Vanishing Remainder Paradoxes
A set of
interrelated paradoxes come up when we reexamine the well-known
paradoxical result that all real numbers (usually based implicitly on the
popular ZFC variant of Cantorian set theory) have a unique infinite
decimal representation, except the integers. E.g.
2.999... = 3.000... are ostensibly 2 distinct but numerically equivalent
infinite decimal expansion representations of the integer 3. Key to
this reexamination is to study how the infinite decimal representation of
the rational number 1/3 is constructed.
The zeroth
decimal place of 1/3 is “0”, i.e. the quotient of 1/3. The first decimal
place is obtained by multiplying the remainder of 1/3 by 10 (decimal) and
again dividing by 3, giving us so far “0.3” (the “3” being the quotient of
10/3). The succeeding decimal places are obtained in the same way, giving
us “0.333...”.
But certain
questions, that can be considered paradoxes, were never asked (nor answered), such as:
1) In constructing
1/3 = 0.333... or 1/9 = 0.111..., what happens to that strictly non-zero
remainder of 1?!
2) Does it vanish just like the
1 in a0 + 1 = a0
does on the right hand side of the equation?
3)
If it becomes a strict zero, “vanishing”, as real number theory
assumes by ignoring the issue, how does it do so?!
The
questions sound satirical, which they are, but they also have very serious
import:
4)
If we divide 1 by n enough times,
does the remainder of 1 become 0?!
5)
If we divide 1 by n, does the
remainder of 1 become 0 if n is big
enough?! (More on this in a later section.)
We should
also ask:
6)
What happens to the remainder of 2 when
constructing 2/3 = 0.666...?
7)
What happens to the repeating sequence of non-zero remainders (3,
2, 6, 4, 5, 1,...) when we construct the infinite decimal expansion of
e.g. 1/7 = 0.142857142857...?
If the
remainder doesn’t become a strict zero, then there is more to a real
number than heretofore suspected. If it does become a strict zero, there
is more to real number theory than heretofore suspected.
E.g.
“1/3 = 0.333...” must have a remainder of 1 ≠ 0 in the “last” decimal
place, which by standard theory doesn’t exist, allowing us to overlook
and/or ignore the problem easily. (This 1 ≠ 0 links us back to the 1 = 0
question that is raised by the paradoxical a0 + 1 = a0
and its reexamination above.) This remainder could conceivably be either
1, 2, or the 0 usually implicitly assumed, since we have a modulus 3
situation. When we multiply “1/3 = 0.333...” by 3, we actually get:
“1 = 0.999... + 3 × the remainder of 1 in the ‘last’ decimal place,
which last, when divided by the divisor of 3, gives 1; this last 1 then
needs to be added to the quotient of 10 / 3 = 3 (i.e. the value in the
‘last’ decimal place) × 3 (the divisor again) = 9; and when that 1 is
added to that 9 we get 10, i.e. a 0 in the ‘last’ decimal place with the
1 carrying into the ‘next to the last’ decimal place, which also doesn’t
exist, and so on ripple-carrying all the way back to and just past the
decimal point giving us 1.000...”.
But if
0.999... is distinct from 1.000... it raises the spectre of
infinitesimals, the existence of which is still denied by standard theory.
(They are included in non-standard analysis, but forcibly; they are not
naturally derived.)
We can also
note that the standard proof that e.g. 2.999... = 3.000... involves
multiplying 2.999... by 10 and then subtracting the original 2.999...
(ostensibly) giving us 27.000... which we then divide by 9 giving us the
3.000... we saw above. The multiplying by 10 has an essential
correspondence to the n → n + 1
mapping we saw above since it maps the nth
decimal place onto the (n – 1)st
decimal place, for all n.
The
“vanishing remainder paradox” gets more complicated when we consider two
more things. The first is that if we had started with 1/9 instead of 1/3,
the possible remainders for the “last” decimal place would obviously be 0
through 8, but we would still have “0.999...” as the representation of
both 3 × 0.333... and 9 × 0.111.... Just looking at “0.999...” doesn’t
tell us whether there should be a remainder in the 0 to 2 range or the 0
to 8 range. We could also try to carry along information about the
divisor, but... if we studied all the rational arithmetic expressions
which were arithmetically equal to 1, we would get more than just this
simple “vanishing reminder paradox”. The vanishing numbers we would have
to take into account would probably require a Galois to unravel.
The second
thing is that if we look at the infinite ternary (base 3) representation
of 1/3, we find that the vanishing remainder problem itself vanishes, at
least temporarily. The rational number 1/3 can be described in an infinite
ternary expansion as 0.1000..., i.e. with not even the “infinitesimal”
loss of accuracy associated with a “vanishing remainder”. The real
numbers, as defined by infinite base expansions, are highly dependent on
the base used in a way obviously relating to the prime decomposition of
the base.
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