> Darren New<dne### [at] sanrrcom>  wrote:
>> On 9/16/2011 9:49, Warp wrote:
>>> Darren New<dne### [at] sanrrcom>   wrote:
>>>> But at what point and for what reason wouldn't they apply?
>>>
>>>     For the same reason that if you kick footballs towards a wall with
>>> two slits on it (slightly wider than the football), you don't get a
>>> diffraction pattern on a wall behind it where the balls hit.
>
>> Yes you do. It's just that the diffraction pattern is very, very fine.
>> Probably finer than you can actually measure. But theoretically it's there.
>
>    The diffraction pattern isn't there even with elemental particles if you
> measure which slit the particles go through.
>
>    How do you set up a situation where it's not possible to tell which slit
> the football went through? I don't think it's physically possible.
>
>    You could perhaps try having the experiment in an absolute vacuum (something
> which is already very hard), and in an environment with no electromagnetic
> radiation of any kind, that could hit the ball and tell its trajectory
> (maybe it would be theoretically possible, but I'm not sure it is in
> practice). Also anything else that could hit the ball and hence possibly
> tell its trajectory (eg. neutrinos and cosmic rays) would have to be
> completely absent.
>
>    In fact, thinking about it. would the ball and the walls themselves emit
> photons that could tell the trajectory? Are they black body radiators?
> I suppose that if that's the case, the ball and the walls would have to be
> cooled to absolute zero to stop them from emitting any particles.
>
>    So let's see, absolute vacuum, complete isolation from external
> electromagnetic radiation and other particles (such as neutrinos and
> cosmic rays), and the objects cooled to absolute zero to stop them from
> emitting any particles.
>
>    But is that enough? What about vacuum energy? Virtual particles that
> pop up into existence spontaneously, hitting the ball? Could they be used
> to measure its trajectory?
>
>    Even if *all* of those things were somehow taken care of, would there
> be an interference pattern?
>
>    If yes, what explains the deviation in the trajectory of the ball?
> One of the fundamental interactions (gravity, electromagnetism, strong
> interaction, weak interaction)? How can they deviate the ball so much?
>

I remember a day in my physics class when we where studying waves. We 
had to calculate the effective wave lenght of common, macroscopic, objects.
It depended on mass and dimentions, both tending to give smaller values 
as they get larger.

For a footbal, it would be in the 10e-20 to 10e-30 m range. So, your 
interference pattern would be smaller than a proton.

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