On 26 October 2002, two days before closing a deal to purchase Twitter for US$44 billion (A$61.4 billion), Elon Musk walked into its San Francisco headquarters carrying a white porcelain sink. He walked up to an unattended front desk in the lobby and said, to no one: ‘You can’t help but let that sink in.’ Of course, he didn’t really say this to no one. His triumphant entrance at Twitter HQ was staged, the video shared with his 120 million Twitter followers, with the phrase: ‘Let That Sink In!’

Reading a book about online polarisation is a bit like reading a murder mystery novel where the murderer is revealed on page one. We all know it was social media, on our devices, with the trolls, in the bedroom. What we don’t know is the human cost of our newly fragmented online world: the lives destroyed, the families torn apart, the friends permanently estranged when someone falls down an online rabbit hole.