Exercise Slows Cancer Growth, 3I Atlas Comet Chemistry, and a Bohr-Einstein Quantum Test | World, the Universe and Us

The latest World, the Universe and Us episode from New Scientist investigates three front-line science stories. First, a mouse study suggests exercising muscles may outcompete cancer for glucose, potentially slowing tumour growth and highlighting metabolic and microbiome pathways. Second, data from the interstellar comet 3I Atlas point to unusual levels of carbon dioxide, methanol, and other carbon-bearing species, offering clues about prebiotic molecular reservoirs in other star systems. Third, researchers perform a cutting edge quantum experiment that experimentally probes the Bohr-Einstein debate on wave-particle duality using a single photon and a movable atomic slit, reinforcing Bohr’s complementarity with unprecedented precision.

Overview

This episode weaves together three distinct science threads: cancer biology and exercise, astrochemistry from a recently observed interstellar object, and a fundamental quantum mechanics experiment that revisits a famous Einstein-Bohr disagreement. Each segment distills new data, careful interpretation, and the potential implications for future research and public understanding of science.

Exercise and Cancer: Metabolic Competition in Mice

In a mouse model of breast cancer, researchers allowed 18 mice to choose their activity level on running wheels for four weeks. Obese mice that exercised showed 60% smaller tumours than sedentary peers, with exercise also reducing tumour size relative to non-obese controls. The mechanism appears to be metabolic: exercise increases glucose uptake in skeletal and cardiac muscles and decreases uptake by tumours, effectively outcompeting cancer cells for glucose. Gene expression analyses revealed hundreds of metabolic genes altered by exercise, and an important growth signalling protein MTOR was downregulated, which may further slow tumour progression. While the work is preliminary and in mice, the metabolic parallels across mammals offer a plausible pathway for similar effects in humans, though real-world exercise regimens would need medical guidance in cancer patients.

3I Atlas: Clues from an Interstellar Comet

Astronomers have studied the comet 3I Atlas using JWST, Hubble, and other facilities. The object displays a coma with unusual chemistry, including high carbon dioxide levels compared with typical solar system comets, abundant methanol, hydrogen cyanide, and even traces of nickel vapour. The observing team interprets these signals as reflecting the comet’s interior composition, heated and released as it approaches the Sun. Inferences drawn from methanol and other molecules hint that other star systems could host different prebiotic inventories than our own, potentially influencing the likelihood of life elsewhere. The discussion also touches on broader debates about the origin of life and whether complex organic molecules are common across space, as well as how these observations relate to earlier findings from asteroid samples like Bennu.

Bohr-Einstein Quantum Test: A Century Later

The episode closes with a groundbreaking experiment that finally tests a 1927 Bohr-Einstein proposal using modern technology. A single atom acts as a movable slit on springs, allowing precise control of momentum, while a single photon reveals interference patterns. The results reaffirm Bohr’s complementarity: measuring momentum to determine which path a photon takes destroys the interference pattern, while allowing some information about recoil reveals a nuanced, intermediate regime where wave and particle aspects coexist. Although the experiment confirms established quantum principles, conducting it at the ultimate quantum limit represents a remarkable technical achievement and a mind-bending demonstration of fundamental physics.

Context and Takeaways

Across these segments, the programme emphasizes how small, carefully designed experiments in animals, space chemistry, and quantum optics can illuminate broad questions about health, life’s origins, and the nature of reality. The researchers underscore that while mouse data do not translate directly to clinical recommendations, they point to achievable activity levels that could complement cancer care in the future, under appropriate medical supervision. The astrochemical findings from 3I Atlas remind us that prebiotic chemistry may be more widespread than previously thought, raising exciting possibilities about life beyond Earth. The Bohr-Einstein experiment demonstrates the power of modern instrumentation to probe classic theoretical debates, reinforcing the wave-particle duality framework that underpins quantum theory. Altogether, the episode showcases how diverse STEM fields converge on the same scientific goal: understanding complex systems through measurable, testable mechanisms and data-driven interpretation.