Other topics:
Emergence
Strings
Gravity and Cosmology
Condensed Matter Physics
Nanoscience
Quantum Mechanics
Elementary Particles
Quantum Fluids
EMERGENCEPhysicists and biologists talk about the 'emergence' of properties, in complex physical systems, that are not apparently connected with the underlying laws and mechanisms governing these systems. The most dramatic emergent property is LIFE. Other emergent phenomena that are widely discussed include the emergence of spacetime from some more fundamental theory like string theory, the emergence of classical physics from quantum mechanics, and the emergence of ordered structures in otherwise chaotic systems. Some emergent phenomena depend in an essential way on quantum mechanics (eg., superfluidity).Before modern science it was widely believed that things like life demanded non-physical explanations (eg., a 'vital force', or some other supernatural or superhuman cause). Now the pendulum has swung the other way- most modern scientific explanations are 'reductionist', ie., they aim to explain everything in terms of fundamental building blocks and the laws governing their interactions. Thus, eg., life is explained in terms of molecular building blocks and complex structures formed by these, and the emergence of classical physics from quantum physics is supposedly explained by 'decoherence'. However this 'lego block' approach to Nature has certain problems. Scientists have to invent 'effective theories' to explain emergent phenomena, and it is sometimes impossible to connect these with the building blocks. Moreover, Quantum Mechanics itself seems to contain emergent features, particularly those connected with 'entanglement'. The 'reductionism vs emergence' debate, with highly publicised contributions opposing Anderson vs Weinberg, may be the most important philosophical dedate in science today. |
    
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