On Tuesday, December 4, 2012 1:51:55 PM UTC-5, Brent wrote:
>  On 12/4/2012 8:29 AM, John Clark wrote: 
> On Mon, Dec 3, 2012 at 3:26 PM, meekerdb <meek...@verizon.net<javascript:>
> > wrote:
>> > That's where you're wrong; read the paper more carefully.  If you 
>> record the which-way the interference is lost. [...] The interference 
>> pattern occurs *only* if the which way information is *erased*
> Nope, you've got it exactly precisely backwards yet again. I quote from
> http://en.wikipedia.org/wiki/Wheeler%27s_delayed_choice_experiment:<http://en.wikipedia.org/wiki/Wheeler%27s_delayed_choice_experiment>
> " If the experimenters know which slit it goes through, the photon will 
> behave as a particle. If they do not know which slit it goes through, the 
> photon will behave as if it were a wave when it is given an opportunity to 
> interfere with itself. "
> That's why you need to read the technical papers instead of Wikipedia.  
> The above is correct when there are just photons going through one pair of 
> slits.  But in the Delayed Quantum Eraser experiment there are *two* 
> entangled photons one of which goes through slits and one of which *could 
> be detected and give which-way information*.  The point is that if it is 
> not detected (flys off to infinity, absorbed in the wall,...) the 
> interference pattern is still destroyed.  To maintain the pattern the 
> information in the entangled photon has to be *erased* - that's the 
> function of the lens.  
> Loss of the interference isn't because "they do not know"; it's a 
> consequence of the information being "out there" - and being absorbed in a 
> wall still leaves it "out there".  This is even clearer in the buckyball 
> Young's slits experiment, quant-ph/0402146v1.  The interference pattern is 
> lost when the buckyballs are hot enough that their IR radiation is 
> sufficient to localize them to the slit spacing - even though nobody ever 
> observes or detects the IR photons.
> All those below fail to consider the relevant case too; they assume all 
> cases in which no experimenter measures which-way are equivalent.  They 
> ignore the possibility that "the environment" may measure which-way but no 
> person does.
> Brent

It's confusing. Can you simplify it?

One photon heads toward the slits.
One entangled photon heads toward the detector. (They are both entangled 
with each other, but I assume you mean one pair of entangled photons, not 
two pairs.)

Is there a detector on the slits too?

It seems like the point of the experiment is that the interference pattern 
only shows up when the ability to discern which-way is not available - 
which seems to me to support observer-principle type interpretations.

Certainly I don't see any suggestion that there is a such thing as 
'information' which is independent of some kind of sense receptivity. To 
the contrary:

Time 6. Upon accessing the information gathered by the Coincidence Circuit, 
> we the observer are shocked to learn that the pattern shown by the 
> positions registered at D0 at Time 2 *depends entirely* on the 
> information *gathered* later at Time 4 and available to us at the 
> conclusion of the experiment. 
> The position of a photon at detector D0 has been registered and scanned. 
> Yet the actual position of the photon arriving at D0 *will be at one 
> place if we later learn* more information; and the actual position will 
> be at another place if we do 
> not.-http://www.bottomlayer.com/bottom/kim-scully/kim-scully-web.htm

I intentionally bolded the terms where the true nature of quantum is 
revealed - with the capacity to detect, 'learn', 'gather', i.e. to become 
informed through a sensory-motor event within the matter which makes up a 
physical instrument (including, but not limited to, human eyes, brains, 

Physics is sensory-motor participation. Nothing more and nothing less. 
There is no such thing as 'information'.


You received this message because you are subscribed to the Google Groups 
"Everything List" group.
To view this discussion on the web visit 
To post to this group, send email to everything-list@googlegroups.com.
To unsubscribe from this group, send email to 
For more options, visit this group at 

Reply via email to