Fuddland

Occasional ponderings.

Did you know that it is perfectly legal, in the UK, to record telephone conversations — without the person on the other end consenting, or even knowing that they’re being recorded, provided that the recording is for personal use and will not be handed-over to a third party? I didn’t.

I found out because I’ve been wondering, for a while now, why on Earth all the major chat clients — MSN Messenger, Yahoo! Messenger, and so on [even Skype] — provide the option to log all chat conversations without the individual say-so of each contact, or without any warning message telling the person on the other end of the chat that everything they say is being stored, unencrypted, on their friend’s hard-disk? I was hoping to draw parallels between logging chats and being able to record phonecalls at the push of a button, and aim for a legal minefield, but that’s been shot to pieces by the above information, so I can only fall back on the moral argument: how’d you like it if your mate suddenly revealed that they’d been taping all the conversations you’ve ever had with them?

Whilst I admit that I used to have the logging features of various chat clients turned on, some time ago I decided it wasn’t really right to build and keep those logs for no particular reason, and went about disabling the feature and erasing all chat-logs sitting on my drive. But that’s only half the issue, because — as far as I’m aware — no chat client flashes up any kind of warning or notification that says, “The other user is logging this conversation.” I think they should.

Google Talk has taken the best stab at it so far, with its Off the Record feature, but it’s not enabled by default for every user: I had to go through each of my contacts and set them to Off the Record. And whenever we begin a chat, it ominously informs us both, “This conversation is off the record,” as if I’m about to divulge some deeply private information.

I’m not saying that chat-logs can’t be useful, just that it should be mutually agreed if they’re to be kept. But what if a one party wants to renege an agreement? Should the other party be obliged to delete their copy? Should the chat client provide the ability for people both sides of a chat to delete the log, regardless of where the physical copy is. Ooh, not sure about that one.

But for now, you’ll just have to rest assured that, if you’re chatting with me online, I’m not keeping a record of what we’re saying. [I am, however, watching you from across the street through my thermo-binoculars.]

After checking with a few friends, I’m fast coming to the conclusion that, far from being something that every child has done since the dawn of Man, the splitting of the end of a recently-fallen sycamore seed, and the subsequent sticking of said seed to one’s nose, may well have been something that only the youths of Neasden who were around in the early Eighties did.

Please tell me someone else did this when they were young?

a word of warning: this post contains a bit of maths, and not a single fart gag. so you’ll probably find it quite boring. i’d skip it if i were you.

a brief conversation at the ucas visitors buffet lunch [translation: free food for hungry postgrads, and also the opportunity to check out next year’s potential undergrads] earlier today left me wondering what the speed of smell is.

the current first hit off the google search isn’t what i’m after — it looks like it describes the speed at which a rat [or, specifically, a rat’s brain] can distinguish two different smells. what i wanted to know is: if i’m on one side of a room filled with still air [that is, no draughts, and ignoring the minor turbulance caused by my breathing], and on the other side of the room some smelly substance is spontaneously released, how long will it be before i can smell it?

it turns that there’s some fairly interesting little bits of maths behind the answer. it’s something to do with so-called ‘random walks’ — given a single particle, bouncing off all the others in a random fashion, what is the probability that it will make its way to a particular point in space after some time, and how many steps will it take to reach the point [the number of steps relating to the time, and hence the speed]?

some chap called póyla showed way back in 1921 that, in two dimensions, a particle will eventually visit every point in space [‘eventually’ meaning ‘in an infinite number of steps’], but in three dimensions [as in our smelly room], the probability that a particular will visit a particular point in space is less than one, no matter how much time elapses; as a special example, the chances of it revisiting the point where it started from are about one in three. weird stuff.

this means there’s a teeny-tiny [and basically neglible, but i like the fact that it exists] chance that i’ll smell nothing at all. anyway, back to the original question: the speed.

hidden behind a shroud of crudeness is the likely answer, namely: the speed is proportional to the reciprocal of the square root of the time elapsed. so say i was at such a distance away from the source that it took 4 seconds for the smell to reach me. if i then moved twice as far away and repeated the experiment from the beginning, it would take the smell 16 seconds to reach this new location.

however, i’m having trouble finding this verified elsewhere — for example, i can’t check that this rule isn’t only for two dimensions. [perhaps my housemate has a physics book i can look in.] of course all the theory goes out the window in real-world examples like: how long will it take for the smell of the roast dinner in the oven to reach someone sitting in the lounge [draughts, walls, doors, etc. to contend with]? still, being able to come up with a believable theoretical answer is quite fun.

right, back to that phd thing…

it’s quite disheartening when some fact or other that for years you’ve been confidently offering to anyone you think might be remotely interested, however tenuous the link in the conversation, turns out to be completely false.

i’m not sure where i first heard it, but i’ve always enjoyed the little tidbit of information about glass being really a liquid; that the bonds between the molecules — although strong — are not rigid, and that if you look at the terribly-old stained-glass windows of cathedrals, you can see they’re noticably thicker at the bottom, proving the glass has flowed ever-so slightly over hundreds of years.

turns out that’s bollocks.

Edgar Dutra Zanotto of the Federal University of Sao Carlos in Brazil calculated the time needed for viscous flow to change the thickness of different types of glass by a noticeable amount. Cathedral glass would require a period “well beyond the age of the universe,” he says.

The difference in thickness sometimes observed in antique windows probably results from glass manufacturing methods, says LaCourse [assistant director of the NSF Industry-University Center for Glass Research at Alfred (N.Y.) University]. Until the 19th century, the only way to make window glass was to blow molten glass into a large globe then flatten it into a disk. Whirling the disk introduced ripples and thickened the edges. For structural stability, it would make sense to install those thick portions in the bottom of the pane, he says.

and the killer counterexample:

Why don’t we find that Egyptian cored vessels or Hellenistic and Roman bowls have sagged and become misshapen after lying for centuries in tombs or in the ground? Those glasses are 1,000-2,500 years older than the cathedral windows.

still, i always find it’s more fun to debunk than to propagate myths — one of my favourite websites is snopes — anyone who sends me one of those emails that claims to be being tracked by microsoft or aol on the off-chance they’ll receive a fat cheque usually gets a reply from me pointing them to the relevant debunking page. annoying, aren’t i?

[glass info via not a blog.]

what did they check the first spirit-level with?