Ok so here is the first post in this forum....


What do you all think of the infamous 9 Card Trick???

I like it about 9/21 of the 21 Card Trick. (And 9/21 is a fantastic effect, in and of itself!)

I just wanted to know what was down here at the bottom of the forum...
...and to agree with Steven.

Apparently magicians no longer care about mathematics. Plato would roll over in his grave!

Matt,
I would think Euclid and Archimedes would not consider Plato knowlegeable enough in mathematics to roll over in his grave.

I'm sorry, Larry, but you are mistaken.

Plato was the founder of the Academy in Athens. The entrance to the school purportedly read "Let no one enter here who does not have knowledge of mathematics". Plato was, in essence, a highly developed Pythagorean (by way of Socrates), who took mathematics very seriously (perhaps more than anyone else in Western history), and this is evident in Plato's rationalistic epistemology and idealistic metaphysics. Aristotle (a student of Plato's) reported that Plato's knowledge of mathematics was incredible, including not only the practical aspects of calculation, but a deep understanding of mathematics on a metaphysical level (which is why we call mathematicians who include numbers in their ontology "platonists").

Hi Matt,
I respectfully, disagree with you. Plato and his pupil Aristotle were great thinkers but poor mathematicians compared to the educated Greeks of their time. For example, Antiphon discovered the "Principle of Exhaustion" in his effort to approximate Pi. Euclid refined it. His method was used until the invention of Calculus by Newton. Aristotle judged this principle to be false but offered no proof or plausible explanation. This is the man who through pure intellectual reasoning deduced that heavier objects fall faster than light ones, the Earth is the center of the Universe, and men have more teeth than women. Aristotle's Physics was a long list of unfounded speculations devoid of any quantitative process. There were many great Greek mathematicians and physicists, notably Euclid and Archimedes. Their writings were factual and proveable and not opinions based on speculation and intuition.

While it is true that Aristotle's science was entirely qualitative (and we now know that quite a bit of it is incorrect), I do not see how that has any bearing on my claim that Plato (not Aristotle) would roll over in his grave if he found out how little interest magicians have in magic. (Keep in mind that, while Aristotle was a student of Plato's, he disagreed with much of Plato's philosophy, including the significance of mathematics.)

My point was that you did not seem to realize the importance of mathematics for Plato. Perhaps, in the future, I should stick to less esoteric metaphors.

OK, now that the Greek issues have been pacified, let's challenge the assertion that calculus was invented by Newton.

There are those who claim it was Liebniz.

0pus

Both Newton and Liebniz are credited with this. They both came up with separate notations, which are both used today. Both were fairly ugly men.

Ummm, back on topic - Jim Steinmeyer's new booklet Impuzzibilities has an absolutely fantastic version of the nine card trick. Strongly recommended.

I agree with the last post. "Impuzzibilities" is highly recommended.

Hold on a sec!

I see a new effect in the making in the posts above. An argument climaxed by something turning over in its grave, or two graves representing positions ... Guess this would need something to monitor the 'graves'. Kind of an extension of the old 'lie detector' theme.

Thanks Matt and Count for the great history on Math. I for one found your observations very enlightening.

Snidini

Going back once again to the topic of the nine card trick, Terry LaGerould created a great version of the effect, entitled, "Cardboard Lie Detector," that I wrote up in Pasteboard Presentations II.

The lie detector angle gives it a reason for being, and makes the trick far more mind boggling. It also provides a ingenious and satisfying reason for the revelation.

My first encounter with the Nine Card Trick was in a "lie detector" format, and it stunned me for awhile -- I couldn't figure out how it worked, even while doing the trick. I have since figured it out! But, it's still a really neat principle. Jim Steinmeyer does give some fun suggestions for it in "Impuzzibilities," though I don't think he mentions the "lie detector" idea.
-- Hushai

A few people put a lie detector presentation to the nine card effect.

It is superior to the 21 card effect in that it allows far more presentational variations.

When first published it was tremendously popular, one of those effects magicians showed other magicians, who showed other magicians to the extent people lost track of where it came from and started publishing variations with no credit to Jim. Some effects were even marketed!

One of my favorite variants is one by Peter Duffie that appeared in his booklet "Deck Direct" called "Phone Zone 2". Obviously with that title, a nice presentation for doing over the phone. I did give it a quick mention in my book "Small But Deadly".

Paul.