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27. Natural Reality / B. Modern Physics / 2. Electrodynamics / d. Quantum mechanics

[particles are partly wave and partly particle]

13 ideas
Radiation interference needs waves, but radiation photoelectric effects needs particles [Heisenberg]
     Full Idea: How could it be that the same radiation that produces interference patterns, and therefore must consist of waves, also produces the photoelectric effect, and therefore must consist of moving particles.
     From: Werner Heisenberg (Physics and Philosophy [1958], 02)
Nobody understands quantum mechanics [Feynman]
     Full Idea: I think I can safely say the nobody understands quantum mechanics.
     From: Richard P. Feynman (The Character of Physical Law [1965], 6)
     A reaction: It is really important that philosophers grasp this point!
Uncertainty says that energy can be very high over very short time periods [Krauss]
     Full Idea: The Heisenberg Uncertainty Principle says that the uncertainty in the measured energy of a system is inversely proportional to the length of time over which you observe it. (This allow near infinite energy over very short times).
     From: Lawrence M. Krauss (A Universe from Nothing [2012], 04)
     A reaction: Apparently this brief energy is 'borrowed', and must be quickly repaid.
Quantum theory explains why nature is made up of units, such as elements [Watson]
     Full Idea: Planck's quantum idea explained so much, including the observation that the chemical world is made up of discrete units - the elements. Discrete elements implied fundamental units of matter that were themselves discrete (as Dalton had said).
     From: Peter Watson (Convergence [2016], 4 'Intro')
     A reaction: The atomic theory was only finally confirmed by Einstein in 1905. This idea implies that the very lowest level of all must have distinct building blocks, but so far we have got down to 'fields', which seem to be a sort of 'foam'.
The Schrödinger waves are just the maths of transforming energy values to positions [Farmelo]
     Full Idea: Dirac showed that the Schrödinger waves were simply the mathematical quantities involved in transforming the description of a quantum based on its energy values to one based on possible values of its position.
     From: Graham Farmelo (The Strangest Man [2009], 08)
     A reaction: Does this eliminate actual physical 'waves' from the theory?
Uncertainty allows very brief violations of energy conservation - even shorter with higher energies [Martin,BR]
     Full Idea: The uncertainty principle states that energy conservation can be violated, but only for a limited period of time. As the energy violation increases, the time period within which 'borrowed' energy has to be 'paid back' decreases.
     From: Brian R. Martin (Particle Physics [2011], 01)
     A reaction: This is the only reason modern physicists ever seem to mention the uncertainty principle. You can ask why this debt must be paid, but it seems to be hidden where the laws of physics may not even apply.
The Exclusion Principle says no two fermions occupy the same state, with the same numbers [Martin,BR]
     Full Idea: The 'exclusion principle' initially stated that no two electrons in a system could simultaneously occupy the same quantum state and thus have the same set of quantum numbers. The principle actually applies to all fermions, but not to bosons.
     From: Brian R. Martin (Particle Physics [2011], 02)
     A reaction: This principle is said to be at the root of atomic structure, making each element unique. What exactly is a 'system'? Why does this principle hold? How do you ensure two women don't wear the same dress at a party?
The Schrödinger equation describes the evolution of an object's wave function in Hilbert space [New Sci.]
     Full Idea: A quantum object's state is described by a wave function living in Hilbert space, encompassing all of its possible states. We see how the wave function evolves in time, moving from one state to another, using the Schrödinger equation.
     From: New Scientist writers (New Scientist articles [2013], 2013.06.15)
     A reaction: [These idea are basic explanations for non-scientific philosophers - please forgive anything that makes you wince]
Quantum states are measured by external time, of unknown origin [New Sci.]
     Full Idea: When we measure the evolution of a quantum state, it is to the beat of an external timepiece of unknown provenance.
     From: New Scientist writers (New Scientist articles [2013], 2013.06.15)
     A reaction: It is best not to leap to philosophical conclusions when studying modern physics. Evidently time has a very different status in quantum mechanics and in relativity theory.
Quantum Theory describes events and possible interactions - not how things are [Rovelli]
     Full Idea: Quantum Theory does not describe things as they are: it describes how things occur and interact with each other. It doesn't describe where there is a particle but how it shows itself to others. The world of existence is reduced to possible interactions.
     From: Carlo Rovelli (Reality is Not What it Seems [2014], 04)
     A reaction: Fans of 'process philosophy' should like this, though he is not denying that there may be facts about how things are - it is just that this is not mentioned in the theory. There is not much point in philosophers yearning to know the reality.
Quantum mechanics is our only theory, and is very precise, and repeatedly confirmed [Hesketh]
     Full Idea: Quantum mechanics is the only working description of the universe that we have. It is amazingly precise, and so far every experimental test has verified its predictions.
     From: Gavin Hesketh (The Particle Zoo [2016], 02)
     A reaction: I take it from this that quantum mechanics is simply TRUE. Get over it! It will never turn out to be wrong, but may be subsumed within some more fine-grained or extensive theory.
Physics was rewritten to explain stable electron orbits [Hesketh]
     Full Idea: Explaining the stable electron orbits would require a complete rewriting of the physics of subatomic particles.
     From: Gavin Hesketh (The Particle Zoo [2016], 03)
     A reaction: This really looks like a simple and major landmark moment. You can ignore a single anomaly, but not a central feature of your entire theory.
Virtual particles can't be measured, and can ignore the laws of physics [Hesketh]
     Full Idea: We can never measure these virtual (transitory) particles directly, and it turns out that they don't even have to obey the laws of physics.
     From: Gavin Hesketh (The Particle Zoo [2016], 05)
     A reaction: These seems to be the real significance of the Uncertainty Principle. Such particles 'borrow' huge amounts of energy for very short times.