[Music Fanatic]

Persi Diaconis (a former stage magician turned statistics professor) has proven that coin flips by human are not random -- if the coin starts heads, it is more likely to end up heads:

http://www.npr.org/features/feature.php?wfId=1697475

 

[Oddball]

Okay, now you've just screwed up everything I believe in my math class...and we're learning probability right now.

 

[Flasken]

That is such and incredibly informative article. "using high speed cameras and equations..." They actually used equations! Wow, that means they've got to be right. And I'm suprised at the fact that the fact that coins flipped repeatedly in the exact same way land in the exact same way could impress this "scientist" so much...

 

[Lisa]

Quote:

Originally posted by Flasken And I'm suprised at the fact that the fact that coins flipped repeatedly in the exact same way land in the exact same way could impress this "scientist" so much...

Noticed that one too.

One would think they thought the coins would fall back to ground at different speeds when flipped the exact same way before they did this study.

 

[Rendition]

This is just silly.

 

[Hajime]

Quote:

Originally posted by Lisa Noticed that one too. One would think they thought the coins would fall back to ground at different speeds when flipped the exact same way before they did this study.

Lisa,

It's very interesting. If flipped on the same side of the equator then the coin lands the same way, if all elements of the flip were the same. However, if you cross the equator due to the rotational inertia of the Earth and it's gravitational effect on the coin it will actually land the opposite way. For instance, if Doug (ServingIn Ecuador) flipped a coin and it landed heads down in Ecuador it would land tails up here in Chicago if flipped the same way!

[size=xx-small]I made this up.[/size]

 

[ServinginEcuador]

A bit OT, but living near the Equator is pretty cool. They have a demo setup where a guy fills a sink with water and then lets it drain. He then moves to the other side of the Equator and it drains the opposite rotational direction. If he stands right on the Equator it drains straight down without rotating like it did on either side of the Equator.

At least this is what I have been told by some friends. One day soon I will go back to Mitad del Mundo and verify it for myself. It could be a hoax, but we'll see.

 

[Music Fanatic]

Quote:

Originally posted by Flasken That is such and incredibly informative article. "using high speed cameras and equations..." They actually used equations! Wow, that means they've got to be right. And I'm suprised at the fact that the fact that coins flipped repeatedly in the exact same way land in the exact same way could impress this "scientist" so much...

Yeah, its NPR. I'm sure the journal article will be more informative. Diaconis is really a first rate professor.

 

[spaceman]

Well, if you take the human element out, and build a machine to flip a coin the exact same way, of course your going to see a decline in randomness. If a human can learn to flip with the same precision as a machine, then I will be more accepting, but until then, I still believe that it is all by chance. I would like to see the empirical data obtained in his research, and if the research has gone through peer review yet.

 

[jpburton5150]

i never really thought a coin flip was random in the first place, it just depends on about a million variables... plus i find a hard time beleiving anything is truly random

 

[jefemeister]

Quote:

Originally posted by ServinginEcuador A bit OT, but living near the Equator is pretty cool. They have a demo setup where a guy fills a sink with water and then lets it drain. He then moves to the other side of the Equator and it drains the opposite rotational direction. If he stands right on the Equator it drains straight down without rotating like it did on either side of the Equator.

This an urban legend. Taken from http://www-astronomy.mps.ohio-state....4/notes13.html :

Quote:

Debunking paragraph: there is a common misconception that the Coriolis Effect causes water to spiral down the drain counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere. (In fact, this was the premise of an episode of the Simpsons during which Bart places a long-distance phone call to Australia to ask whether toilets flush clockwise down under.) In truth, the Coriolis Effect inside something as small as a sink, toilet, or bathtub is negligibly tiny. The direction in which water swirls down the drain is actually determined by any residual eddying motions of water; if you swim your rubber ducky in a clockwise direction, the water in your tub will go down the drain clockwise, but if you swim your ducky in a counterclockwise direction, the water go down the drain counterclockwise. The Coriolis effect is too minuscule to affect the situation.

 

[Chinchy]

I didn't read the article, but as to the coin flips, I can flip a coin starting heads and make it end heads. I can also flip a coin starting tails and make it end tails. Well for the most part. Enough to skew it away from 50/50.

It's all part of the juggling thing and knowing how to make something flip only 1 rotation or 2 rotations or whatever. Isn't it? The randomness only enters because of the different angles and force with which you begin the flipping..

 

[greenhorn]

Quote:

Originally posted by Flasken That is such and incredibly informative article. "using high speed cameras and equations..." They actually used equations! Wow, that means they've got to be right. And I'm suprised at the fact that the fact that coins flipped repeatedly in the exact same way land in the exact same way could impress this "scientist" so much...

I loved this part too: "Harvard University engineers build him a mechanical coin flipper"...

 

[Daemoth]

If all the forces are the same for every coin flip... duh it'll come out the same. I'm not sure why they ever bothered to test it. He should have walked down to the physics department, and I'm sure they would have given him the same answer as the study showed.

 

[Duncan]

Quote:

Originally posted by jefemeister This an urban legend. Taken from http://www-astronomy.mps.ohio-state....4/notes13.html :

Thats funny, because I heard about this way before the Simpsons was even conceived by Matt Groening...

All we need is someone who lives on the equator, and someone who lives south of it, and we'll have our answer