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  • #16
    Originally posted by tabibito View Post
    Last I heard, the idea that the universe is cyclic or eternal had been deemed incorrect. Of course, science does tend to get revised from time to time.
    That is just Shunya's personal belief.

    Comment


    • #17
      Originally posted by Sparko View Post
      So what is new about this? I was watching a "How the Universe Works" episode from around 2010 and they said all this.
      I think what's new is that they changed their minds in between.

      https://futurism.com/new-research-su...etary-nebula-2

      (Although there is arguably nothing new about that.)

      Comment


      • #18
        Originally posted by Sparko View Post

        So, do you believe God would allow mankind to perish or destroy itself?
        I did not say anything of the sort. I just describe the physical evidence that is presently available. Again your statements are too anthropomorphic. God does not allow nor disallow as humans think. God Creates how God Creates.
        Glendower: I can call spirits from the vasty deep.
        Hotspur: Why, so can I, or so can any man;
        But will they come when you do call for them? Shakespeare’s Henry IV, Part 1, Act III:

        go with the flow the river knows . . .

        Frank

        I do not know, therefore everything is in pencil.

        Comment


        • #19
          Originally posted by tabibito View Post
          Last I heard, the idea that the universe is cyclic or eternal had been deemed incorrect. Of course, science does tend to get revised from time to time.
          No, it remains a possible option of explaining the nature of our universe and all possible universes. It is not my opinion one way or the other. It remains an unresolved problem concerning the origins and history of our universe. Yes, there is disagreement among physicists and cosmologists concerning th history of our universe, because there is evidence on both sides and the solution is unknown

          Source: ttps://physicsworld.com/a/cyclic-universe-could-explain-cosmological-constant/




          Cyclic universe could explain cosmological constant

          05 May 2006 Isabelle DuméTwo theoretical physicists have developed a model that could explain why the cosmological constant takes the small, positive value that it does in today's universe. The value of the constant is responsible for the observed acceleration in the expansion of the universe. However, the new model, developed by Paul Steinhardt of Princeton University in the US and Neil Turok at Cambridge University in the UK, will be controversial. It requires that time existed before the Big Bang, assumes that the universe is older than the 14 billion years we think it is, and says that the universe regularly undergoes repeating "cycles" of big bangs and big crunches (Sciencexpress 1126231).
          Figure 1
          The cosmological constant, or Λ, was first introduced by Einstein in 1917 to explain why the universe did not appear to be expanding. Edwin Hubble later showed that the universe was expanding, causing Einstein to call the constant his “biggest blunder”. But when scientists first measured a value for Λ in 1998, they found it had a tiny, positive value — indicating that acceleration of the universe is speeding up.

          However, it is unclear why this value is an incredible 120 orders of magnitude smaller than would be expected if the universe formed under the “standard” Big Bang theory. Solving this mystery is one of the most important challenges in cosmology today.

          Physicists have proposed several theories to explain why Λ is so small. One of the most popular — the “anthropic principle” — states that Λ is randomly set and has very different values in different parts of the universe (figure 1). We happen to live in a rare region, or “bubble”, where Λ has the value we observe. This value has allowed stars, planets and therefore life to develop. However, this theory is also unsatisfactory for many scientists because it would be better to be able to calculate Λ from first principles.

          Figure 2
          Steinhard and Turok’s new theory assumes we live in a cyclic universe, where each cycle from Big Bang to big crunch takes about a trillion years. It postulates the existence of a long sequence of vacuum states, in which Λ changes in a small series of steps, or cycles, of steadily decreasing cosmological constant. The constant is assumed to start out large and positive and hops down the steps to ever lower values.

          Each hop takes longer and longer so that the entire universe spends vastly more time at the lowest positive value of Λ, which we see today, than at any other value (figure 2). The last jump, to a negative value, terminates the cycling behaviour of the universe so that it rapidly ends in a big crunch.

          Although a similar model was developed by US physicist Larry Abbot in the 1980s, he showed that the descent to small values of Λ took so long that all the matter in the universe would have completely dissipated during this time, therefore resulting in an empty universe. Steinhardt and Turok have fixed this flaw by combining his model with their cyclic model of the universe. The difference now is that a high density of matter is created at the beginning of each cycle so that the universe is never empty.

          “We have proposed a mechanism whereby superstring theory and M theory (our best unified theories of quantum gravity to date) allow the universe to pass through a Big Bang,” Turok told PhysicsWeb. “But more theoretical work is needed to see whether our proposal is fully consistent.”

          There will, however, be a way of testing the new theory. According to the standard model of the universe, there was a period of rapid expansion shortly after the Big Bang, known as inflation, that bathed the universe with gravitational waves. A series of experiments are currently underway to detect these waves, which have never been seen before. However, Steinhardt and Turok’s model says the gravitational waves generated if their model is correct would be too small to be detected. So if gravitational waves are found in the next few years, it would rule out their theory.

          © Copyright Original Source



          Worthy of note here: I do not have an 'opinion' either way.
          Last edited by shunyadragon; 09-07-2021, 01:01 PM.
          Glendower: I can call spirits from the vasty deep.
          Hotspur: Why, so can I, or so can any man;
          But will they come when you do call for them? Shakespeare’s Henry IV, Part 1, Act III:

          go with the flow the river knows . . .

          Frank

          I do not know, therefore everything is in pencil.

          Comment


          • #20
            Originally posted by shunyadragon View Post

            No, it remains a possible option of explaining the nature of our universe and all possible universes. It is not my opinion one way or the other. It remains an unresolved problem concerning the origins and history of our universe. Yes, there is disagreement among physicists and cosmologists concerning th history of our universe, because there is evidence on both sides and the solution is unknown

            Source: ttps://physicsworld.com/a/cyclic-universe-could-explain-cosmological-constant/




            Cyclic universe could explain cosmological constant

            05 May 2006 Isabelle DuméTwo theoretical physicists have developed a model that could explain why the cosmological constant takes the small, positive value that it does in today's universe. The value of the constant is responsible for the observed acceleration in the expansion of the universe. However, the new model, developed by Paul Steinhardt of Princeton University in the US and Neil Turok at Cambridge University in the UK, will be controversial. It requires that time existed before the Big Bang, assumes that the universe is older than the 14 billion years we think it is, and says that the universe regularly undergoes repeating "cycles" of big bangs and big crunches (Sciencexpress 1126231).
            Figure 1
            The cosmological constant, or Λ, was first introduced by Einstein in 1917 to explain why the universe did not appear to be expanding. Edwin Hubble later showed that the universe was expanding, causing Einstein to call the constant his “biggest blunder”. But when scientists first measured a value for Λ in 1998, they found it had a tiny, positive value — indicating that acceleration of the universe is speeding up.

            However, it is unclear why this value is an incredible 120 orders of magnitude smaller than would be expected if the universe formed under the “standard” Big Bang theory. Solving this mystery is one of the most important challenges in cosmology today.

            Physicists have proposed several theories to explain why Λ is so small. One of the most popular — the “anthropic principle” — states that Λ is randomly set and has very different values in different parts of the universe (figure 1). We happen to live in a rare region, or “bubble”, where Λ has the value we observe. This value has allowed stars, planets and therefore life to develop. However, this theory is also unsatisfactory for many scientists because it would be better to be able to calculate Λ from first principles.

            Figure 2
            Steinhard and Turok’s new theory assumes we live in a cyclic universe, where each cycle from Big Bang to big crunch takes about a trillion years. It postulates the existence of a long sequence of vacuum states, in which Λ changes in a small series of steps, or cycles, of steadily decreasing cosmological constant. The constant is assumed to start out large and positive and hops down the steps to ever lower values.

            Each hop takes longer and longer so that the entire universe spends vastly more time at the lowest positive value of Λ, which we see today, than at any other value (figure 2). The last jump, to a negative value, terminates the cycling behaviour of the universe so that it rapidly ends in a big crunch.

            Although a similar model was developed by US physicist Larry Abbot in the 1980s, he showed that the descent to small values of Λ took so long that all the matter in the universe would have completely dissipated during this time, therefore resulting in an empty universe. Steinhardt and Turok have fixed this flaw by combining his model with their cyclic model of the universe. The difference now is that a high density of matter is created at the beginning of each cycle so that the universe is never empty.

            “We have proposed a mechanism whereby superstring theory and M theory (our best unified theories of quantum gravity to date) allow the universe to pass through a Big Bang,” Turok told PhysicsWeb. “But more theoretical work is needed to see whether our proposal is fully consistent.”

            There will, however, be a way of testing the new theory. According to the standard model of the universe, there was a period of rapid expansion shortly after the Big Bang, known as inflation, that bathed the universe with gravitational waves. A series of experiments are currently underway to detect these waves, which have never been seen before. However, Steinhardt and Turok’s model says the gravitational waves generated if their model is correct would be too small to be detected. So if gravitational waves are found in the next few years, it would rule out their theory.

            © Copyright Original Source



            Worthy of note here: I do not have an 'opinion' either way.
            That was from 2006.

            The latest studies of the mass of the universe and dark energy show that the universe will keep expanding forever, faster and faster, until dark energy just rips apart the very atoms. Of course that could change again one day as we learn more about dark energy.

            Comment


            • #21
              Originally posted by Sparko View Post

              That was from 2006.

              The latest studies of the mass of the universe and dark energy show that the universe will keep expanding forever, faster and faster, until dark energy just rips apart the very atoms. Of course that could change again one day as we learn more about dark energy.
              References . . .

              2019 better . . .

              Source: https://www.accessscience.com/content/cyclic-universe-theory/176017



              Cyclic universe theory


              Article By:

              Steinhardt, Paul J. Princeton Center for Theoretical Science and Department of Physics, Princeton University, Princeton, New Jersey.

              Last reviewed:November 2019

              DOI:https://doi.org/10.1036/1097-8542.176017

              Content
              Hide

              • Cosmic evolution in the cyclic model
              • Braneworlds and the cyclic model
              • Distinguishing models
              • Related Primary Literature
              • Additional Reading

              The cyclic universe theory is a model of cosmic evolution according to which the universe undergoes endless cycles of expansion and cooling, each beginning with a “big bang” and ending in a “big crunch”. The theory is based on three underlying notions: First, the big bang is not the beginning of space or time, but rather a moment when gravitational energy and other forms of energy are transformed into new matter and radiation and a new period of expansion and cooling begins. Second, the bangs have occurred periodically in the past and will continue periodically in the future, repeating perhaps once every 1012 years. Third, the sequence of events that set the large-scale structure of the universe that we observe today took place during a long period of slow contraction before the bang; and the events that will occur over the next 1012 years will set the large-scale structure for the cycle to come. Although the cyclic model differs radically from the conventional big bang–inflationary picture in terms of the physical processes that shape the universe and the whole outlook on cosmic history, both theories match all current observations with the same degree of precision. However, the two pictures differ in their predictions of primordial gravitational waves and the fine-scale statistical distribution of matter; experiments over the next decade will test these predictions and determine which picture survives.

              © Copyright Original Source



              The problem remains unresolved . . .
              Glendower: I can call spirits from the vasty deep.
              Hotspur: Why, so can I, or so can any man;
              But will they come when you do call for them? Shakespeare’s Henry IV, Part 1, Act III:

              go with the flow the river knows . . .

              Frank

              I do not know, therefore everything is in pencil.

              Comment


              • #22
                How about 2021. . .



                Source: https://astronomy.com/news/2021/08/what-would-this-cyclic-model-of-the-universe-mean-for-the-big-bang



                Meet the Big Crunch: In this theory on the origins of the universe, the Big Bang was not the beginning, but a repeating pattern of expansion and contraction.
                By Sophie Putka

                What would this cyclic model of the universe mean for the Big Bang?


                The cyclic model and its spinoffs


                A cyclic model of the universe is designed to solve some of the seemingly unsolvable problems of the Big Bang and inflation models. “It allows us to go beyond the Big Bang, but without any kind of magical philosophical issues,” says Stephon Alexander, a professor of physics at Brown University, and the co-inventor of an inflation model of the universe based on string theory. “Because time has always existed in the past.”


                Scientists have proposed a cyclic model that could work mathematically in a few ways. Steinhardt and Turok’s model of a cyclic universe is one of them. Its core principles are these: The Big Bang was not the beginning of time; there was a previous phase leading up to it, with multiple cycles of contraction and expansion that repeat indefinitely; and the key period defining the shape of our universe was right before the so-called bang. There you would find a period of slow contraction called the Big Crunch.

                So, instead of a beginning of time arising out of nothing, the cyclic model allows for a long period of time in the lead-up. It claims to fix the same problems as the inflationary theory did, but builds even further. For one thing, the existence of time before the Big Crunch removes the singularity problem — that undefined number. It also utilizes string theory and quantum fluctuations.

                Like the LCDM, a cyclic model would also account for dark energy, an unobservable force that scientists believe is behind the accelerating expansion of the universe. But in Stenhardt and Turok’s model, things get a little more like science fiction: Two identical planes, or “branes,” (in string theory, an object that can have any number of dimensions) come together and expand apart. We can observe the three dimensions of our plane, but not the extra dimensions of the other. Dark energy is both the force leading the branes into a collision, with separation between them. Expansion of the branes themselves follows, and dark energy draws them together again once they’re as flat and smooth as they can become.

                Giani, the researcher, isn’t so sure, because of some of the assumptions this model brings in from string theory. He likes another cyclic model from Roger Penrose, a theoretical physicist at Oxford who came up with what Penrose himself called “an outrageous new perspective” on the universe. “I was completely amazed by it,” Giani said.

                It’s hard to wrap your head around: In the distant, distant future, our solar system and galaxy will be engulfed by black holes, which eat up all the other mass in the universe, and then after an unimaginable amount of time, only black holes will exist. Eventually, only photons exist, which have no mass and therefore no energy or frequency, according to our accepted laws of physics.

                Measurements of scale, Penrose explains, no longer apply at this stage, but the shape of the universe remains. At the moment of the Big Bang, he argues, when particles are so hot and close together that they also move at almost the speed of light, they also lose their mass. This creates the same conditions at the Big Bang as the cold, distant future universe. Their scale is no longer relevant, and one can beget the other. The remote future and the Big Bang become one and the same.
                Disproving the models

                Ultimately, what humans can observe of our universe is limited. That’s why theories of the universe are never complete. They balance the small sliver of the universe we can observe with mathematical models and theory to fill in the rest. So, in cosmology, scientists search for observable phenomena that disprove their models, and reshape their theories again to suit the problem.

                But as our technology rapidly advances, observations that support or detract from one model or another come more often. “It's completely worth making all this speculation in this work, because we are getting to the point in which this data will arrive,” Giani says. One such observation could produce compelling support for either a cyclic model or confirm the more accepted inflationary theory.

                Because of how matter is distributed in our view of the oldest part of the universe (seen in the CMB), gravitational waves that reach us may be polarized, like light, at a particular frequency. Soon — within a few years, in fact — scientists may be able to determine whether this polarization exists. If it does, it will support the inflationary model. If this polarization doesn’t exist, it will undermine “slow contraction,” a hallmark of the cyclic model.

                We’ll be one step closer to making sense of time and space, yet still on a journey within the cosmos that’s far from over.

                © Copyright Original Source

                Glendower: I can call spirits from the vasty deep.
                Hotspur: Why, so can I, or so can any man;
                But will they come when you do call for them? Shakespeare’s Henry IV, Part 1, Act III:

                go with the flow the river knows . . .

                Frank

                I do not know, therefore everything is in pencil.

                Comment


                • #23
                  You are just posting pop articles that describe what the theory IS, not that it is what current science thinks will happen. Currently the consensus is that dark energy is going to cause the universe to expand forever. But as I said, things can change as more information becomes known.

                  Comment


                  • #24
                    Originally posted by Sparko View Post
                    You are just posting pop articles that describe what the theory IS, not that it is what current science thinks will happen. Currently the consensus is that dark energy is going to cause the universe to expand forever. But as I said, things can change as more information becomes known.
                    Reading comprehension appears to be your problem. ALL the articles I posted consider that the cyclic theory remains an equal possibility to the history of our universe and NONE raised any serious objection to the various versions possibility of a cyclic universe. My references are from peer reviewed journals.

                    Still waiting . . .
                    Glendower: I can call spirits from the vasty deep.
                    Hotspur: Why, so can I, or so can any man;
                    But will they come when you do call for them? Shakespeare’s Henry IV, Part 1, Act III:

                    go with the flow the river knows . . .

                    Frank

                    I do not know, therefore everything is in pencil.

                    Comment


                    • #25
                      Originally posted by Sparko View Post
                      You are just posting pop articles that describe what the theory IS, not that it is what current science thinks will happen. Currently the consensus is that dark energy is going to cause the universe to expand forever. But as I said, things can change as more information becomes known.
                      I believe rogue06 supports my conclusions. If you read the peer reviewed articles I cited it is thought that it may be resolved in the near future when more information is achieved the question may be resolved, but at present it is an open question and unresolved.
                      Glendower: I can call spirits from the vasty deep.
                      Hotspur: Why, so can I, or so can any man;
                      But will they come when you do call for them? Shakespeare’s Henry IV, Part 1, Act III:

                      go with the flow the river knows . . .

                      Frank

                      I do not know, therefore everything is in pencil.

                      Comment

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