|Go red, you horrors!|
In my role of occasional domestic lab assistant I was asked to prepare a classic 'carnations with food dye to demonstrate osmosis' jobby. No worries. I did it all by the book. Fresh flowers? Check. Newly cut diagonally under water to prevent air bubbles? Check. Warm but not hot water? Check. Ten to twenty drops of food colouring? Check. And three days the later the little horrors have not taken on a hint of colour.
My suspicion is that they are now treating flowers to make them last longer out of water without wilting with something that prevents or at least reduces their ability to take in water. But that's not the point. This is science. Repeatability is everything. I have been let down.
On a more serious note, it demonstrates how a small variation in materials/initial conditions can be disastrous in terms of outcome - and this does make you wonder just how many real science experiments, with much more complicated setups, have elements in their construction that the scientists aren't aware of that could introduce a variation in output. Could a new type of oil on some minor component in ALICE produce a different result for the LHC? I doubt it, but can we be certain?
Last year's brief 'neutrinos go faster than light' shock demonstrated that it is entirely possible in one of these big experiments for a small aspect that doesn't seem central to the measurement to totally throw the results, just like my carnations.
Of course it's not really science I have a problem with, it is our ability to know exactly what we are dealing with when we assemble an experiment. In his fascinating book Time Reborn, Lee Smolin makes the point that we tend to assume our experiments are closed systems. That most fundamental of physical principles, the second law of thermodynamics, only applies to closed systems. Yet, in fact, we have no experience of a true closed system (unless the universe is a closed system, but even that may well not be the case).
There are many ways that closing a system is impossible, but the most obvious one is gravity. We can't exclude the impact of external gravitational forces because we have no way of shielding against gravity. We are just very lucky that gravity is incredibly weak compared with the other physical forces, so on the whole (but not always) we don't have to worry about its impact.
So spare a thought for scientists, whether building an experiment on the desktop or something on the scale of the LHC. They don't just have to get the right equipment together to make their measurements, they have to try to exclude all possible misleading inputs - even when they don't know what they are. There are unknown unknowns, as Donald Rumsfeld might say.
I think I might have to ring CERN for some help with my carnations...