That used to give me problems, until I read somewhere – can’t remember where, probably on Ask a Mathematician / Ask a Physicist (askamathematician.com), which I heartily recommend for this sort of thing – that the many-worlds interpretation doesn’t actually say that the universe splits.
Rather, it proposes that particles exist in multiple states all the time (i.e., the wave function never collapses), and that this by necessity includes the particles in our brain. So what we perceive as a wave-function collapse is actually our brain getting entangled with the particle under observation.
So in the double-slit experiment, for example, with no detector on either slit, the particle appears to pass through both: the states of the particle and of our brain are uncorrelated.
But if we place a detector at each slit, we entangle ourselves with the particle as it passes through, and the joint particle/brain system now exists in a superposition of these states:
particle passes through left slit / brain observes particle going through left slit
particle passes through right slit / brain observes particle going through right slit
No universe-splitting required.
(Apologies to any actual physicists out there who are currently choking on their beverage of choice at this layperson’s mangling of a scientific theory.)
I would have thought that our brains are only tangentially related. The double-slit experiment works whether or not a human is observing it at the time. The detectors are what makes the difference, so wouldn’t it be the fact that the particle interacting with the detector on one or both slits is what’s semi-collapsing the wavefunction and our brains are just observing what happened later?
It’s right… for now! But we have to expect a paradigm shift one day, right? i remember a friend of mine explaining how an MRI works. She said, at one point, it forces certain electrons to be in one of four places, but then she corrected herself, clarifying that it makes sure that if we observe those electrons we will only observe them in one of four places.
What I honestly can’t understand, is what does “observe” mean. Apparently exerting gravitational force on one another doesn’t count, leaving a mark on a piece of film doesn’t count, but leaving a mark on a piece of film when you would’ve been polarized a different way if you’d passed through a different slit does? What the hell is that?
Eyes are the imperfect detectors of light for the brain.
It sounds like what you’re calling the “detectors” are essentially non-attached prosthetics to allow better human observation of the experiment.
If a tree falls in the forest and no one is there, does it make a noise? Well, let me use some remote sensing equipment and see . . . Apparently when a human observes it remotely it still makes a noise. But what about when there’s no remote sensing equipment?
What I’m getting at, and apologies it this turns out to be a non-sequitor, is that pretty much everything in the universe is in some way a “detector” since everything is interacting on some level (usually gravity if nothing else). Attempts to isolate out the “magical” essential quality of human observation seemed doomed to failure, since careful enough observation of one’s surroundings could in theory “detect” anything within one’s light cone.
The point about the tree as I understand it is that “sound” is human or animal perception, vibrating air is not sound till a brain has processed it (or something designed by a brain). If nobody hears the tree there is no sound.
The observer question in physics is similar. Without something to process data, collisions do not have meaningful outcomes. Stuff happens but there are no events. This is what worries me philosophy of science wise about the foundations of quantum indeterminacy: I think there is lurking Judaeo-Christian theology in there somewhere.
It is heartening to hear an Evangelical basically say, “yeah we really should help the poor and oppressed”. But the repetition of Jew and Crazy Hair was off putting.
If they want to see crazy hair, I’ll send them a selfie from five AM.
Yes, it would be surprising if their brand of Christian was at all excited by someone who lives more of an ideal than the staff and leaders. But no. Same protestant lack of ethics.
Leaving a mark on a piece of film does count. In the standard double slit experiment, electrons that hit the screen end up marking a single defined position, and it is only when you look at the pattern made by many of them that you can tell they were self-interfering on the way there.
In the one version that makes sense to me, what determines an observation of this sort is quantum decoherence. When some property of a particle gets entangled with huge numbers of other particles, the states end up practically guaranteed to be independent and so all the weirdness from the superposition goes away.
How many it takes is really just statistics. As you add more dimensions to a vector space, the chance that random vectors won’t be perpendicular (within whatever tolerance) goes to zero. Anything big enough we would consider a detector is going to have more than enough particles that their degrees of freedom will cover it.
Sorry to continue the tangent, but it’s something I think is interesting.
I just read it as repeating the initial impression that many had had - Bernie Sanders is not the typical person that they would listen to, but like central Jewish characters in the Bible, he has a prophetic message that people have to hear. The repetition of “Jew” is supposed to sting for evangelicals who have allowed themselves to become so prejudiced and complacent towards justice that they laugh at someone for looking and talking like an older John the Baptist or Jesus and ignore some of the central teachings of Christianity (and Judaism).
