Can somebody explain this online shuffle?

[Sciolist]

52 * 51 is 2652, then when you put in the other fifty multiplications... I'm not too sure where you got your number from, but I think it's down to a misapprehension of what !52 means.

[DreamMaster]

Thanks for the explanations. Actually these explainations are a lot simpler and less drawn out than PS's explanation. Also interesting post about the time of day shuffle. =p

Ok now a little side (possibly noobish) question. So they use a combination of a random number generator and user input to make it random. Who/what user input are they using and couldn't that technically be explioted? Also I was told random number generators can't be technically random?

[Sciolist]

Yes, RNG are technically not random. That's why there's input from other sources. The program allows a random seed to be picked.

For example, measuring minute variations in background temperature isn't random, but it's also not predictable in practice - I believe it's related to brownian motion, if you did that in Physics classes. The overall picture is predictable, but a very small sample is effectively random unless you can model all the molecules in the room at the time.

As for taking user input, again, this is technically not random, but it's also impossible to predict. You'd have to know the algorithm, but you'd also have to know exactly what's happening on every single PC connected to the site at the time. If anyone has a trojan on all 60,000 people connected to stars, then yes, it might be possible to predict this.

You can't make a PC generate a truly random number, so every (reputable) site uses something else too - like the Thermal Noise generator from Intel that PS uses. I guess the only real source of random would be via atomic decay in small samples, but as there're easier ways to get numbers that are not predictable in practice, then that's what happens.

I guess if you were omniscient, the sites shuffle wouldn't be random, because the numbers may theoretically be possible to predict. However, in practice it's insanely difficult. Measuring the location of every molecule in a room may be something that sounds possible, but how do you freeze things in place long enough to do so? How do you measure it without changing the outcome? How do you model the collisions past the first nanosecond? Why exactly would PS let you into the same room as the thermal noise generator with your lasers, liquid nitrogen and supercomputers? Etc.

[CORed]

52!=8.0658175170943878571660636856404e+67 according to the Windows calculator in sientific mode. It's one of the few "free" programs that come with Windows that is not overpriced.

[Sciolist]

Nice number. I heard that every time a deck of cards is shuffled, there's never been that configuration of cards before, and likely won't be if you shuffle again for the lifetime of the universe. Those *10^67 numbers do that I guess.