Where exactly does the quantum world end and concrete reality begin?
One of the quietest places in the universe is an unremarkable room on the southern coast of the UK. Here, in one of the University of Southampton’s physics labs, overseen by Hendrik Ulbricht, a preposterous amount of effort has gone into eliminating every conceivable disturbance: a 1-tonne slab of granite absorbs all vibrations aside from the faintest tremors, while a pendulum repurposed from a gravitational wave observatory catches the last leftover wobbles and a fridge lowers temperatures to within a whisker of those in the deepest reaches of outer space. All of this is done in the slim hope we might answer a question that has plagued scientists since the advent of quantum mechanics a century ago.
In the microscopic quantum realm, reality seems to work differently t...