Thanks to a kind invitation from the Simons and John Templeton Foundations and the World Science Festival, last Friday (30 May) I participated in a public discussion on ‘Evidence in the Natural Sciences’ with Professors Brian Greene and Peter Galison.
This discussion was the final act in a one-day symposium of the same name, held at the Simons Foundation’s Gerald D. Fischbach Auditorium on 5th Avenue, in New York City. These were comfortable, well-appointed surroundings. But the overwhelming message from the symposium was actually quite discomfiting. In its 300-year maturity, it seems that science is confronted with nothing less than a crisis of evidence.
The crisis takes many forms. I learned that mathematicians are increasingly resorting to computer-based proofs that signal a loss of certainty and the ‘end of conviction.’ Efforts are underway to develop computer-based algorithms that will soon provide the only way to review such proofs, leading one audience member to wonder how long it will take to eliminate mathematicians entirely from the process.
Eliminating humans, and their biases and general lack of self-criticism, appears to be the only workable solution to a crisis of evidence in the bio-medical sciences as well. This is a field in which John P. Ioannidis (now at the Stanford School of Medicine) famously declared in 2005 that ‘most published research findings are false’ . This was real sit-up-and-take-note stuff. The research findings in question are of the kind that can lead eventually to clinical trials of new drugs.
I’d been invited to address yet another type of evidence crisis. Last year I published a book, called Farewell to Reality, which challenges some of the prevailing opinions about contemporary theoretical physics of the kind which address our ‘big questions’ concerning the nature of the physical universe. In it I argue that some theorists have crossed a line. They are suffering a ‘grand delusion,’ a belief that they can describe physical reality using mathematics alone, with no foundation in scientific evidence. I call the result ‘fairy-tale’ physics.
My role in our public discussion was that of interlocutor and facilitator. Greene is of course widely known for his Pulitzer short-listed The Elegant Universe and follow-ups The Fabric of the Cosmos and The Hidden Reality, his many radio and TV appearances and his growing role as a popular science educator (he is co-founder of the World Science Festival with his wife, former ABC News producer Tracy Day). Galison is a Harvard science historian with a flair for popularization, author of Einstein’s Clocks, Poincaré’s Maps and Objectivity. He has developed a couple of TV documentaries, about the H-bomb and about national secrecy and democracy, and is currently working on a film about the long-term storage of nuclear waste.
And then there was me, sitting in the middle. An interlocutor with an agenda. What follows is not a transcript of our discussion (I’m hoping that the Simons Foundation will post a video of this online), but rather a summary of my position.
So What’s the Problem?
Wind the clock back. On 4 July 2012, I watched a live video feed from the CERN laboratory near Geneva, and celebrated the announcement that a particle that looked a lot like the Higgs boson had finally been discovered.
This was a triumph for a theoretical structure called the standard model of particle physics. This is the theory that describes physical reality at the level of elementary particles and the forces between them and which helps us to understand the nature of material substance.
But our joy at the discovery of the Higgs was tempered by concern. We know that the standard model can’t be the whole story. There are lots of things it can’t explain, such as the elementary particle masses and the nature of dark matter. And it is not a ‘theory of everything’: it takes no account of the force of gravity.
We build scientific theories in an attempt to describe and hopefully explain empirical data based on observations and measurements of the physical universe around us. But in the twenty-first century we’ve run into a major obstacle. We have evidence that tells us our theories are inadequate. But we have no data that provide meaningful clues about how our theories might be improved. Theorists have therefore been obliged to speculate.
But in their vaulting ambition to develop a ‘theory of everything,’ some theorists have crossed a line without any real concern for how they might get back. The resulting theories, invoking superstrings, hidden dimensions and a ‘multiverse,’ among other things, are not grounded in empirical evidence and produce no real predictions, so they can’t be tested. Arguably, they are not science.
Albert Einstein once warned : “Time and again the passion for understanding has led to the illusion than man is able to comprehend the objective world rationally by pure thought without any empirical foundations — in short, by metaphysics.” What did Einstein mean? Quite simply, there can be no science without evidence or at least the promise of evidence to come.
How Should We Interpret ‘Reality’?
I believe that the root of the problem lies in the way we seek to interpret the word ‘reality.’ Pick up any text on philosophy and you’ll find discussions of reality under the general heading ‘metaphysics.’ How come? Physical reality seems really rather tangible and logical. It confronts us every morning when we wake up. Surely, despite what the philosophers might say, we can be pretty confident that reality continues to exist when there’s nobody looking. The science fiction writer Philip K. Dick once declared: “Reality is that which, when you stop believing in it, doesn’t go away.” 
But reality is curiously schizophrenic. There is an ‘empirical reality’ of things as we observe or measure them. This is the reality that scientists try to address. The purpose of science is to seek rational explanations and ultimately an understanding of empirical reality by establishing a correspondence between the predictions of scientific theories and the results of observations and measurements. Such a correspondence gives us grounds for believing that the theory may be ‘true.’
Here’s an example. In 1964, Peter Higgs, Francois Englert and Robert Brout speculated that there must exist a special kind of quantum field — which became known as the Higgs field — responsible for giving mass to elementary particles. In 1967 Steven Weinberg used this field to predict the masses of some exotic particles called W and Z bosons, which we can think of as ‘heavy photons.’ These particles were discovered at CERN in 1983, with more-or-less the masses that Weinberg had predicted. Consequently, the Higgs field was incorporated into the standard model of particle physics.
But there could in principle have been other possible explanations for the masses of the W and Z particles. If the Higgs field really exists, then it should produce a tell-tale field quantum — the Higgs boson. In 2012, establishing a correspondence between the empirical data produced at CERN and theoretical predictions for the behavior of the Higgs boson gave us grounds to believe that the Higgs field really does exist and that the standard model is ‘true’ within its domain of applicability.
We would perhaps not hesitate to declare that lying beneath this empirical reality must be an independent reality of things-in-themselves, a reality of things as they really are. But such an independent reality is entirely metaphysical. Kind of by definition, we cannot observe or measure a reality that exists independently of observation or measurement. We can only speculate about what it might be like. As Werner Heisenberg once said: “We have to remember that what we observe is not nature in itself, but nature exposed to our method of questioning.” 
It is this independent reality that philosophers try to address, which is why their speculations appear under the heading of ‘metaphysics.’ Now, philosophers are not scientists. They don’t need evidence to establish a correspondence between their interpretation of an independent reality and our empirical world of observation and measurement. They’re more than satisfied if their interpretation is rationally and logically structured and coherent. There is truth here, but of a subtly different kind.
Crossing the Line
Contemporary theorists find themselves caught in a bind. Without any clues from empirical data to guide theory development, and ever eager for answers to the ‘big questions’ of human existence, it seems that theorists have had no choice but to cross the line from physics to metaphysics.
There’s nothing wrong with this. Theorists have been doing this for hundreds of years. But, as scientists rather than philosophers, they have speculated about the nature of an independent reality of things-in-themselves with the aim of getting back across the line as quickly as possible. Einstein’s special and general theories of relativity were founded in arguably metaphysical speculations about the nature of space and time. But Einstein was at pains to get back across the line and show how this interpretation of space and time might manifest itself in our empirical reality of observation and measurement. The rest, as they say, is history.
Contemporary theorists have simply stopped trying to find their way back. Worse, they have built a structure so complex and convoluted and riddled with assumptions that it’s virtually impossible to get back.
What do I mean? As they have explored the metaphysical landscape of a mathematically-defined independent reality, the theorists have misappropriated and abused the word ‘discovery.’ So, they ‘discovered’ that elementary particles are strings or membranes. They ‘discovered’ that there must be a supersymmetry between different types of particle. They ‘discovered’ that the theory demands six extra spatial dimensions which must be compactified into a space so small we can never experience them. They ‘discovered’ that the five different types of superstring theory are subsumed in an over-arching structure called ‘M-theory.’ Then, because they ‘discovered’ that there are 10-to-the-power-500 different ways of compactifying the extra dimensions, each of these must describe a different type of universe in a multiverse of possibilities. Finally, they ‘discovered’ that the universe is the way it is because this is one of the few universes in the landscape of 10-to-the-power-500 different kinds that is compatible with our existence.
I want you to be clear that these are not discoveries, at least in the sense of scientific discoveries. They are assumptions or conclusions that logically arise from the mathematics but for which there is absolutely no empirical evidence. It’s not really so surprising that the theory struggles to make any testable predictions. There is simply no way back to empirical reality from here.
Don’t be blinded by all the abstract mathematics, all the ‘dualities’ which connect one kind of mathematical description with another. These help to establish ‘coherence truths,’ of the kind X = Y. But when neither X nor Y correspond to anything in the empirical world that even hints at the possibility of an observation or a measurement, then we can be clear that this all remains firmly metaphysical.
We have a problem. The theorists are stuck on the wrong side of the line, and most believe there is no viable alternative. As Nobel laureate Steven Weinberg remarked to me a little while ago :
“String theory still looks promising enough to be worth further effort. I wouldn’t say this if there were a more promising alternative available, but there isn’t. We are in the position of a gambler who is warned not to get into a poker game because it appears to be crooked; he explains that he has no choice, because it is the only game in town.”
Obviously, we sympathize. But what if, instead of being obliged to attend remedial therapy, those addicted to gambling were able somehow to influence the rules, to make gambling an acceptable pastime? No scientist likes to be stigmatized, to be accused of pseudo-science. This is why some in the theoretical physics community are seeking to change the way we think about science itself.
For example, string-theorist-turned philosopher Richard Dawid recently argued : “final theory claims introduce the new conception of a scientific process that is characterized by intra-theoretical progress instead of theory succession … The status of a merely theoretically confirmed theory will always differ from the status of an empirically well-tested one. However, in the light of the arguments presented, this difference in status should not be seen as a wide rigid chasm, but rather as a gap of variable and reducible width depending on the quality of the web of theoretical arguments.”
The problem with this is that as soon as we accept the notions of ‘intra-theoretical progress’ and ‘theoretically confirmed theory’ we risk completely disconnecting from any sense of real scientific progress. We risk losing respect for evidence, deepening the crisis, unplugging from empirical reality and training — how many? one, two? — generations of theorists to believe that this is all okay, that this is science fit for our modern, post-empirical age. We ensure they inherit an addiction to gambling.
Some are already talking of these theorists as ‘lost generations’ : “It is easy to estimate the total number of active high-energy theorists. Every day hep-th and hep-ph bring us about thirty new papers. Assuming that on average an active theorist publishes 3-4 papers per year, we get 2500 to 3000 theorists. The majority of them are young theorists in their thirties or early forties. During their careers many of them never worked on any issues beyond supersymmetry-based phenomenology or string theory. Given the crises (or, at least, huge question marks) in these two areas we currently face, there seems to be a serious problem in the community. Usually such times of uncertainty as to the direction of future research offer wide opportunities to young people, in the prime of their careers. To grab these opportunities a certain reorientation and re-education are apparently needed. Will this happen?”
Maybe it’s already too late. In a more recent assessment, Dawid writes : “Many physicists may wish back the golden old days of physics when fundamental theories could (more often than not) be tested empirically within a reasonable period of time and a clear-cut empirical verdict in due time rendered irrelevant all tedious theoretical considerations concerning a theory’s viability. Empirical science, however, must answer to the situation it actually faces and make the best of it. A sober look at the current situation in fundamental physics suggests that the old paradigm of theory assessment has lost much of its power and new strategies are already stepping in.”
There’s more. Scientists have a duty of care to a public that has developed an unprecedented appetite for popular science. This is an appetite that was greatly enhanced by the success of Stephen Hawking’s A Brief History of Time and has been fed by some excellent science writing, not least from Greene himself.
I haven’t done the research, but I very much suspect that if you were to ask a randomly selected group of scientifically literate readers about the theories we use to describe and understand the universe, many of these readers will likely tell you something about superstrings, hidden dimensions and the multiverse.
In truth, today these theories describe nothing and add nothing to our understanding, because this is metaphysics, not science. These theories do not form part of the accepted body of tried-and-tested scientific theory used routinely to describe our physical world, the kind used at CERN in the hunt for the Higgs boson. As Nobel laureate Tini Veltman claimed, paraphrasing Wolfgang Pauli, these theories are ‘not even wrong.’ 
Now readers of popular science might just want to be entertained with the latest ‘Oh wow!’ revelations from contemporary theoretical physics. But surely they also deserve to know the truth about the scientific status of these theories. I think Danish science historian Helge Kragh hit the nail squarely on its head when he observed, in a review of John Barrow and Frank Tipler’s The Anthropic Cosmological Principle :
“Under cover of the authority of science and hundreds of references Barrow and Tipler, in parts of their work, contribute to a questionable, though fashionable mysticism of the social and spiritual consequences of modern science. This kind of escapist physics, also cultivated by authors like Wheeler, Sagan and Dyson, appeals to the religious instinct of man in a scientific age. Whatever its merits it should not be accepted uncritically or because of the scientific brilliancy of its proponents.” Amen.
In the end
I believe that contemporary theoretical physics has lost its way. It has retreated into its own small, self-referential world. In search of a final ‘theory of everything,’ theorists have been obliged to speculate, to cross the line from physics to metaphysics. No doubt this was done initially with the best of intentions, the purpose being to get back across the line carrying some new insight about the way the universe works that would provide an empirical test. Instead, the theorists have become mired in a metaphysics from which they can’t escape.
We might ask if there’s any real harm done. I personally think there’s a risk of lasting damage to the nature of the scientific enterprise. Admitting ‘evidence’ based on ‘theoretically confirmed theory’ is a very slippery slope, one that risks undermining the very basis of science. In the meantime, the status of this fairy-tale physics has been mis-sold to the wider public. We’re in crisis, and we need a time-out.
I’d like to acknowledge a debt to Columbia University mathematical physicist Peter Woit, and especially his book Not Even Wrong: The Failure of String Theory and the Continuing Challenge to Unify the Laws of Physics, Vintage, London, 2007.
Jim Baggott completed his doctorate in physical chemistry at the University of Oxford and his postgraduate research at Stanford University. He is the author of The Quantum Story, The First War of Physics, and A Beginner’s Guide To Reality. Most recently he published Farewell to Reality: How Modern Physics Has Betrayed the Search for Scientific Truth.
 J.P.A. Ioannidis, ‘Why Most Published Research Findings are False,’ PLoS Medicine, 2(8), e124, August 2005.
 Albert Einstein, ‘On the Generalised Theory of Gravitation,’ Scientific American, April 1950, p. 182.
 Philip K. Dick, from the 1978 essay ‘How to Build a Universe that Doesn’t Fall Apart Two Days Later,’ included in the anthology I Hope I Shall Arrive Soon, edited by Mark Hurst and Paul Williams, Grafton Books, London, 1988. This quote appears on p. 10.
 Werner Heisenberg, Physics and Philosophy: The Revolution in Modern Science, Penguin, London, 1989 (first published 1958), p. 46.
 Steven Weinberg, personal note to the author, 13 January 2013.
 Richard Dawid, ‘Underdetermination and Theory Succession from the Perspective of String Theory,’ Philosophy of Science, 73/3, 2007, pp. 298-332.
 M. Shifman, ‘Frontiers Beyond the Standard Model: Reflections and Impressionistic Portrait at the Conference’, arXiv:1211.0004v2, 14 November 2012.
 Richard Dawid, ‘Theory Assessment and Final Theory Claim in String Theory,’ Foundations of Physics, 43/1, 2013, pp. 81-100.
 Martinus Veltman, Facts and Mysteries in Elementary Particle Physics, World Scientific, London, 2003, p. 308.
 Helge Kragh, Centaurus, 39, 1987, pp. 191-194. This quote is reproduced in Helge Kragh, Higher Speculations: Grand Theories and Failed Revolutions in Physics and Cosmology, Oxford University Press, 2011, p. 249.
196 thoughts on “The evidence crisis”
It’s important to realize that Peter Woit is only talking about small parts of QFT and string theory. He’s only talking about those QFTs that appear in the standard model and the more complicated theories that you get by enlarging the gauge groups or adding supersymmetry. Likewise, when he talks about string theory, he’s only talking about very specific string theory models obtained by compactifying on a Calabi-Yau manifold.
But QFT and string theory offer many other possibilities. There are a gazillion different QFTs in condensed matter physics and string theory that are important for a variety of reasons that have nothing to do with the standard model. There are also alternative ways of getting the standard model from string theory that don’t involve compactification.
If you think about string theory from this more general point of view, then Woit’s aesthetic argument becomes totally irrelevant. There are lots of ways in which string theory could be related to the real world, and it’s not so clear what are the simplest string theory models. Moreover, the question of what one means by the statement “string theory is right” becomes extremely subtle and complicated.
Because of this, I think it’s best to view string theory as a kind of theoretical tool or formalism. It’s possible that elementary particles are well described by string theory compactified on some Calabi-Yau manifold, but there are lots of other ways in which string theory could describe our world, and there are probably lots of applications that we haven’t even imagined yet.
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You are right. I included that point in my original discussion of this in my previous article, but not in the summary on this thread (though perhaps I should have done).
Personally I don’t think that there is an “anthropic issue” that actually needs solving. It may indeed be the case that all multiverse bubbles have exactly the same physics — I don’t see anything wrong with that suggestion at all (though asking the question of whether they do is also worthwhile).
Sure you will, if you offer people jobs and money they will take them. But whether you then get worthwhile results is a whole other issue. It’s easy to ask for areas or avenues of research that simply will not make progress. So the question is really, who is in the best position to judge which are the best routes to progress? I think you’re underestimating ns’s comments about the difficulties of starting with a blank sheet of paper and the likelihood of getting anywhere given the vast array of physics that the novel idea needs to be compatible with. Most string theorists do indeed spend a lot of time thinking about other alternatives also. If they could see promising avenues they would take them. And grant-awarding bodies would want to support them.
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But while that Feynman sum-over-integrals is solid science in some applications, whether it has any validity as applied to the origin of the universe is hugely speculative. Vast swathes of that book are highly speculative, and one couldn’t keep repeatedly including lots of caveats and cautions about this without it being unreadable prose.
One could of course say that someone of Hawking’s statute should not speculate in public like this, because the public cannot tell what is and is not speculation, and that is a fair point and criticism to make. But is it really a problem? Should we hide cutting-edge speculation from people even though they are interested in it? It’s not as if it is about the efficacy and safety of a novel drug, or about the science of global warming, where things have serious consequences for society.
As far as I remember Kant was just drawing attention to a common confusion of concepts in metaphysical discussion.
To be clear, Robin, I wasn’t accusing you of quote mining. I only meant to say that the interpretation of that paragraph could be taken quite differently if you included “In this view”, and indeed my interpretation is quite different from yours.
As an obviously simple minded observer, may I ask a simple question?
Doesn’t the field vs. string conflict go back to the wave vs. particle duality, as to whether reality is fundamentally holographic, or atomized and that both sides have tunneled into this complex to enormous extremes, yet encounter feedback issues that pose ever more dimensions?
If so, then isn’t there a basic philosophic issue here, as to the inherently duality of nature?
Researchers do that routinely. The paper you point to discusses structure formation and the how galaxies form in a Lambda-CMD cosmological model, and a lot of work is indeed being done on those topics, but this sort of cosmology is also supported by a lot of hard evidence (and is vastly different from string theory in that regard). Thus there is no real reason why anyone is “going to have to go back and review a lot of what is currently considered settled” other than the usual discussion of this that is normal and continual in science at the cutting edge.
You are right that we should be careful to keep inflation (and a possible eternal-inflation multiverse) distinct from string theory. Cosmological inflation is largely an observationally driven idea, with little or no understanding of the underlying physics. String theory is the opposite, an attempt at the underlying physics with little or no link to observation.
That’s right, one could state that public intellectuals like Hawking, Greene, etc ought (morally) to be careful about what they present to the public and how. It is a question of integrity, as well as of the reputation of science itself, already fairly battered in the United States.
No offense taken (at the least, not by me), but it does seem a strange position you are depicting. So we (meaning society at large) give millions, no, billions of dollars to the fundamental physics community, and the inner circle of such community cannot be bothered to engage competent outside critics in a public arena? But I’m a bit more optimistic, actually. Greene has engaged his critics, and as a matter of fact has retreated significantly from his boisterous attitude of a few years ago. Indeed, I get the impression that the entire string theory community is very much on the defensive these days, and that more and more young people are jumping ship looking for something else to do, something that yields actual (empirical) results. So the criticism, internal and external, is actually doing its job.
I agree. I had stated that in my original exposition (last thread) but forgot to include it in my summary to labnut. The evidence for D holds only if we can not otherwise account for A, B and C.
Yes, I agree. Two points: I don’t regard inflation as proven, but I do think there is good empirical evidence for it (my argument is that inflation and an eternal-inflation multiverse are sensible and scientific concepts, but I don’t regard them as proven). Second point, science is always the best we can do, rather than giving absolute truth. Given that, I do think that my basic argument above about falsification is sound and that indeed it is a necessary part of the scientific method. One can never directly verify things in a model-independent way.
Peter– These are all very thoughtful comments, and I agree with a lot of it.
I’m a little concerned with a few things. You write, for example: “The public deserves a more honest account of what is going on than they’re getting, and people in the field seem to need to be reminded of what is solid and what is flimsy conjecture.” Are you sure about this? I know there are some people in the field (often the loudest people) who seem to confuse what is solid and what is flimsy, but most of the people I encounter will gladly tell you the difference if you ask them. Nobody in the field thinks string theory or supersymmetry or brane worlds etc. are on the same footing as W and Z bosons, or, since 2012, the Higgs, for example. Just because a lot of effort is being spent on these speculative ideas doesn’t mean that most people working on them think they’re as solid as Standard Model physics. As I said, there are other reasons people work on this stuff, in part because people hope one day that they might become solid and experimentally verified or because they might spin off such ideas.
Supersymmetry is a great case in point. It is true that there are many possible SUSY models. But if the LHC switches back on at higher energy and starts seeing superpartners, SUSY will go from speculation to experimental science. Would criticisms today of SUSY as unscientific then retroactively be incorrect? If SUSY changes from bad science that people shouldn’t be spending their time on to good, real science if it is detected experimentally, then was it really bad science to begin with? (The same goes for if we found missing energy that was consistent with extra-dimensional models, or if, heaven be kind, we see a giant stretched string fossilized on the CMB that got blown up during inflation. Why would people be studying such possible experimental signatures if they didn’t think experimental verification were important?)
One reason for working on SUSY, string theory, holography/AdS/CFT, etc., that I didn’t mention, other than consistent theory-generation, is that some of these ideas have provided powerful tools for analyzing good old quantum field theory and general relativity, which many critics say would be a good way to spend one’s time. As everyone knows, QFT, in particular, is a very, very hard subject, and there are precious few calculations that can be done to learn what’s going on even at a qualitative level. If you think that more time needs to be spent trying to understand QFTs like the Standard Model, or general relativity, then a lot of people who use SUSY or string theory or conformal field theory or holography/AdS/CFT would fully agree with you, because that’s part of the work they’re doing. (Some examples are the work being done on strongly coupled gauge theories or condensed-matter systems using holography, or N=2 SYM to understand confinement better, or work on scattering amplitudes, or holographic methods to study rapidly spinning Kerr black holes in our plain old 3+1 dimensional universe.) People are attracted to these techniques because there are very few techniques that work, and, again, this is hard to get across sometimes to people who don’t use these sorts of techniques.
Another thing about new ideas: If someone does come up with something new that is both consistent with all the many constraints and can connect better with experiment — and a lot of people even doing string theory are trying this all the time — then the community will absolutely take notice. When AdS/CFT was proposed, and seemed to provide a nonperturbative definition of quantum gravity in asymptotically AdS spacetimes in terms of a 3+1 dimensional quantum field theory, people noticed and a lot of people began working on these sorts of ideas pretty much full time.
So, again, I don’t think the problem is fads or a regime of tenured faculty, because people would switch (and have switched) to new ideas if those ideas could be found and actually navigated all the constraints. And starting with a blank sheet of paper has never, ever worked. As Coel points out, “I think you’re underestimating ns’s comments about the difficulties of starting with a blank sheet of paper and the likelihood of getting anywhere given the vast array of physics that the novel idea needs to be compatible with. Most string theorists do indeed spend a lot of time thinking about other alternatives also. If they could see promising avenues they would take them. And grant-awarding bodies would want to support them.”
The real trouble with (high-energy) physics is points (1) (lack of experimental data) and (2) (minefield of constraints) that I’ve made before. Solving these problems will take miracles from the LHC or from the CMB or some other experiment, or the good fortune of stumbling on a new idea in an already very mature field that is riddled with roadblocks. Telling people to drop everything and start from scratch with a blank piece of paper is a career ender, not because it would mean going against a fad or would upset old professors, but because in physics it’s a recipe for making no progress at all.
The area on which I (and many others in the high-energy community) would partially agree with many critics and partially disagree with Coel is about the multiverse. There are still a lot of people both big and small in the field, both string theorists and not, who either think the multiverse is bad science (one can always solve any problem by proposing a multiverse, just like one can solve any problem by citing divine intervention, and the multiverse, unlike string theory, is so vague that it has never had to navigate the minefield of constraints), or who accept it as a possibility only very unwillingly because it’s a generic prediction of most models of inflation and because of Weinberg’s successful prediction of the value of the cosmological constant. There is not the sort of excitement around the multiverse that there was earlier on with string theory, for example. The otherwise-amazing new movie “Particle Fever,” which painted a marvelous picture of the experimental side of high-energy physics (many of whom wanted to see superpartners, by the way!), really offended a lot of people I know in high-energy theory because all the theorists in the film were saying repeatedly and quite definitively that it’s “either” SUSY (if the Higgs is light) or the multiverse (if the Higgs is heavy). That’s it! SUSY or multiverse! I was pleased that everyone I’ve spoken to in the high-energy theory community found that patently ridiculous, and it’s a shame that it gave the public that erroneous impression.
Again, I agree that some people in the community are saying things that are unacceptable, but, again, that’s not the source of the basic troubles that face the field today.
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That comment may explain some of the difference in opinion, since on this side of the Atlantic we don’t have the anti-science “religious right” of the US (at least, not nearly to the same extent). The public here seem pretty ok with reading about speculative cutting-edge science and I don’t see that as a problem.
I can see why things like creationism and climate-change are contentious, but I’m unclear on why string theory would be a political issue. In the UK the reputation of particle physics is currently pretty high, owing to Higgs and Brian Cox, and there isn’t really a popular issue over string theory.
I apologize for missing your earlier post.
You write: “No offense taken (at the least, not by me)…” I appreciate that, because I assure you that none was ever meant!
Then: “…but it does seem a strange position you are depicting. So we (meaning society at large) give millions, no, billions of dollars to the fundamental physics community, and the inner circle of such community cannot be bothered to engage competent outside critics in a public arena?”
I think it’s important to be careful not to conflate the two sides of high energy here. The experimental side is the one getting “billions of dollars,” and there is wide agreement that they are doing real science. The LHC has won well-deserved plaudits from all sides. What they have built is truly a testament to the powers of the human spirit and ingenuity.
The main focus of critics is on the theorists, but theory funding is a totally different ball game. I don’t know as well how things work in other fields like, say, biology or chemistry, but in theoretical physics, most grad students, for example, do not have consistent funding at all, and the population of theorists is much smaller than the population of experimentalists. And a lot of the funding that does exist comes from foundations and private sources. This isn’t to say that less money from taxpayers means that criticism from the outside is less legitimate, but one cannot point to billions of taxpayer dollars as something that high-energy theorists somehow need to answer for.
But, hey, give them billions of dollars, and I can assure you people in the high-energy theory community would be happy to engage in more criticism!
You also write: “Indeed, I get the impression that the entire string theory community is very much on the defensive these days, and that more and more young people are jumping ship looking for something else to do, something that yields actual (empirical) results. So the criticism, internal and external, is actually doing its job.” There are a lot of assumptions here.
First, it is true that string theory is less exciting nowadays, but if you talk to lots of people deep on the inside, many of whom don’t pay much attention to non-specialist critics, it’s precisely because of the lack of contact with experiment and the long period of time that has gone by without major progress. That’s how things are supposed to work in science! There is no hard evidence that it’s because *external* criticism “is actually doing its job.” But we can be scientific about this — I’d be happy to see some sort of good data that I’m incorrect.
Second, as to your suggestion that “more and more young people are jumping ship looking for something else to do,” that’s both true and false. It’s false in the sense that the supply of young people trying to get into string theory, supersymmetry, etc. is just as high as ever, at least if PhD admissions data are to be believed. But it’s true in the sense that there are fewer job openings for them, and lots more are leaving for finance. (There are some who might wonder if society would be better served if they stayed in string theory.)
What doesn’t appear to be the case is that any significant number of them are leaving these areas of high-energy theory and heading into other areas of physics, which is presumably what many external critics are hoping for.
Coel, you may be underestimating the anti-science crowd in Europe (think anti-GMO, low levels of acceptance of the idea of climate change, etc.). Moreover, I think a scientist who engages in public intellectualism has an ethical duty to explain things clearly and honestly regardless of where he happens to live on the planet.
ns, quickly: it was actually Brian Greene who admitted during his debate with Jim that string theory is loosing bright students and young practitioners, but of course I don’t know the numbers.
Yes, there is a deep, pervasive and increasing distrust/fear of any evidence-based knowledge (“science”) which challenges existing power structures and cultural norms and beliefs in the US. All good “science” challenges existing beliefs and myths, of course.
This has increased as reactionary forces/money now control all public dialogs and media. ANY mention of “science” is now readily attacked, including in Congress, where the goal is to silence knowledge exchange. And it has worked – climate denial, vaccines, anti-evolution, etc.
In addition, 80% of Americans believe: Satan is a living being and in ghosts, guardian angels. miracles and that the government is hiding evidence of alien visitations.
Thank you for taking the time to reply. I suppose I’m not getting any interest in my original observation about time, or in asking how there remains a constant speed of light against which to measure the very expansion of space, so raising current headlines about divergences between theories and observation, especially when the conversation has been largely about problem in HEP, rather than cosmology, seems a futile effort.
I would say though, that “hard evidence” and its interpretation are two different things. As you say to gfrellis, inflation is an observation driven theory. To which I would point out, so was epicycles, since we very clearly observe the sun moving overhead. As such, it is a patch between what we think and what we observe.
I don’t think that the UK has the anti-science attitude of the US. On GMOs, most of the public accept the science but are dubious about the risk/benefit equation. On climate change, most in the UK accept the science but are fatalistic about what can be done about it. Overall, promotion of cutting-edge physics (even when gee-whizz speculative) is very much on the plus side for the public standing of science.
thanks, you have clarified that nicely.
For Coel’s benefit I want to make an additional point.
Verification of the Higgs boson field always lain within the domain of the observable. We believed it was possible to observe it and so were ready to spend a great deal of treasure on the search. So when people wrote about it they did so in a responsible way, keenly aware of the possibility of being shown to be wrong.
Verification of the multiverse does not lie within the domain of the observable. This makes it a safe domain for elaborate and fanciful speculation. After all, no one can show you to be wrong. But does this mean it is responsible to speculate? It is the essential spirit of science to make careful claims capable of being verified. When we do not do this we enable others in the counter-knowledge movement to do the same. If we, in science, can make elaborate, fanciful claims that defy validation then why should the counter-knowledge movement not do the same? How can we dismantle their arguments when we are just as guilty?
It is no use saying that Hawkings, Greene, Vilenkin and others qualify their claims in the small print. They have very publicly lent their name to the concept and that automatically creates the implication that it is well founded. The kindest thing I can say about them is that they are guilty of a grave deception. They have betrayed the spirit of science which has guided science for the last 400 years.
I really think it ought to be possible to point out the problems you see with the status quo without making accusations like that. I have no major problem with Jim, but I think you should perhaps moderate your tone a little.
“I don’t think that the UK has the anti-science attitude of the US.”
Then you should read Damian Thompson’s book Counterknowledge(http://amzn.to/1n7KATU). The problem is much bigger than ‘anti-science’ and is far more pervasive than you seem to understand. I earnestly urge you to read this book so that you understand why we should not feed this dangerous counterknowledge movement by indulging in unfounded speculation.
By the way, have you read Jim Baggott’s book? I asked this in an earlier comment and got no reply. If you want to seriously engage with his ideas you should read his book, otherwise your objections will be ill informed. It really is worth reading.
“(even when gee-whizz speculative) is very much on the plus side for the public standing of science”
No it is not, it is very damaging. To understand why you should read the final chapter of Damian Thompson’s book, Counterknowledge, where he make a profound analysis of what is going wrong.
“I really think it ought to be possible to point out the problems you see with the status quo without making accusations like that. I have no major problem with Jim, but I think you should perhaps moderate your tone a little.”
The fact that you can call beliefs about the multiverse the ‘status quo‘ illustrates just how serious the problem is, and that demands strong words.
Let me remind you what Peter Woit said:
“Then there’s the “multiverse”, which I think is just a major intellectual scandal and looming disaster threatening the subject and its credibility with the public. ”
Those are strong words and they come from a major expert in the field. Therefore we should pay close attention.
I stand by my words and see no need to moderate them. Major scientific figures have published substantial books about a subject that is unproven and in all probability will never be proven. They have created a clear implication which is false. That was an irresponsible act and it should be strongly criticised. Prominent figures have a correspondingly greater duty than you or I to act responsibly.
Coel, I think you may be underestimating the problem, especially in the UK. Newspaper articles and surveys I’ve read over the last few months put acceptance of climate change, for instance, at almost US levels (not a good thing). As for GMO, not accepting that the science pretty clearly says there are little or no health risks is, well, not accepting the science! (On a side note, I’m critical of GMO usage for other reasons, that have more to do with the politics of farming.)
Can you give actual documented examples of damage done by “promotion of cutting-edge physics (even when gee-whizz speculative)”?
My comment was specifically about the UK, but I’d be interested in examples from elsewhere also.
once again, my advice stands. Read Damian Thompsons’s book. And while you are about it you really should read Jim Baggott’s book. Naturally, you should augment that reading, as Massimo advises, with the books by Lee Smolin and Peter Woit.
Coel, when you ask about “documented” damage, do you actually want empirical studies to prove the point? If so, it seems to me you are raising the bar a bit too high for a discussion in a forum like this one. The hinted damage is at the credibility of the scientific enterprise: “oh, those scientists, one day it’s multiverse, another it’s climate change. They really can’t be trusted with solid truths.” There certainly are plenty of examples of this sort of attitude in the media and the public at large. How widespread it is and how damaging (in terms of what? Money? Reputation?) it is remains an open empirical question. Got any student who would like to pursue it as a PhD project?
to add to what Massimo says(much more clearly than I could!).
Naomi Oreskes, in her book, Merchants of Doubt, makes the strong point that certain industries manipulate compliant scientists to advocate alternative narratives. They then publicise these alternative narratives widely. The intent is to create doubt in the public’s mind and thus delay, minimise or prevent adverse legislation. This is damaging in its own right. But there is a knock on effect where the image of science itself suffers. When prominent figures in science start to lend their names to dubious hypotheses they tend to weaken the image of science still further. This plays right into the hands of the merchants of doubt. And that causes very real damage.
You asked for references and I have given you two substantial references, Counterknowledge and Merchants of Doubt.
Yes, examples of that sort of comment in mainstream or semi-mainstream media would answer my question. From the perspective of the UK (which I made my comment about), I don’t recognise that sort of comment about *physics*.
Climate change, yes. Medical stuff (e.g. whether wine is beneficial) , yes. GMO, yes. Autism/vaccinations, yes, though largely died out now.
But physics, or specifically string theory, the multiverse, Hawking’s books, any of that stuff, well, no, I’m not aware of anything such. If you mention any of this stuff in the UK these days they think Higgs, LHC, British Nobel Prize, and Brian Cox, all of which they generally regard positively.
That’s in the UK. If this is a negative issue in the US then that’s interesting.
I see the issue. I wasn’t saying that people in the UK (or the US) see fundamental physics the way they see climate science. I was saying that enough damage has been done/suffered to/by science in general that we don’t need to add more sloppy sensationalism in yet another scientific field to the mix. And there is the (separate) question of the ethics of public intellectualism, regardless of consequences.
You’re entirely right about some industries. Those related to medical science (drugs), the food industry (sugar in food etc), and smoking, are all examples. All of these have immediate implications for the public.
I’m not sure that theoretical physics is at all in the same boat, simply because none of this has actual consequences for society.
By the way, I wouldn’t trust Damien Thompson an inch given various other stuff of his that I’ve read, and it’s highly ironic that he talks about a “pandemic of credulous thinking” given his strong Catholic beliefs.
“By the way, I wouldn’t trust Damien Thompson an inch … it’s highly ironic that he talks about a “pandemic of credulous thinking” given his strong Catholic beliefs.”
To smear somebody because they hold religious beliefs is a very poor tactic. It is nothing but blatant prejudice in an age when we should be discarding prejudices. His arguments should be examined on their own merit and nothing else. I am truly surprised that you should prejudge him in this way. As a matter of fact he never once brings his religious beliefs into the book, but you will never know that since you have prejudged him.
I am a devout Catholic. If that makes my arguments untrustworthy then I invite you to stop interacting with me.
Guys, I’d say keep religion out of it. Speaking of which, signing off to see the World Cup opener…
As my comment stated, I had read other things by Thompson, and that is how I formed my opinion of him.
The comment about his religious beliefs was about the irony of him excusing them from being part of the “pandemic of credulous thinking”, which he does in his book.
Anyhow, his book is a run though of all the usual pseudoscientific stuff, which is worthy but not all that novel.
I had guessed! By the way, are you objecting to scientists discussing speculative stuff in public at all, or are you just complaining that the disclaimers labelling it as speculative are not prominent enough?
What an interesting discussion! I’ve missed the opportunity to participate ‘live’ because I’ve been working with a client in London all day, but then perhaps there are some advantages in postponing a contribution…
ns12345 – you’re clearly very passionate about this and I totally respect your position.
So, let’s try to bring this discussion to a close.
The simple truth is, I’m a symptom, I’m not the cause. You can attempt to undermine my arguments by claiming that I don’t what I’m talking about (and – honestly – I don’t mind). I confess I don’t have the time or the inclination to compute a one-loop scattering amplitude, but this is not really the point, I think. It’s naïve to suggest that only those who have experienced the trials and tribulations of theoretical physics’ front line can be sufficiently qualified to judge its merits.
Here’s what you should be really worried about. That a science writer supposedly unqualified to hold an opinion about these things can be invited by high-profile private foundations to participate in a discussion on this subject. Read the runes, here. These are foundations that are involved in supporting a lot of contemporary theoretical physics. It’s only right that they should seek to clarify the scientific basis of the work they’re funding, and promoting healthy debates in this area is right and proper.
You say that lowering ambitions isn’t going to work. Maybe. But if the string theory community can’t come together and find a research programme that enables somebody to predict *something*, then I can tell you that patience will eventually run out (I just can’t tell you when). I sincerely don’t think this needs to be a prediction related to ‘new physics’, involving energy regimes that are in any case likely to be forever out of reach of terrestrial colliders. And I’d avoid predicting subtle manifestations of string physics in the CMB as these may be really hard to prove, given the inevitable assumptions and approximations required to implement current (accepted) theories.
If you’re convinced that nature is essentially ‘stringy’, then a prediction of an already known physical property, of a kind that yields genuine insights into the nature of this stringy reality, will be more than enough. We might gain no new empirical knowledge, but such a prediction would nonetheless be regarded as progressive if it promises the prospect of a deeper understanding of reality that *could* lead eventually to new physics.
Remember that when Feynman first published his ‘sum-over-histories’ approach to quantum mechanics, this was dismissed as just another mathematical structure that offered nothing that couldn’t already be predicted by existing structures. But the simple truth was that Feynman’s approach offered a whole new way of understanding quantum processes that yielded genuine, progressive, advances.
Of course, if the answer is as Peter has outlined in his responses to MathPhysPhd, above, and it remains all to difficult to provide predictions without putting in more information than you get out, then I fear the problem is real and we rest our case.
“The comment about his religious beliefs”
this is plainly irrelevant and you had no business dragging it into the conversation.
“all the usual pseudoscientific stuff, which is worthy but not all that novel.”
Usual or not, novel or not, that is simply beside the point. What is important is that he documents a dangerous process that is infecting society. He does it in a clear, insightful way and you should carefully consider its implications.
If you read the final chapter and understood his thesis about the underlying cause you would see that it is far from usual.In fact it is a very insightful explanation that we should be carefully considering.
Massimo has explained the issue clearly. What he has said is transparently obvious and I have no more to add to that.
The author’s credulous thinking is relevant to a book about a “pandemic of credulous thinking”.
So what is his thesis? And, is this sort of pseudoscience actually getting worse, or is it much as it always has been?
“The author’s credulous thinking is relevant to a book about a “pandemic of credulous thinking”.”
A book should considered on its own merits. If you refuse to consider a book on its own, intrinsic merits then you are giving away to blatant prejudice.
That is your choice but if you give way to prejudice you won’t see much of the world besides a narrow, blinkered view.
Yes, the counter-knowledge movement is getting worse. But don’t take my word for it, read the book.
Guys, I think this needs to be toned down a bit, or I’ll start filtering stuff… Cheers!
Jim– I appreciate your note and your engagement on this.
You write: “The simple truth is, I’m a symptom, I’m not the cause.” I assume by this that you mean that your writing and public involvement on these issues is not the cause of the underlying troubles with high-energy theory these days, but is simply a reflection of problems that are present. On this, and with full respect, I agree.
I think our disagreement is more about identifying the source of those problems. There’s a tremendous amount of public blaming being placed on the physicists themselves here, in part because a small number of prominent individuals have been saying irresponsible things in public. High-energy theorists are being condemned in some quarters not just for ruining physics, but for debasing science as a whole.
What I have argued here is that while there are serious challenges confronting the field, the problems aren’t primarily due to bad behavior or hyping by certain personalities, but due to deeper and less flashy problems with experimental progress and with the calcification of the subject by its sheer maturity, manifested in the dense snarl of constraints that (correctly) doom the vast majority of attempts to find genuinely new directions. (Some of these problems are growing issues for the scientific enterprise as a whole, and I believe they are deeply connected with the gradual disappearance of low-hanging fruit.)
And I think it’s absolutely crucial to make clear what the primary source of the trouble is, because if the source is identified incorrectly, then people will go after the wrong solutions that will only alienate members of the community who are dealing with these problems head on.
This is the reason I keep pointing to the issue of expertise. It’s not simply to discredit critics. It’s because the lack of expertise and inside knowledge by many critics is the reason why so much of the criticism these days misses the mark and alienates rather than helps. It’s because when I read so much of the criticism, what I and many others see is a failure to understand the field well enough to pinpoint and help deal with the real problems facing it.
I said critics had to know what a 1-loop amplitude calculation looks like — or, better, how ideas like supersymmetry and string theory are technically motivated, or what is actually involved in trying to create a new direction that navigates all the constraints — not simply because they need credibility or are otherwise unqualified, but because without that knowledge, they’re unlikely to be able to see up close what the real problems are and give helpful advice. And given a lot of the criticism I hear, that’s a well-founded judgment. Criticism would be better and more helpful if it were coming from people who better understood the challenges of the field today — and, indeed, there is a lot of internal criticism of just this sort by practitioners. But criticism is not the same thing as constructive suggestions, which are in short supply precisely because the challenges facing the field are very, very hard to overcome.
I hope I’m correct in thinking that everyone involved here wants what’s best for science. So why should so many high-energy theorists despise what all these “well-meaning” critics are doing? If the advice is intended to be helpful, why would the practitioners ignore it and even get angry about it?
Because it’s not enough to be well-meaning. Criticism and advice has to be well-informed and reflective of the actual problems on the ground and furthermore be constructive, and instead a lot of the criticism amounts to public character attacks on the people doing the actual work and on the value of the work itself, or calls for practitioners to halt their work and “do something better,” whatever that is. For me, the difference between reading a lot of this criticism before joining the community and seeing what things were actually like inside was like night and day.
You write: “You say that lowering ambitions isn’t going to work. Maybe. But if the string theory community can’t come together and find a research programme that enables somebody to predict *something*, then I can tell you that patience will eventually run out (I just can’t tell you when).”
I should begin by saying that there is no unified string community. People have always worked on lots of different things (including non-stringy physics — I can tell you from personal knowledge that “even” string theorists are hard at work trying to improve our understanding of “mainstream” questions in quantum field theory), precisely because there is no overarching cabal. One hope is that working on many directions simultaneously will be more likely to make progress, but the truth is that people just have different interests, and interests are what make people into scientists in the first place.
As for the “patience” question, whose patience are we talking about here? The people funding the research? That’s certainly a problem, but, again, it doesn’t suggest an obvious solution. It’s all well and good to point out that funding will dry up unless the impasse facing high-energy theory is overcome — this is an ongoing concern among people in the field — but how precisely does one bell the cat? That’s the whole question here. It’s a very hard problem.
You suggest that a more reasonable ambition would be just to try to use string theory to explain something new about physics in regimes we already know about. Well, string theory (and ideas like supersymmetry) have taught us a great deal about quantum field theories that would have been difficult to guess otherwise. And although AdS/QCD isn’t string theory in its original quantum-gravity sense, it has provided calculational tools for studying and making predictions about various properties like viscosities. There have also been advanced in computing scattering amplitudes in collider calculations.
Is that close enough to Feynman’s sum-over-paths formulation being helpful for better understanding quantum theory? The trouble is that quantum gravity is associated with the Planck scale, which is so far removed from everyday experience that the first quantum corrections to gravity in the solar system are 10^-70 effects. (A fun exercise: Compute the “Bohr level” of the Earth moving in the Sun’s 1/r Coulomb-like potential. The number is mind-blowing.) So unless there’s a miracle, like amplified quantum-gravity effects in the CMB, seeing a signature is going to be very, very hard, regardless of which model of quantum gravity one is using. Again, this is Nature’s fault, not the fault of physicists.
You conclude by writing “I fear the problem is real and we rest our case.” I agree with the first part of this sentence but not the second part. I’ve never argued that there weren’t real problems. What I’ve argued is that the case often being made by many critics is the wrong one, and hasn’t been very helpful to anyone. It is in everyone’s best interest that the case be improved.
In particular, it would be helpful if this whole discussion changed from its current confrontational posture (“Not even wrong!!!”) in favor of a more cooperative one.
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” It’s because the lack of expertise and inside knowledge by many critics is the reason why so much of the criticism these days misses the mark and alienates rather than helps. It’s because when I read so much of the criticism, what I and many others see is a failure to understand the field well enough to pinpoint and help deal with the real problems facing it.”
What is your actual, specific, scientific proof that no one outside the field can possibly offer any useful criticism?
For those of us who are not completely brainless and do have to function in that pedestrian everyday world, there are two ways to address a problem; One is to step forward and examine it in detail and identify where the gaps are and how best to fill them. The other is to step back and try to put the issue in some larger context to see if some big picture factor is being overlooked.
Physicists are the epitome of the first method, but not to put it too bluntly, really suck at the second method, as this is mere philosophy to the shut up and calculate crowd and will invariably step on some sacred/no go territory.
Why is that? For those of us who don’t have the time to examine every infinitely small detail and can’t spend our lives focused on a particular detail of the very small, very large, or very abstract, there is a lot of fuzzy math inherent in understanding the big picture. The connections matter more than the details. There really is no clear line where the chicken ends and the fox begins. It is all entangled. From the top down, it’s all about the network and the nodes are dispensable, as you are likely all too aware, from your own personal life and as we all know, those in management suck at understanding all the details.
Now most any twelve year old science geek probably finds the idea of multiple universes and all those extra dimensions really cool, as they play video games based on some alternate reality. Yet your average forty five year old CPA understands all too well what can be done with the math, when, like any good magician, you get everyone hyper-focused on favored details and completely ignore the others. They can readily understand what people like Greene and Tegmark are selling, but in the grand scheme of things, where large numbers of peoples lives are being shredded, it really is small potatoes.
So while you might be really, really clever, you are still looking at only one side of a fundamentally dualistic reality. For example, further up this thread, I raised the point that time is better understood as the process by which future becomes past, rather than a measure from prior events to succeeding ones. To give a basic analogy of this duality, consider a product and production line; The product goes from initiation to completion, while the process, the production line, points the other direction, as it consumes raw material and expels finished product. So the product, going start to finish, goes from beginning to end, while the process points to the future as it creates and expels these units, which fall away into the past.
Now cosmology has modeled the entire universe as only one side of this relationship, that of the universe as a single entity, forming and fading, because it models time as nothing more than that narrative arc, from beginning to end.
Now you are likely to ignore this, as it doesn’t fall within your particular model, but I can safely say that at the end of your model, “The physics breaks down.” And you are never going to quite understand why.
Sorry, but physicists see this sort of thing as well as or better than anyone. It is complete conceit that physicists are limited in this way and that others are much better at it.
It’s not that others are better at it. We all have our biases and points of view. It is just that groups of people can create negative feedback loops as easily as they create positive feedback loops and so re-enforce assumptions.
If you really want to refute my argument, why not directly dispute my point about time, that physics has simply reduced the narrative function to particular measures of duration, because of the past to future sequencing of individual perspective is fundamental to the thought process, rather than actually considering how the dynamic of changing configuration creates this effect and that measures of time are basically distinct frequencies. Making time an effect of action, like temperature, not some dimensional basis for it.
Yes, spacetime is clever geometry, but we could use ideal gas laws to relate volume to temperature, but we don’t, because we understand temperature is an emergent effect of a multitude of amplitudes.
I know its a little late to put this in, but I think the following question is the key:
* What potential experimental or observational evidence is there that would persuade you that the theory you are proposing is wrong?
If there is none, then in my view it is not a scientific theory, it’s philosophy – and of course there is nothing wrong with philosophy! – it just should not be confused with science..
If there is such evidence, please clarify what it is, and we’ll be on our way to look for it. You’ll have made clear what makes the multiverse science – provided you will indeed give up the theory if the evidence comes out negative! That will be the test of devotion to real science, as opposed to hanging on to a dogma.
By the way this has been an excellent discussion, thanks for hosting it, Massimo.
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