Is gravity quantum in nature, just like all the other particles and forces? Or is it fundamentally different? For nearly a century, physicists have attempted to define gravity using the framework of quantum mechanics. But it turns out that “quantizing” gravity leads to some thorny dead ends.
To chart a path forward, the physicist Jonathan Oppenheim and his students have proposed a different idea: What if gravity simply can’t be quantized?
Building on work from the 1990s, Oppenheim’s theory keeps gravity classical and then searches for a way to couple the quantum and classical realms.
Such hybrid theories could solve long-standing problems in physics. But they also lead to a conclusion that many physicists may find unsettling: the universe is deeply random.
To make his point, Oppenheim made a bet with two quantum gravity researchers that he’s right. Upcoming experiments could determine the winner of the bet.