John VanSickle wrote:
> I wouldn't say that it is truly random, but merely that predicting the 
> outcome of any interaction requires information that is presently not 
> available.

You would be incorrect. Google on "Bell's Inequality".

> For instance, the decay of unstable particles appears to happen 
> randomly, but at what appears to be a predictable rate for aggregate 
> amounts of like particles.  What is likely is that the particles decay 
> when they encounter certain conditions (such as a gradient in the 
> electric or magnetic potential) that is high enough to overcome the weak 
> internal cohesiveness of the particle, causing it to come apart. 

That's the "hidden variable" theory. It has been disproven, multiple 
times and with hundreds of different experiments. Boggling, isn't it?

-- 
   Darren New / San Diego, CA, USA (PST)
     "That's pretty. Where's that?"
          "It's the Age of Channelwood."
     "We should go there on vacation some time."

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Darren New <dne### [at] sanrrcom> wrote:
> No, it only interferes with other electrons. The electrons it interferes 
> with are electrons from other times. There's always a possibility that 
> it lands at any particular place. Why is it any stranger that it 
> interferes with electrons in the future than it is it interferes with 
> itself?

  Because time travel doesn't exist?

-- 
                                                          - Warp

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Mueen Nawaz wrote:
>     There's the whole issue of "renormalization" to deal with infinities 
> in physics. I won't go into any detail as I've never formally studied 
> it. But it's another often cited example of "fishy mathematics".

I understand it enough to explain informally. When you're calculating 
the probability of an event, you have to take into account every way 
that event could occur, and add them up. So maybe the photon leaves the 
candle and hits the film. Or it leaves the candle, splits into an 
electron and positron, which then later recombine into a photon, which 
hits the screen. Or it splits into an electron and positron, and the 
positron goes off to the Sun back in time to combine with an electron 
there, which makes it turn into a photon which happens to come back to 
Earth which strikes the electron which pushes it into the wall which 
emits a photon which hits the film. And so on.

So basically, you're adding up more and more events of lower and lower 
probability. And it turns out that if you add them all up, you get 
infinite probability everywhere.

But if you stop at, say, 10^-50 probability, and then renormalize 
(something like divide by 10^-50), you get a number. And if you stop at 
10^-60 and then renormalize (something like divide by 10^-60), you get 
the same number. As long as you renormalize to where you stopped, you 
get the same number. But nobody knows why you have to stop, and there's 
so far no physical reasoning as to where you have to stop.

Speculation is that space is actually quantum, so the mathematics of 
"real numbers" breaks down because they can get smaller than reality. 
Which is where the Plank's constant seems to come in - speculation that 
it's describing the quantum of size.

-- 
   Darren New / San Diego, CA, USA (PST)
     "That's pretty. Where's that?"
          "It's the Age of Channelwood."
     "We should go there on vacation some time."

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Darren New <dne### [at] sanrrcom> wrote:
> Warp wrote:
> >   So when the electron hits the sensitive film *after* it has passed the
> > slits, it goes back to the past and changes it so that it goes through
> > only one of the slits after all?

> No. It either interferes with itself or not. You're assuming the only 
> way it can interfere with itself is to go through both slits. There's no 
> evidence that's the case, and much evidence that it isn't.

  So why does it interfere with itself when there are two slits but not
when there is only one? If it was just one regular physical macroscopical
particle it wouldn't matter how many slits there are: If it goes through
one of them, it just goes through one of them, that's it. It doesn't even
"know" that there are other slits.
  However, when there are two slits, the electron passes through and starts
interfering with itself, as if it has passed through both and changed
direction in different ways.

  How else can this be explained? How does the electron "know" that there's
another slit so that it "knows" to start interfering with itself, other than
actually going through the other slit as well?

  (I believe this has something to do with wave-particle duality: In the
double-slit experiment the wave nature of the electron shows up: The wave
goes through both slits and starts interfering with itself.)

> >   So you are saying that, even though the only possible explanation for
> > interference patterns is that the electron passed through both slits,
> > there's still no evidence of that?

> Yes. What makes you think that the only *possible* explanation is that 
> the electron passed through both slits?

  What is the other explanation?

> >   If there's "no evidence", what do you call the interference pattern?
> > "Non-evidence"?

> Interference.

  The interference can be explained with the electron passing through both
slits at the same time. Ergo the interference is evidence of that happening.
(Note that "evidence" is not the same thing as "proof".)

-- 
                                                          - Warp

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Warp wrote:
>   Your statement is like that. You are starting from the assumption that
> an electron is an extremely small particle with well-defined boundaries,

By the way, this is why it's called "quantum" physics. :-) Because it's 
*not* a wave - there *is* a well-defined particle in a particular place.

-- 
   Darren New / San Diego, CA, USA (PST)
     "That's pretty. Where's that?"
          "It's the Age of Channelwood."
     "We should go there on vacation some time."

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Mueen Nawaz <m.n### [at] ieeeorg> wrote:
> Warp wrote:
> >   It's not like you could shoot an electron to some direction, and then
> > the electron suddenly hits the other side of the Earth (or the solar
> > system). It hits a quite accurately calculable place.

>         There is a non-zero probability that this can happen.

  I bet the probability is so small that it hits the barrier of some
physical constant (Planck maybe?)

-- 
                                                          - Warp

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Darren New <dne### [at] sanrrcom> wrote:
> >   What the mathematical model *can* do is to give a distribution function
> > which tells how the electron is distributed in space (a bit like a
> > function which tells how the water is distributed, except that with
> > the electron the "density" of the "water" is not constant).

> No, actually, it tells you the likelihood of finding it at any 
> particular place, were you to look.

  Assuming the particle *is* at some specific location at any given time
instead of being distributed in space.

> Yes, it can actually hit the other side of the Earth. It can also hit a 
> week before you shoot it. Very unlikely, but possible.

  I don't believe in the time travelling. As for the location, I assume
the probability of it hitting the other side of the Earth is so small that
some physical constant prevents it.

-- 
                                                          - Warp

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Darren New <dne### [at] sanrrcom> wrote:
> Warp wrote:
> >   Your statement is like that. You are starting from the assumption that
> > an electron is an extremely small particle with well-defined boundaries,

> By the way, this is why it's called "quantum" physics. :-) Because it's 
> *not* a wave - there *is* a well-defined particle in a particular place.

  Actually "quantum physics" means that everything is quantified. That is,
there's a minimum amount of everything (for example electric charge and
mass), and everything is an integer multiple of that amount. You just can't
have eg. half of the electric charge of an electron, for example.

  Waves are also quantified for the same reason: There's a minimum amount
of amplitude, for example, and all amplitudes are integer multiples of
that amount.

  These "quants" behave oddly. Sometimes they behave like particles,
sometimes they behave like waves, and sometimes they behave like both
at the same time. Different measurements of the exact same quant can
show wildly different behavior in this respect. (One experiment will
clearly show that light behaves like a wave and not like a stream of
particles, while another experiment will show the exact opposite.)

-- 
                                                          - Warp

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On Mon, 02 Jun 2008 09:29:24 -0700, Darren New <dne### [at] sanrrcom>
wrote:

>Stephen wrote:
>> Indeed, a straight edge and compass. What more do you need?
>
>A ruler?

No, I don't think so. ;)
-- 

Regards
     Stephen

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Warp wrote:
> Darren New <dne### [at] sanrrcom> wrote:
>> Warp wrote:
>>>   So when the electron hits the sensitive film *after* it has passed the
>>> slits, it goes back to the past and changes it so that it goes through
>>> only one of the slits after all?
> 
>> No. It either interferes with itself or not. You're assuming the only 
>> way it can interfere with itself is to go through both slits. There's no 
>> evidence that's the case, and much evidence that it isn't.
> 
>   So why does it interfere with itself when there are two slits but not
> when there is only one? If it was just one regular physical macroscopical
> particle it wouldn't matter how many slits there are: If it goes through
> one of them, it just goes through one of them, that's it. It doesn't even
> "know" that there are other slits.
>   However, when there are two slits, the electron passes through and starts
> interfering with itself, as if it has passed through both and changed
> direction in different ways.
> 
>   How else can this be explained? How does the electron "know" that there's
> another slit so that it "knows" to start interfering with itself, other than
> actually going through the other slit as well?
'It' knows that the second slit is there because an electron has an 
infinite size. Part of the problem is that you use 'it', implying that 
it is an identifiable object and it has a subconscious connotation of 
something finite.
> 
>   (I believe this has something to do with wave-particle duality: In the
> double-slit experiment the wave nature of the electron shows up: The wave
> goes through both slits and starts interfering with itself.)
Both 'wave' and 'particle' are concepts from classical physics that 
don't apply here.
In the double slit experiment you have a source of electrons, a double 
slit and a screen. You know that you had an electron at the source and 
you can compute the likelihood of the position on the screen that will 
light up, enabling you to estimate the pattern if you use a large number 
of electrons. Between the source and the screen, the electron passes 
through ever point in the universe and you are not even sure that the 
same electron hit the screen as the one you started with. Simply because 
'same' is not defined here.
A basic rule of quantum mechanics: don't try to visualize what happens. 
You can either visualize it or compute it, not both at the same time. ;)

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