Science

Ryan wills/istock/Amtitus When Seth Lloyd first published his ideas about quantum time loops, he hadn’t considered all the consequences. For one thing, he hadn’t anticipated the countless emails he would get from would-be time travellers asking for his help. If he could have his time over again, he jokes, he “probably wouldn’t have done it”. Sadly, Lloyd, a physicist at the Massachusetts Institute of Technology, won’t be revisiting years gone by. Spoiler alert: no one will go back in time during the course of this article. But particles? That is another matter. Theoretical routes to the past called time loops have long been hypothesised by physicists. But because they are plagued by impracticalities and paradoxes, they have been dismissed as impossible for just as long...

Sheila Foster, Columbia Climate School visiting professor of climate and Georgetown University professor of law and public policy, has been elected as a fellow to the American College of Environmental Lawyers in recognition of her career achievements, thought leadership and significant contributions to the field of environmental law. Foster is a distinguished scholar of environmental and climate justice. Her research spans a wide range of topics, including land-use policy, innovative resource governance regimes and the role of subnational governments and local leaders in addressing cross-border challenges such as climate change. “Receiving the fellowship was quite a surprise, as it recognizes lawyers who are renowned in the field of environmental law, like Michael Gerrard and Mi...

If you take even a passing interest in artificial intelligence, you will inevitably have come across the notion of artificial general intelligence. AGI, as it is often known, has ascended to buzzword status over the past few years as AI has exploded into the public consciousness on the back of the success of large language models (LLMs), a form of AI that powers chatbots such as ChatGPT. That is largely because AGI has become a lodestar for the companies at the vanguard of this type of technology. ChatGPT creator OpenAI, for example, states that its mission is “to ensure that artificial general intelligence benefits all of humanity”. Governments, too, have become obsessed with the opportunities AGI might present, as well as possible existential threats, while the medi...

It can be hard to wrap our minds round the very large and the very small. Ron Koeberer/Millennium Images, UK Imagine setting off on a spacecraft that can travel at the speed of light. You won’t get far. Even making it to the other side of the Milky Way would take 100,000 years. It is another 2.5 million years to Andromeda, our nearest galactic neighbour. And there are some 2 trillion galaxies beyond that. The vastness of the cosmos defies comprehension. And yet, at the fundamental level, it is made of tiny particles.”It is a bit of a foreign country – both the small and the very big,” says particle physicist Alan Barr at the University of Oxford. “I don’t think you ever really understand it, you just get used to it.” Still, you need to have some grasp of scale to have ...