On 9/24/2012 9:25 PM, [email protected] wrote:
Citeren meekerdb <[email protected]>:
On 9/24/2012 8:57 PM, Stephen P. King wrote:
On 9/24/2012 11:17 PM, meekerdb wrote:
On 9/24/2012 8:02 PM, [email protected] wrote:
Citeren meekerdb <[email protected]>:
On 9/24/2012 9:28 AM, Stephen P. King wrote:
On 9/24/2012 12:02 PM, John Clark wrote:
Thus the moon does not exist when you are not looking at it.
Hi John,
I expected better from you! This quip is based on the premise that "you" are
the only observer involved. Such nonsense! Considering that there are a HUGE
number of observers of the moon, the effects of the observations of any one is
negligible. If none of them measure the presence of the moon or its effects, then
the existence of the moon becomes pure the object of speculation. Note that being
affected by the moon in terms of tidal effects is a measurement!
So who or what counts as an observer. Young's slit experiments on fullerenes seem
to indicate that a few IR photons or gas molecules qualify.
http://arxiv.org/pdf/0903.1614v1.pdf
Brent
If I don't observe it, then it doesn't matter who/what else observes something, the
rest of the universe is still a superposition. It doesn't matter whether or not an
interference pattern can be detected.
?? I could matter. Suppose I bet you $100 there's no interference pattern when the
buckyballs are hot? Then it would matter. But apparently it wouldn't matter whether
anyone observed the IR photons or not.
Brent
Hi Brent,
If we are consistent with the rules of QM, the mere possibility of detection of
position basis information is sufficient to prevent the interference pattern. Thus my
prediction is that the temperature of the buckyballs is irrelevant for the two slit
experiment, so long as a position basis measurement is not possible. Very hard to do...
No, the temperature is crucial and proves your point. When the buckyballs are cold
they form an interference pattern. When they are hot, they don't - because they are
hot enough to emit enough IR photons on their way through the apparatus to localize
themselves, even though nobody and no instruments are recording the IR photons.
It might be interesting to do this experiment out in space where there are no walls or
anything else to absorb the IR photons, but I think the outcome would be the same.
Just the photons and their eventual interactions with the vacuum would be enough to
produce decoherence.
Brent
Note that in such experiments, you can restore the interference pattern by measuring the
photons. The photons are entangled with the buckyballs, the reason why you don't get a
itnerference pattern is simply because the state of the phtons conain the information
about the which way path of the buckballs. Then to restore the interference pattern, all
you need to do is look at those buckballs hitting the sceen for which the photon is
detected in some fixed state X. Then as a function X, the interference pattern changes,
if you average over the range of states X can be in, the interference patten will be
completely washed out.
But with no control over the direction or timing of the emissions it's essentially
impossible. It's not enough to just detect one photon and condition on that, you'd need
to detect all the photons and then quantum erase the information.
Brent
This shows that there is still an interference pattern to be detected (at least in
princicple), decoherence is nothing more than the state getting entangled with more and
more degrees of freedom.
Saibal
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