[_yb2s]

Counterintuitively, extremely unlikely events like this happen very often. The odds of a specific event like this are astronomically small, but there is an even more astronomically large number of different possible unlikely events. The sheer number of possible events is orders of magnitude greater than the odds of individual unlikely events, causing them to occur regularly.

The universe is a really weird place, where really weird stuff happens constantly.

[ckastner]

> Counterintuitively, extremely unlikely events like this happen very often.

As the saying goes, "people win the lottery every day", and there are a lot of lotteries active on this planet.

[gerdesj]

Sir Terry Pratchett often declaimed in his novels that "Million to one chances happen one times in ten".

The statistical terms used are completely wrong but the intention is clear: weird shit happens.

[NaturalPhallacy]

"Fiction has to make sense, reality can do whatever it wants."

[lostlogin]

You sound like someone who has witnessed the last 5 years.

[NaturalPhallacy]

The idea is a bit older than that:

Clancy here expresses an idea evoked in similar statements made by others, all derived from the orignial made by Lord Byron:

Lord Byron: Truth is always strange; stranger than fiction.

Mark Twain: Truth is stranger than fiction, but it is because fiction is obliged to stick to possibilities, truth isn't.

G. K. Chesterton: Truth must necessarily be stranger than fiction, for fiction is the creation of the human mind and therefore congenial to it.

Leo Rosten: Truth is stranger than fiction; fiction has to make sense. (attributed)

https://en.wikiquote.org/wiki/Tom_Clancy#Larry_King_Live_(20...

[hutzlibu]

I just thought, he made fun of the stereotypical heros taking their one in a million chance and allways succeeding, meaning it is a physical or dramatic law that one in a million chances are 100% guaranteed.

(mainly refering to "Guards! Guards!", where they intentionally make one guards bow shot harder, to make his shot (at a dragon) a million to one chance, so it becomes a 100% shot, nice absurd logic and of course it does not work, but the chance for them surviving the stunt was one in a million..)

[WalterBright]

Sometimes, I drop something by accident, and the object falls in a strange way. I think "I could never in a million years duplicate the path that took."

[notacoward]

"I could never in a million years duplicate the path that took."

I still remember, from at least twenty years ago, an anti-duplication technology based on this idea. IIRC it involved embedding glitter in clear plastic and then measuring the reflections at different angles. Devilishly hard to duplicate, especially since one wouldn't know which angles would be used in a reading so the placement would have to be nearly perfect in every dimension. Unfortunately so would the alignment in a reader, which I think is what sank the idea. Still, the idea of physically embodying something so similar to a mathematical proof of work seems valid and quite appealing. "I could never in a million years make the glitter fall that way again."

P.S. Here's a modern application of a similar technique to detect tampering with a laptop. https://archive.ph/g1kDW

[hammock]

https://en.wikipedia.org/wiki/Birthday_problem

[DieBruderBauer]

Imagine if you took the Everettian interpretation of Quantum Mechanics.

[skissane]

If it is true, doesn’t it follow that there are (very rare) universes where unlikely events happen so often that anyone in such a universe would effectively observe a different probability distribution of events?

The thing is, if the theory is true, how do we know we are not in such a universe? We can say it is extremely unlikely because they are very rare - but we say it is “unlikely” and “rare” because we assume the global (multiverse-wide) probability distribution is similar to the local (this universe) one - but isn’t that assumption effectively equivalent to the assumption that we are not in such a universe? An argument which begins by assuming its conclusion is not much of an argument.

However, if we can’t rely on that assumption, it seems in principle impossible for us to know what the global probability distribution is - how is that not a lethal blow to the entire theory?

[_yb2s]

If you insist on using old fashioned logic to reason when in a probabilistic universe where that kind of reasoning is only an approximation, you can say that the universes you are talking about don't exist. They are such a small fraction of possible universes, that you can safely 'know' you aren't in any of them without checking.

[realgeniushere]

This comment misses the point and just plays with the meaning of “know”. Not that epistemology isn’t interesting, but parent was referring to absolute certainty (contingent on your senses being accurate, of course).

[skissane]

Not sure which parent you mean, but if you mean my comment, I wasn't talking about absolute certainty at all. Rather, I was attempting a reductio ad absurdum against theories which talk about the probability of different universes within a multiverse. Nothing I said is an argument against probabilistic reasoning/knowledge limited to the confines of this universe only.

[_yb2s]

I don't understand your criticism, and I think you might have been mis-understanding my intent. The Everettian (Many Worlds) interpretation of Quantum Mechanics is itself at odds with the concept of absolute certainty. I am thinking about this in terms of E. T. Jaynes perspective that probability theory is an extension of traditional logic, and is required for reasoning about the MWI.

I'll also note that I did miss the point of the OPs comment, but I think not in the way you suggested.

[_yb2s]

skissane, after re-reading your comment, I realize I did mis-understand your point, but in a different way than the other commenter suggested.

I don't think MWI is assuming the global (multiverse-wide) probability distribution is similar to the local (this universe) one, but rather than local probabilities directly arise from the global probability distribution, they are the same. If you do an experiment (e.g. wavefunction collapse) the outcomes we observe in a given experiment are each a single sample from the global distribution. Some outcomes can be highly unlikely and give a skewed view of the global distribution, but a larger number of experiments will always converge to the global distribution.

[skissane]

> but a larger number of experiments will always converge to the global distribution

But don't there exist universes in which that fails to happen? Consider a binary quantum experiment for which the global distribution is 0.5 (we might call it a "quantum coin flip"). If I repeat the experiment often enough, will it always converge to the global distribution? Well, suppose I have an ordinary (non-quantum) fair coin, and flip it one million times – what is the odds of it coming up heads every time? If I've got my maths right, 2^(-10^6) – so beyond astronomically unlikely, its probability is for all practical purposes indistinguishable from zero.

And yet, if MWI is right, then if I flip a "fair quantum coin" one million times, there are universes (just as "real" as ours) in which it comes up heads every single time. 2^(-10^6) is unbelievably small, but it isn't zero. Indeed, no matter how many observations occur, the probability of getting them all wrong just by chance remains non-zero – and, according to the MWI, everything with a non-zero probability in the global distribution actually exists. If MWI is true, there is no limit to how misled some actually existent observers will be.

Hence, by MWI, there are universes, just as real as ours, containing observers who (purely by chance) are consistently misled by their experiments, and therefore conclude that the global distribution is very different from what it actually is. But, if such observers exist, how do we know we are not them? We can say that, by the global distribution, they must be exceedingly rare, so it is exceedingly unlikely we are among them – but that argument relies on the assumption that our locally observed distribution is a reliable guide to the global distribution, which is the very thing it is setting out to prove – and hence must fail as a circular argument. With that argument dismissed, we are left with this conclusion: if MWI is true, we cannot know what the global distribution actually is. That contradicts one of the foundational claims of MWI; therefore, reductio ad absurdum, MWI is false.

This is different from classical sceptical arguments "what if our senses mislead us?", because it argues (if MWI is true) that such misled observers will exist, and the only question is how do we know we are not among them. Classical sceptical arguments are a lot weaker because they are not arguing from the (assumed) actual existence of such deceived observers, only from the (even remote) abstract possibility of their existence. But, if MWI gives sceptical arguments a huge boost - isn't that in itself a good argument against MWI? It renders MWI a self-undermining theory, and theories which undermine themselves ultimately refute themselves.

One might save MWI from this argument by assuming there is some "minimum probability", such that only universes whose probability rises to that minimum actually exist – if all the "misleading" universes are beneath that probability cutoff, no misleading universes exist, so we who exist could not possibly belong to any of them. However, this solution seems rather reminiscent of Ptolemy's epicycles.

[TedDoesntTalk]

Like separate rolls of a single dice, I thought the occurrence of one event has no affect on the probability of another?

[shawnz]

The person you are replying to isn't saying anything about the probability of individual events. They are talking about the probability of at least one of many events occurring, which does change with the number of events being considered

[_yb2s]

Indeed, but I think you might be misunderstanding what I said. Think of the universe as a nearly infinite number of dice rolls all independent and in parallel. Any possible rare combination of dice rolls will actually be happening constantly.

[kelnos]

Right, but while it may only be a 1/6 chance that a single die roll will give you a six, rolling more and more dice eventually makes it a near-certainty that at least one will give you a six.

[xboxnolifes]

What are the odds of you winning the lottery? Now think of how many people win the lottery every year.