100 Essential Things You Didn't Know You Didn't Know Read Free Page A

should expect to find a straight-line correlation when we plot the cube of the weight lifted against the square of the bodyweight of weightlifters. Here is what happens when you plot that graph for the current men’s world-records in the clean and jerk across the weight categories:

    It’s an almost perfect fit! Sometimes mathematics can make life simple. The weightlifter who lies farthest above the line giving the ‘law’ is the strongest lifter ‘pound for pound’, whereas the heaviest lifter, who lifts the largest weight, is actually relatively the weakest when his size is taken into account.

8
    Why Does the Other Queue Always Move Faster?
    The other man’s grass is always greener.
    The sun shines brighter on the other side.
    Sung by Petula Clark
    You will have noticed that when you join a queue at the airport or the post office, the other queues always seem to move faster. When the traffic is heavy on the motorway, the other lanes always seem to move faster than the one you chose. Even if you change to one of the others, it still goes slower. This situation is often known as ‘Sod’s Law’ and appears to be a manifestation of a deeply antagonistic principle at the heart of reality. Or, perhaps it is merely another manifestation of human paranoia or a selective recording of evidence. We are impressed by coincidences without pausing to recall all the far more numerous non-coincidences we never bothered to keep a note of. In fact, the reason you so often seem to be in the slow queue may not be an illusion. It is a consequence of the fact that on the average you
are
usually in the slow queue!
    The reason is simple. On the average, the slow lines and lanes are the ones that have more people and vehicles in them. So, you are more likely to be in those, rather than in the faster moving ones where fewer people are.
    The proviso ‘on the average’ is important here. Any particular queue will possess odd features – people who forgot their wallet, have a car that won’t go faster than 30 mph and so on. You won’t invariably be in the slowest line, but
on the average
, when you consider all the lines that you join, you will be more likely to be in the more crowded lines where most people are.
    This type of self-selection is a type of bias that can have far-reaching consequences in science and for the analysis of data, especially if it is unnoticed. Suppose you want to determine if people who attend church regularly are healthier than those who do not. There is a pitfall that you have to avoid. The most unhealthy people will not be able to get to church and so just counting heads in the congregation and noting their state of health will give a spurious result. Similarly, when we come to look at the Universe we might have in mind a ‘principle’, inspired by Copernicus, that we must not think that our position in the Universe is special. However, while we should not expect our position to be special in
every
way, it would be a grave mistake to believe that it cannot be special in
any
way. Life may be possible only in places where special conditions exist: it is most likely to be found where there are stars and planets. These structures form in special places where the abundance of dusty raw material is higher than average. So, when we do science or are confronted with data the most important question to ask about the results is always whether some bias is present that leads us preferentially to draw one conclusion rather than another from the evidence.

9
    Two’s Company, Three’s a Crowd
    What goes up must come down.
    Anon.
    Two people who get on well together can often find their relationship destabilised by the arrival of a third into their orbit. This is even more noticeable when gravity is the force of attraction involved. Newton taught us that two masses can remain in stable orbit around their centre of mass under their mutual gravitational forces – as do the Earth and the Moon. But if a third body of