Quantum mechanics questions the fundamental nature of reality - Toys Matrix

At its roots, reality is described by the mysterious set of mathematical rules known as quantum mechanics.

Conceived at the turn of the 20th century and then emerging in its full form in the mid-1920s, quantum mechanics is the math that explains matter.

It’s the theory for describing the physics of the microworld, where atoms and molecules interact to generate the world of human experience.

But quantum theory taught scientists much more than how to make computer chips.

It’s plausible, Carroll argues, that this quantum realm of mathematical possibilities represents the true, fundamental nature of reality.

In fact, a fair reading of history suggests that quantum theory is the most dramatic shift in science’s conception of reality since the ancient Greeks deposed mythological explanations of natural phenomena in favor of logic and reason.

With aid from German physicists Max Born and Pascual Jordan, Heisenberg’s math became known as matrix mechanics.

Schrödinger’s “wave mechanics” turned out to be mathematically equivalent to Heisenberg’s particle-based approach, and “quantum mechanics” became the general term for the math describing all subatomic systems.

In that year, Einstein, with collaborators Nathan Rosen and Boris Podolsky, described a thought experiment supposedly showing that quantum mechanics could not be a complete theory of reality.

In a brief summary in Science News Letter in May 1935, Podolsky explained that a complete theory must include a mathematical “counterpart for every element of the physical world.” In other words, there should be a quantum wave function for the properties of every physical system.

Yet if two physical systems, each described by a wave function, interact and then fly apart, “quantum mechanics … does not enable us to calculate the wave function of each physical system after the separation.” (In technical terms, the two systems become “entangled,” a term coined by Schrödinger.) So quantum math cannot describe all elements of reality and is therefore incomplete.

He declared that Einstein and colleagues’ criterion for physical reality was ambiguous in quantum systems.

Quantum mechanics, Bohr explained, preserved different possible values for a particle’s properties until one of them was measured.

In the early 1950s physicist David Bohm developed such a theory of “hidden variables” that restored determinism to quantum physics, but made no predictions that differed from the standard quantum mechanics math.

Beginning in the 1970s, and continuing to today, experiment after experiment confirmed the standard quantum mechanical predictions.

Still, many physicists expressed discomfort with Bohr’s view (commonly referred to as the Copenhagen interpretation of quantum mechanics).

He insisted that an experiment did not create one reality from the many quantum possibilities, but rather identified only one branch of reality.

Some emphasize the “reality” of the wave function, the mathematical expression used for predicting the odds of different possibilities.

Others emphasize the role of the math as describing the knowledge about reality accessible to experimenters.

Scientists continue to grapple with what quantum math means for the very nature of reality.

In the 1990s, the quest for quantum clarity took a new turn with the rise of quantum information theory.

Physicist John Archibald Wheeler, a disciple of Bohr, had long emphasized that specific realities emerged from the fog of quantum possibilities by irreversible amplifications — such as an electron definitely establishing its location by leaving a mark after hitting a detector.

Answers corresponded to bits of information, the 1s and 0s used by computers.

Taking the analogy further, one of Wheeler’s former students, Benjamin Schumacher, devised the notion of a quantum version of the classical bit of information.

Schumacher’s qubit provided a basis for building computers that could process quantum information.

In 1994, mathematician Peter Shor showed how a quantum computer manipulating qubits could crack the toughest secret codes, launching a quest to design and build quantum computers capable of that and other clever computing feats.

By the early 21st century, rudimentary quantum computers had been built; the latest versions can perform some computing tasks but are not powerful enough yet to make current cryptography methods obsolete.

For certain types of problems, though, quantum computing may soon achieve superiority over standard computers.

Deutsch believed that quantum computers would support the many worlds view.

And decades of quantum experiments have not provided any support for novel interpretations — all the results comply with the traditional quantum mechanics expectations.

Quantum systems preserve different values for certain properties until one is measured, just as Bohr insisted.

But nobody is completely satisfied, perhaps because the 20th century’s other pillar of fundamental physics, Einstein’s theory of gravity (general relativity), does not fit in quantum theory’s framework.

If so, the mysterious behavior of the quantum world defies understanding in terms of ordinary events in space and time because quantum reality creates spacetime, rather than occupying it.

Three centuries later quantum physics revolutionized science’s grasp of reality to a comparable extent.