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The study is small and limited to the greater Salt Lake City region of Utah. But it shows how physical mementos such as locks of hair stashed in scrapbooks for decades can reveal how our environment has changed over time.

Researchers gathered 47 hair samples dated from 1916 to 2024 and called in Diego Fernandez, a geochemist at the University of Utah, to analyze the lead content in the hair. The analysis didn’t distinguish between lead in the sheathlike cuticle that surrounds a hair and that found in the hair itself. The former would have been picked up from contaminated air, and the latter would have stemmed from the consumption of contaminated food or water.

The trend over time is stunning. Peak lead rates occurred in samples from the 1960s, when lead was enriched by some 120 times compared with 2020–2024 samples. But since the 1960s, lead exposure rates steadily plummeted.

The decline occurred alongside the formation of the Environmental Protection Agency in 1970 and the passage of landmark legislation, including the Clean Air Act and the Clean Water Act, in the same decade, although the researchers also note that the greater Salt Lake City region had been home to two smelting facilities that closed during that period.

Still, the decline is stunning. “I think it’s kind of a showstopper for showing the power of environmental protections,” Smith says.

Many historians have thought that U.S. Navy funding of oceanography paved the way for plate tectonic theory. By funding extensive investigations of the deep ocean, Navy support enabled scientists to discover and understand sea-floor magnetic stripes, the association of the deep trenches with deep-focus earthquakes, and other key features. Historian of science and geologist Naomi Oreskes presents a different view: the major pieces of plate tectonic theory were in place in the 1930s, and military secrecy in fact prevented the coalescence of plate tectonics, delaying it for three decades.

Naomi Oreskes is Professor of the History of Science and Affiliated Professor of Earth and Planetary Sciences at Harvard University. She has worked on studies of geophysics, climate change and the history of science. She sits on the board of US based not-for-profit organisations the National Center for Science Education and Climate Science Legal Defense Fund. She is a distinguished speaker and has published 10 books, including Science on a Mission and The Big Myth.

As soon as inequality in resources tipped over into inequality in power, Goliath-like states and empires, with vast bureaucracies and militaries like our own, began carving up and dominating the globe.

What brought them down? Compounding inequality and concentrations of power, says Luke Kemp, research associate at the Centre for the Study of Existential Risk at the University of Cambridge.

According to Kemp — nicknamed "Dr. Doom" by some of his colleagues — we now live in a single, global Goliath. In this talk, recorded at BESI on September 30, 2025, Kemp explore the ways growth-obsessed, extractive institutions like the fossil fuel industry, Big Tech, and military-industrial complexes rule our world and produce new ways of annihilating our species, from climate change to nuclear war.

In what ways do unresolved questions in physics and mathematics shape the possibilities of quantum research? What can the history of semiconductors teach us about the future of quantum research? How do government investments shape research priorities? And what happens when scientific breakthroughs encounter markets?

How is mathematical knowledge recorded and preserved across generations? Contrary to the idea that mathematics itself is somehow ‘permanent’, in this talk we will explore heritage-making in mathematics, that is the people, institutions, and material objects that can give mathematical ideas longevity. We will explore the heritage-making found in two very different types of French nineteenth-century libraries: those of famous mathematicians and those of secondary schools. We will especially focus on how the recording – and forgetting – of mathematical ideas is influenced by their publishing, political, and intellectual contexts. This lecture was recorded by Professor Caroline Ehrhardt on 8th October 2025 at Barnard’s Inn Hall, London.

Jo is Britain’s first female fast-jet pilot and later a transformative leader specialising in generative AI. Jo will address the importance of The Power of Connection 2025, examining how trust, collaboration and innovation must be harnessed to build resilience and lasting change, in the fragmented world we see today.

What does it mean to “see” atoms? How have we reached a stage in which it is possible to perform microscopy down to the atomic level? And what do we learn by doing this? The fascinating story that will explain this involves a question that has long been debated in Oxford, dating back to the seventeenth century when Robert Hooke became one of the first practitioners of the optical microscope: is light a particle or a wave? In the twentieth century, physicists asked the same question of electrons. The modern microscopy techniques that will be described utilise an effect called tunnelling, in which particles can behave like ghostlike entities, passing through solid walls. It’s often described as a counter-intuitive quantum mechanical effect, but in fact originates in classical nineteenth century physics. Now these methods are being used to unravel the mysteries surrounding the newly discovered materials of the twenty-first century, whose behaviour is fundamentally quantum-mechanical.