Explanation of Key Scientific Topics |
Other topics:
Emergence |
QUANTUM MECHANICSQuantum Mechanics, discovered in 1925, has probably had a greater impact on human history than any other invention of the human mind. It is a theory which has explained every physical phenomenon it has been applied to, and which has shown no limits to its validity. The revolutionary advances in physics, astronomy, chemistry, and biology in the 20th century can be almost entirely attributed to quantum mechanics, as can the extraordinary developments in technology. Yet there is every reason to suppose that we have hardly used the resources of this theory so far, so that future changes will be far more striking.The irony is that the most powerful and successful theory in history is fundamentally mysterious to us. It involves concepts like (i) 'entanglement' (the formation of quantum states of composite systems, even when the individual members of the composite do not possess a definite state), or (ii) quantum superposition (in which a system that can exist in different states can also exist simultaneously in all of them). These features violate common sense, and yet are central to the theory- and are seen in labs every day, at the atomic scale. Thus quantum mechanics poses very deep philosophical questions about the nature of physical reality to which we have no answer at present. Until recently the strangest consequences of quantum mechanics had only been seen at the atomic and molecular levels. In the last 3 years experiments have found quantum superpositions in much larger 'superconducting quantum interference devices' (SQUID's for short). This has raised the extraordinary possibility of 'Schrodinger's Cat' states (this refers to Schrodinger's remark that quantum mechanics in principle allowed a Cat to be simultaneously in alive and dead states). The possibility of entangling the states of many different quantum systems has led to a large drive to build a 'quantum computer', and bizarre possibilities, like the 'quantum teleportation' of quantum states between 2 places, have already been achieved. It is virtually certain that the 21st century will end up being decisively influenced by the development and use of quantum mechanics. |
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Pacific Institute for Theoretical
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