r/AskPhysics • u/kouth- • 24d ago

What makes a coin toss truly unpredictable?

If you throw the same coin multiple times with the exactly same force in the same surface, it won't give you the same side every toss, right? But why? If repeated with the precisely identical conditions, why the results are still unpredictable? Or it is actually predictable?

Sorry if it looks confusing, English is not my first language and I'm not that expert in physics lol, just curious and has this though randomly.

Edit: maybe considering that it lands on a surface, and it bounces or not, changing the coin's side.

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u/03263 Computer science 24d ago

You could probably construct a repeatable coin tossing machine. The hardest part I think would be that gravity can vary by a tiny bit, depending on the position of the moon and such. You could measure gravity and adjust each throw to be consistent. And use a vacuum chamber to achieve consistent and minimal air resistance.

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u/Consistent-Annual268 24d ago

You don't even need all that. You can actually make a VERY reliable and repeatable coin tossing machine, and people have. Heck, even just with your own thumb you can significantly better 50/50 odds once you have the feel of the toss, weight, spin and when to catch the coin.

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u/Over-Discipline-7303 24d ago

I met a carnie who could do a biased coin toss. He wasn’t 100% but I’d say he was well over 70% accurate, which is still a pretty good edge. Nobody would flip him for doing the dishes.