Politically correct physics?

Abstract

If you were a caring, thinking, liberally minded person in the 1960s, you marched against the bomb, against the Vietnam war, and for civil rights. By the 1980s, your voice was raised about the destruction of the rainforests and the threat to our whole planetary environment. At the same time, you opposed discrimination against any group because of race, sex or sexual orientation. You reasoned that people who spoke or acted in a discriminatory manner should be discriminated against. In other words, you became politically correct. Despite its oft-quoted excesses, the political correctness movement sprang from well-founded concerns about injustices in our society. So, on balance, I am all for it. Or, at least, I was until it started to invade science. Biologists were the first to feel the impact. No longer could they refer to 'higher' and 'lower' orders, or 'primitive' forms of life. To the list of undesirable 'isms' - sexism, racism, ageism - had been added a new one: speciesism. Chemists remained immune to the PC invasion, but what else could you expect from a group of people so steeped in tradition that their principal unit, the mole, requires the use of the thoroughly unreconstructed gram? Now it is the turn of the physicists. This time, the offenders are not those who talk disparagingly about other people or animals, but those who refer to 'forms of energy' and 'heat'. Political correctness has evolved into physical correctness. I was always rather fond of the various forms of energy: potential, kinetic, chemical, electrical, sound and so on. My students might merge heat and internal energy into a single, fuzzy concept loosely associated with moving molecules. They might be a little confused at a whole new crop of energies - hydroelectric, solar, wind, geothermal and tidal - but they could tell me what devices turned chemical energy into electrical energy, even if they couldn't quite appreciate that turning tidal energy into geothermal energy wasn't part of the same game. In today's PC physics, no such complications arise because all forms of energy are equal and unlabelled. I accept the reasoning behind this - that understanding processes is more important than attaching labels - but what am I supposed to call ½mv2, mgh and mcΔθ? On which subject.... What am I allowed to say about heat? It seems that objects can be heated up. I can switch on the central heating. But I cannot get heat from a Bunsen burner. In PC physics, heat is banned - at least as a noun. Instead, I have to talk about 'energy transferred because of a temperature difference'. And I must stop saying 'transferred' in circumstances where I really mean 'transformed'. I find it difficult to argue with the logic behind the new approach to energy, but the loss of such an elegantly simple word as 'heat' is proving a severe restriction on my use of language. The loss is especially galling because engineers will go on talking about heat engines, heat pumps and heat sinks. In primary schools, saucepans will still conduct heat, and the Sun will continue to give off heat and light. Moreover, I suspect that most teachers will be using 'heat' in the privacy of the classroom, even if they won't admit to it in public. We shall all become closet heatists. Before PC physics takes over by stealth, we need a full and open debate on what is or isn't conceptually acceptable for students at different stages. Perhaps we need a conference. If so, I will be there at the back with my banner. But this time, it won't read 'Save the whale' or 'Save the rainforests'. It will read 'Save heat', or maybe 'Save all forms of energy'.