On 9/25/2012 12:25 AM, smi...@zonnet.nl wrote:
Citeren meekerdb <meeke...@verizon.net>:
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, smi...@zonnet.nl wrote:
Citeren meekerdb <meeke...@verizon.net>:
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.
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
Hi Saibal,
You remark implies that decoherence is just a measure of the
difficulty of recovering information required to reconstruct the initial
state, no? It never actually vanishes. This seems to imply a possible
lowest upper bound on the number of degrees of freedom involved such
that below it interference effects can still be recovered. This seems
somehow wrong...
--
Onward!
Stephen
http://webpages.charter.net/stephenk1/Outlaw/Outlaw.html
--
You received this message because you are subscribed to the Google Groups
"Everything List" group.
To post to this group, send email to everything-list@googlegroups.com.
To unsubscribe from this group, send email to
everything-list+unsubscr...@googlegroups.com.
For more options, visit this group at
http://groups.google.com/group/everything-list?hl=en.
