Is Carroll-Chen's AS-dS time-reversing inflationary model true?

Reasons given for answering "No"
  • It implies you're a Matrix brain that just popped into existence

      The model implies the your brain probably just popped into empty space with Matrix-like beliefs (E.g. falsely thinking it has a body and is reading right now.) After all, far more of these kinds of brains are created in the Carroll-Chen model than real brains. (Specifically, the model runs into Poincare recurrence version of the Boltzmann Brain scenario)1

      1. After all, for each baby universe formed, there is exactly one actual Big Bang expansion, but the potential for innumerably many Boltzmann Brain’s with spontaneously created beliefs about being in a Big Bang universe. The baby universe may yield baby universe’s of its own, but for each and every baby universe the same ratio applies: one actual internal Big Bang expansion phase vs. innumerably many Boltzmann Brains over time. A philosophy of physics specialist introduced this problem.
        Eric Winsberg (Philosophy professor at USF): “it is far from clear that the most plausible thing to think is that, even in a branching multiverse, BB with big-bangy memories and records will not still vastly outnumber real big bangs—even though there are now a whole lot more big bangs than there were in the single Universe (only one!). That’s because it seems plausible to suppose that as each new Universe springs into being, it creates exactly one new actually big-bangy state, but the potential for innumerably many BBs with big-bangy memories and records. And so even on the multiverse model, it still seems plausible to suppose that, from only the evidence that is at my disposal and from the postulates of the model, it is still overwhelmingly more likely that I am a BB than that I have veridical records of a big-bangy past.” [“Bumps on the Road to Here (from Eternity)”, Entropy 14 (2012), 404.]
  • It requires a highly improbable bounce stage.

      The model requires a highly improbable bounce stage. After all, it allegedly avoids singularities, but in order to avoid such singularities it has to be highly fine-tuned (not "generic" at all as proposed).1

      1. Alexander Vilenkin: “[the scenario] proposed by Carroll and Chen,.... does require special boundary conditions at the bounce. ...[otherwise the hourglass inflating regions] will be surrounded by singularities and will have singularities in their past or future.” [“Arrows of time and the beginning of the universe,” Phys. Rev. D 88 (2013) 043516.]
  • The model destroys probability

      The model “wrecks havoc on probability judgments.”1 This is relevant because human probability judgments are justified (e.g. we are justified in believing dinosaur bones are veridical evidence of dinosaurs having exist, that everyday objects obey gravity predictions, that Rome actually existed etc.). This so-called “measure problem” seems intractable for many multiverse models, and especially plagues the Carroll-Chen model.2

      Paul Steinhardt: “[m]any remain hopeful even though they have been wrestling with this issue for the past 25 years and have yet to come up with a plausible solution.” [“The Inflation Debate: Is the Theory at the Heart of Modern Cosmology Deeply Flawed?”, Scientific American (April 2011), 42.]
      1. If everything is happening an infinite number of times, then what is you’re dealing with ratios of infinity:infinity.
        Christopher Weaver: “[t]his wreaks havoc on probability judgments. If your sample space is infinite, it does not appear possible to have a well-defined probability measure to underwrite your probability and likelihood judgments. This problem of infinities and probabilities in eternal inflation-based cosmologies is well-known. However, it is also well-known that there is no current satisfactory solution to the problem. []
        2 • Alan Guth: “…we still do not have a compelling argument from first principles that determines how probabilities should be calculated.” [([2004], 50.]
        Steinhardt and Turok: “What is the probability distribution? In models such as eternal inflation, the relative likelihood of our being in one region or another is ill-defined since there is no unique time slicing and, therefore, no unique way of assessing the number of regions or their volumes. Brave souls have begun to head down this path, but it seems likely to us to drag a beautiful science towards the darkest depths of metaphysics.” [(2005), 44.]