Q&A: Is Statistical Probability Preserved Even Across Infinite Universes?
Is Statistical Probability Preserved Even Across Infinite Universes?
Question
With God's help,
Hello Rabbi,
If we assume that there are infinitely many universes parallel to our own, as atheists claim, and right now we are in our own world (as we know it),
and a die comes up with a strange sequence of one hundred 6s in a row, or any other exceptional and rare event,
wouldn't it still be preferable to say that the die is not fair? True, there are indeed infinitely many rolls being made in infinitely many parallel universes, but the result is still unique in our world, or in any world where we would see it.
Or does such an assumption undermine the whole possibility of probabilistic calculation, because after all infinitely many rolls have been made? (But they have no memory…)
Answer
If you know that there are rolls in other universes (or even in our own universe—there is no need at all to reach for other universes), then in principle there is no problem with there being one universe in which such a result occurs. Therefore there is no basis for concluding that the die is unfair. Of course, if the probability of this is higher than the probability of the result given the other rolls, then yes. But when one brings evidence that the die is unfair, one assumes by default that it is fair, and in that situation the result we got is not evidence that this is false.
However, you can ask how it came about that this result occurred דווקא where there are human beings who would appreciate it (unless in those universes too there are such creatures). Or if it occurred in a context where it has special significance (a lottery where one wins a lot of money). If in all the universes there are such creatures and such situations, then there really is no problem with that claim.
But you cannot really know that there were infinitely many rolls in other universes (or in our own universe).
Discussion on Answer
I did not understand your claim. Someone who speaks about infinitely many universes with different systems of laws of nature (or different values of constants) proposes this as an alternative to a proof of God.
As for a roll made in front of you, that has no significance, as I explained. As long as the total number of rolls makes it statistically possible.
I meant that there are two understandings of infinite universes: those with identical laws of nature and identical constants, and those where there is one of everything.
But I am asking regarding the philosophical idea: does this undermine our ability to make probabilistic inferences?
In any case,
if so, why wouldn't you say about an ordinary die that comes up 6 many times that since every day billions of people around the world play and have played with dice, if a very rare sequence came up, what's so surprising? After all, for 1,000 years people have been constantly rolling dice. That doesn't mean the die isn't fair….
I do say that. If you get one hundred 6s, that explanation is no good, because there are not enough such trials.
So in practice, if every day billions of Chinese people were occupied with rolling dice,
if you got a sequence of 100 sixes, you would not conclude that the die was unfair.
Isn't that a bit strange? Why should I care about the Chinese in China?
It reminds me of the joke about someone who boarded a plane with a bomb because he thought the probability of there being two bombs on the plane was negligible.
There is no point repeating this again and again. You are missing basics in statistics. Go and learn.
I would be glad if you would explain the distinction with the Chinese after all.
What difference does it make to me in the Land of Israel if in China there are billions who roll dice all day? It is not very different from if I were not informed about them.
And I would make decisions based on what is here.
If you do not know that the Chinese carried out masses of such trials, you cannot simply assume it. It is just not true. You also do not know what results they got. To do a statistical calculation you need data, not inventions. However, if there is a reasonable chance that throughout the world many trials of one hundred rolls were indeed carried out, then it really is not surprising that you got such a result. But if that is not known, there is no logic in making it up.
Statistics deals with probabilities in light of the information you have, and therefore what the Chinese trials change—assuming you have information about them—is your information about the result.
Likewise, if you yourself performed trillions upon trillions of trials and somewhere in the middle got 100 sixes, that is certainly reasonable. Even though if you had rolled only one hundred times, it would not be reasonable. The other rolls affect the probability of getting the result, and it does not matter whether the rolls are yours or those of Chinese people.
Another example: in England a few years ago, a woman was sent to prison because her two babies died at home. The assumption was that crib death is unlikely (1 in 8,000), and two children dying of crib death is even less likely (they mistakenly assumed independence: 1 in 60 million). Therefore it was obvious that they did not die of crib death but that she murdered them.
But that is of course nonsense. There are tens of millions of other mothers in the world whose two children did not die of crib death, so it is reasonable that for one mother this would indeed happen. And that one is this mother. The fact that more trials are taking place definitely affects the probability that something rare will happen.
Another example: in John Verdon's thriller "Think of a Number," a man receives an envelope containing a letter and another small envelope. The letter tells him to think of a number between 1 and 1000, then open the small envelope, and he will find inside it the number he guessed. The fellow guessed a number and, to his amazement, found exactly that number in the small envelope. The writer told him that if the guess was indeed correct, he should send him $10,000 and he would use his supernatural powers to make him rich. He sent the money and never heard from him again. It turned out that the sender had written ten thousand such letters, and therefore about ten people did in fact find the number they had guessed in the small envelope they received and were sure he was a prophet with supernatural powers. In fact, it was just statistics. The fact that there are more trials affects the probability of getting a result.
In short, I do not see what here is unclear and requires explanation.
Sorry Rabbi, I really did not manage to understand the answer.
It is obvious that information changes the probabilities (for example, that an even number came up on the die), and I understood the examples היטב.
But you never narrow the range of uncertainty, for example by calculating only with respect to the rolls of this particular die. You do not look and compare relative to all the dice and rolls in the world, but only to what is in front of you.
If so, it comes out that the claim speaking about infinitely many other constants—so that in every world there are slightly different constants—does not damage statistics. Because the question is why the result occurred specifically where there are human beings who would appreciate it.
But still, why, if there are infinitely many rolls and infinitely many people, when my friend rolls a die, would I calculate why specifically before me a rare sequence appeared? (I myself do not exist in additional copies.) And I would prefer to attribute it to the die being unfair.
Why look from the point of view of all worlds and not from the point of view of the person asking? Or how is that different from a single world versus theoretical worlds?