The firestorm ignited by Ijjas, Loeb & Steinhardt’s blog post in Scientific American, is very much worth your time reading. It engages Peter Woit’s string-theory criticism on his blog. But the scientists do not divide into sides very rationally, as Woit notices, “This is getting very weird. It’s not normal to respond to a scientific argument by enlisting letter writers on your behalf, even less normal to put your university press office to work on a response..”
Abraham Loeb is a cosmologist age 55 at Harvard who came from a Jewish farming community in Israel. He is known for creativity and writing on many sides of an issue. Paul Steinhardt is a theoretical physicist and cosmologist age 65 at Princeton, whose early 1980’s papers laid the foundations of inflationary cosmology (along with Linde and Guth) but in 2002 concluded it couldn’t work. Anna Ijjas is ~30 post-doc at Princeton, with most of her publications in this decade. She describes herself as a “theoretical cosmologist” and “actively participating in the dialogue with Philosophy and the Humanities” who wrote an “award-winning thesis at Munich University, studying philosophical implications of quantum physics.”
It would seem that these critics, for all different reasons, have abandoned “inflationary cosmology”, finding the results of recent theory to be very disquieting. Ijjas doesn’t explain her antipathy, which may simply arise from working for Steinhardt, but is no doubt motivated by her thesis in the philosophical implications of QM. Loeb is not shy about proposing outlandish hypotheses, so his dislike of inflation likely comes from his Jewish upbringing and belief in a rational universe. But it is Steinhardt who is the most puzzling of the dissidents.
Not only did Steinhardt start the theory that he later abandoned, but he has also championed equally questionable theories of dark energy, “eternal inflation,” an eternally “bouncing big bang,” and “self-interacting dark matter” (e.g. dark sector). From this, one would have thought that Steinhardt is not the least bit shy of changing the laws of physics to accommodate observations. Why then does he suddenly criticize his colleagues for holding to an “unfalsifiable” theory?
Steinhardt’s objections to inflation is explained in a PBS blog and summarized in his Wiki page:
“Based on observations from the Planck satellite (reported in 2013) Anna Ijjas, Abraham Loeb and Steinhardt showed in a widely discussed pair of papers that the inflationary model was much less likely to explain our universe than previously thought. According to their analysis, the chances of obtaining a universe matching the observations after a period of inflation is less than one in a googolplex. Steinhardt and his team dubbed this result the “unlikeliness problem.”
The two papers also showed that the remaining inflationary models require more parameters, more fine-tuning of those parameters, and more unlikely initial conditions than the simplest models. As a result, the startling conclusion was that Steinhardt and his colleagues had essentially shown that, by the standards of normal scientific reasoning, the inflationary theory is unlikely to be correct based on the observations.”
In short, the whole purpose of the inflationary theory is negated by its development. It was invented to explain the 1:10^66 fine-tuning of the Big Bang, but in the end, it required 1:10^10^100 fine-tuning. (The first number has 66 zeroes after it, the second number has a hundred, trillion, trillion, trillion, trillion, trillion, trillion, trillion, trillion zeroes after it.) Steinhardt pleads ignorance as to why he advocated the theory in the first place. At the time it looked like it had just one or two zeroes after the probability, but research added a few more until the theory just wasn’t justified any more.
So the real question becomes, why do 33 famous physicists included Nobel prize-winners, still like the theory and think Steinhardt has lost his marbles? They wrote a blog in Scientific American to list their rebuttal to Ijjas, Loeb and Steinhardt (IL&S) Here’s the summary:
D1. 14,000 papers by 9,000 scientists w/ “inflation” in their title or abstract.
D2. If “inflation” is outside scientific method, then all this work is wasted and wasteful.
D3. Inflation is testable, and has passed all tests (see #6 below)
D4. Inflation is a family of models, only one has to be correct–just like “Standard Model”
D5. Some models (sub-families) are excluded, but many remain empirically successful.
D6. Particular predictions of the model have been confirmed:
. a) Flatness
. b) perturbations are adiabatic: matter, radiation & dark matter
. c) perturbations are Gaussian
. d) CMB polarization shows E-modes (and B-modes)
D7. Testable can have fitting parameters–the standard model does.
D8. Even with fitting parameters, the models are still falsifiable.
D9. Even the standard model is tweaked when new data appear.
D10. Multiverse accusations are “guilt by association”, in no way diminishing the empirical bases of inflation.
D11. Inflation doesn’t have to explain everything to be useful.
D12. Progress on inflation continues, even empirically.
IL&S Rebuttal.
R1. Diachronic versus synchronic truth: “Confirmation” was claimed in the ignorant past, but could not be so claimed now.
R2. We can reject the current synthesis without discounting the value of published literature.
R3. The problem solved by inflation (fine tuning) turned out to be worse in the solution, i.e., metaphysical purpose is no longer valid.
R4. A parameterized model is not the same as an infinitely adjustable model, which is what inflation has become.
R5. Inflation models cannot be falsified.
Now what is peculiar about this debate, is the way both sides dance around two or three elephants in the living room while trying to execute pirouettes. For example, D1 & D12 are claims to social and historical relevance. R1 says that these claims equivocate since initially promising “confirmations” were later found to be wrong, so clinging to historical victories is irrelevant to the march of science. But is it? Is a theory’s “validity” not also a function of time and history? After all, isn’t that how progress is made, by a sequence of theories getting progressively better? Is IL&S saying that progress is irrelevant to truth, and better no theory at all than one that is 99% correct?
The elephant here is whether science is progressing or regressing, whether it is possible for 9000 scientists to all be wasting their time and other people’s money. Philosopher of science, Imre Lakatos, called this real possibility “a degenerate science program” and listed the criteria for detecting this situation. (Money, prestige, inertia, ad hoc solutions, etc.) Not surprisingly, inflationary cosmology fits the description. So why doesn’t IL&S mention this? Because many of Steinhardt’s other projects (bouncing big bang, dark matter interactions) also fit Lakatos’ description. Hence the elephant foxtrot.
It all seems rather dry and academic to put it that way. So let’s use the ad absurdum approach to this debate. Let’s look at some elephants, using extreme examples of “good science,” “pseudo-science,” and “degenerate science.” The dance here is to define our preferences as “good” and our opponents as “pseudo” or “degenerate”. Is the criteria proposed by 33 eminent scientists better than the criteria of IL&S?
The comparison that our Nobelists draw, is to the “Standard Model” (SM) of particle physics, in which we have 3 families of quarks and leptons (12 particles) plus neutral exchange bosons (5), for a grand total of 18 arbitrary masses needed to describe the building blocks of creation. In some ways it is very complete, but it does have these 18 adjustable parameters. So if we were to substitute “Standard Model” for “Inflation”, these 33 argue, there would be no discernible difference. D1-D11 is certainly applicable to SM, but much angst and spilled ink over the lack of progress with D12. What about R1? Doesn’t apply to SM but does apply to Inflation. R2 is certainly IL&S attitude toward dark matter self-interactions, which amounts to a rejection of SM as well as a rejection of D1. R3 agrees that the SM certainly simplified the assumptions down to 18 from the several hundred sub-atomic particles discovered, but then D4, D7, D9 are illegitimate comparisons for Inflation to make. R4 hammers home the difference between SM and inflation. And R5 is self-evidently true that if inflation incorporates an infinite number of independent solutions, then indeed, proving it wrong is logically impossible.
So it would seem that SM passes through unfazed by the rebuttal, while Inflation is stopped cold. But perhaps we have proved too much. Let’s look at an example of supposed pseudo-science. Replace the word “inflation” with the word “creationism”, and “Standard Model” with “Darwinism”. D1 lots of papers, check. D2 avoid waste. D3 its testable (according to its proponents). D4 there are certainly flavors. D5 seems true. D6 also. D7 check. D8 check. D9 check. D10 requires a mapping of “multiverse” to “miracles”, but otherwise is correct. D11 check. D12 check. So in this version of the debate, if inflationary cosmology models are okay, then so are creationist cosmology models! Surely this isn’t what our Nobelists were trying to prove, was it?
Now let’s see what this does to the rebuttal. R1 sounds a lot like Biologos. As does R2. And R3. R4 may not be a Biologos criticism, but many Panda’s Thumb argue this. And R5 seems to be bandied by everyone. So if IL&S have a valid complaint, then so does Biologos!
And that is what makes this such an interesting and relevant debate to the ID community.
Well, what do I think?
I think D6 overstates the evidence for inflation, and that IL&S are correct in their analysis of the empirical disconfirmation, making inflationary cosmology a seriously degenerate science program.
Which raises another question–how can 33 eminent scientists all be so wrong?
IL&S address this in a separate article: They claim that there has been a “bait-and-switch” involving Guth and Linde, so that 29 of the signatory scientists are simply gullible.
If true, what made them so gullible?
To me, this is the crux of the matter. If a scientist claims that his goal is to ferret out the truth from a “not malicious but subtle” Nature, then gullibility is as damning an epithet as “simpleton”. If we are ready to believe other people over our innate objections, over empirical observations, then we have no business being in science, we should be in politics. I am not advocating being a loner, or a one-man university, but we must always test what we hear, continually evaluating our current understanding. If Andre Linde tells you in 1982 that inflation has only one free parameter, but then in 2002 tells you that inflation has a million free parameters, it might be time to re-evaluate his reliability. And if Alan Guth says that disagreeing with his most recent theory is as criminal as breaking the Internet, you might tag him not just unreliable but unhinged as well.
Why then are these 29 co-signers still so gullible? To restate Tolstoy, the truth is univocal, falsehood cacophonic. Some may be personal friends of Guth. Others may have their own version of inflationary cosmology that they fear is under attack. Still others may see advantage in joining arms with the establishment. As far as I can tell everyone is a theorist that you wouldn’t let in your lab (excepting Mather, Smoot and Weiss), and theorists really and truly have no skin in the game–they can as easily write a paper supporting inflation as attacking it–just as long as both papers get published. What they get irate about, is not being able to publish both papers.
Experimentalists have a different problem. They have to justify expensive equipment and years of paperless research for a teleological goal. They have no problem publishing null results–such as lower and lower thresholds for gravity waves or WIMPS–as long as the search can continue to be funded. To deny an effect is measurable, however, is an existential sin. The reason Mather, Smoot and Weiss have signed this document tells me that they are no longer worried about funding or managing the funding of an experimental group. They have moved up the administrative ladder sufficiently to stop being experimentalists. And this is true of Rees as well, whether or not he ever spent a long night in the observatory while becoming Royal Astronomer.
Then we can add a new item to Lakatos’ signs of a degenerate science program: when theorists and experimentalists deny the other a job.