After watching the controversy around the recent Nature article on Wheeler's delayed choice experiment (attached below), I've come to the final realization that I truly don't understand classical physics and how the particle perspective on measurement has anything to do with quantum mechanics. At all.
This delayed thought experiment clearly demonstrates that the particle does not "make a decision" before going one way or another; it goes both ways, as a wave, before collapsing as much as it is measured.
In field theory, it's even more odd; we can clearly predict the breakdown of fundamental particles into other "fundamental" particles, which, if we think in terms of particles, is clearly contradictory! The only reason we describe particles as particles, in either quantum mechanics or field theory, is because of quantization.
So I guess my question is: Are there really examples out there where we should be using the term particle, and thinking of it philosophically in that manner, at all? Or should we just stop doing so entirely?
http://www.nature.com/nphys/journal/vaop/ncurrent/full/nphys3343.html
It is way too simple solution to "wave-particle dualism". It is nihilistic solution: no particles, just waves. Have you heard about David Bohm's interpretation of quantum effects? He has the particles, which are driven by the "quantum potential".
It's an optical and perhaps physical imagination. It comes from the experience that atoms consist of smaller particles like electrons, protons and neutrons.
On Quantum Level we started with mathematical encountering and till now about 8 different theories. We don't know exact facts because we have no possibility to measure these quants - as particles - because the measurement influences the result.
So all theories in QM are positioned on mathematical theories with methods of probabilities and statistics.
We shouldn't speak of "mechanics". We - in sharpest way - can call it Qantum "Physics". But even this topic is not perfect because we have defined already terms (logical objects) without "physis" (f.i. Photons).
It's true. It is. I guess I'm just trying to reconcile the quantum informatic background I have with the field theories I'm now learning.
As far as I understand, Bohm's interpretation of quantum mechanics would be dual to the computational output of a physical realization of a quantum computer; the most probable thing in terms of states is what comes out the other end.
I no longer really see particles as fundamental things anymore, I just see quanta as informatic states, and state evolution as gate operations. In a field theory though, gate operations are hard to see through a path integral. Not sure how to tackle it.
It would be great to model the entire system as waves, and think of the waveform evolution as state progression; any sort of quanta may not immediately be in another, distinct state, but grow to it through a series of slow operations from other states. It might be that we are seeing a state which is actually a mixed state, in which case our particle is actually composite.
This would also be powerful because it could enable a new kind of solid state computing. But we stick with the particle model, most often ignoring the identities & shapes of individual waveforms. This, I suppose, is why I'm uncomfortable with the traditional particle perspective.
Yes, When we think of 'particles' or 'waves' we are thinking of concepts or the models we use to describe and explore 'particle-like entities' and 'wave-like' entities in physics.
As for the "collapse", our understanding is refined by the concept of quantum decoherence - when a quantum system is not perfectly isolated, but in contact with its surroundings, the coherence decays with time - a process called quantum decoherence.
And by the way - the robot doesn't require a human observer for collapse - as mentioned in the above sentence decoherence (and ulitmately collapse) are caused by interactions between the robot and its surroundings.
Dear Henry,
thanks for your sentence :"gate operations are hard to see through a path integral. Not sure how to tackle it".
Would like to enforce this "gate" as human-created and therefor chemically-physically in last time not yet found real fact. If you use an integral as mathematical tool then you enter the opposite direction of differentiation till an "imagined continuum without leaks". But a gate is imagined as physical entity steered by "steps" of what else (f.i. electrical energy).
The great chance for this is founded in Einsteins and others term "quant" as physical smallest entity. 100 year after his and Planck's time we can be sure that this term "quant" can be defined as "set of all particles and energetic singularities smaller then atoms". The relations are much more complex then we could imagine 100 years ago - of course.
Genuine mathematically for gates BOOLs Algebra and Quantum Information Theory is recommendable. Even the intention to rebuild these complex quantum mix by the logical tool "superposition" is not clear and finally definable. The "collapse by measuring" is - for me - not yet usable for further definitive and later commercial purposes.
But "something" seems to be inside in Quantum Physics and Computing which may come to reality.
Besides: Do you have an Open Source version of your Link in your question?
Thanks if so!
- Badges
- Science topic
- Similar topics
- Elementary Particle Physics
- Particle