November 8, 2007

...Learn TDD with Codemanship

Schrodinger's Plan

Physicist Erwin Schrodinger devised a famous thought experiment to illustrate the Copenhagen interpretation of quantum mechanics when scaled up from the invisible world of subatomic particles to everyday objects that are visible to the naked eye.

In quantum theory, particles can exist in a superposition of possible states - imagine a light switch being off and on at the same time - until it is observed, at which point this superposition collapses into a single reality (off or on).

Schrodinger asked us to imagine a cat in a box. Completely at random - in Schrodinger's version, when a nucleus of a radioactive isotope decays - poisonous gas is released into the box that kills the cat.

We cannot see inside, and we cannot know if the gas has been released. We do not if the cat, at any specific moment, is alive or dead.

In the quantum world, the cat is both alive and dead simultaneously - but only while we can't see it. As soon as we remove the lid of the box and observe the cat, the superposition of probabilities collapses into a single reality, and the cat is found to alive or dead.

When we try to understand the behaviour of, say, electrons orbiting the nucleus of a hydrogen atom, quantum mechanics forces us to model it as not being a particle in one specific location at any given moment (like a moon orbiting a planet). Instead, it behaves more as if it exists simultaneously across a range of locations - each with a specific probability that when we observe it, that will turn out to be the reality. So an electron has what's called a probability distribution, being more likely to be measured in one location than in another, but literally existing simultaneously as a superposition of all those possible positions until the observation takes place.

Project plans are a bit like this, too. Until the reality is observed - the day we actually delivered - our plans exist as a superposition of possible outcomes, some more likely than others. A delivery date is like our quantum electron. It has no specific location that we can pinpoint until the day actually arrives. The only time we know with certainty that a feature will be delivered on a specific date is because we observed it happening.

Until then, a project delivery is a bit like Schrodinger's unfortunate cat - being both on time and behind schedule simultaneously.

Posted 3 weeks, 6 days ago on November 8, 2007