Musings on the Multiverse

I’m thinking about what is probably the most common layman understanding of the multiverse, the “parallel universes” theme that frequently shows up in science fiction (e.g. Sliders, select episodes of every Star Trek show ever) and fantasy (e.g. The Chronicles of Narnia). In particular, the two aforementioned science fiction programs employ the idea that upon reaching a choice with two possibilites, both are actually selected, and reality bifurcates, as in the figure above. In fiction, a common plot device is the unusual mechanism (whether technological or supernatural) that allows travel from one world-branch to another. Such a mechanism must be unusual, because we don’t experience such reality shifts in daily life.

What would salvation look like in such a reality?  For every choice Abraham ever made, there would be one or more additional Abrahams. Actually it’s worse; the number of Abrahams would be roughly the factorial of the number of choices Abraham faced. Assuming for a moment that most choices are binary (i.e. there are only two options), that the average person faces 1000 choices a day, and that the Bible is correct as to Abraham’s age at death, that gives [thanks, Wolfram!] about 10^(10^9) Abrahams. That’s a one followed by one billion zeros. Abraham alone would require many mansions in every degree of every kingdom, and probably a good bunch in outer darkness as well. Note that this only includes bifurcations caused by Abraham’s choices; the full picture would be much more complicated if we considered the choices made by other sentient beings alive during Abraham’s lifetime. That’s a whole lot of multiplying entities needlessly, so I don’t like it.

Instead consider a version in which for a given choice all possibilities exist in a sense, but only one is actually chosen. Perhaps this is not actually different from how you picture reality without all this multiverse nonsense, but bear with me. I had a striking mental image of a branching tree of possibilities, with most branches dark except for the highlighted pathway from the root to the present moment, which moves along the tree as time proceeds. The following image gives the same idea, only it’s not nearly as pretty as what I imagined.

timeline_simple

Here’s the thing: in this scenario God would not have to do any fancy calculations to discover all the potential future states. He could be located outside of this branching structure, able to observe any part or the whole of it, and yet remain completely inside linear time. Thus this view is compatible with Open Theism (the idea that the future is completely undetermined and unknown, even to God), which, as Geoff J. has so stridently argued over at New Cool Thang, is itself compatible with libertarian free will and Mormonism.

Among all the obvious questions to which I hope you will provide answers (Is this blog post self-consistent? Is it even clear? What are your thoughts?), I hope you’ll consider this one: are the old, unfruitful branches of such a structure plucked off, cast into the fire and burned?

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About Ben Pratt

I am married to a brilliant and lovely woman. Remarkably, our union has produced three brilliant and lovely daughters! We enjoy reading, going for walks and bike rides, and Friday night pizza picnics in the family room. Descended from Parley P. Pratt (founding editor of this blog's namesake), Charles Henry Wilcken, Zachariah Bruyn Decker, Jesse N. Smith, Frederick G. Williams, and a host of farmers, missionaries, colonizers, businessmen, and pilots, I was raised in Chandler, AZ. I have degrees in physics from both Brigham Young University (BS) and the University of Washington (MS). I earn my filthy lucre teaching physics, mathematics, and fine arts at a public charter school in Mesa, AZ.

34 thoughts on “Musings on the Multiverse

  1. What you are calling the multiverse most physicists refer to as the “many worlds interpretation of quantum mechanics.” It is true there may be something to this.

    Even more likely is the possibility that many universes are created by inflation that goes on during the big bang. In some sense the results are similar in the sense that given enough universes everything that is possible eventually happens. However, from a physics point of view the “many worlds” scenario is considered far fetched and this second scenario, also called eternal inflation, is very, very possible if not likely.

  2. Ah, Ben, you and your peers make me feel like a lab monkey in a room full of Einsteins. ^_^

    Well I’m sure there are several branches that can run parallel for very long periods of time, or branches that always remain only a few splits away. Or maybe it’s like a return policy. Maybe I had a choice to return my copy of ExoSquad for up to thirty days. But I didn’t, so it’s stuck with me now. Or I could have chosen any moment to drop out of college, but now I have my degree, and I’m not in school anymore, so I don’t have that choice to make anymore. So I guess once a choice runs out…. *then* is it plucked off and burned?

    There must be billions of outlandish parallels that everybody certainly has the capacity to carry out, and would be very easy to do. A man could end his life at any moment by any number of means. He could also tell himself and assure himself that he would never purposefully do that. But if the capacity is still there, what happens to that branch?

    Ah, I feel like I’m confusing myself.

    What did you end up making the graph with? It looks prettier than anything *I* could have suggested….

  3. Welcome, Joseph. I’ve seen you around, but I don’t think we’ve interacted (unless it’s in another guise). Like you, I have a BS in physics from BYU and currently find myself in a physics PhD program.

    I chose the term “multiverse” carefully, trying to start out as generally as possible. Tegmark seems to label what I have described (the version in which many possibilities result in many worlds) as the Many Worlds Interpretation, but to me MWI relates specifically to the (meta)physics of quantum wavefunctions, not to the more general question of a set of possibilities. Of course MWI applies if one thinks of a pre-choice individual as being in a superposition of “I choose door #1″ and “I choose door #2″ states, but that seems like a stretch to me.

  4. Ben, I think you’ve explained the multiverse concept pretty well, and I think there are big thinkers who are coming to accept it because if there are infinite universes then it increases the possibility of human evolution taking place without a Creator having to step in at any point. (The point is that if there are an infinite number of choices at ever step of evolution, then it is easier to believe that one of those choices would have resulted, through pure chance, in our evolving from primordial muck and becoming the advanced beings we are).

    I agree with you, however, that an infinite number of choices means there are an infinite number of Abrahams and Ben Pratts and Geoff Bs, and that is just too much for me to get my head around. I’m more inclined to believe there is one Geoff B and that he does have choices at every turn, and he used to make more bad choices than he does now, so fewer bad branches are being burned.

  5. Heh, Andrea. I stole it outright once I found it, because it showed almost exactly what I wanted.

    You raise a fascinating question: possibilities that are always there. One could model that as a really thick branch, but since I suspect time is discrete if you look small enough, another model would be many, many branchings in a row. Since any one of those choices would lead to similar results (e.g. no matter when one chooses to kill oneself, one still dies [sorry for the macabre example]), would they JOIN? To be completely general, joining must be allowed in my preliminary model of this hypothetical branching structure.

  6. @Ben Pratt
    Hi Ben, it’s good to know your a fellow BYU physics grad in a PhD program.

    Yes, Tegmark is big into the multiverse stuff. He is a cosmologist as I am training to be and turns out is an incredibly nice person.

    By the way, I wasn’t trying to argue as much as to point out that there are a lot of cosmologists who think that inflation, which is becoming very experimentally established physics, implies a multiverse.

    It is something real that cosmologists, and therefore everybody else, needs to seriously be open to.

  7. Geoff B. (#4), indeed, many version of the multiverse idea provide ample space for even minutely possible things to occur at least once somewhere, including the eternal inflation mentioned by Joseph.

    Joseph (#6), that’s awesome that you’ve met Tegmark. I completely agree that eternal inflation strongly suggests the existence of what Tegmark classifies as a Level I multiverse.

  8. Since you seem to be after ties with Mormonism and the multiverse I will will give you all my own crazy spin on things.

    *If* eternal inflation, and all the endless universes it creates in its wake, is true (and there is good physical reason to believe it might) then:

    1. Every type of possible level of intelligence is eventually created somewhere.
    2. There will be one level of intelligence greater than the rest.
    3. This Supreme Intelligent being would have to learn to become such.
    4. It would in our best interest to be like Him/Her.

    Therefore eternal inflation => Mormonism. There I said it! (Or at least one version you could come away with after reading the King Follet discourse and the obvious verses in Abraham with one intelligence greater than they all.)

    But for that matter physicists are also concerned eternal inflation creates things like boltzman brains so maybe something does put an end to the eternal nature of inflation. Otherwise…

  9. Interesting; and what you say does fit with the Star Trek definition of multiverse, but Stephen Hawking has another definition of multiverse. In Hawking’s definition, as I understand it, each universe is a finite bubble that flares off of a bigger “thing” like a fractal. The universe-bubbles are created and collapsed, perhaps in a fashion that is described in scriptures as “the heavens come into being, and then eventually pass away.” And perhaps black-holes and white-holes are a microcosm analog to the larger universes coming into being and passing away.

    Some scientists now concur that what we perceive as our universe is indeed finite, otherwise, the night sky would be all bright from the light of an infinite number of stars in all directions having shined on us for an infinite length of time.

    Any-hoo, this may be classified as “pondering the solemnities of eternity” or it may be “looking beyond the mark”, as our job here is to press forward and endure to the end of our mortal lives, which I’m not presently doing very well.

    “Have I done any good in the world today?”

    One problem with Geoff J’s viewpoint (of his soap-box paradox) is that he (Geoff J) doesn’t have room for the concept of how time is a local phenomenon, and how Heavenly Father is not bound or constricted by our local phenomenon of time, and how we don’t (or even can’t) comprehend how an “eternal” being is not bound into or constrained by our local phenomenon of time. We don’t even have the vocabulary to fully describe how “eternal” is in contra-position to “time.” “Eternal” has a dimension to it far beyond “time x forever” that has yet to be explained to us.

    I also posit that understanding what “Eternal” means as applied to Heavenly Father, and his level/plane of existence, is also necessary in order to understand the next higher level (ie, a multiverse) above our universe in terms of cosmology.

  10. I have to say as an erstwhile physics major myself that I the many world interpretation of quantum mechanics is the most ridiculous idea I encountered during my studies in physics. Or as Wolfgang Pauli once said, it is “not even wrong”.

    There is no possible way, even in principle, to verify whether this proposition is correct. Placing God above it all won’t work, because the very possibility of causal interaction between God and two or more time lines either eviscerates the premise or reduces God to an impotent abstraction.

  11. Ah, I suddenly had some new thoughts, once I looked at this as quantum wavefunctions in action.

    Obviously, the presence of an external observer creates reality. It is interesting to think of each of us, and all of reality, existing like an electron, with its location only becoming real when observed.

    So, we move in a multiverse of potential (rather than actuality), distilled by God as an observer.

  12. Andrea make that two lab monkeys.

    I do not have much to add except I agree with Bookslinger. I believe God works in space time continuum. We work in linear time.

    How I relate to this conversation is Star Trek-Next Generation and Star Trek Voyager, I am a fan of both series. ST-NG and ST-V had a few episodes in which the characters experienced parallel universe. Interesting to contemplate.

    Ben, thanks for the deep thoughts for today.

  13. The main problem with the orthodox interpretation of quantum mechanics is that it provides no way to define who or what is an “observer”. It also brings to question the reality of the world when God (or whoever) isn’t looking.

    It is like Schroedinger’s cat. Can we really believe that the cat is both dead and alive until we open the box? Or does the cat observe itself and collapse its own wavefunction?

    It is for these reasons and others that I am a fan of Bohmian quantum mechanics, which provides equivalent results while dispensing with all the subjective mumbo jumbo. With the added benefit that the world is real when no one is looking. No intrinsic randomness, no parallel worlds either.

  14. @Mark D.
    Okay, but you all have to understand that quantum mechanics is just a “low energy” approximation of some grander theory.

    Trying to understand quantum mechanics philosophically is not what we should be doing. We need to find the more fundamental theories and realize once we do some of these bewildering philosophical concepts might go away.

    Don’t get me wrong, any fundamental theory should be quantum in nature, but that doesn’t mean it will have all of the philosophical baggage.

  15. I agree. The good thing about Bohmian mechanics is that it doesn’t have those problems. A wave function “collapse” is about the most un-physical thing one can imagine. In Bohmian mechanics, wave functions don’t.

    More generally, if God has a body, that means he is embedded in both space and time. So if the many worlds interpretation were correct, that would imply that there would be many versions of God as well, equally unverifiable and inaccessible.

    Bohmian mechanics doesn’t have any intrinsic randomness, but libertarian free will leaves open similar alternative possibilities. The problem with the MWI interpretation of free will is that it removes the moral significance of any particular choice, by asserting that in some alternative time line, *every* possible choice has been taken. That is a little morally corrosive, I think.

  16. Many of you have elucidated well the problems with the Copenhagen Interpretation of quantum mechanics, as well as difficulties with how the Many Worlds Interpretation meshes with libertarian free will. This is exactly why I proposed what I did: a version of this idea in which the various possibilities exist in some sense, but I remain the unique instance of Ben Pratt after I make a choice. I hope to explore facets of where this can take us in future posts. In the meantime, I really enjoy the idea of God as the Lord of a vineyard of possibility trees, pruning them, digging about them, and nourishing them. It’s fun to think that this may lead to a model of how God fulfills prophecy without knowing the future or circumscribing libertarian free will, but it’s a very undeveloped idea.

    Bookslinger, I am not certain that the scriptures require us to believe that Heavenly Father is not limited by time as we are. If He can travel through time in any sense, how can his decrees truly be unalterable and eternal? Thus I don’t have the same problems you do with Geoff’s ideas. However, this is my best understanding at present, and of course I remain open to greater knowledge.

  17. Well. All this makes me slightly more enthused about the QFT seminar this semester! And I like inflation. Is there a heavenly federal reserve?

  18. Ben, I don’t assert that Heavenly Father travels through time. But the scriptures and the modern prophets have clearly stated that He _sees_ or _perceives_ backwards and forwards through time. _How_ He does it, we don’t know.

    The scriptural references that imply that _time_ is in contraposition to _eternity_ and how “eternal” is not equal to “time x infinity” are more fuzzy.

    But as space bends and stretches, in some way time must also bend and stretch.

    It may be that Heavenly Father’s view of the future is done by omniscient computation: by calculating the trajectories of all present things, and computing the future decisions of sentient creatures based on His perfect knowledge/understanding of them. Or, it may be simply by using His powers/abilities as an “eternal” and _looking_ and by merely looking, He sees/perceives it. The latter may be because time “bends” around Him in a circle, He being located in a place that the scriptures describe as being “in the bosom of ‘eternity.’”

    I don’t think “in the bosom of eternity” is merely a flowery poetic phrase. I think it is descriptive of something, if we only knew better what the scriptures mean by “eternity.”

    There’s that one section in the D&C that is almost a “gotcha” on the definition of “eternal” in the phrase “eternal punishment”. It doesn’t mean punishment that lasts forever. That gives a hint as to deeper meanings of “eternal” and “eternity.”

    This non-traditional definition of eternal (or at least new since the advent of modern mainstream Christendom), and the concept of “time” having a scope, lent Joseph Smith a whole new interpretation of the scriptures containing those words. Elohim has “always” been a God, but the word “always” seems to be limited to the _scope_ of _this universe_. If Elohim was once a man (as man now is), it was likely in a previous/different universe, and not in _our_ scope of time, or _our_ scope or “round” of eternity.

    It may (or may not) be proper to say that Elohim attained His godhood in the “eternities” that existed before our universe was created, or outside of _our_ “universe/time-bubble.” And this model I describe presupposes that there is a multiverse out there, and that our perceived universe is not exhaustive of all existence. (And “our” time being a local phenomenon within “our” bubble.) If I’ve come anywhere close in my description, that may be a partial explanation of how Elohim “is God from all eternity (prior to our universe/time-bubble coming into existence) to all eternity (after our universe/time-bubble passes away).

  19. So many physicists. Okay, so let me see if I have this right (and I may note). Cosmological inflation = infinite and continued expansion of the known universe. Would this not eventually result in heat death? Unless the 2nd law of thermodynamics proves not to hold.

    Schroedinger’s cat is either alive or dead. My limited understanding of Quantum Mechanics states that we can not know the state of the cat until we open the box and observe him. This of course is because of the decaying radioactive isotope triggering the poison in the box. The same holds true for an electron. Heisenberg’s uncertainty principle says that we can’t know the exact position and speed of the electron, the more we learn about one the less we know about the other. This doesn’t mean that it doesn’t have an exact position and speed prior to us observing it and messing with it in the process.

    Okay, so now that the engineer in me has that off my chest. Interesting speculations about multiverses. I don’t like the model of creating a new universe at every decision point. Fails common sense to me. Conservation of energy etc. I do like the idea of a multiverse of possibilities. Though this becomes more of a metaphysical tool to help us understand things. The key take away from the branching tree with parallel paths and deadends to me is that there are costs associated with each decision we make, and that those costs must be paid to return to the branch that leads to the celestial kingdom. Interestingly enough, there are only two dead end branches in theological terms, one each for the unpardonable sins. All else can be repented of and branched back to the “straight and narrow.”

    In terms of a more physical universe interpretation of the multiverse of possibilities and God, I have one question. Where does God stand that he is able to view the entire universe and all of it’s branching paths, but is not subject to it Himself?

    Good post. Good replies from folks. It is always interesting to see what people think about these issues that are not clearly outlined in our doctrines.

  20. @Doug D.
    Since I brought up inflation I will answer that part. It is possible the universe is infinite, but the prevailing view by far is it is finite but inflating in certain regions at an exponential rate. This means, you give me any finite number no matter how large, and eventually the universe/multiverse is that big.

    What happens is this, you start with a finite universe that then starts to inflate and because of physical reasons it seems impossible to get every region of this inflating universe to actually stop inflating. Some regions stop and they become separate inhabitable universes. This keeps going forever making it eternal inflation with every finite number of universes eventually.

    Inflation has passed every experimental test so far and the above are real predictions from this theory nobody knows how to get rid of. Some think eventually we will get rid of it but the growing consensus is maybe we can’t and this is real stuff.

    Atheists like it because it gives legitimate reason why life forms naturally without a God. (Roll the dice enough and you get what you see.) I personally like it because to me it becuase:

    1.) It may be real so I have no choice in the matter. As Joseph Smith said “Facts are stubborn things” whether people think it is consistant with scripture or not.
    2.) To me this echos what one would get from the Book of Abraham/King Follett Discourse style Mormonism so I admit I get a little excited.

    “My limited understanding of Quantum Mechanics states that we can not know the state of the cat until we open the box and observe him.”

    This is correct.

    However, as for Schrodinger’s cat, I think people would be wise to ignore philosophical issues with quantum mechanics. It is a true theory, but not the fundamental theory of nature so you have to always be careful.

  21. Joseph:

    Thanks for the further explanation. I’m still not getting something though. Big Bang still applies for the inflation theory right? So at some time, t=0 we had a tiny spec of exceedingly dense matter or likely energy. This amount of energy, that became the universe, was finite. Correct? So we have a finite amount of matter / energy (since they are different states of the same thing). I can accept infinite inflation since the matter / energy density just decreases with increasing volume, but this does make for a much less amiable universe.

    If I understood what you said correctly, and I may not have, then universes are spawn off of this one due to local inflation. I have a couple of issues with that, if that is the proposition. First, you are limited to a finite number of universes then because the new universe takes matter/energy from the previous universe. Second, has anyone proposed a pinch off mechanism for separating the newly formed universe from it’s parent universe? If a channel remains between the two, it seems to me it would still be one universe.

    I’m sure that larger minds than mine have asked these and better questions, but that doesn’t lower my curiousity.

  22. @Bookslinger

    I’m with you on the universe/time-bubble idea. Doug and Joseph have been discussing one version of this idea that is seriously discussed among cosmologists.

    Bookslinger :

    Ben, I don’t assert that Heavenly Father travels through time. But the scriptures and the modern prophets have clearly stated that He _sees_ or _perceives_ backwards and forwards through time. _How_ He does it, we don’t know.

    If it were so clear, you and I wouldn’t be having this discussion! :-)

  23. Bookslinger, to be fair I am happy to admit that there is an overwhelming amount we simply do not know, and most of it I suspect we won’t be able to discover while in a telestial world. But that doesn’t keep me from trying to learn as much as I can, including speculative exercises that may, at first glance, go against another’s interpretation of the scriptures.

    In other words, I think our disagreement lies in which topics we each consider open to speculation.

  24. Doug, these are good and common questions and yes, all the details have been

    First, to address you energy conservation issue: The overly simplistic answer is there is in reality an infinite amount of energy at every point, all we can measure with instruments are energy differences. I don’t want to, because it is hard in a small comment section, go into all the crazy detail, but there is no possibility to have zero energy in a quantum system. If you suck out all the energy, there is still some more left. (By the uncertainty principle and the fact if you “integrate over the energy density” you find the total energy is infinite.)

    Some people talk about this being some “zero point energy”. Cosmologists refer to it as vacuum energy which we know is real. (Sometimes associated with dark energy.) As space expands, there is always this non-zero energy vacuum energy at every point which.

    If you don’t understand this don’t worry, vacuum energy/dark energy/ zero point energy isn’t very well understood by anyone. All we know is it is predicted by the physics and is verified in experiments.

    About pinching off: sure, if space time can tear. People have thought about this but I don’t know if anyone seriously thinks about it since 1. How would you test it? 2. All the grant money is for solving other problems. :)

  25. @Bookslinger
    Bookslinger, it turns out eternal inflation and this bubble cosmology is part of the same theory.

    I emphasized the piece that says if inflation starts anywhere, you can’t get it to completely stop in all regions that start to inflate. The regions that do stop produce inhabitable universe.

    *But it is also true* that if you take a region where it has stopped then it is possible it will start up again in some part of that region. This is what produces the bubble: inflation beginning in a universe where inflation has stopped.

    Eternal inflation and these bubbles are both predictions of current inflation models.

  26. Okay, more questions from the peanut gallery.

    I looked at the picture Ben provided, and read the info there. The only way for there to be a portion of the universe further away than we can observe is if the difference in it’s velocity away from the big bang origin point and our’s equals or exceeds the speed of light. So, assuming a spherical expansion and that we are exactly opposite from the proposed point, the sum of our expansions velocities would need to be equal to or greater than c. Assuming a roughly spherical explosion, that would mean we would need to be moving at something close to 1/2 c. This is certainly a testable hypothesis, does anyone know if it has been tested? (I know I made a few simplifications along the way, but hey I’m an engineer.)

    I must disagree with distance being a sufficient method for pinch off and creation of another universe though. It would be possible for matter to get from here to there, and it is my understanding that the universe, as generally defined, includes all observable matter. Given that the opposite side of the universe in my thought experiment is traveling at something like 0.5c, if we jumped in one of those great thought experiment spaceships and traveled at 0.75c we would eventually get there, or our progeny would. So to my simple view, it’s still the same universe. Has the term been redefined?

    Joseph, thanks that’s one of the clearer definition of dark matter or dark energy I’ve ever seen. Would you have a reference that might include the math that demonstrates infinite energy in vacuum? I’ll do a quick look on wikipedia, but I’ll be surprised if the math is there. Even though I am not a specialist, I find these areas of physics interesting. The areas I work in pay the bills but are not so grandiose. :o)

    I guess I’ll have to wait for the grant money to catch up to my curiousity. Black holes could always be blamed as pinch points. :o)

  27. @Doug D.

    Doug, if you want to see the exact calculation go too Google Book and search for the quantum field theory book by peskin and schroeder. Under contents click on “Klien Gordon Field”. This is chapter 2 starting on page 13 of the book. The relevant equations as 2.5 and 2.31. All the equations around these equations are the derivation.

    After 2.31 the authors discuss what I have said, the energy, represented as the Hamiltonian, is infinite. The say it sounds disturbing but since we can only measure energy differences things are fine and if you remove the “zero point energy” contribution what is left is something we can measure. They then admit they will come back to places such infinite energy is useful. They are partly referring here to things like vacuum energy/dark energy in cosmology though there are more places this stuff seems to rear its head.

    “The only way… exceeds the speed of light.”

    And that is exactly what happens. Inflation is not an ordinary expansion of space. Inflation, by definition, is a period in the universe’s history where space expanded faster than light. This does not violate relativity because relativity says you can’t move through space faster than light. The space itself can expand as fast as it wants, and according to experiments, actually did expand faster than light at some point.

  28. Joseph, I don’t know if you’re still checking this thread or not, but I hope so. I have to ask one more question, how does space expand? I know this might sound silly, but my understanding is that space has always been defined as a region or area where matter / energy is / was. I guess if we included can be then space could expand on it’s own. Is that what is going on here? Or is there a different definition for space that I’m missing?

    BTW, this is very interesting stuff. Gonna check Google books now. Thanks for the time and effort.

  29. @Doug D.

    Doug, space has to expand according to general relativity. How does it expand is a very interesting question that I do not know the answer to. In physics, and especially general relativity, you assume space, or specifically the “metric” of the space, has equations that govern its behavior just as we have equations governing the behavior of an electron. These equations predict space either expands or contracts based on the type of matter it contains and how much. We are living in a universe where the dominate type of matter/energy is dark energy and so space not only expands but accelerates.

    Now, there is so much more to say, and I would say it but to be honest, it would be ten times easier if you followed my blog in addition to this one since we will discuss all of these things ad nauseum over the next few years. There you can ask all the questions you want and I will write entire blog posts answering your questions. (If you ask.)

    I don’t mind answering here, there just isn’t space for very complete answers.

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