September/October 2025

For the perfect dinner party, the best number of guests is a multiple of four. That is because four is the maximum number of people who can maintain a successful conversation, according to an expert on social interaction. The rule of four is seen in Shakespeare plays, the first Sex and the City film, with its four female best friend characters, and even the rom-com Love Actually. Professor Robin Dunbar, who highlights the conversation number limit in his recent book The Social Brain, has seen it repeatedly in groups of people, everywhere from the park to the pub, when people in these settings were studied. He says we can only keep in mind five people's mental states at once, including our own.

In July 2017, Google engineer James Damore distributed a memorandum titled "Google's Ideological Echo Chamber," which was critical of Google's diversity policies. The memo "went viral" and was widely distributed inside and outside of Google, leading to extensive media discussions. In August 2017, Google fired Damore for violation of the company's code of conduct. The U.S. National Labor Relations Board concluded that Google did not violate U.S. federal labor law when it fired Damore, but Damore filed a lawsuit against Google for discrimination. The memo's central argument was that the gender disparity observed in the tech industry in general, and in Google in particular, could be partially explained by biological differences between women and men.

The past year has been a momentous one for science and technology. From the detection of gravitational waves (predicted almost a century ago by Einstein) to the rise of virtual currencies like Bitcoin to the creation of genetically modified human embryos, 2017 was marked by all sorts of remarkable discoveries and innovations. No one knows for sure. But as we did for 2017, we asked top scientists and thought leaders in innovation what they expect to see in the new year. Here, lightly edited, are their predictions. Dr. Sean Carroll is a theoretical physicist at the California Institute of Technology in Pasadena.

Are you looking for a book to help you navigate through the extraordinary changes that technology is bringing to our world? Change is a constant in life. Take a quick skim through these four books that help you better understand how artificial intelligence, blockchain, cognitive computing and robotics can impact your life.