Science

The universe follows the arrow of timeWavebreakmedia Ltd DW1802_1 / Alamy Where does time really come from? I am often asked this question after acquaintances or friends of friends learn that I am a physics reporter. There is not a set answer – but to better understand it, it helps to look at the arrow of time. Dating back to the 1920s, this concept stems from the laws of physics that describe energy, heat and entropy. Entropy is the big one, as time seems to move from low- to high-entropy states – this is the direction in which the “arrow of time” flies. Entropy gets a bad reputation for being about disorder, but the more precise way to think about it is to count how many ways something large – a macrostate – can be assembled from smaller constituent parts, or mi...

When we think of artificial intelligence (AI) and climate justice, we can imagine two stars in an orbital waltz; each with its own gravity, sometimes in harmony, while other times in tension. In moments of alignment, their fields reinforce each other, giving new vitality and perspective. Yet not all orbits are stable and the gravitational field of AI is growing at an accelerated pace. The ultimate danger we face is the potential for AI to swallow everything around it, much like a black hole.   AI has the potential to illuminate patterns in climate data, sharpen models and increase our chances to forecast an uncertain future. Yet there is a justified concern over the carbon footprint of big AI model training, the secrecy surrounding it, and the risk of exclusion—particularly with com...

Two graduating seniors from the Sustainable Development Class of 2025 were honored with the Gaffin Award this spring for their leadership and service on and off campus. The award commemorates Stuart Gaffin, who taught the Workshop in Sustainable Development from 2009 to 2019, and spotlights his contributions to the Columbia University community through the recognition of leadership, engagement, dedication and impact in the spirit of sustainable development. Harrison Gerson and Emine Taha have exemplified this spirit throughout their four years at Columbia, taking on educational leadership roles in the classroom, contributing to clubs across campus, and supporting and mentoring their peers through empathetic leadership and long-lasting contributions to the Sustainable Development (SDEV) ...

There is always a “look of indignation” on students’ faces when they first learn about quantum superposition, says physicist Marcelo Gleiser. He has taught quantum mechanics, the theory governing the microcosmic world of atoms and particles, for decades, and his students’ consternation inevitably emerges right on cue: when he reaches the part about quantum objects apparently being in several places at once. This story is part of our Concepts Special, in which we reveal how experts think about some of the most mind-blowing ideas in science. Read more here The trouble is that words like “apparently” crop up an awful lot around this topic. Indeed, in the century or so since the idea of superposition emerged, its true meaning has remained contested. The only thing physi...

A recent climate initiative by the Norwegian government is facing opposition from the Saami Indigenous people, whose territories are directly affected. The proposed 54-kilometer power line would be built by the state-owned energy company Equinor in the northernmost portion of the country, well above the Arctic Circle. The Saami believe their rights to cultural preservation and a healthy environment under international and domestic law have been violated because the power line may affect traditional reindeer herding. At least one group of herders is planning to take legal action.  Herding is a key practice among the Saami: It is central to their traditions and their livelihoods. Reindeer are a major source of meat for Saami, and they use antlers for traditional craft-making and fur for c...