Over Shabbos, the Shalosh Seudos discussion turned to the Monty Hall problem, which confused a lot of people [and which (#Humblebrag) I was able to clear up for them in under 30 seconds ;)].

Then, because I saw they were having such a good time with that thought, I brought up Schrödinger's cat. This isn't really a puzzle, but rather a mashal for an idea in quantum physics.

The basic idea of Schrödinger's cat is that you put a cat in a box, along with a Geiger counter connected to a source of radiation, with a machine that will release poison that will kill the cat should the device detect radioactivity. What they claim is that until you open the box and see what happened, the cat is both alive and dead until observed (see here, here and here). [and this threw my friends for a real loop ;)]

This got me thinking: what would happen if someone's son (only child) found their way into a Schrödinger's cat box, and his father died while he was in there? Would his wife have to do yibbum/chalitza?
What if the father was the one in the box, and the son died while he was in there, and after that the box was opened and the father is found dead in the box -- is there yibbum?

Please note: unless you can tell me otherwise (with a source!) that this is a regular safek, for argument's sake let's assume that it's not; and that there is such a thing as alive and dead until observed.

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    I was gonna name this question something cute, like Schrodinger's yibbum or Schrodinger's nephew but wanted to have a clearer title....think I should change it?
    – MTL
    Jun 15, 2014 at 4:21
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    I thought Shroedinger's cat was an example of Reductio ad Absurdum. Jun 15, 2014 at 4:33
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    Actually, see Wikipedia article: "Schrödinger did not wish to promote the idea of dead-and-alive cats as a serious possibility; on the contrary, the paradox is a classic reductio ad absurdum" Jun 15, 2014 at 4:34
  • @ShmuelBrin That is true....but the other side wasn't chozer....since this observer-created reality and and quantum superposition are still real possibilities in physics (and are still taught in physics classrooms!), I was wondering what would happen in this case
    – MTL
    Jun 15, 2014 at 4:36
  • @ShmuelBrin See here and here [both linked to in the question btw]
    – MTL
    Jun 15, 2014 at 4:36

3 Answers 3


I would say that this is a question of the definition of testimony. We have the halachos in a number of places, including the talmud and Rambam hilchos Yibum, hilchos gittin, and hilchos nashim, about the circumstances as to who is believed if they come before bais din and testify that a person is dead. The implication of all of these is that the witness is testifying that they have seen that the person is dead or they are certifying that a recognized bais din has declared the person dead. Thus, it would be impossible to declare a person dead in the Schrodinger's cat case, because you could not have aidim.

Consider the case of murder (which is discussed in the Talmud) in which witnesses see two people (one of whom is holding a knife) go into a cave (with no known exit) and one of them is stabbed with that knife. The witnesses cannot be used to condemn the survivor of murder, even if he exits the cave holding the bloody knife. Similarly, witnesses can only say that the "cat" is in the box but cannot testify that it is dead until the box is opened and they see it. This is true even if we do not say that the cat is "both alive or dead".

Thus, the witnesses seeing that the person is in the box cannot be used to establish anything. The box must be opened and the witnesses testify as to what was found in the box before the halacha can be established.

Note: that I have no specific sources, but the logic seems to follow from the known halacha of aidus.

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    I'm not sure the eidus of dinei nefashos quite applies here, but either way I think this is the answer - halacha requires observation. Perhaps this hypothetical gives us insight into why.
    – Yishai
    Jun 15, 2014 at 14:25
  • @Yishai even dinei mamanus aidus would apply. I used about a husband dying and the various results because that is closest to the question. That is also why I used the cave. It is the closest thing that I could think of to the box. Jun 15, 2014 at 15:44
  • @sabbahillel Improbably and quite incredibly, the exact same point is discussed here in regards to Chanukah: quantumtorah.com/chanukah-menorah-burning-bush-and-sotah
    – SAH
    Mar 12, 2018 at 23:38

Believe it or not, the gemara discusses cases where an individual can have 2 polar opposite statuses at the same time (for example see here).

There are a number of cases brought in the gemara (Gittin 41b, Mishna Pesachim 8:1, etc.) of a person that is 'half slave, half free'. Of course, if you are a slave then by definition you are not free and vice versa. There are however, rulings for these individual cases. The commentaries discuss how the 'slave' and 'free' aspect of the person impinge on the outcome of the halacha l'maaseh.

In the case that you bring about a person being both dead and alive could be viewed in a similar light. On the one hand, the child is dead and chalitzah would be required. On the other hand he is alive so it wouldn't be done.

What you should really do is open the box and have a look inside. The real question is, that if you open the box and find that the boy is dead, are you now punished for killing the boy?! By making the observation you force one of the realities to exist singly. However, you could argue that the boy was already fully dead. What you have done though, is taken away the chance of him living.

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    half slave, half free is resolvable, as the halacha says - he works a day for his master and a day for himself - you just divide the time. Half living and half dead can't really be reconciled at the same time, and I don't think the theory is suggesting he is alternating between alive and dead. Jun 19, 2014 at 22:30

I think that there's one principle that we're forgetting here, and that's the concept of Chazakah. If a person (or cat) enters a box, that person is assumed alive until otherwise identified.

I would say that we can use Chazakah to resolve Schrödinger's paradox Al Pi Halachah. The cat is alive until proven otherwise.

  • Welcome to MiYodeya and thanks for this first answer. Since MY is different from other sites you might be used to, see here for a guide which might help understand the site. Great to have you learn with us!
    – mbloch
    Apr 18, 2023 at 5:32
  • Welcome, @ElonMusk. Wouldn't this be a case where the chazaka has been undermined (itra) by putting the person has a 50% chance of dying?
    – Avraham
    Apr 18, 2023 at 7:57

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