The sidewalk outside Majed Zeidan's grocery store in San Francisco's Mission District has stayed filled with flowers, candles, memorials and pictures since his cat was crushed under a Waymo in late October. A month later, a Waymo reportedly crushed a dog. Amid the pictures of the cat, a visitor had placed a poster that said, "save the cat, kill the car". That's when Zeidan knew Kit Kat, his bodega cat, had become the face of the simmering discontent over San Francisco's growing number of self-driving cars. Residents became increasingly comfortable riding one, costumed Halloween parade goers clambered on its rooftops and danced, and pedestrians occasionally banged its bonnet to get it to give way to them.

A Waymo car went up in flames in San Francisco's Chinatown after a crowd surrounded it, scrawled graffiti, smashed windows and then threw a firework inside the driverless vehicle in the middle of a crowded street Saturday night. Nobody was in the car and no injuries were reported, police and company officials said. The San Francisco Fire Department was called to the scene about 9 p.m. in the 700 block of Jackson Street, authorities said. Chinatown was bustling as people celebrated Lunar New Year. Videos posted on social media by software engineer Michael Vandi show someone using a skateboard to crush the white Jaguar's windows as the car's rooftop sensors continued to turn.

Despite their incorporeal form, memories have a way of becoming a very real part of our identity, like the pattern of freckles on your face or your favorite jacket might. Remembering a childhood friend while gazing off at a field of dandelions may be pleasant, but being sucked back into a bad memory -- a difficult breakup or a traumatizing loss -- can be unbearable. But what if, a la Eternal Sunshine of the Spotless Mind, we could simply erase those memories? It's something being explored, but Philipp Kellmeyer, a neurologist and head of the Neuroethics & A.I. Ethics Lab at the University of Freiburg, has several concerns. High among them is identity.