5 ms·

Well, the thing is that the MWI is actually simpler than all the other interpretations, because it simply removes the idea of wave function collapse entirely.

Well, the thing is that the MWI is actually simpler than all the other interpretations, because it simply removes the idea of wave function collapse entirely. Any theory involving wave function collapse is adding something extra to quantum physics that can't be demonstrated experimentally. Because we live in the macro world, it feels like a single unitary reality is simpler, but actually, the MWI makes fewer assumptions. So I would turn that around and put the burden on the other theories to show that collapse is real, the default position should be MWI.

TheOtherHobbes 4y ago
You don't think postulating an unknown number of extra universes with a very poorly defined relationship with each other qualifies as an extra assumption?
- pdonis 4y ago
  The MWI does not postulate extra universes, although that pop science description is unfortunately common even though it is wrong. The MWI just says that the one universe that exists is actually very, very different from what we perceive. (To be clear, I'm not saying this correct description makes the MWI any more palatable. I am just clarifying exactly what kind of unpalatableness the MWI requires.)
  - ryeights 4y ago
    Can you elaborate on this? The Wikipedia page for MWI says >The many-worlds interpretation implies that there are most likely an uncountably infinite number of universes. https://en.wikipedia.org/wiki/Many-worlds_interpretation https://en.wikipedia.org/wiki/Many-worlds_interpretation
    - GoblinSlayer 4y ago
      Those worlds are states in superposition, the term "world" is an allegory to help people understand that those states don't interact due to linearity of the Schrodinger equation, because not all properties of linearity are obvious.
    - pdonis 4y ago
      One should not be trying to learn physics from Wikipedia, particularly not for something as complicated as QM, even more particularly not for an aspect of QM as contentious as the MWI. The MWI says that there is one single universal wave function, which evolves in time by unitary evolution forever, and that that universal wave function is all that exists. That is one universe, not an infinity of them. It is just one universe that is nothing like what we think we perceive.
      - jamiek88 4y ago
        Your last paragraph is verbatim gonna be the ‘Lord’s Prayer’ of my space cult. Wanna join? You can be number 2 thus have second dibs at the buffet.
    - d_tr 4y ago
      Not the parent, but I 'd say this amounts to how you define a "universe". There is a single wavefunction which says that one "copy" of you observes result A and another "copy" observes result B. Using the phrase "many universes" implies that these two scenarios are considered as "different universes". I personally do not like this phrase and find it misleading.
      - TEP_Kim_Il_Sung 4y ago
        You are all the "copies", and, under certain conditions, can experience all their observations. Think of yourself more as an aspect of a multifaceted being experiencing the universe through you.
        pdonis 4y ago
        > under certain conditions, can experience all their observations What conditions are these?
        TEP_Kim_Il_Sung 4y ago
        Practice lucid dreaming, so you can maintain a semi-awake meditative state. Practice remembering your dreams -some of them are memories from other aspects like you, others are your subconscious communicating through symbols and situations. Practice asking questions, dreaming, and remembering. Practice reaching the semi-awake meditative state from the awakened end of your day. Realize, what you think of as your body, is the 4D sensory organ of your hyperdimensional self, maintain meditative state, and open your other eyes. The effect is a lot like the collage view of regular stereoscopic vision, except out of the immediate overton-window of aspects of yourself similar enough to you. Getting to that point can take several years. A quicker option seem to be drugs, based on conversations I had with friends, but I never wanted to artificially taint my perception, so I did it the hard way. My findings are that while there is no fate, there exist enough aspects in universes similar enough to yours, but perhaps chronically shifted, that you can learn from their mistakes. This is known as instinct, "guardian angels", premonition, deja-vue, etc. Good luck.
    - olddustytrail 4y ago
      Let's say we generally subscribed to the flat earth theory. But that causes many problems with our actual measurements. So someone proposes the "many earths" theory, where there are many flat earths connected at different angles. If you could travel between these many earths, you could even end up in one - let's call this mythical land "Australia" - where South was up! Sounds a bit crazy but some people believe it could really exist.
  - GoblinSlayer 4y ago
    We perceived flat earth and geocentrism, so not the first time. I can recommend quantum electrodynamics to people who are too attached to corpuscular paradigm.
  - kgwgk 4y ago
    "The MWI" is not one thing. There are many-people saying many-things about those many-worls.
- d_tr 4y ago
  It is the other way around. The "universes" are there when you solve the equations, and you can either let them be or keep only one by invoking the collapse. The collapse amounts to just setting some terms to zero.
tsimionescu 4y ago
It is not simpler, since MWI still needs the Born postulate to actually predict the results of quantum experiments. It replaces this idea of the wave function collapsing with a redefinition of what a measurement apparatus / observer is (in MWI, a measurement apparatus exists in a single "branch" of the wave function). This is especially problematic because QM doesn't predict any particular decomposition of a quantum state into particular classical states. That is, the Schrodinger equation doesn't actually predict that a particle has some amplitude here and some other amplitude there, as is often presented; instead, it predicts that it is described by some vector which can be decomposed in many different ways. You can say it has some amplitude X here and some amplitude Y there, but with any 2 points in space-time (adjusting the amplitudes). Or, it can have some combination of position and spin with amplitude X, and some other combination of position and spin with amplitude Y. You can choose any basis you like for the measurement, and you will get the corresponding answer. But, for MWI to actually predict experimental results (and the classical world we live in) you not only have to choose to look at a single element of that basis, but you also have to believe that the classical basis is somehow preferred.
- GoblinSlayer 4y ago
  >This is especially problematic because QM doesn't predict any particular decomposition of a quantum state into particular classical states. It does predict it, this decomposition is called decoherence, where a classical state splits into a superposition of several different classical states.
  - pdonis 4y ago
    > this decomposition is called decoherence, where a classical state splits into a superposition of several different classical states. No, that's not what decoherence is. Decoherence is the spread of entanglement over a very large number of untrackable degrees of freedom (usually referred to as the "environment"). This makes interference effects unobservable. But decoherence itself does not involve any "splitting"; the entanglement that decoherence spreads over a very large number of untrackable degrees of freedom has to already be there before decoherence can act on it.
lamontcg 4y ago
> Any theory involving wave function collapse is adding something extra to quantum physics that can't be demonstrated experimentally. Title article is literally about trying to test those theories experimentally.
- fallingfrog 4y ago
  ..And failing to find any evidence of collapse. Hence "can't be demonstrated". I didn't mean "can't be looked for" I meant that attempts to find it have not been successful.
sfink 4y ago
Only to the extent that MWI is actually a position. My understanding of MWI is: shit happens, and there's no need to understand why specific shit happens because all shit "happens" (by a definition of "happens" that carries basically no meaning) and you should be happy just to prove that the shit that happens is among the full set of shit that could happen. It's the "don't worry your pretty little head over it" theory of reality. Here's the best poem ever written, or that will ever be written: Roses are red Violets are blue MWI stinks And so do you. Don't think it's that great? Well, that's because there exist other versions of me that wrote different words up there, and you just happened to read a version that wasn't that great. I hereby accept my position as God Poet of the Universe.
- GoblinSlayer 4y ago
  Shit happens because that's how the state of matter changes over time, the wave function is the description of the state and the Schrodinger equation is the description of the state's change. That's as complete and happy understanding as it goes.

TheOtherHobbes 4y ago

You don't think postulating an unknown number of extra universes with a very poorly defined relationship with each other qualifies as an extra assumption?

pdonis 4y ago
The MWI does not postulate extra universes, although that pop science description is unfortunately common even though it is wrong. The MWI just says that the one universe that exists is actually very, very different from what we perceive. (To be clear, I'm not saying this correct description makes the MWI any more palatable. I am just clarifying exactly what kind of unpalatableness the MWI requires.)
- ryeights 4y ago
  Can you elaborate on this? The Wikipedia page for MWI says >The many-worlds interpretation implies that there are most likely an uncountably infinite number of universes. https://en.wikipedia.org/wiki/Many-worlds_interpretation https://en.wikipedia.org/wiki/Many-worlds_interpretation
  - GoblinSlayer 4y ago
    Those worlds are states in superposition, the term "world" is an allegory to help people understand that those states don't interact due to linearity of the Schrodinger equation, because not all properties of linearity are obvious.
  - pdonis 4y ago
    One should not be trying to learn physics from Wikipedia, particularly not for something as complicated as QM, even more particularly not for an aspect of QM as contentious as the MWI. The MWI says that there is one single universal wave function, which evolves in time by unitary evolution forever, and that that universal wave function is all that exists. That is one universe, not an infinity of them. It is just one universe that is nothing like what we think we perceive.
    - jamiek88 4y ago
      Your last paragraph is verbatim gonna be the ‘Lord’s Prayer’ of my space cult. Wanna join? You can be number 2 thus have second dibs at the buffet.
  - d_tr 4y ago
    Not the parent, but I 'd say this amounts to how you define a "universe". There is a single wavefunction which says that one "copy" of you observes result A and another "copy" observes result B. Using the phrase "many universes" implies that these two scenarios are considered as "different universes". I personally do not like this phrase and find it misleading.
    - TEP_Kim_Il_Sung 4y ago
      You are all the "copies", and, under certain conditions, can experience all their observations. Think of yourself more as an aspect of a multifaceted being experiencing the universe through you.
      - pdonis 4y ago
        > under certain conditions, can experience all their observations What conditions are these?
        TEP_Kim_Il_Sung 4y ago
        Practice lucid dreaming, so you can maintain a semi-awake meditative state. Practice remembering your dreams -some of them are memories from other aspects like you, others are your subconscious communicating through symbols and situations. Practice asking questions, dreaming, and remembering. Practice reaching the semi-awake meditative state from the awakened end of your day. Realize, what you think of as your body, is the 4D sensory organ of your hyperdimensional self, maintain meditative state, and open your other eyes. The effect is a lot like the collage view of regular stereoscopic vision, except out of the immediate overton-window of aspects of yourself similar enough to you. Getting to that point can take several years. A quicker option seem to be drugs, based on conversations I had with friends, but I never wanted to artificially taint my perception, so I did it the hard way. My findings are that while there is no fate, there exist enough aspects in universes similar enough to yours, but perhaps chronically shifted, that you can learn from their mistakes. This is known as instinct, "guardian angels", premonition, deja-vue, etc. Good luck.
  - olddustytrail 4y ago
    Let's say we generally subscribed to the flat earth theory. But that causes many problems with our actual measurements. So someone proposes the "many earths" theory, where there are many flat earths connected at different angles. If you could travel between these many earths, you could even end up in one - let's call this mythical land "Australia" - where South was up! Sounds a bit crazy but some people believe it could really exist.
- GoblinSlayer 4y ago
  We perceived flat earth and geocentrism, so not the first time. I can recommend quantum electrodynamics to people who are too attached to corpuscular paradigm.
- kgwgk 4y ago
  "The MWI" is not one thing. There are many-people saying many-things about those many-worls.
d_tr 4y ago
It is the other way around. The "universes" are there when you solve the equations, and you can either let them be or keep only one by invoking the collapse. The collapse amounts to just setting some terms to zero.

tsimionescu 4y ago

It is not simpler, since MWI still needs the Born postulate to actually predict the results of quantum experiments. It replaces this idea of the wave function collapsing with a redefinition of what a measurement apparatus / observer is (in MWI, a measurement apparatus exists in a single "branch" of the wave function). This is especially problematic because QM doesn't predict any particular decomposition of a quantum state into particular classical states. That is, the Schrodinger equation doesn't actually predict that a particle has some amplitude here and some other amplitude there, as is often presented; instead, it predicts that it is described by some vector which can be decomposed in many different ways. You can say it has some amplitude X here and some amplitude Y there, but with any 2 points in space-time (adjusting the amplitudes). Or, it can have some combination of position and spin with amplitude X, and some other combination of position and spin with amplitude Y. You can choose any basis you like for the measurement, and you will get the corresponding answer. But, for MWI to actually predict experimental results (and the classical world we live in) you not only have to choose to look at a single element of that basis, but you also have to believe that the classical basis is somehow preferred.

GoblinSlayer 4y ago
>This is especially problematic because QM doesn't predict any particular decomposition of a quantum state into particular classical states. It does predict it, this decomposition is called decoherence, where a classical state splits into a superposition of several different classical states.
- pdonis 4y ago
  > this decomposition is called decoherence, where a classical state splits into a superposition of several different classical states. No, that's not what decoherence is. Decoherence is the spread of entanglement over a very large number of untrackable degrees of freedom (usually referred to as the "environment"). This makes interference effects unobservable. But decoherence itself does not involve any "splitting"; the entanglement that decoherence spreads over a very large number of untrackable degrees of freedom has to already be there before decoherence can act on it.

lamontcg 4y ago

> Any theory involving wave function collapse is adding something extra to quantum physics that can't be demonstrated experimentally. Title article is literally about trying to test those theories experimentally.

fallingfrog 4y ago
..And failing to find any evidence of collapse. Hence "can't be demonstrated". I didn't mean "can't be looked for" I meant that attempts to find it have not been successful.

sfink 4y ago

Only to the extent that MWI is actually a position. My understanding of MWI is: shit happens, and there's no need to understand why specific shit happens because all shit "happens" (by a definition of "happens" that carries basically no meaning) and you should be happy just to prove that the shit that happens is among the full set of shit that could happen. It's the "don't worry your pretty little head over it" theory of reality. Here's the best poem ever written, or that will ever be written: Roses are red Violets are blue MWI stinks And so do you. Don't think it's that great? Well, that's because there exist other versions of me that wrote different words up there, and you just happened to read a version that wasn't that great. I hereby accept my position as God Poet of the Universe.

GoblinSlayer 4y ago
Shit happens because that's how the state of matter changes over time, the wave function is the description of the state and the Schrodinger equation is the description of the state's change. That's as complete and happy understanding as it goes.