Intriguing discussion with Steven Weinberg
My father has a degree in comparative religion. I’ve always been fascinated by the intersection of metaphysics and science. Dr. Weinberg talks about wave theory, the big bang theory, quantum mechanics, and more. It’s a long discussion ~1 hour 14 min. Cliff Harvey does a great job giving some of his insight on the discussion.
http://en.wikipedia.org/wiki/Steven_Weinberg
#ScienceSunday
Originally shared by Cliff Harvey
Weinberg, Dawkins, and the universe
This is a great discussion exploring all kinds of questions, especially touching on some points of contact between physics and the ‘grand’ religious or quasi-religious questions, including the issue of fine-tuning of physical constants, anthropic selection from a larger reality, what we know about the early universe from experiments, and what we think we know. Its clear from the thunder in the first few minutes that they’ve angered the Gods….
In case you weren’t aware, Steven Weinberg is one of the main co-fathers of the Standard Model, a Nobel laureate, and wrote the book (all 3 volumes) on quantum field theory, so as someone very familiar with the currently most fundamental frameworks he’s among the most trustworthy and well-prepared to discuss these matters.
One of the physical issues they tackle early on is ‘dark energy’ or the vacuum energy. Here Weinberg does a good job clarifying some of the usual confusions often found in the press. We cannot, strictly speaking, calculate the value of the vacuum energy, but what we can do is calculate contributions to it, from fluctuations in various known fields down to whatever distance scales we decide to trust our current model, with the Planck scale being the absolute limit. When this is done we get an answer something around ~10^120 times too high (or possibly more like ~10^60 if there are some low-scale SUSY partners). But strictly speaking this is not a “conflict with experiment” because there is still the freedom to add a simple constant to the whole thing. The assumption that this “constant part” is zero leads to a meaningful constraint on the particle content and ultimate high-energy laws of the universe, but so far we unfortunately don’t know how to do away with that extra freedom. I agree with Weinberg that it still seems natural to expect that (at least most of) this discrepancy will be addressed by contributions from new laws which must take over by the Planck scale at the latest, and also probably from more ordinary particles which haven’t yet been discovered. Still, absent some new and currently unknown principle, this remains a primary candidate for anthropic selection.
They spend some time on the “nightmare scenario” of not finding anything new at the LHC. I don’t plan on getting very worried about this until we see a fair amount of 14 TeV data analyzed, but more importantly, its not a scientist’s place to complain about the laws of nature. I agree that it might not be as enjoyable a time to be a theorist if we don’t find something else, but there is still so much good work to be done in understanding the current frameworks more deeply. Also, its important to recognize that negative results are important too, they constrain future attempts at model building in important ways. But in my opinion there is no avoiding the obvious fact that physics is objectively and dramatically closer to its defined goal of describing the fundamental laws of the universe, and at some point it just becomes unrealistic and unscientific to expect that this period of science has to be directly analogous to the one that existed 150 years ago. They’re qualitatively quite different. The process of science is all about trying to find new ways to test our current best understanding, and in some ways even to try and break it, but that doesn’t mean we’re entitled to a rewriting of all the laws every few years, as a startling number of people seem to believe. That is exactly the kind of unhealthy attachment to an idea (or feeling) that the skepticism that defines science is supposed to dissuade you from. The very assumption that there are laws of the universe implies that this scientific process will inevitably become more stable over time, particularly on the most fundamental end.
Around 54:00 they also venture into the question of interpreting quantum mechanics, and here its extremely clear that there inevitably should be a conflict between your scientific understanding of the fundamental laws and your intuitive understanding of newtonian physics that you use to walk down the street. Something would have to be wrong otherwise. Essentially, because any of the hypotheses that would prevent the “unsettling” implications of QM at human scales require some kind of dramatic revision of its content, even though no evidence supports such a revision. Here Weinberg himself confesses that he thinks the “best” outcome would be to find out that there is some mechanism that breaks QM as we know it when small systems interact with large systems, though he is at least straightforward about the lack of any support from evidence. He himself mentions the many entanglement experiments have proven that quantum mechanics does still operate at distances as far as meters or even kilometers, and should work to any arbitrary distance. I don’t think its rational to “hope” for a way to circumscribe quantum mechanics in this way.This is a big topic I’ve worked on, posted on, and will post again on…
Anyway those are just a few responses to a very far-reaching conversation.
#scienceeveryday
