If this theory is true, quantum mechanics might be more fundamental to the structure of the universe than gravity itself.
Scientists have been trying to reconcile the differences between the two for years. Since the days of Einstein, they have toiled over the confusing contradictions between the macroscopic realm (governed by gravity and Newtonian laws) and the quantum universe, which rules the behavior of the super-small. Some experts have tried to bridge the chasm between quantum mechanics and gravity by introducing a concept they call “ quantum gravity ,” which states that gravity is wrapped up in tiny packets—or quanta. But this theory has its limitations, and physicists are still searching for other explanations.
A sticky point in quantum mechanics is that it requires an “observer” of some kind—whether conscious human or not, it’s unclear—to collapse what’s called a wavefunction (a collection of probabilities) into a single reality. Physicists are using a particular feature of a workaround to this problem as a way to finally merge quantum mechanics and gravity.
Here’s Anil Ananthaswamy, reporting for New Scientist:
One solution to such paradoxes is a so-called GRW model that was developed in the late 1980s. It incorporates “flashes,” which are spontaneous random collapses of the wave function of quantum systems. The outcome is exactly as if there were measurements being made, but without explicit observers.
Tilloy has modified this model to show how it can lead to a theory of gravity. In his model, when a flash collapses a wave function and causes a particle to be in one place, it creates a gravitational field at that instant in space-time. A massive quantum system with a large number of particles is subject to numerous flashes, and the result is a fluctuating gravitational field.
The average of these fluctuations is a gravitational field that is consistent with Newton’s theory of gravity. In this model, gravity is born out of quantum mechanics, but is not in itself a quantum-mechanical force. It is what scientists call “semiclassical.” Until this theory is tested further, it will remain a semi-solution; while the idea does predict certain known phenomena, it doesn’t yet account for Einstein’s theory of general relativity.
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