An Alternative to One-Size-Fits-All Gravity
Some physicists believe that dark matter may not be a form of matter after all. Instead, they think evidence for the mysterious particle can be explained better by altering our theory of gravity. Matt O'Dowd gives a tour through the evolution of increasingly elaborate theories of modified Newtonian dynamics (MOND) for PBS Space Time. Last year, Charlie Wood wrote for Quanta about a new one of those alternatives called "relativistic modified Newtonian dynamics" (RelMOND), in which gravity's behavior changes on different size scales. As he explained, it has held up to an empirical test that earlier MOND theories failed. The peculiar nature of gravity makes our currently best description of it, Einstein's general relativity, an easy target for critics. In 2020 Natalie Wolchover wrote for Quanta about what makes gravity different from the other three fundamental forces and why it's so hard to understand.
An Order of Eggs
A Silicon Valley company is trying to rewrite the rules of reproduction: It plans to reprogram mature human blood cells to make eggs and sperms for people who can't otherwise conceive, Antonio Regalado reports for MIT Technology Review. Mature tissue cells sometimes show an unexpected ability to become less specialized and transform into something like stem cells. In 2018 Jordana Cepelewicz wrote for Quanta about our cells' ability to heal wounds by turning back their physiological clock to a more fetal state. | |
