Ruminations on multiverses; Another view (Introduction)

by David Turell , Sunday, April 03, 2016, 21:39 (3155 days ago) @ David Turell

A new essay covering the arguments on both sides of the question from different scientists:-http://www.space.com/32452-can-science-explain-the-multiverse.html-"the same set of facts, theories and inferences that imply a multiverse also severely limit, and perhaps proscribe completely, humans' capacity to conduct high-grade scientific studies, experimental or observational, to detect a possible multiverse. So is the search for a multiverse "science?" -***-"Van Fraassen said he is not a "scientific realist," meaning that he does not accept that the scientific criterion of success is "truth in every respect" or "truth, period." He said he rejects the prevailing notion that science can penetrate deeper than "just what's observable" and "postulate all things needed in order to explain observable things." -***-"Princeton physics professor J. Richard Gott described the boundaries of science in terms of what science can and cannot know. "We've learned a great deal about the universe — age, structure, initial conditions, how it started, how it's developing. But a theologian might say, 'Well, have you really answered the question of why is there a universe, as opposed to no universe at all?' It's easy to imagine no universe at all. Science is not prepared to answer this question, at least not at the present time," he said. -***-"Ellis, who is well known for challenging the multiverse, argued that "attempts to exempt speculative theories of the universe from experimental verification undermine science. "Because we cannot see them," Ellis told me, "we can't prove anything about them," emphasizing skeptical commentary similar to what he shared in my essay on the multiverse.-**-"'This is a very powerful argument," Linde noted in response. "You cannot prove anything about things that you cannot see. Fortunately, this argument is wrong. Here's what's often missed in the discussion of the multiverse: If we have many experimental or observational facts that can be explained only in the context of one particular theory (e.g., multiverse), these facts constitute experimental or observational evidence in favor of this theory." multiverse.-"'Thus, anybody disliking the theory of the multiverse," Linde continued, "should be asked to present an explanation of these observational or experimental facts in any other context, not involving a multiverse. Many people tried. Nobody succeeded. That's why we take it so seriously." -***-"Steven Weinberg at the University of Texas at Austin, one of the pioneers of this new way of thinking about science, said that assuming "different versions of the multiverse idea, the anthropic principle is just common sense." The reason, he said, was that "if there is a vast number of universes — in which the various constants [of physics], including the energy in empty space [known as the cosmological constant], vary from universe to universe — it is natural that we will be only in the kind of universe that could support life."-"I couldn't make any sense of this 'anthropic principle'," Linde explained, "until I proposed a model of an inflationary universe consisting of many different parts with different properties [different laws of physics]. The same picture appears in a much more convincing way in [cosmic] eternal chaotic inflation and finally became even more convincing after the discovery of 10^500 vacua in string theory." -"This theoretical finding was that there are (very roughly) 10^500 different, theoretically feasible configurations or ways that string theory can generate different, theoretically feasible laws of physics (based on all the possible stable, geometrical or topological configurations of an infinitesimally small, higher-dimensional "manifold" that string theory proposes as the foundation of space and time and particles and forces). -***-"In response, Ellis stated that Linde's argument requires three parts: experimental or observational facts to be explained, a viable theory that can explain these facts and no other theory that can work as well. And Ellis claimed that for the multiverse, "there are problems with each part.'"-Comment: Linde's dependence on String theory skips the fact that strings are not proven. Article goes on and on, round and round. Review it for full flavor.