Saturday, June 21, 2008

Does god know Quantum mechanics

Richard asks the question "does god know about quantum mechanics?"
the argument goes like this

One of the strangest things that we have found out about it over the last thirty years or so is that if there is a way for us to know the path that the photon actually takes, and so determine which slit it actually travels through, then the interference pattern no longer manifests. What we get is ‘nothing but us particles down hir sir’. In Green’s book The Fabric of the Cosmos he details experiments he calls ‘quantuum erasures’ where they showed that what matters is whether someone could know the path taken by the photon. Tis is obviously extremely strange and anti-common sense, but it is a robust experimental finding. But now consider God. If He knows the path that the photon takes then it will not act like a wave. It will act like a particle. So from God’s point of view particle physics has to be correct. Since He is always holding the door of the refrigerator open, metaphorically speaking, the light inside will always be on. But this really reduces to the first option in claiming that God can’t have any direct knowledge of quantuum physics.

Sounds reasonable - but the problem is that that most modern physisists don't agree that this

what matters is whether someone could know the path taken by the photon.

is an accurate way to describe what is going on.

What IS going on is quite complex and its possible I don't have the writing skills to describe it in an eloquent way but...

The model proposed is an approximation as is any model I propose here - however some models are better than others. the former model is wrong in that
A) decoherence is caused not only by minds but by ANY complex system.
B) decoherence is a gradual change not something that is 'on" or "off"

First regarding A - Quantum mechanics refers to systems. So lets say a cat in a pefect box observes a light flash as a result of a photon movement - he makes that movement coherent in regard to himself but not me unless I open the box. Now I can still open the box and find the cat that observed the light flash or the one that didn't. It all depends on my perspective. This isn't all that strange, it is just some more relativity.

More scientifically - possible outcomes 'interfere' with each other if the resulting situations are similar. So if I fire a photon through a slit experiment the two possibilities have almost the minimum amount of difference and so there is a lot of interference between them. But if someone observes the evidence of the particle going through one slit as part of an experiment (prior to the photons hitting the target behind the slits) and he yells "it went through the left slit!" that creates a massive difference between the possible worlds. they cant interfere anymore because they are in a sense displaced from each other. The leading model to explain this is probably the 'multiple universe model' in this model every option is 'real' and much of what we consider magical about decoherence is related to how WE are being decohered in relation to the photons.

regarding B - decoherence is just a matter of how easily those worlds can interfere. Every 'world' interferes with every other - just some do so to an almost infinitely small degree because they are so dissimilar or because the options they represent are so unlikely.

So how does this relate to God? And under what situation would he cause decoherence in a photon?
Well first god would need to be able to be significantly different to what he is now. If that was not possible then there would be no decoherence as a result of him. That seems possible but is already at odds with theories that suggest he is by definition perfect.

Second - it needs to be possible to have a greater wave function than god - ie god plus the photon. again the sort of thin some theories might deny.

third - because decoherence relies to how different two possible worlds are he would need to be changed by the experiment. So God needs to be the sort of god that might for example be undesided whether to use Moses or Bob as his prophet, and then on observing a photon confirm that Moses is his man. Further this implies that the uncertain god is a decoherent mixture of possible gods. I don't think that matches with the usual perception of 'god' (although I'm not saying it is impossible).

Forth - god needs to be somehow locked into OUR universe for us to observe his decoherence. Just like the cat in the box unless god decoheres himself to us his decoherence of the photon doesn't matter to us. (in this case most theologists would probably suggest he IS decohered to us)

Simply - God has a number of special traits that mean I wouldn’t expect him to cause decoherence in accordance with modern quantum physics theory.

I expect the average theologist quantum physicist would go with the following

If there are multiple universes he sees them all, if there are not multiple universes that fact that there is only one possible god (in the sense of quantum physics) places God above quantum physics - so he see the world 'as it is' and doesn't observe/cause decoherence.


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