Does the word ‘real’ have any use in natural science? Certainly. Some experimental conversations are full of it. Here are two real examples. The cell biologist points to a fibrous network that regularly is found on micrographs of cells prepared in a certain way. It looks like chromatin, namely the stuff in the cell nucleus full of fundamental proteins. It stains like chromatin. But it is not real. It is only an artifact that results from the fixation of nucleic sap by glutaraldehyde. We do get a distinctive reproduction pattern, but it has nothing to do with the cell. It is an artifact of the preparation.

To turn from biology to physics, some critics of quark-hunting don't believe that Fairbank and his colleagues have isolated long-lived fractional charges. The results may be important but the free quarks aren't real. In fact one has discovered something quite different; a hitherto unknown new electromagnetic force.

What does ‘real’ mean, anyway? The best brief thoughts about the word are those of J.L. Austin, once the most powerful philosophical figure in Oxford, where he died in 1960 at the age of 49. He cared deeply about common speech, and thought we often prance off into airy-fairy philosophical theories without recollecting what we are saying. In Chapter 7 of his lectures, Sense and Sensibilia, he writes about reality: ‘We must not dismiss as beneath contempt such humble but familiar phrases as “not real cream”.’