What would a multiverse really be like?

Multiverse theory goes back at least to the ancient Greeks. Although some modern scientists may use it as "an attempt to short circuit discussion of apparent fine-tuning by appealing to the idea that no conclusions can be drawn because there is an infinite series we do not know about," that is really the least-common, least-historical perspective. Modern multiverse theory was not even in response to the modern fine-tuning argument - it actually predates that argument by 4 years. The "Many Worlds Interpretation" was one theory used to explain the evidence acquired via experimentation in quantum physics. As BA and others point out, it cannot even be used in an argument against the existence of God or even against fine-tuning, since it has been pointed out that any non-deliberate universe generating cause must be finely tuned to even have the potential for creating a universe like ours. "The multiverse is not a logical deduction from the state of our universe." I can't even imagine anyone supporting that statement in any reasonable way. If one begins with the premise that it's a choice between multiverse theory and fine-tuning, then there might be a reasonable way to make such a claim about what cannot be logically deduced, but that's an outrageously false dichotomy. There could be infinite intelligently-designed universes; and even in MWI theory, no potential universe would be actualized into form until and unless there was some act of observation occurring to collapse wave potentials into specific locations and characteristics. The logical arguments for the existence of many universes dates back to Parmenides; the direct inference of his logic is that if we can imagine a thing, it necessarily exists somewhere. As far as "not being able to trust our memory" and "not being able to trust science" ... that's just good common sense, whether that distrust is based on the fallibility of the human condition, or based on the idea that we may be constantly traversing through different dimensions. And, as KF routinely points out, some things are true in all possible worlds." And to steal his line, that should be a very sobering realization. William J Murray

Sev:

If travel back in time is possible,

Bold mine. Is there no delusion that you won't entertain to avoid the obvious? Latemarch

It's not an easy problem. If travel back in time is possible, how do you escape the grandfather paradox? If there are loops in time built into the history of the Universe, a bit like in Groundhog Day, so that we cycled back to an earlier point time repeatedly, that's a possibility. The problem with that is that the movie narrative depended on Bill Murray's character remembering what had happened on the preceding cycles. But, as was pointed out in the movie, what if his memory was reset back 24 hours just like everything else? He would never know he was constantly looping back through time. We would never know if it was happening to us. Perhaps it is. Would that be more or less weird than a multiverse? Seversky

Sev:

The multiverse is a speculative explanation which, amongst other things, tries to get around the grandfather paradox which must arise in a single universe in which travel backwards in time is not forbidden.

Hahahahahaha....Yeah that's what I thought of first as a reason for postulating a multiverse. I have a used time machine with only 235,000 years on it for sale if you want it. Latemarch

The multiverse is not a logical deduction from the state of our universe. It is an attempt to short circuit discussion of apparent fine-tuning by appealing to the idea that no conclusions can be drawn because there is an infinite series we do not know about.

The multiverse is a speculative explanation which, amongst other things, tries to get around the grandfather paradox which must arise in a single universe in which travel backwards in time is not forbidden. Proponents of a single, finely-tuned universe, in many cases, prefer it because it can be argued as evidence for the God in which they believe. Seversky

I never understood the argument "If we can't account for this ONE then let's conjure up infinite verses" ET

It's worse than you think. (Ain't it always?) Darwin himself explicitly attacked the available physical evidence in formulating his atheist creation myth, setting aside the actual fossil evidence of the time and claiming that further investigation would discover the trillions of missing gradations. The multiverse theory is, like darwinism, not really a theory at all, since like darwinism there's no possible way to test it. And it's also alike in that it rejects the available evidence in favour of some future discovery. Atheism and darwinism are both Gap theories: they rely explicitly on a belief in things we simply have not discovered. Unfortunately for darwinism, in the years since Darwin we've filled in an enormous proportion of the biochemical gaps and we now know for absolutely certain that darwin's entire shaky edifice has no foundation at all but relied for its (even then) slim shreds of credibility on the ignorance of the times. The massively complex and fragile nature of genetics does not admit any possibility of chance advancement. ScuzzaMan

BA77: I was introduced to St. Anselm's argument in the early 70's. At the time it was strangely attractive but seemed not sufficient. As the years have rolled on I find that the argument has taken on a power that I did not appreciate. The genius of the author is evident. Latemarch

Of particular interest, the article in the OP states, "if space can be curved". The main evidence that Tegmark puts forth for postulating that the space of this universe may be infinite, what he refers to as the LEVEL I MULTIVERSE, is that Tegmark speculates that the universe may not be 'closed',,, or more precisely, the universe does not have a “positive” convex topology,,, Specifically he speculates that “Space could be finite if it has a convex curvature”

Parallel Universes by Max Tegmark - 2003 Excerpt: Space could be finite if it has a convex curvature or an unusual topology (that is, interconnectedness). A spherical, doughnut-shaped or pretzel-shaped universe would have a limited volume and no edges. The cosmic microwave background radiation allows sensitive tests of such scenarios [see “Is Space Finite?” by Jean-Pierre Luminet, Glenn D. Starkman and Jeffrey R. Weeks; Scientific American, April 1999]. So far, however, the evidence is against them. Infinite models fit the data, and strong limits have been placed on the alternatives.,,, The Level I multiverse framework is used routinely to evaluate theories in modern cosmology, although this procedure is rarely spelled out explicitly. For instance, consider how cosmologists used the microwave background to rule out a finite spherical geometry. Hot and cold spots in microwave background maps have a characteristic size that depends on the curvature of space, and the observed spots appear too small to be consistent with a spherical shape. http://space.mit.edu/home/tegmark/PDF/multiverse_sciam.pdf

Yet, the topology of the universe is not positive and closed nor is it negative and open, and therefore infinite as Tegmark had apparently presupposed.

Picture of three topologies Recent observations (such as the BOOMERANG and MAXIMA cosmic microwave background radiation results, and various supernova observations) (2001) imply that the expansion of the universe is accelerating. If so, this strongly suggests that the universe is geometrically "flat". https://starchild.gsfc.nasa.gov/docs/StarChild/questions/question35.html

In fact, the topology of the universe is now found to be the least likely of all topologies. Absolute flatness. John Gribbin commented that “Finding the Universe in a state of even approximate flatness today is even less likely than finding a perfectly sharpened pencil balancing on its point for millions of years,,, any deviation of the Universe from flatness in the Big Bang would have grown, and grown markedly, as the Universe expanded and aged.”

"The Universe today is actually very close to the most unlikely state of all, absolute flatness. And that means it must have been born in an even flatter state, as Dicke and Peebles, two of the Princeton astronomers involved in the discovery of the 3 K background radiation, pointed out in 1979. Finding the Universe in a state of even approximate flatness today is even less likely than finding a perfectly sharpened pencil balancing on its point for millions of years, for, as Dicke and Peebles pointed out, any deviation of the Universe from flatness in the Big Bang would have grown, and grown markedly, as the Universe expanded and aged. Like the pencil balanced on its point and given the tiniest nudges, the Universe soon shifts away from perfect flatness." ~ John Gribbin, In Search of the Big Bang - 2000 The universe is flat as a pancake. Coincidence? – Oct. 2016 Excerpt: NEXT time you fancy doing something really frustrating, try balancing a pencil on its sharpened tip. Your efforts will succeed for a second at most. Yet the universe has been succeeding at a similar gravitational trick for the last 13.8 billion years.,,, https://www.newscientist.com/article/mg23230970-800-cosmic-coincidences-the-universe-is-flat-as-a-pancake/

Moreover as the following paper states, by analyzing the tiny variations in the temperature of this background radiation, (Which is exactly what Tegmark was trying to do in his 2003 multiverse paper), researchers have now found that “These tiny temperature variations correspond to the largest scale structures of the observable universe. A region that was a fraction of a degree warmer become a vast galaxy cluster, hundreds of millions of light-years across.” The researchers go on to state, “if the universe was curved in any way, these temperature variations would appear distorted compared to the actual size than we see these structures today. But they're not. Our best scientific instruments can't detect any distortion at all between the tiny temperature variations in the microwave background and the largest scale structures of the observable universe.

How do we know the universe is flat? Discovering the topology of the universe - by Fraser Cain - June 7, 2017 Excerpt: With the most sensitive space-based telescopes they have available, astronomers are able to detect tiny variations in the temperature of this background radiation. And here's the part that blows my mind every time I think about it. These tiny temperature variations correspond to the largest scale structures of the observable universe. A region that was a fraction of a degree warmer become a vast galaxy cluster, hundreds of millions of light-years across. The cosmic microwave background radiation just gives and gives, and when it comes to figuring out the topology of the universe, it has the answer we need. If the universe was curved in any way, these temperature variations would appear distorted compared to the actual size that we see these structures today. But they're not. To best of its ability, ESA's Planck space telescope, can't detect any distortion at all. The universe is flat. https://phys.org/news/2017-06-universe-flat-topology.html

As well, the researchers then go on to state that, the universe must have been flat to 1 part within 1×10^57 parts over its entire 13.8 billion years of expansion. And in regards to Tegmark's claim that the universe is infinite, they state,, the biggest thing about the universe being flat is what it doesn't tell us. We still don't know if the universe is finite or infinite.

How do we know the universe is flat? Discovering the topology of the universe - by Fraser Cain - June 7, 2017 Excerpt: We say that the universe is flat, and this means that parallel lines will always remain parallel. 90-degree turns behave as true 90-degree turns, and everything makes sense. But what are the implications for the entire universe? What does this tell us? Unfortunately, the biggest thing is what it doesn't tell us. We still don't know if the universe is finite or infinite. If we could measure its curvature, we could know that we're in a finite universe, and get a sense of what its actual true size is, out beyond the observable universe we can measure. We know that the volume of the universe is at least 100 times more than we can observe. At least. If the flatness error bars get brought down, the minimum size of the universe goes up. And remember, an infinite universe is still on the table. Another thing this does, is that it actually causes a problem for the original Big Bang theory, requiring the development of a theory like inflation. Since the universe is flat now, it must have been flat in the past, when the universe was an incredibly dense singularity. And for it to maintain this level of flatness over 13.8 billion years of expansion, in kind of amazing. In fact, astronomers estimate that the universe must have been flat to 1 part within 1×10^57 parts. Which seems like an insane coincidence. https://phys.org/news/2017-06-universe-flat-topology.html

Thus, Tegmark has exactly zero empirical evidence substantiating his belief that the universe's topology is negative and open and that it therefore must be infinite in size and contain an infinite number of parallel universes. The best Tegmark can claim from the evidence we now have is that we cannot yet rule out an infinitely large universe completely. Whereas the Theist, on the other hand, with the 1 part within 1×10^57 parts finding for the flatness of the universe can claim another fairly incredible piece of evidence for the fine tuning of the universe. As the following author commented,,, there are,,, no laws of physics that predict or restrict the topology of the universe to be flat.

Yes, the world (universe) really is flat - December 8, 2016 Excerpt: The universe has all sorts of deformations in space-time where it varies from the perfectly flat. Any place where there’s mass or energy, there’s a corresponding bending of space-time — that’s General Relativity 101. So a couple light beams would naturally collide inside a wandering black hole, or bend along weird angles after encountering a galaxy or two. But average all those small-scale effects out and look at the big picture. When we examine very old light — say, the cosmic microwave background — that has been traveling the universe for more than 13.8 billion years, we get a true sense of the universe’s shape. And the answer, as far as we can tell, to within an incredibly small margin of uncertainty, is that the universe is flat.,,, ,,, but there are also no laws of physics that predict or restrict the topology. https://uncommondesc.wpengine.com/intelligent-design/yes-the-world-really-is-flat/

And yet, despite the laws of physics failing to predict a flat universe, on the other hand, thousands of years ago, long before modern science came along, the Bible spoke of God stretching a measuring line to mark off the dimensions of the earth's foundations.

Job 38:4-5 “Where were you when I laid the earth’s foundation? Tell me, if you understand. Who marked off its dimensions? Surely you know! Who stretched a measuring line across it?

It is also interesting to note that the observations for temperature variations in the Microwave Background that disconfirmed Tegmark's claim that the universe must be open and infinite, have instead now confirmed, as Tegmark himself admitted in the following video, that the earth and solar system have a surprisingly special position within the universe. At the 13:55 minute mark of this following video, Max Tegmark, an atheist, finally admits, post Planck 2013, that the CMBR anomalies do indeed line up with the earth and solar system

"Thoughtcrime: The Conspiracy to Stop The Principle" - video https://www.youtube.com/watch?feature=player_detailpage&v=0eVUSDy_rO0#t=832

Here is an excellent clip from “The Principle” documentary that explains these recently discovered ‘anomalies’ in the CMBR, that ‘coincidentally’ line up with the earth and solar system, in an easy to understand manner.

Cosmic Microwave Background Proves Intelligent Design (disproves Copernican principle) (clip of “The Principle”) – video https://www.youtube.com/watch?v=htV8WTyo4rw

Thus, not only is the universe not curved as Tegmark had imagined, but the universe is found to be the most unlikely of all topologies, i.e. perfect flatness. Moreover, that perfect flatness enabled us to discover that the Earth was intended from the very beginning of the universe and that the Earth is not some cosmic accident and/or fluke of random chance. In other words, Tegmark's supposed evidence for his "Level 1 Multiverse", i.e. the curvature of space, actually supports the Theistic view of creation not Tegmark's conjecture of a multiverse.

Isaiah 45:18-19 For thus says the Lord, who created the heavens, who is God, who formed the earth and made it, who established it, who did not create it in vain, who formed it to be inhabited: “I am the Lord, and there is no other. I have not spoken in secret, in a dark place of the earth; I did not say to the seed of Jacob, ‘seek me in vain’; I, the Lord speak righteousness, I declare things that are right.” Genesis 1:1-3 In the beginning God created the heavens and the earth. The earth was without form, and void; and darkness was on the face of the deep. And the Spirit of God was hovering over the face of the waters. Then God said, “Let there be light”; and there was light.

bornagain77

The materialistic conjecture of an infinity of other universes to ‘explain away’ the fine tuning of this universe also insures, through the ontological argument, the 100% probability of the existence of God:

God Is Not Dead Yet – William Lane Craig – Page 4 The ontological argument. Anselm’s famous argument has been reformulated and defended by Alvin Plantinga, Robert Maydole, Brian Leftow, and others. God, Anselm observes, is by definition the greatest being conceivable. If you could conceive of anything greater than God, then that would be God. Thus, God is the greatest conceivable being, a maximally great being. So what would such a being be like? He would be all-powerful, all-knowing, and all-good, and he would exist in every logically possible world. But then we can argue: 1. It is possible that a maximally great being (God) exists. 2. If it is possible that a maximally great being exists, then a maximally great being exists in some possible world. 3. If a maximally great being exists in some possible world, then it exists in every possible world. 4. If a maximally great being exists in every possible world, then it exists in the actual world. 5. Therefore, a maximally great being exists in the actual world. 6. Therefore, a maximally great being exists. 7. Therefore, God exists. Now it might be a surprise to learn that steps 2–7 of this argument are relatively uncontroversial. Most philosophers would agree that if God’s existence is even possible, then he must exist. So the whole question is: Is God’s existence possible? The atheist has to maintain that it’s impossible that God exists. He has to say that the concept of God is incoherent, like the concept of a married bachelor or a round square. But the problem is that the concept of God just doesn’t appear to be incoherent in that way. The idea of a being which is all-powerful, all knowing, and all-good in every possible world seems perfectly coherent. And so long as God’s existence is even possible, it follows that God must exist. http://www.christianitytoday.com/ct/2008/july/13.22.html?start=4 What is the Ontological Argument? (William Lane Craig) - video "It (This argument) puts the atheist in a very awkward position. The atheist must deny, not merely that God exists, he must maintain that it is impossible that God exists. And that is certainly a radical claim that would require great justification." https://www.youtube.com/watch?v=6rlxuHK49KY

The multiverse also forces the atheist into the uneasy dilemma of accepting that fluffy pink unicorns dancing on rainbows is real is some other universe, and yet not accepting that the omnipotent God of Christianity is real in some other universe, (and therefore, via the ontological argument, real in this universe).

Atheist Accepts Multiverse Theory Of Every Possible Universe Except Biblical One - February 9th, 2017 Excerpt: The ardent Multiverse proponent went on to state that he readily accepts that a universe governed by Mr. T riding a cyborg ostrich is possible. Also, one with floating, flaming bears instead of stars, one that contains planets full of hairy toasters made out of grape-flavored pudding, a universe that is just one humongous chicken in a bikini, and a universe that is literally a zit wearing a chef’s hat with the “@” symbol tattooed on its face. “I like to think there is a universe where Richard Dawkins has 20 heads, waffles rain from the sky covered in ice cream, the only plant that grows is pot and weiner dogs are the most socially progressive and advanced animal there is,” Hemsworth said with a cheerful glimmer in his eye. “Also there are only ponies, no horses.” When asked if this means that the universe outlined in the Bible might be one of these infinite possibilities, Hemsworth scoffed and said, “I am a scientist. I don’t have the luxury of engaging in that kind of wishful thinking.” https://babylonbee.com/news/atheist-accepts-multiverse-theory-every-possible-universe-except-biblical-one Why Most Atheists (must) Believe in Pink Unicorns - May 2014 Excerpt: Given an infinite amount of time, anything that is logically possible(11) will eventually happen. So, given an infinite number of universes being created in (presumably) an infinite amount of time, you are not only guaranteed to get your universe but every other possible universe. This means that every conceivable universe exists, from ones that consist of nothing but a giant black hole, to ones that are just like ours and where someone just like you is reading a blog post just like this, except it’s titled: “Why most atheists believe in blue unicorns.” By now I’m sure you know where I’m going with this, but I’ll say it anyway. Since we know that horses are possible, and that pink animals are possible, and that horned animals are possible, then there is no logical reason why pink unicorns are not possible entities. Ergo, if infinite universes exist, then pink unicorns must necessarily exist. For an atheist to appeal to multiverse theory to deny the need of a designer infers that he believes in that theory more than a theistically suggestive single universe. And to believe in the multiverse means that one is saddled with everything that goes with it, like pink unicorns. In fact, they not only believe in pink unicorns, but that someone just like them is riding on one at this very moment, and who believes that elephants, giraffes, and zebra are merely childish fairytales. Postscript While it may be amusing to imagine atheists riding pink unicorns, it should be noted that the belief in them does not logically invalidate atheism. There theoretically could be multiple universes and there theoretically could be pink unicorns. However, there is a more substantial problem for the atheist if he wants to believe in them and he wants to remain an atheist. Since, as I said, anything can happen in the realm of infinities, one of those possibilities is the production of a being of vast intelligence and power. Such a being would be as a god to those like us, and could perhaps breach the boundaries of the multiverse to, in fact, be a “god” to this universe. This being might even have the means to create its own universe and embody the very description of the God of Christianity (or any other religion that the atheist otherwise rejects). It seems the atheist, in affirming the multiverse in order to avoid the problem of fine-tuning, finds himself on the horns of a dilemma. The further irony is that somewhere, in the great wide world of infinities, the atheist’s doppelganger is going to war against an army of theists riding on the horns of a great pink beast known to his tribesman as “The Saddlehorn Dilemma.” https://pspruett.wordpress.com/2014/05/12/why-most-atheists-believe-in-pink-unicorns/

As well, the article in the OP claims that,

All of the scientific multiverse-hypotheses are somewhat speculative (although there is also scientific evidence in their favor)

I clicked on the link that he provided for supposed scientific evidence and, lo an behold, his supposed scientific evidence for all these multiverse theories comes from none other than Max Tegmark's old 2003 article

Parallel Universes - Max Tegmark - 2003 https://space.mit.edu/home/tegmark/PDF/multiverse_sciam.pdf

Contrary to what the author of the OP may falsely believe, Max Tegmark has no scientific evidence for his claims. Here is a video I made that focused precisely on Tegmark's paper

Multiverse Mania vs Reality - video https://www.youtube.com/watch?v=nQJV4fH6kMo

George Ellis himself wrote a paper pointing out the fact that multiverse advocates, Tegmark included, do not have any experimental evidence validating their claims for the various forms of multiverse theories that they have postulated over the last twenty years or so,,,

Physics on Edge - George Ellis - August 2017 Excerpt: Theoretical physics and cosmology find themselves in a strange place. Scientific theories have since the seventeenth century been held tight by an experimental leash. In the last twenty years or so, both string theory and theories of the multiverse have slipped the leash. Their owners argue that this is no time to bring these subjects to heel. It is this that is strange.,,, The multiverse is a collection, set, or ensemble of possibly disjoint universes. They are possible because no one knows whether they exist. Max Tegmark has contemplated four different kinds of multiverse, and Brian Greene, nine.1 Nothing exceeds like excess. The cosmologist, Martin Rees, has argued that our universe cannot plausibly end at the visual horizon.,,, Alan Guth, Andrei Linde, and Alexander Vilenkin have embraced the multiverse because its existence follows from some current cosmological theories.,,, String theory, Leonard Susskind has argued, is the correct theory of quantum gravity. Different string vacua are sufficiently distinct that their physics varies, or may vary. Each of them, in principle, embodies a universe. They may be related to inflationary universes. Since no one can determine which one is real, Susskind is disposed to accept them all. Roger Penrose, Lee Smolin, Paul Steinhardt, and Neil Turok have all proposed that the multiverse arises in time rather than space. If the constants of nature are different in each new expanding universe, as Smolin has suggested, the result is endless variety; if they are the same, as Penrose suggested, the result is a form of eternal return. Sean Carroll, David Deutsch, Max Tegmark, and David Wallace have all claimed that the quantum wave function of the universe splits into multiple branches every time a measurement is made. Each branch is a universe.4 This idea was originally advanced by Hugh Everett III in his Princeton dissertation.,,, David Lewis and Dennis Sciama have argued for a strong form of modal realism. Whatever is possible is real.,,, Not to be outdone, Tegmark has argued that every consistent mathematical structure exists in some disconnected universe.,,,,,, Carlo Rovelli has responded to Dawid: "… The very existence of reliable theories is what makes science valuable to society… Dawid’s merit is to have emphasized and analyzed some of the non-empirical argument that scientists use in the “preliminary appraisal” of theories. His weakness is to have obfuscated the crucial distinction between this and validation: the process where a theory becomes reliable, gets accepted by the entire scientific community, and potentially useful to society. The problem with Dawid is that he fails to say that, for this, only empirical evidence is convincing.36" Hear, hear. http://inference-review.com/article/physics-on-edge - George Ellis is Emeritus Distinguished Professor of Complex Systems in the Department of Mathematics and Applied Mathematics at the University of Cape Town in South Africa.

Tegmark's 'mathematical multiverse' was particularly ripe for ridicule,,,

Physics on Edge - George Ellis - August 2017 Excerpt: Tegmark has argued that every consistent mathematical structure exists in some disconnected universe. Tegmark also believes that nothing else exists beyond the consistent mathematical structures. Tegmark is himself nothing more than a consistent mathematical structure. This is a view that assigns to mathematical structures a degree of agency that they are not otherwise thought to possess. http://inference-review.com/article/physics-on-edge

In critique to Max Tegmark’s 2015 book, Our Mathematical Universe:,, Nobel Laureate Sheldon Glashow, professor of Mathematics and Physics at Boston University, quips that “I may be a blockhead but I am certainly not a mathematical structure akin to a triangle.”

A Hand-Waving Exact Science - Sheldon Glashow Excerpt: And our ToE is just one among an infinity of mathematical structures, each of them its own universe. If Tegmark is correct, there must exist a slightly different mathematical structure, whose equations are emblazoned on another T-shirt, wherein I am Tegmark’s psychiatrist rather than a physicist. I do not believe a word of it. Paraphrasing Danny, I may be a blockhead but I am certainly not a mathematical structure akin to a triangle. - Sheldon Glashow Sheldon Glashow is professor of Mathematics and Physics at Boston University and professor emeritus of Physics at Harvard University. He received the Nobel Prize in Physics in 1979. http://inference-review.com/article/a-hand-waving-exact-science

bornagain77

The multiverse is not a logical deduction from the state of our universe. It is an attempt to short circuit discussion of apparent fine-tuning by appealing to the idea that no conclusions can be drawn because there is an infinite series we do not know about.

It's also an obfuscated way of reintroducing an infinite past. Our current universe is a branch of a branch of a branch...... There dare not be a beginning! Why, that implies things. Latemarch