’re looking at now. The other two are the strong nuclear force and the weak nuclear force, which are what keeps atoms together. We actually briefly touched on beta decay (for which the weak nuclear force is responsible) in Classical Mechanics III, on conservation laws.)

So, two questions that might be on your mind are:

  1. The electrons-pushing description might explain why forces transfers from an astronaut’s hand to the space shuttle… but where does that force come from in the first place?
  2. If opposite charges attract, and the nucleus of an atom is positive charged (from protons) and the electrons are negatively charged, why don’t the electrons fall into the nucleus?

I promise to answer at least the second of those questions, eventually. :)

Anyway, that gives us some background for why electricity and electromagnetism is actually really really important, even if we ignore all their technological applications. Next, we’ll look at the electric field and how we can quantify the effect that electric charges have on the real world. Then we’ll deviate wildly off topic and into special relativity.

Posted in Communicating Science and Technology, Physics, Science | Leave a comment

University Advertising

University of Melbourne Executive Master of the Arts Facebook AdvertismentApparently advertising on Facebook is sufficiently effective that even I look at it. Exhibit A, to the right:

The title: “Affect real change”.

The copy: “The EMA (Executive Master of Arts) combines social engagement & ethical leadership with real-world skills so you can effect real change”. (Emphasis mine in both quotations.)

I can’t tell if this is a mistake or whether the copywriter is bored and trolling.

(Interestingly, it seems to me that the title can be interpreted two ways. Firstly, one affects change by causing that change to be different from how it otherwise would be: like atmospheric carbon dioxide affecting the global climate. The other reading is developing an affectation of real change, i.e., get the Executive Master of Arts and you too can pretend you’re making a difference!)

Posted in Grammar, Miscellany | Leave a comment