Quantum mechanics and a moral dilemma

This past spring for my quantum mechanics course, I again used Schumacher and Westmoreland’s book Q-PSI which I had the good fortune to test over the past couple of years, prior to its publication.  But I also used, as a supplement, Aharonov and Rohrlich’s Quantum Paradoxes.  Interestingly enough, they couch Schrödinger’s cat ‘paradox’ in terms of morality.  For readers not familiar with the paradox, here is the way Schrödinger envisioned it.

Place a cat in a box that also contains a vial of cyanide gas, a hammer, a Geiger counter, and a single radioactive atom.  The hammer is connected to the Geiger counter in such a way that when the atom decays and the decay product is detected by the Geiger counter, the hammer swings down to break open the vial of cyanide gas killing the cat.  According to Schrödinger, quantum mechanics tells us that, until we open the box and look inside, the cat is simultaneously both alive and dead – it is in a superposition of the two states.  This is because the decay of the atom is probabilistic and we can have no way of knowing (until we open the box) whether the decay has happened or not (and thus whether or not the cat is dead).

There’s a subtlety here though.  This paradox has been at the heart of discussions of the ‘measurement problem’ in quantum mechanics since it was proposed.  That is, does the act of measurement cause the state to collapse to a definite outcome?  In other words, does the opening of the box have an effect on the outcome?  Schrödigner’s point in proposing this paradox was to show that the answer to the latter ought to be ‘no’ because it sounds absurd.  And yet it is fairly well-accepted that, indeed, the act of measurement can have an effect (and it’s not hard to imagine scenarios – even classical ones – in which this is the case).

Aharonov and Rohrlich take this one step further.  Let us assume that killing the cat is immoral, i.e. since we know that opening the box might kill the cat, we can’t unintentionally kill it.  Now if the act of measurement does not have an effect on the state of the cat and the cat’s state is solely determined by the random process of the decaying atom, then, if it dies before we open it, whomever built the fiendish contraption is guilty of the cat’s murder.  However, if the act of measurement does have an effect on the state of the cat, i.e. it truly exists in a superposition of states until the box is opened, and we find it dead upon opening the box, then we are guilty of the cat’s murder!

While fairly far-fetched, it nevertheless highlights the fact that science does not occur in a vacuum.  There may be consequences – sometimes subtle – to what we do as scientists.  It also highlights the importance of foundational research.  I can envision a future in which a clearer understanding of the measurement problem could be morally important depending on the nature and state of technology.  Let us hope funding agencies, politicians, and even corporations realize this.


12 Responses to “Quantum mechanics and a moral dilemma”

  1. Ian, thank you for mentioning these moral points … which IMHO have immense practical importance. Our UW Quantum Systems Engineering group has been touching upon these issues in posts to Scott Aaron’s blog (in an Alice and Bob dialog), and our “www.mrfm.org” site even evokes the story of Tamar and Judah to make these points.

    This post is a test to see if the above two hyperlinks links pass-through your blog’s filters … assuming they do, then I’ll write an Alice-and-Bob essay on this topic … emphasizing (Venter-style) some of the practical moral aspects that are emerging in quantum systems engineering.

  2. quantummoxie Says:

    Thanks John. Your links worked so please do share your essay. I am glad that others are touching on these topics! If only there was a journal that would publish this kind of stuff (would Foundations of Physics do it, I wonder?).

  3. “when the atom decays and the decay product is detected by the Geiger counter…”

    Does this not count as a measurement? I don’t think QM requires a person to be conscious of the measurement in order for the waveform to collapse. Is there some subtlety here that I’m missing?

  4. quantummoxie Says:

    It depends on who you ask. This was actually (if I recall) one of the objections leveled at Schrödinger when the cat paradox first came out. But it is not at all clear if a spontaneous and random act is the same as a non-spontaneous and random act in QM (if anyone tells you otherwise, they’re lying or blinded by some pet interpretation).

  5. marsman Says:

    What prevents the observer from being in a superposition of “seeing a live cat” and “seeing a dead cat”?

  6. quantummoxie Says:

    Well, there are two ways to look at it. The first is that you could say the observer can only experience a single “reality” and thus there can’t be any superposition, or you could say that once the observation is made it collapses. But, ultimately, it is entirely possible that the observer could be in such a superposition. This then brings up Rovelli’s relational quantum mechanics interpretation which looks at relative states. The observer may not experience a superposition, but a second observer observing the first may see a superposition.

  7. >> Let us hope funding agencies, politicians, and even corporations realize this.

    So you think that politicians are impressed by questions about morality ?

  8. quantummoxie Says:

    So you think that politicians are impressed by questions about morality ?

    Nope. And that’s the problem.

  9. The question then becomes what does the THIRD observer have going on seeing the first seeing the reality and the second observer seeing the first experiencing reality while experiencing a superposition? Could the third observer, seeing both, actually see the cat alive and dead at the same time?

    Expectations alter reality with varying results.

    I can say for certain Schrodinger never owned a cat…. any cat I have ever owned would have escaped the box after first fixing the mechanism so that when Schrodinger looked in the box, the hammer would have broken the vial and killed HIM.

    Cats thoroughly understand and use Spacetime……

  10. quantummoxie Says:

    I’m trying to remember if he owned a cat or not. But cat owners usually take your viewpoint. Personally, I’m a dog owner. I prefer lovable and dumb over aloof and clever, but it’s just a personal preference. I do enjoy wild cats, though, like bobcats, lynx, mountain lions, etc. (the latter from a safe distance).

    Anyway, your point is very interesting since I had thought about what would happen if you kept going out to fourth, fifth, sixth, etc. observers. Based on QM, the probability of being able to determine who is responsible gets lower and lower as you go out.

  11. So this would actually point to those furthest from the action/event be the most suitable to be Politicians (least responsible). Oh wait.. that is how it is (at least here in the US). I think your entire discussion ahs been fully supported.

    FWIW I own a dog and I train dogs. Dog #2 (puppy 8 weeks old) is arriving Saturday (at which point I can study random activity as there is nothing more randomly active than a Puppy). German Shepherds… which probably also explains a lot about me and my interest in Mathematics (but mostly as a lay person.. the folks responding on this forum are, by and large, for more schooled than I in both math and physics). I too have a soft spot for Wild Cats or all species. Have painted pictures of them.

    My interest in math, physics and chemistry/biology does not at all indicate my level of knowledge or education in those subjects. My Father (who wa an automobile mechanic) would describe it as “just enough knowledge to get me in trouble.” I find it a fascinating consideration that there is an equation out there that can explain everything we see, from a bubble’s formation and path in a stream rapids to the behavior of subatomic particulates and pure energy.

    I do read academic text books for amusement (and because it is cheaper than paying for college credits). My degree (’78) is not science or math based.

    This site is really highly interesting for me (the seat o’ the pants lay person with an interest). It makes me ‘reach’ mentally. I also love that it is in colors that remind me of slate and chalk. 🙂

  12. quantummoxie Says:


    You’ve reminded me that I ought to write this stuff down somewhere in technical jargon…

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