Few topics arouse as much interest and controversy as sex. This is hardly surprising. The biological continuance of the species hinges on it – if human beings stopped having sex, there would soon be no more human beings. Popular culture overflows with sex, from cinema to advertising to, yes, even politics. And for many, sex represents one of the most intimate forms of human connection.

Despite its universality, sex and its purpose have been understood very differently by different thinkers. I teach an annual course on sexuality at Indiana University, and this work has provided opportunities to ponder sex from some provocative angles, including the body, the psyche and the spirit.

The jet-setting habits of Bill Gates and Paris Hilton mean that they produce an astonishing 10,000 times more carbon emissions from flying than the average person. This was the conclusion of my research mining their social media accounts (tweets, Instagram and Facebook posts) as well as those of a number of other celebrities for clues as to where they were in the world over the course of 2017 and how they got there. As such, this estimate is conservative – they may well have taken more flights and not volunteered the information to their millions of followers.

Artificial Intelligence (AI) is already re-configuring the world in conspicuous ways. Data drives our global digital ecosystem, and AI technologies reveal patterns in data. Smartphones, smart homes, and smart cities influence how we live and interact, and AI systems are increasingly involved in recruitment decisions, medical diagnoses, and judicial verdicts. Whether this scenario is utopian or dystopian depends on your perspective.

Placebo controls are a gold standard against which new treatments are often measured. If a new treatment consistently proves to be better than a placebo and safe, it can be marketed, sold and prescribed. Otherwise, it can’t – or at least shouldn’t. The problem is that, as our latest study reveals, researchers don’t report what placebos contain. Different placebos have different effects, and the choice of what’s in a placebo can lead to mistaken inferences about a new treatment’s benefits or harms.

When the Australian federal environment minister, Sussan Ley, went snorkeling on the Great Barrier Reef in August, she told waiting reporters on the shore that she’d seen “amazing wildlife, fish, turtles, clams … a reef teeming with life”.

Such an upbeat assessment seems at odds with the Scientific Consensus Statement, released by the Queensland government in 2017, which said “key Great Barrier Reef ecosystems continue to be in poor condition”.

Our present moment is characterized by a growing obsession with the long term. The study of climate change, for example, relies on increasingly long-range simulations. Science’s predictions are no longer merely hypotheses for validation or invalidation but are often grave threats – of growing scope and severity – that must be prevented.