However, recent theories in physics, including one called string theory, are now telling us there could be countless other universes, built on different types of particles, with different properties, obeying different laws. Most of these universes could never support life, and might flash in and out of existence in a nanosecond, but nonetheless, combined they make up a vast multiverse of possible universes.
And the leading version of string theory predicts a multiverse made of up to 10 to the universes. That's a one followed by zeroes, a number so vast that if every atom in our observable universe had its own universe and all of the atoms in all of those universes each had their own universe, and you repeated that for two more cycles, you'd still be at a tiny fraction of the total — namely, one trillion trillion trillion trillion trillion trillion trillion trillion trillion trillion trillion trillion trillion trillion trillionth.
But even that number is minuscule compared to another number: infinity. Some physicists think the space-time continuum is literally infinite, and that it contains an infinite number of so-called pocket universes with varying properties. How's your brain doing? But quantum theory adds a whole new wrinkle. I mean, the theory's been proven true beyond all doubt, but interpreting it is baffling. And some physicists think you can only un-baffle it if you imagine that huge numbers of parallel universes are being spawned every moment, and many of these universes would actually be very like the world we're in, would include multiple copies of you.
In one such universe, you'd graduate with honors and marry the person of your dreams. In another, not so much. There are still some scientists who would say, hogwash. But from the inside, it looks like an infinite open universe. Of course, 'looks like' means that someone is looking, but nobody can see an infinite universe.
Tegmark's Level I is accepted by almost all cosmologists i. All this shows how far and how fast our knowledge of the cosmos has expanded: Generating multiple universes by eternal chaotic inflation, a theory developed in the last four decades, is now the standard model of cosmology. I asked Steven Weinberg, a founder of the Standard Model of particle physics now at the University of Texas at Austin, about other kinds of multiple universes.
Because the fundamental quanta in quantum mechanics is not the individual particle or billiard ball but is something called the 'wave function,' which describes all possibilities, it may be that the universe, the comprehensive universe, the whole thing, is some kind of quantum mechanical superposition of different possibilities. The philosopher David Lewis proposed a similar theory of "modal realism" in which all possible worlds, astonishingly, are actual worlds. But to achieve such immensity and diversity, wouldn't there still have to be, at a deeper level, some rock-bottom, fundamental "universe-generating laws" to create all the multiple universes in the first place, each of which has its own different laws?
Where is bedrock reality? Not every cosmologist is a full convert to the multiverse. As cosmologist George Ellis told me, "I don't like the word 'multiverse. Moreover, he stresses the basic problem of other domains of space-time.
Maybe we are seeing the same patch of space-time over and over again. Einstein's theory [of general relativity] allows this to happen because space-time not only is curved, but also it can have a different connectivity structure. So maybe we can go for several hundred million light-years [in one direction] and then suddenly we return from that side [to where we started from], just like Pac-Man did in those early computer games.
We would be seeing many images, maybe hundreds of images, of the same galaxy. Physicist Paul Davies, director of the Beyond Center for Fundamental Concepts in Science at Arizona State University, said he gives "two cheers [not the full three] for the multiverse," because "although there are good reasons for supposing that what we see may not be all that exists, the hypothesis falls far short of being a complete theory of existence.
You're going to need some laws of physics. All theories of the multiverse assume quantum physics to provide the element of spontaneity, to make the bangs happen. They assume pre-existing space and time. They assume the normal notion of causality, a whole host of pre-existing conditions.
Davies then made his deep point. What about those meta-laws that generate all the universes in the first place? Where did they come from? Then what about the laws or meta-laws that impose diverse local laws upon each individual universe?
How do they work? What is the distribution mechanism? Davies dismissed the idea that "any universe you like is out there somewhere. I think such an idea is just ridiculous and it explains nothing. Having all possible universes is not an explanation, because by invoking everything, you explain nothing. Davies' critique of the multiverse goes deeper.
To explain the universe, he rejects "outside explanations," he said. Then Davies makes his damning comparison. In fact, I think both explanations — multiverse and God — are pretty much equivalent.
Davies said he appreciates all the motivations and mathematics that drive inflation theory, along with the multiple universes that seem the compulsory consequences. But still, he said, he feels that an infinite number of universes does not make sense. Something's amiss. What's my take? Long out of childhood, but still feeling childlike in the presence of a multiverse, I try to assess the possibilities.
I like to categorize things, to discern scope and breadth. Here are seven possible mechanisms that could generate multiple universes. What's more, these seven mechanisms for generating multiple universes are not mutually exclusive. Several, or even all of them, could be true — and they could nest in various ways, one within others, others within one. In a multiverse, one cannot avoid infinity, and infinity does strange things. There are two types of possible infinities in a multiverse: Type I: A single universe may be infinite in size e.
The consequences of either infinity become bizarre. First of all, even Tegmark's Level I multiverse, assuming it's infinite, must contain everything that's physically possible. This means, for example, that every "Star Wars" scenario really exists out there, including those that didn't make it into the films and even all those the writers didn't think of!
Similarly, as long as there is sufficient space for unending random shufflings of particles and a universe of infinite size certainly has sufficient space , there would have to be a sector of space out there identical to our sector of space, with persons identical to you and to me.
I'm not so impressed even by this bizarre proposition. There would also have to be a sector of space identical to our sector of space except for, say, one hair on the head of one person, which is skewed 1 nanometer to the right. And another sector of space in which all else is the same except for that same hair, which is now skewed 2 nanometers to the left.
Then all the hairs on all the people, skewed this way and that way. And then all the things in whole sectors of space, arranged in every possible combination and permutation. There would be innumerable minute differences and innumerable large differences, with every one a separate sector of space — all enabled because the one infinite universe with infinite sectors of space goes on forever. Obviously, on this vision, randomized particles in the overwhelming majority of vast sectors of space yield nothing much at all.
To be clear, a truly infinite universe means that anything that is not impossible no matter how obscure will happen, must happen and must happen, weirdly, an infinite number of times.
An infinite universe goes on forever, not only generating uncountable variations, but also requiring each of the uncountable variations to occur an infinite number of times. That's the strange nature of a true infinity. If multiple universes are real, and especially if a true infinite number of universes really exist, then our worldview changes. Everything changes. Whatever you believe — even about God that God exists? If only the material world exists, then the material world becomes inconceivably larger.
If an infinite God exists, then God's infinity becomes expressed by science and enriched with new meaning. But would the real existence of a multiverse undermine arguments for the real existence of God by undercutting the modern "argument from design" based on the "fine-tuning" of our universe? How would God, if there is a God, relate to a multiverse? If one believes in God, or wonders whether to believe in God, this issue cries out to be addressed.
Why would God, if there is a God, create multiple universes? Why would God create infinite multiple universes? Could a multiverse elucidate what God, if there is a God, would be like?
And if God does not exist, then what? Does a multiverse have meaning? In our own cosmos, Livio said, astronomers will be better able to refine the number upon the launch of the James Webb Space Telescope for which his institute will manage the mission operations and science. Hubble is able to peer back at galaxies that formed about million years after the Big Bang. After James Webb launches in , astronomers anticipate they can look as far back as million years after the Big Bang.
While it is interesting to count the number of galaxies in our universe, astronomers are more interested in how galaxies reveal how the universe was formed. According to NASA, galaxies are a representation of how matter in the universe was organized — at least, on the large scale. Scientists are also interested in particle types and quantum mechanics, on the small side of the spectrum. Because Webb can look back to the early days of the universe, its information will help scientists better understand the structures of the galaxies around us today.
Webb will also allow scientists to gather data on the types of stars that existed in these very early galaxies," NASA said of Webb's mission. These studies will also reveal details about merging galaxies and shed light on the process of galaxy formation itself. Scientists are also interested in the role that dark matter plays in the assembly of galaxies.
While some of the universe is visible in forms such as galaxies or stars, dark matter is what makes up most of the universe — about 80 percent of it. While dark matter is invisible in wavelengths of light or through emissions of energy, studies of galaxies dating back to the s indicated there was far more mass present in them than what was visible with the naked eye. The visible matter we see collects inside this scaffolding in the form of stars and galaxies.
The way dark matter 'clumps' together is that small objects form first, and are drawn together to form larger ones. Webb's powerful mirrors will allow scientists to look at galaxy formation — including the role of dark matter — up close.
While this investigation doesn't directly answer how many galaxies there are in the universe, it does help scientists better understand the processes behind the galaxies we see, which in turn better informs models about galactic populations. Join our Space Forums to keep talking space on the latest missions, night sky and more! And if you have a news tip, correction or comment, let us know at: community space.
Elizabeth Howell is a contributing writer for Space. She is the author or co-author of several books on space exploration. Elizabeth holds a Ph. She also holds a bachelor of journalism degree from Carleton University in Canada, where she began her space-writing career in Besides writing, Elizabeth teaches communications at the university and community college level, and for government training schools.
To see her latest projects, follow Elizabeth on Twitter at howellspace. Elizabeth Howell.
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