For those of us who pay attention to quantum mechanics comes a possible solution to the conundrum of observation. Speaking as a simple software engineer, it has never made sense to say that for some (very small) entity, its various attributes do not have set values until it comes under observation. This is known as the Copenhagen interpretation:
… it says that a particle’s state before observation is fundamentally, intrinsically, insurmountably uncertain. If the wave function says a particle could be here and there, then it really is here and there, however hard that is to fathom in terms of everyday experience. Only the act of looking at a quantum object “collapses” its wave function, jolting it from a shadowy netherworld into definite reality.
Not only is it intuitively puzzling, it also leaves open important questions concerning how the Universe ever got started. I’ve given some thought to the possibility that, if true, it might constitute a clue as to whether we’re in a computer simulation, and this is an artifact of late resolution of “reality”, but it’s hard to see my way to really believing that.
And now perhaps that won’t be necessary. From NewScientist (16 July 2016, paywall) comes a longish article on the work of Daniel Sudarsky of National Autonomous University of Mexico (UNAM), who is extending a theory from the 1970s:
… Sudarsky began with a third option: that wave functions are real things and do indeed collapse – but randomly, by themselves. “Something like a measurement occurs, but without anybody actually measuring,” says Sudarsky. It doesn’t need a human observer, so this process is known as an objective collapse.
Objective collapse would be rare, but catching. Wait for a single particle’s wave function to collapse and you could be waiting longer than the age of the universe. Group many particles together, however, and the chance swiftly escalates. With a few billion particles, you might only have to wait a few seconds for one wave function to collapse – and for that to set the rest off.
Objective collapse theory was first put forward in the 1970s by Philip Pearle at Hamilton College in New York, and later refined by Giancarlo Ghirardi and Tulio Weber at the University of Trieste and Alberto Rimini at the University of Pavia, Italy. Their goal was to tweak Schrödinger’s equation so that the wave function evolves naturally, without an observer, from a mix of states into a single, well-defined state. To do so, they added a couple of extra mathematical terms: a non-linear term, which rapidly promotes one state at the expense of others, and a stochastic term, which makes that happen at random.
At least superficially, these tweaks can explain quite a lot that’s inexplicable about quantum theory. We never see ghostly quantum effects in large objects such as cats or the moon because, with so many interacting particles, their wave functions readily collapse or else never form. And in the early universe, as Sudarsky and physicist-philosopher Elias Okon, also at UNAM, showed a decade ago, it was only a matter of time before the wave functions of matter collapsed into an uneven distribution from which stars and galaxies could form, God or no God.
All still tentative, but it’s good to see someone takes my intuitive unease seriously and is investigating an alternative to one of the most successful scientific theories ever.
