BBC: Representatives from some 170 countries are meeting today at the United Nations headquarters in New York to sign the Paris climate agreement. Formalized in December 2015 following last year’s international conference on climate change, the agreement furthers the efforts of the United Nations Framework Convention on Climate Change, an international treaty enacted in 1994 and aimed at stabilizing atmospheric greenhouse gas emissions. One of the provisions of the Paris agreement is to limit global temperature rise to 2 °C above pre-industrial levels. Although 10 nations have already ratified it, dozens more need to do so. The process is expected to take some time because the agreement can only enter into force if approval comes from at least 55 countries that produce at least 55% of global greenhouse gas emissions.
An ultracold atomic gas can sync into a single quantum state. Researchers uncovered a speed limit for the process that has implications for quantum computing and the evolution of the early universe.