Multiverse Or Parallel Universes

[Time_Travel]

What are some of the scientific problems with Multiverse or Parallel Universe.

Some even suggest that the Universe splits into 2 for each event. The famous one being the Schrodinger's Cat Schrodinger's Cat.

 

What are the real problems with parallel universes and multiverse theories??

[CraigD]

What are the real problems with parallel universes and multiverse theories??

One problem often raised about the many-worlds interpretation of the theory quantum mechanics as a scientific theory is that it isn't a theory, but an interpretation of a theory - that is, it's an aid to understanding quantum mechanics, not an alternative theory to it. In it's original form, the MWI explicitly makes no predictions different than QM, so it can't be tested scientifically in any way that would distinguish it from QM interpreted some other way. In other words, as a theory, the MWI isn't falsifiable, so isn't really a theory.

 

If some theory predicting some way that the many parallel universes could interact, it would be (at least in principle) testable. There are some old and serious such theories, but frankly, I have a hard time imagining them - it takes me a bit or re-reading to "get" their ideas, which after a week or two I mostly forget. :(

[Sci]

I'd vote for the multiverse, which is still really just one overall place. The justification is that if our universe could pop out, which was at any old unspecial time and location, then so could another one, and more. These bubbles popping out may be very low probability events, but that's fine, for they must still happen, eventually, given eternity.

[CraigD]

I'd vote for the multiverse, which is still really just one overall place. The justification is that if our universe could pop out, which was at any old unspecial time and location, then so could another one, and more. These bubbles popping out may be very low probability events, but that's fine, for they must still happen, eventually, given eternity.

I think the "multiverse" you're talking about, Sci, is one where Big Bangs happen in many places distant from one another. This is a different idea than the MWI (typically associated with Everett and DeWitt) associated with the "universe splitting into 2" whenever a measurement is made.

 

In the case of the MWI, these "bifurcated universe" can't interact in an ordinary way. In the case of many "universe" separated from one another only by ordinary 3 dimensional space, these universe can, when light from them have had time to reach one another, eventually interact. In some variations of such "multiple creation event" theories, such as Hoyle and other's "quasi-steady state cosmology", the events are fairly nearby, ongoing, and already interacting.

[Sci]

I think the "multiverse" you're talking about, Sci, is one where Big Bangs happen in many places distant from one another. This is a different idea than the MWI (typically associated with Everett and DeWitt) associated with the "universe splitting into 2" whenever a measurement is made.

 

Yes, I'm letting MWI be in the class of parallel universes. Maybe I'll just call the Big Bangs of many places the Cosmos, as it is still just one verse.

 

Instead of the two-slit experiment (and everything else) causing a spitting, perhaps the photon comes back in time to go through the other slit, or else the slits themselves remember and conserve the quantum states. Too weird, in any way, to say.

[Maine farmer]

I've always wondered, since first reading about parallel universes, if perpendidcular would be a better word. In our ordinary three dimensions of space, the dimensions are perpendicular, are they not?

[Time_Travel]

............. , it's an aid to understanding quantum mechanics, not an alternative theory to it. In it's original form, the MWI explicitly makes no predictions different than QM, so it can't be tested scientifically in any way that would distinguish it from QM interpreted some other way. In other words, as a theory, the MWI isn't falsifiable, so isn't really a theory.

 

 

If its an interpretation for the Quantum Mechanics then its really not a good one.

One of the problems i can think of is when the Universe splits at an event then, where would all the extra mass,energy ,space time etc etc come from. Not sure whether my thinking is correct or wrong as i hear theories like Universe getting created from NOTHING, if its true, then it might be possible that whenever Universe splits into the other Universe getting created with alternate history might also be possible.

[joekgamer]

If its an interpretation for the Quantum Mechanics then its really not a good one.

One of the problems i can think of is when the Universe splits at an event then, where would all the extra mass,energy ,space time etc etc come from. Not sure whether my thinking is correct or wrong as i hear theories like Universe getting created from NOTHING, if its true, then it might be possible that whenever Universe splits into the other Universe getting created with alternate history might also be possible.

 

As far as I can see (and correct me if I'm wrong), these 'alternate universes' are purely stand-in/placeholder/virtual in that they only exist as a concept (different events = different universe). I admit that I have only a very basic knowlege of Quantum Mechanics, but as far as I can tell (and again, correct me if I'm wrong), there can only be one series of events from one initial event (the Big Bang), due to cause-effect relations.

[Time_Travel]

......... there can only be one series of events from one initial event (the Big Bang), due to cause-effect relations.

 

 

Exactly what i was thinking wrt cause-effect.

It is the Big Bang(BB) event that has been creating these unbroken chain of events from the beginning of Universe.

When the first event occurs then the second occurs, the third will be as a result of the first and second, the fourth will be a result of the second and third and so on.

We need only one event for the rest of the series of events to follow.

 

The Universe splitting into 2 something i can't imagine/interpret with as it will lead to probably an infinite number of Universe being created for infinite period of time (eternity).

[Sci]

…i hear theories like Universe getting created from NOTHING,…

 

You know, when you get right down to it, there is literally nothing to make any original stuff out of. Having it around forever doesn't solve the problem, for how could anything be already made and defined in all its particulars without ever having been made and defined in the first place (that never was). Maybe this isn't the place to discuss this, but I do have some ideas.

[CraigD]

As far as I can see (and correct me if I'm wrong), these 'alternate universes' are purely stand-in/placeholder/virtual in that they only exist as a concept (different events = different universe).

I think that’s a pretty good interpretation of the many worlds interpretation. Hey, with this stuff, even interpretations need interpretations! :)

 

I admit that I have only a very basic knowlege of Quantum Mechanics, ...

If you mean to truly be a polymath, you’ll need to do something about that!

 

… but as far as I can tell (and again, correct me if I'm wrong), there can only be one series of events from one initial event (the Big Bang), due to cause-effect relations.

What you’re describing is purely classical mechanical, deterministic physics - what nearly every rational person believed was real prior to the 1920s. Quantum mechanics overturned this view. In it, wave functions are entirely deterministic, but the outcome of measurements of their associated particles are probabilistic. Experimental evidence shows classical physics to be approximately right (on a sufficiently large scale), but exactly wrong, quantum mechanics exactly right (put practically terribly difficult to calculate on large scales), so, in short, Polymath, you’re approximately right, but inspected closely enough, wrong.

 

It might put the MWI in perspective to consider the main alternative to the MWI, known as the Copenhagen interpretation. In this, there’s a single universe, but it’s has only probabilities (strictly speaking, quantum wave functions, from which probabilities of any given event can be with no uncertainly calculated) of being observed to be in a particular state until such observations are made. When an observation is made, yielding a definite result (eg: Schrodinger’s cat is alive, or dead), the probability of all future events must be recalculated – an non-physical occurrence called wave function collapse.

 

The CI was deeply philosophically upsetting to nearly everyone disposed to both mathematical formalism and intuitive philosophical thinking – interpreting wave functions as probabilities are what prompted Einstein to pronounce his famous “God does not play dice” opinion, the non physical nature of the CI’s wave function collapse to call is “spooky action at a distance.”

 

Neither interpretation – the CI or the MWI - change the formalism of quantum mechanics – the theory still predicts the same things – but many find the MWI less philosophically unsettling, as it replaces wave collapse meta-functions that instantly change the probabilities of every event everywhere in the universe with selecting from myriad universes. It builds on our intuitive comfort with the idea that wandering somewhere and perceiving something is due to many somethings being there, rather than the wanderer somehow creating them as they go along (a cousin of the more comfortable answer to the “if a tree falls in the forest, and nobody is there to hear it, does it make a sound” riddle, “yes, of course it does”)

[CraigD]

One of the problems i can think of is when the Universe splits at an event then, where would all the extra mass,energy ,space time etc etc come from.

Both split-off universe have the same past, with the past mass, volume, etc.

 

In principle, the past and future of the MWIs many universe can extend infinitely – the interpretation is neutral on the subject of creation ex nihilo and eternity, leaving those questions to deep developments of quantum theory.

 

Not sure whether my thinking is correct or wrong as i hear theories like Universe getting created from NOTHING

This is one deep (though not very extensively developed) development of quantum theory, sometime credited to Edward Tyron, who likely didn’t truly originate it, but in 1973 gave the catchy summary of it : "the universe is simply one of those things that happens from time to time".

 

The MWI is good for describing this “nothing theory”: starting with an actual mass-less, energy-less universe, an occasional quantum vacuum fluctuation results some virtual particles briefly actually appearing, then disappearing back into the “virtual particle sea” of the false vacuum, splitting into many universe where different virtual particles briefly appear. A few rare branching paths result in a cascade of actual particles numerous and dense enough to be … the Big Bang, leading to the universe as we know it, including real scenarios like Schrodinger’s cat.

[Fedgie]

As a lay person relying on average "common sense"...

if math allows for infinite universes,

then all "imagined" & "yet to be imagined" universes exist,

not only infinite universes "similar" to ours,

but infinite universes exactly like ours,

& infinite universes nothing like ours;

each universe has either no "living beings" at all or living beings

more advanced, less advanced, or exactly as in our universe,

& infinite universes have beings so advanced that they have nearly reached "omnipotency",

yet however close to omnipotent, there are infinite beings still more omnipotent elsewhere

(Gods - 1, Gods - .01, Gods - .001, etc.)

suggesting "Gods" evolve from "lesser" beings in universes with laws of physics unlike ours

that allow "nearly" omnipotent beings to evolve to infinitely omnipotent Gods,

(God - 0)

& therefore Gods evolve from men and men from Gods...?

but doesn't answer who-what created original creation, even if creation is infinitely cyclic;

one might as well imagine the extra unexplained "weight" in our universe currently

called "dark energy" is due to "visiting" omnipotent beings from other universes...

[newdealtn]

Most physicists place little credence in the many worlds interpretation, since an uncountable number of events that would generate alternate universes are happening every nano-second in this universe alone, and a similar number would be happening in every one of the alternate universes. The concept is based on a faulty understanding of quantum events to begin with and builds quickly to complete absurdity.

 

There may indeed be many universes in the multiverse, but they have no relationship between them other than their source, a single initial condition adequate to explain all the universes that arise from it. The Big Bang is not that source; it is a secondary event.

 

I don't know more than anyone else here, but I do know that space-time establishes a cause-effect protocol that cannot be escaped by anything existing within space-time (e.g., within a universe). The initial condition is outside of space-time, which means that whatever exists in it can have no size or shape, no inside or outside, no motion or location, nor any other quality associated with space; neither can it have any quality associated with time, no change or process, no beginning or end. But something must exist outside of space-time universes and that something must have the capacity, the potentiality, to serve as a catalyst for the "birth" of universes without being directly involved in the process of those births; that is to say that whatever initial condition universes come from must not be changed or diminished in any way by those universal births.

 

The ground-state of existence, outside of space-time, is ideally suited to this because it cannot be caused, it has no beginning, it simply is or is not. If it is not, then all universes lose their source, nothing can come to be because only nothing can ever come to be from nothing. Existence or non-existence, whichever occupies the initial condition of the multiverse can never be replaced by the other. Since we now exist in a space-time universe, it follows that existence is the initial condition of the multiverse, from which all universes are "born". It also follows that existence as the initial condition of the multiverse must incorporate the potential from which universes arise, and that such potentiality cannot be manifest in any form requiring space-time since space-time too can only have latent existence in the initial condition.

 

I am bothered by M-theory and the concept of membranes explaining the Big Bang because membranes exist in both space and time, so we must ask where did the space and time come from. Any ultimate explanation must explain all manifest being including space-time. The only ultimate explanation I can find is this explanation that existence itself is outside of space-time, as surely it must be since it is not an element of space-time--rather space-time is an element of things that exist. In some ontologies, existence is seen as some manner of property or quality belonging to each being, but existence is a universal and belongs to no particular thing. That's one reason we have such trouble understanding non-existence, nothingness. What does not exist can have no properties or qualities or attributes, so it cannot be identified or conceived or specified in any manner. We say that unicorns don't exist, but they do exist, if not as substantial beings, then as conceptual beings, objects of nature or objects of imagination. Everything we can think of or speak about exists in some fashion; we must only discern whether it is part of nature or contingent upon something that is a part of nature.

 

Sorry if this gets on toward metaphysics.

 

Samm

[G Anthony Kent]

Many Worlds is an invention of Hugh Everett, a student of John Archibald Wheeler. Everett also invented a calculus of quantum mechanics that does away with probabilities.

 

The Universal Wave Function is a term introduced by Hugh Everett in his Princeton PhD thesis The Theory of the Universal Wave Function, and forms a core concept in the relative state interpretation or many-worlds interpretation of quantum mechanics. It has also received more recent investigation from James Hartle and Stephen Hawking in which they derive a specific solution to the Wheeler-deWitt equation to explain the initial conditions of Big Bang cosmology.

 

So, to say that MWI has no use unique to itself that goes beyond the Copenhagen Interpretation is simply untrue. Many physicists take MWI seriously, like Stephen Hawking. It may be unimaginable that events bifurcate in infinite progression from the time of the “first event” at the Big Bang, but much of quantum mechanics is unintuitive and basically unimaginable anyway. Universes that spin off from this bifurcation process themselves undergo a complex multiple bifurcation process in their own event trains. So, the multiverse may be not only infinite, it may be infinitely infinite.

 

Some of these alternate universes may be detectable because gravity may be “leaky” so that their gravitational effects can impinge on us (Georgi Dvali, Lisa Randall). So, MWI is not necessarily unfalsifiable. Wheeler’s idea of the quantum waveform always having an interference partner is intriguing. If the universe that we observe has an interference twin, this may be the home of antimatter. There could be harmonics of this pair, each having an allotment of mass equal to our own universe. The total mass of this little multiverse may be sufficient to account for the “missing mass” of Dark Matter and Dark Energy. Our universe could have some spin in the environment of this multiverse and this spin may allow for accelerating Hubble expansion as it slows down upon getting larger. There may, in fact, be testable consequences.

 

If Alan Guth’s “inflaton” ultra-massive point particle sprang into existence like a quantum mechanical virtual particle in an excited inflaton field because its high degree of excitation made its appearance more probable, even inevitable, then it (the universe) was indeed a quantum mechanical entity. If it was once a quantum entity, then it still is. This makes Wheeler’s notion plausible. Everett’s ideas cannot be dismissed so easily either. Once upon a time, the wave-particle duality was unacceptable to many rigid thinkers. Quantum mechanics gets weirder every day.

[Deepwater6]

Sorry if this gets on toward metaphysics.

 

Samm

 

This thread has drifted toward metaphysics. I'm not sure the two can be detailed apart, but the concepts, suggestions, and thoughts for all these posts are fascinating. Great thread!

[Fedgie]

"Most physicists place little credence in the many worlds interpretation"

 

Really? Most? Links to supporting evidence please!