On 3/6/20 9:54 PM, Keith Medcalf wrote:
On Friday, 6 March, 2020 19:25, Richard Damon <rich...@damon-family.org> wrote:
It is sort of like NaN, where a Nan is neither less than, greater than
or equal to any value, including itself.
NULL (as in SQL NULL) means "missing value" or "unknown". NULL represents any value
within the domain, we simply do not know what that value is. That is, the value "NULL" for colour
of a car means that we do not know the colour -- however, it still has one.
NaN, on the other hand, means that the value is outside the domain and that
there is no possible value of the domain which well render the proposition true.
For example, the state of Schroedingers Cat is NULL. It has a state, either
dead or alive. That state is merely unknown until one looks in the box.
However, if when you looked in the box there was no cat, then the cat would be
a NaN since its state was outside of the domain of states for a cat in a box
with a time release poison after the release of the poison, that is, the
non-existance of a cat in the box precludes the possibility of the state of the
cat in the box being either either dead or alive.
It may have a different meaning, but similar effects on logic.
As an aside, for the quantum effect Schrodinger's Cat is designed to
demonstrate, the cat ISN'T just one of dead or alive but not know which,
but exists as a probability wave between the two states. This is why the
photon which goes through one of two slits generates an interference
pattern unless you detect which slit it goes through, if you measure the
slit it went through, you get a different pattern of light, as the lack
of knowledge allows it to be less precise in its position and the
probability of going through the left slit interferes with the
probability of that same particle going through the right slit, so the
pattern implies it sort of went through both at once.
Detecting the state of Schrodinger's Cat actually changes its state,
collapsing the wave into one of the definitive states.
--
Richard Damon
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