Schroedinger's cat is always dead

by PhilGoetz 1 min read26th Aug 201156 comments


Suppose you believe in the Copenhagen interpretation of quantum mechanics.  Schroedinger puts his cat in a box, with a device that has a 50% chance of releasing a deathly poisonous gas.  He will then open the box, and observe a live or dead cat, collapsing that waveform.

But Schroedinger's cat is lazy, and spends most of its time sleeping.  Schroedinger is a pessimist, or else an optimist who hates cats; and so he mistakes a sleeping cat for a dead cat with probability P(M) > 0, but never mistakes a dead cat for a living cat.

So if the cat is dead with probability P(D) >= .5, Schroedinger observes a dead cat with probability P(D) + P(M)(1-P(D)).

If observing a dead cat causes the waveform to collapse such that the cat is dead, then P(D) = P(D) + P(M)(1-P(D)).  This is possible only if P(D) = 1.

If you don't say that only conscious agents can collapse waveforms, then you have to agree that something in the box collapses the waveform as seen from inside the box, while it's still uncollapsed to Schroedinger. And Schroedinger's opening the box collapses that waveform for him; but it is still uncollapsed for someone outside the room.  This seems like it might be equivalent to many worlds - all possibilities already exist; you just haven't chosen which one you're going to access until you open the box.

But if you do say that only conscious agents can collapse waveforms, then it's something about their mental processes that does the collapsing. This could mean their beliefs matter. And then, the cat is always dead.

ADDED:  People.  Read the entire post before responding.  I am not claiming that the cat is always dead.  I am not claiming that consciousness collapses waveforms.  I am claiming that there are only 2 known alternatives:

  1. Interactions collapse waveforms, regardless of whether conscious entities are involved.  It is not possible, under this view, for any waveform to be either collapsed or not collapsed, because there will be some viewpoints from which it has collapsed, and some from which it hasn't.  So this appears to be equivalent to many-worlds.
  2. Consciousness collapses waveforms.  Leading to weirdness such as, potentially, the cat always being dead.

If you can't produce another alternative, and you don't believe in many-worlds, you owe me an upvote.

Finally, this post is supposed to be fun!  You are crushing all whimsy and playfulness on LessWrong when you pile downvotes like bricks on anything playful because it does not provide a complete and satisfactory resolution.