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Archive for June, 2011

I have a problem with Fenyman’s sum over histories and the buckyball twin slit experiment. Well, I have several problems, the worst of which is being far too stupid to understand what it’s all about, but that is not what I want to explore here. No, the topic for discussion today is observation.

 

As I understand it, a C-60 molecule buckyball is fired at a screen with two slits in it and hits a screen behind. Due to the whole sum-over-histories malarkey, the  buckyball interferes with itself as it passes through the twin slits*: there is a possibility of it passing through both slits on the way to the screen, hence the interference. This works as long as the buckyball is not observed, at which time the path of the buckyball is fixed and the interference no longer happens.

 

Now, surely something as massive as a buckyball is being observed all the time. It is moving in the earth’s gravitational field, so surely must have some interaction with it. This is a form of observation, no? Even if conducted in a vacuum outside of any field, there is a chance that particles would spontaneously arise in the path of the buckyball and so observe it during the collision. In the weird world of quantum, isn’t it the chance of things happening that counts?

 

Surely it should not matter what is doing the observing, however small or unconscious it is, as long as something is there to observe. I see no reason that any interaction with the buckyball should be insufficient to count as an observation, just because it cannot allow a human researcher to find the location or path of the buckyball. Is it not true that anything that exists (or has probability of existing) can observe, whether quantum particle, energy, wave, planet or person?

 

The alternative is that the observation has to be orchestrated by something sentient, such as the person doing the experiment. This opens a whole new can of worms, such as any interference of solo buckyballs meaning that there cannot be a God, as otherwise His omnipresent omniscience would be an observation and so stop interference from happening. Or, perhaps, that He does exist but has a wicked sense of humour, putting this little conundrum into the universe on purpose.

 

I realise the whole sentient observer thing is complete nonsense, so where am I going wrong in my reasoning? What makes an observation an observation?

 

Thanks for your help!

 

(*ooh-errr misses!)

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