Many-Worlds again


Though I'm constitutionally unable to understand why everybody isn't
as agog as I am about Many-Worlds, it does seem difficult to get
people interested. As another attempt to communicate this scientific
conjecture that makes all the religions that have ever been invented
look like gnats in comparison, here's what I just emailed to a friend
at the bar who's responded to my earnest propagandization about
it by showing some interest:

&&&&&&&&&&&&&&&&&&&&&

Here's a URL to the famous two split experiment, which shows
how "particles", such as photons of light, or such as
electrons, act as "waves".

http://abyss.uoregon.edu/~js/21st_century_science/lectures/lec13.html

The baffling part of this experiment, which is one of
things that the many-worlds conjecture was proposed to
explain, is in the section "The role of the observer",
at the URL above. The observer seems like he must be
a "god" because his mere knowledge of something changes
reality.

When the electrons are unobserved before reaching
the screen behind the slits, each electron goes through
the two slits simultaneously, and the electron
"interferes with itself", the way an ocean wave forced
to go around both sides of a rock will interfere with
itself after it goes past the rock: the left and right
sides of the wave come back together some distance
after the rock and create a wave interference pattern.

However, if one of the slits is monitored to see
if the electron goes through it or not, it goes
through only either the monitored slit or the
unmonitored slit but not both, so there is no
interference pattern. That's as if instead of a
water wave, bowling balls were bowled at the rock and
had to go on one side of the rock or the other. The
balls would appear to accumulate in two clumps on
each side of the rock, with no bowling balls in the
middle because to have done that they would have had
to go through the rock, but they can't do that.

The most remarkable thing about the two-slit
experiment is that even if an electron goes through
the slit that is not being observed, the mere fact
that the observer was observing the other slit, and
knows the electron was not seen going through that
slit, prevents the particle from "interfering with
itself" like a wave. That's even though the
observer did not interact with that electron at all,
because he was not observing the slit that the
electron did go through. The mere knowledge that
the electron must have gone through the unobserved
slit, because it was not seen to have gone through
the observed slit, changes the nature of the electron.

It makes no "common sense" that the knowledge of
an observer can make a physical change in reality.
It's as if a rabbit were in an unknown location
behind a hill, and might pop up anywhere between
two trees, but only if you weren't monitoring a
camera that had been placed behind the hill pointed
at one of the trees. If you did have a camera
looking at one of the trees and were monitoring it
(but not if you had one but WEREN'T monitoring it!)
the rabbit could no longer pop up just anywhere:
it must pop up near the tree you were looking at if
you saw it in the camera image near that tree, and
MUST pop up near the UNOBSERVED tree if you DIDN'T
see it in your camera that was pointed at the
observed tree. The rabbit can no longer pop up
between the trees if you monitor either of the
trees: it must pop up near one or the other. Leave
the camera running but don't look at the output,
and the rabbit could pop up anywhere again.

---------------------------------------------------

Below is a URL to a discussion of an effect
appearing before the cause that created the effect
could have arrived to "tell" the effect what to be.
The particular discussion at the URL below is in
terms of a special effect between two particles
known as "entanglement", but also applies to the
scenario I mentioned to you about sending a signal
to the moon, in which a receptor on the moon
records that the signal was sent BEFORE the signal
can have gotten there at the speed of light, though
NOT SO SOON that the receptor could send a message
to the person back on earth who was sending the
signal, which message would arrive in time to tell
him not to send the signal. Thus, causality is not
violated, but we have to look with new eyes at the
relationship between cause and effect, because
although the effect is tied to the cause, the
effect is not directly "caused" by being "touched"
by the cause or anything related to the cause.

http://seattlepi.nwsource.com/local/292378_timeguy15.html

----------------------------------------------------

Feynman's "sum over histories" is another famous
situation in which an unobserved particle takes all
routes to a solution, as a wave going around rocks
would do, rather than picking just one route as a
bowling ball would have to do. To use the bowling
ball analogy again, you can calculate the probability
of a bowling ball arriving on the shore after going
around some rocks by calculating all the possible
ways it could avoid rocks and end up on shore, and
then just ADD THEM UP! Unbelievably, this works!
As with the two-slit experiment, it only works if
you're just looking at the shore, and not looking
at the possible ways the bowling ball might get to
the shore.

I haven't yet found an explanation of Feynman's
"sum over histories" on the web that's as simple as
I think it should be, that's any better than my
first paragraph just above. There are lots of
sites that launch into equations right away, but
equations and understanding are mutually exclusive
unless one takes the time and energy to really
become a geek in a field of study.

----------------------------------------------------


The above are things that are completely
baffling except in the light of Many-Worlds, but
in Many-Worlds, they are no problem at all, they
vanish as completely as Poland once did. It's
because many-worlds easily accommodates what is
otherwise incomprehensible that, I've read, 60%
of physicists, including 70% of cosmologists,
feel that Many-Worlds must be true.

----------------------------------------------------

The very nice question-and-answer site about
Hugh Everett's original formulation of the
Many Worlds Conjecture, with questions that can
be clicked on to get to the explanations, is at:

http://www.hedweb.com/manworld.htm

(It's not just "hedweb.com" as I thought it
was in the bar, and I didn't easily see how to
get to the above URL starting from Hedweb.com.
Hedweb.com itself looks like some new-age trash
to me, judging from a quick glance at it.)






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Relevant Pages

  • Re: Is a fact something that has been proven?
    ... There's nothing there at all about a double slit experiment ... A single electron is not entangled with another, ... 1.TURN OFF THE ELECTRON DETECTORS AT THE SLITS. ... An individual photon passing ...
    (talk.origins)
  • Re: Double Slit Puzzle Explained (?)
    ... Normally, when only one slit is open, the pattern on the plate is a ... let's look at where that radiation might come from. ... I believe the way an electron experiment is done is ... An electron is also a wave. ...
    (sci.physics.electromag)
  • Re: Double Slit Puzzle Explained (?)
    ... shone at a solid thin plate that has two slits cut into it. ... Normally, when only one slit is open, the pattern on the plate is a ... where that radiation might come from. ... I believe the way an electron experiment is done is ...
    (sci.physics.electromag)
  • Re: Double Slit Puzzle Explained (?)
    ... Normally, when only one slit is open, the pattern on the plate is a diffraction pattern, a fairly narrow central band with dimmer bands parallel to it on each side. ... Since the mechanism for recording these "baffling" events is photographic plates, and since the plates are sensitive to radiation, let's look at where that radiation might come from. ... I believe the way an electron experiment is done is that it is actually an electron hitting the detection "plate" that is recorded. ... So it will morph -- on impact -- into a wave that just happens to have the exact pattern of peaks and valleys as would have formed if another electron had simultaneously gone through the other slit. ...
    (sci.physics.electromag)
  • Re: A little challenge for relativists.
    ... > | Androcles wrote: ... > |> reflects and then comes back to the observer. ... > Does the electron fall toward the proton to emit a photon or does the proton fall toward the electron? ... << The free charge is the total charge less the charge ...
    (sci.physics.relativity)