It is the issue that has asked researchers to look Janus-like in both directions: forwards for Research Councils UK and backwards for the Higher Education Funding Council for England's research excellence framework. A year on from the research assessment exercise results, it has exercised the academy and infuriated researchers, with almost 18,000 - including a number of Nobel laureates - voicing their fierce opposition in a petition. Yes, it's impact, serendipity's evil twin.
This week, the second consultation on the REF reaches its conclusion with submissions from some 300 organisations. With nearly £1.5 billion of research cash at stake annually in England, feelings are running high on how to translate the potential outcome of universities' research into social and economic terms.
Not many people, not even James Ladyman, professor of philosophy at the University of Bristol and dreadlocked "anti" hero of the ivory tower, would disagree that academics have a responsibility to make the case for their funding from the taxpayers' purse. But it is the fact that the receipt of cash would rest on the demonstration of impact, a slippery snake of a concept that eludes definition, elides blue skies and defies measurement.
Professor Ladyman dismisses impact totally as "corrupting" and is unashamedly purist in arguing that scholarly work should be judged only on quality and pursued solely for its own sake. He is joined in his lofty thinking by the Royal Astronomical Society and the University and College Union.
Other learned societies and mission groups accept the notion but not Hefce's suggested weighting of 25 per cent. Lower, say Universities UK, the Russell Group, Million+, the University Alliance, the British Academy, the Society of Biology, the Academy of Social Sciences, the Political Studies Association, the British International Studies Association and more. Higher, says the CBI (no surprises there).
Human nature being what it is, there is no doubt that the weighting will, to the delight of those with a utilitarian bent (no prizes for guessing who), prove a significant behavioural driver, with academics moving away from work with value that is less immediately predictable and towards that which has the most direct short-term economic benefit. The effect of this is summed up neatly by the University of Cambridge in its submission: it would turn "first-rate universities into second-rate companies".
The pilot taking place in more than 25 institutions in the coming months should shed more light on the many problems surrounding impact: it can, of course, vary a great deal depending on the discipline and cannot always be measured in cash terms; some research can take decades, if not centuries, to have an effect (the REF proposal allows for only ten to 15 years from research to impact).
The most sensible approach would be to wait before weighting, as both the 1994 Group and the Campaign for Science and Engineering advocate. Let's get some idea of whether impact assessment would work and if so how, before we rush into deciding how much of it we might or might not want.
And while we mull it all over, maybe it's worth bearing in mind that not for nothing was the word "serendipity" once voted one of the hardest to translate.
Happy Christmas, and have a socially and economically prosperous New Year!