Even when the itchy-burn make me wanna let go.

An old photo of a frost.

I missed the last bus home last night, mainly because I stayed back to work and throw sunnick down on the old bog. Having only ridden the bus 3 times, and having not paid an awful lot of attention where it went, I decided to walk it. Considering I have all the sense of direction of your average spin-zero particle (Oh! a physics pun, I am branching out), this was a bad idea. I got mildly lost, and got home about an hour later. If I had have known how long it was going to take me, I wouldn't have done it.

I feel that's an appropriate metaphor for me being here. I don't know what I don't know, and if I did, I probably wouldn't be here. It's gonna be a bloody long walk. Today I agonized over one line of a derivation, and when I asked someone, it turned out to be rather simple, and was just a notational thing. I'm going to have to weigh off annoying people by asking daft questions against sitting there getting angry.

For Ian's benefit and mine, I am going to attempt clear up the whole 'Quantum information can be negative' bruhaha. Allow me to switch to my annoying lecturing tone. A state can be pure, which means we know exactly what it is, and hence has zero entropy. In contrast, a state can be mixed, which means it is in a superposition of states (and it's not possible to find a new basis where the state is pure), and hence has positive entropy. Now, it's possible for a qubits to be entangled, the classic example being the EPR state, (|00>+|11>)/sqrt(2). This entangled state is pure, and has (Von Neumann) entropy S(A,B)=0. However, it can be shown that each qubit is in a mixed state, i.e., the entropies S(A) and S(B) are positive. So the conditional entropy, given by S(A|B) = S(A,B) - S(B), is negative. That is, we know less about A by itself than we do about the joint state AB. This is rather odd from the perspective of classical info theory, where H(X) is always less than or equal to H(X,Y), and so H(X|Y) = H(X,Y)-H(Y) is always non-negative.

I got a one month pass for the UQ gym this evening, and rolled the old heavy artillery down there for some special ops training (I'm being generous, honest, and sarcastic here, but the proportions escape me). It's a bit rough and ready. That's being nice, it's mostly rough with a garnish of ready. However, it is full of hot tanned Brisbanians. This is as opposed to me being snow white and hot, and by hot I mean wearing an inch thick bodysuit composed entirely of sweat. HELLO, LADIES.

Ok, enough drivel. I've got that dizzy feeling that comes over me before I get the KAY-BAB FEVER.