In fact, 99.999999% is an extremely low estimate. The number of ways that a deck of cards can be shuffled is 52! Which is equal to 8065817517094387857166063685640376697528950544088327782400000000000 possibilities.

If you shuffled cards every second from the birth of the universe until now, you still wouldn’t even come close (statistically) to getting the same arrangement twice.

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[–] 21 points 9 months ago (1 child)

This is definitely mostly true.
It does breakdown some when every new deck has the same starting order, and people frequently shuffle poorly. Those 52! possibilities shrink massively.

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  • [–] 8 points 9 months ago

    I always think that when I see this fact - what counts as a shuffle? If I sloppily cut the deck once and reassemble, that's most likely not unique. I wonder how many moves before a shuffle is statistically close to a random order. I'm guessing just a few, but I don't really know.

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  • [–] 9 points 9 months ago* (1 child)

    What’s fun is how often this principle is used every day. For example, when you upload a video to YouTube, you’re assigned a unique URL, but it would be too slow to simply add your URL to a list to make sure nobody else uses it. There are millions of videos uploaded every day, and thousands of servers spread all over the world.

    Instead, YouTube just generates a truly random URL and depends on the odds of two videos having the same URL being effectively zero.

    The same is true for Bitcoin. If you could guess a Bitcoin private key for any currently used wallet, you’d have full access to the funds within that wallet. This can even be done offline. Even if you could guess trillions of private keys per second, the odds of you hitting even one that’s already been used is low enough to be totally secure.

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  • [–] 5 points 9 months ago

    For generating unique IDs, you can combine a random part with some other data, like the current time, so if it's only those that are generated within the same millisecond that you even need to worry about.

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  • 32 comments in c/mildlyinteresting@lemmy.world view that post
    [–] 55 points 9 months ago (4 children)

    Since cards start in order and the majority of shuffling is done the same method, there will be a bell curve of repeated combinations.

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  • [–] 5 points 9 months ago (2 children)

    If the deck began its life randomly sorted, would the statistic be true then?

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  • [–] 3 points 9 months ago (1 child)

    From a production point of view I think that it would be very difficult (which generally means expensive) to create a randomised deck while ensuring that the deck has all 52 cards in it (although I’m just thinking aloud and have no experience in this area so could be wrong)

    However, if the starting deck is truly random then the output of the shuffle would also be random so there wouldn’t be a bell curve.

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  • [–] 24 points 9 months ago* (6 children)

    Or you could go with it either is or it isn't, that way it's 50%.
    That's the principle I use for gambling, although for some reason I've had an insanely long streak of bad luck?
    /s 😂

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  • [–] 20 points 9 months ago (5 children)

    Don't stop now. You're obviously due for an equally long winning streak. Isn't that how it works?

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  • [–] 13 points 9 months ago* (last edited 9 months ago) (3 children)

    Yes. It's called gambler's fellacy because it leads to free blowjobs.

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  • [–] 15 points 9 months ago* (last edited 9 months ago)

    V-Sauce had an incredible video on this, outlining exactly how unfathomably colossal the number 52! actually is. If I remember correctly:

    Stand at the equator and set a timer for 52! seconds, press start, then stand still and wait for 1 billion years. Then, take one single step forward, and wait another billion years.

    Continue walking at this pace until you've made your way around the Earth and back to your original starting position, then remove one drop of water from the Pacific ocean, and set it aside.

    Repeat this process until you've completely emptied the Pacific Ocean drop by drop, then set a single sheet of paper on the ground beside you. Refill the Pacific Ocean again (instantly), and do it all over again.

    Continue this process, setting each sheet of paper on top of the last, until the stack of papers reaches the sun. Then tear it all down and do the whole thing over again, 999 more times.

    At this point, the timer would be about a third of the way to 0 seconds.

    The video continues with an alternative mind-boggling process to kill the rest of the time while you're waiting for the timer to reach 0, which involves dealing yourself 5 cards from a well-shuffled deck once every billion years, and buying a lottery ticket for each royal flush you deal yourself. If that lottery ticket hits the jackpot, you'd (EDIT: throw a grain of sand into the grand canyon, repeating until it's full - forgot this step) then remove 1 ounce of rock from Mount everest, and repeat all of this until Mount Everest is completely leveled.

    After doing this 256 more times, then the other two-thirds of the timer will have elapsed, and it would finally reach 0.

    That's how long 52! seconds would be.

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  • [–] 7 points 9 months ago

    This looks a lot like AI slop to be honest

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  • [–] 10 points 9 months ago

    This isn't true in practice since we don't shuffle cards well enough for it to be true but at least this isn't AI Slop haha.

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  • [–] 5 points 9 months ago

    Thanks to auto-capitalization, that factorial looks like the end of an exclamatory sentence with very unremarkable odds.

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  • [–] 8 points 9 months ago (1 child)

    Incorrect, if it was a true random shuffle from an already true randomly shuffled deck you are would have these odds or possibly even better since the majority of all shuffles were not random, but if wo could know I think we would be surprised how poorly randomized the average shuffled deck is.

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  • [–] 4 points 9 months ago

    I've shuffled so poorly that my discard hand ended up Identical the next round in MTG.

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  • [–] 1 point 9 months ago
    [–] 1 point 8 months ago
    [–] 1 point 9 months ago (10 children)

    How many cards from a 52 card deck does it take to have a 50% chance of a unique order?

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  • [–] 3 points 9 months ago (9 children)

    Unique against what? This almost sounded like the birthday problem, but there's only one deal?

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  • [–] 1 point 9 months ago (8 children)

    Unique as in never having happened before in the history of cards.

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  • [–] 2 points 9 months ago (4 children)
  • [–] 1 point 9 months ago (3 children)

    What's your estimate of the number of shuffles in history?

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  • [–] 2 points 9 months ago (2 children)

    We need to have an estimate of the number of hands ever dealt (I think), which isn't given in the infographic. I am suspecting you need a better estimate for the 50% calculation than a 99.999999% calculation, but I don't have the math to back it up.

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  • [–] 1 point 9 months ago (1 child)

    The creator of this factoid doesn't have an estimate and is misrepresenting a basic permutation and assuming no hands have been dealt before.

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  • [–] 1 point 9 months ago

    When considering a full deck you don't really need to estimate the number of dealt hands, because any estimate that is anywhere close to realistic is completely negligible compared to 52!

    We're talking: If every person that ever lived became 100 years old and shuffled one deck of cards every minute of their life, the number of shuffled decks in history is still in practice indistinguishable from zero when compared to 52!

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