The first third of the 20th century saw the collapse of many absolutes. Albert Einstein's 1905 special relativity theory eliminated the notion of absolute time, while Kurt Gödel's 1931 incompleteness theorem questioned the notion of absolute mathematical truth. Most profoundly, however, quantum mechanics raised doubts on the notion of absolute objective reality. Is Schrödinger's cat dead or alive? Nearly 100 years after quantum mechanics was introduced, scientists still are not in full agreement on what it means.This is wrong on many levels. Relativity did not eliminate absolute. It just clarified it. Einstein added nothing to our understanding of time. Goedel remained a firm believer in absolute mathematical truth.
The problem with objective reality stems from the superposition principle. In a nutshell, quantum systems can exist in a superposition of their possible observable states before measurement. While a classical bit has a unique value, 0 or 1, a quantum bit, or qubit, exists as a superposition of two classical bits.
Saying that Schroedinger's cat is dead and alive at the same time is just another bit of bad philosophy.
Superpositions do not really create a problem with objective reality. Just saying that two measurements are possible does not mean that none are real.
In fact, several quantum-computing researchers have expressed skepticism regarding the physical realizability of the quantum-computing dream.a Quantum skeptics agree that quantum computation does offer an exponential advantage of classical computation in theory, but they argue it is not physically possible to build scalable quantum computers. Gil Kalai is one of the most prominent quantum skeptics. All physical systems are noisy, he argues,b and qubits kept in highly sensitive superpositions will inevitably be corrupted by any interaction with the outside world. In contrast, quantum-skepticism skeptics, such as Scott Aaronson, view the realizability of quantum computing as an outstanding question in physics,c and regard the skeptical view as representing an implausible revolution in physics.Aaronson is professionally invested in the possibility of quantum computing. There are good scientific reasons for skepticism about quantum computing, both in theory and in practice.
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