My understanding of probabilities in many worlds is following:

If I would decide to start smoking and we know that 10% of smokers get cancer that means that in 10% of all worlds during my lifetime I would get cancer (assuming I would smoke average and I am genetically average to get cancer and average in every way).

or another example:

If I would decide to start building parachute jumping and we know that 5% of building parachute jumpers die in the process that means that in 5% of all worlds where I made such decision I would die from jumping (assuming I am average jumper and average in every way)

Edit: To some this question seems to be confusing. I used examples since I am not a physicist, and when one is using technical language what he does not understand the outcome usually is pathetic.

@count_to_10 has linked to Many world interpretation and I can confirm that this is exactly what I am talking about. Question rephrased in technical language would be:

If some event (like a toss of a dice has chance of 16.(6)% to roll 6) does that mean that 16.6% of world branches (on average) will get 6 rolled? Same thing with cancer example would there be 10% of world branches that one would get cancer?

Do many world probabilities can be understood in such a way or they are something completely different? If not how should I understand them?

  • $\begingroup$ You probably want to ask this on MathStackexchange don't you...? Is there a specific reason for your asking it here? $\endgroup$
    – Matt
    Nov 4, 2015 at 14:29
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    $\begingroup$ @MattS I believe it has a better chance getting answered here (I don't see how this could be interpreted as anything but physics question). If any other forum I would say Philosophy (but one would need metaphysics knowledge and argument would be to move it here from Philosophy), what makes you think it belongs in Math and not here? $\endgroup$ Nov 4, 2015 at 14:38
  • $\begingroup$ To me it's statistics and probability all the way, thus the maths reference, how likely are your chances of ending up in a universe where there is a cure for cancer? For the best way to follow the MWI, Wikipedia does a good summary, imo en.m.wikipedia.org/wiki/Many-worlds_interpretation $\endgroup$
    – user81619
    Nov 4, 2015 at 14:49
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    $\begingroup$ I'm voting to close this question as off-topic because it is not about a specific physics concept. $\endgroup$
    – Bill N
    Nov 4, 2015 at 15:16
  • $\begingroup$ @BillN Are you claiming that Many worlds is not physics concept? Could you elaborate which field of science does this belong too then, please. Or you read title and voted to close without looking into question itself? (It's not about cancer) $\endgroup$ Nov 4, 2015 at 16:18

1 Answer 1


Yes, your interpretation is correct, but only if the probabilistic nature of these events is caused by quantum mechanics.

To give a counterexample. If you throw a die,the probability of throwing six is around 16.6 %. However in this case there is no splitting of worlds. The reason is that in this case the uncertainty in the outcome is a result of an uncertainty in the way you throw. Something which can be explained classically.


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