Post by peteolcottPost by Jim BurnsYou're presenting some sort of hypothetical whereby,
if we did such and such and didn't notice it, we would
be making an error and not noticing it. You don't
address the Banach-Tarski theorem, you imagine addressing
it, and -- in your imagination -- you vanquish it.
Other than making you feel good (I assume),
this is pointless. Go. Read.
The provided example video says that there are gaps
in the spheres.
http://youtu.be/s86-Z-CbaHA
Q: "What's an anagram of Banach-Tarski?"
A: "Banach-Tarski Banach-Tarski."
Post by peteolcottThe first big mistake is when he names the same point twice
RUL PURPLE **
DD BLUE
RDR RED
U ORANGE **
Now when he moves RUL and does not move U he has just
copied a point without knowing it.
Okay, I'm going to accept this as an attempt on your part
to make some sort of argument. I have pretty much accused
you of not even knowing what an argument is, but this is
an argument. I withdraw that claim.
It's a wrong argument, but it gives me more to work with
than just you repeating a claim (something that you seemed
to be addicted to doing).
I encourage you to make more _arguments_ , even wrong
arguments. TIA.
----
This objection of yours is wrong _because_ the point RUL
(ending in R, so purple)
(arrived at by moving, from the origin, left-up-right on
the sphere's surface)
is not the same point as the point U (ending in U, so orange)
(arrived at by moving up)
You're moving on the surface _of a sphere_ .
On a plane, left-up-right RUL would land you at the same point
as up U, but this is not a plane, it's a sphere.
Yes, for small enough steps right-left-up-down RLUD,
the endpoints of RUL and U will be "close enough" to
the same point for any positive ammount of error in
what "close enough" is. (We could say "In the limit,
the surface of a sphere is flat.")
However, in this video, we are given a fixed size step,
cos(1/2). We are NOT allowed to shrink our step size down
until RUL is close enough (whatever that might be) to U.
----
The point RUL is not the point U.
I think the easiest way to see this is to _increase_ the
size of the steps RLUD until four of them take us all
the way around the globe and back home again.
(These are not the same as the Banach-Tarski steps.
For the Banach-Tarski steps, we don't want to return
home, not for any finite number of steps. I only intend
to show that traveling on a sphere and traveling on a plane
are different.)
You start at Home, point H, facing north.
Ahead of you is the Up pole, behind you is the Down pole.
To your left, the Left Pole, to your right, the Right pole.
Step to your left.
You are at the Left pole, facing north.
Ahead of you is the Up pole, to your right is Home.
Step north.
You are at the Up pole, with the left pole behind you.
To your right is Home.
Step right.
You are Home.
So, with the quarter-globe steps, RUL brings you back Home.
But U takes you to the Up pole.
These are not the same.
----
The Banach-Tarski paradox does depend upon the concept
of infinity, as you said. That you don't want Banach-
-Tarski to be valid does not make the concept of
infinity wrong somehow.
----
We can make the same sort of argument for the natural
numbers.
(Though it's not as impressive as the Banach-Tarski
result. Spheres have a more material-like appearance,
for example, like chocolate, as the video points out.)
Take all the natural numbers and label them with their
binary numerals: 0, 1, 10, 11, 100, 101, 110, 111, 1000, ...
Take all those labels and append a '0' to their right end:
00, 10, 100, 110, 1000, 1010, 1100, ...
These are the label for the even numbers.
Now, take all those original labels and append a '1':
01, 11, 101, 111, 1001, 1011, 1101, ...
These are the labels for the odd numbers.
We can take the even numbers and map them to all
the numbers, and we can take the odd numbers and map
them to all the numbers. In a sense, there are
two copies of the natural numbers inside the natural
numbers.
This is not some sort of error. It's only what it
means to be infinite.
----
Consider a one-ended chain. You can hold that unique link
at which it ends in your hand, but there is no other
link that is an end. Follow the chain across fields,
across the oceans, wrapped around the world, stretched
to the moon, to the stars, to the end of the universe
and beyond: no link is another end.
This chain is literally infinite: not-ended on one side.
Yes, it's imaginary, but we can describe it. Every link
except the unique end in your hand is directly connect
to exactly two other links.
(We can add more description to make sure there are
no _extras_ but this is enough for _at least_ one
infinite chain.)
Obviously, this is not at all a normal chain. And it
has some highly abnormal properties. For example, if
one deletes every other link, joining the two to keep
the chain continuous, the other end of a _normal_
chain would be half as far away. _But this chain doesn't_
_have "the other" end_ . If one deletes every other link
of a one-ended chain, what one is left with is still
a one-ended chain.
And so on.
Why would a one-ended chain be like a two-ended chain,
anyway?