Busted Bandwagon: The Sociology of BICEP2 Groupthink

It's finally official. Today the online version of the journal Nature (an authoritative source for scientists) has an article headlined “Gravitational Waves Discovery Now Officially Dead.”

In March 2014 the BICEP2 study was released, and it claimed to have found evidence for gravitational waves from the beginning of time. It was a result that would have confirmed the theory of cosmic inflation, a theory about what went on during the universe's first second. In March of that year, cosmologists around the world started crowing about how the discovery of the decade (or even the century) had been made. It was claimed that “smoking gun” evidence for the cosmic inflation theory had been found. For months many scientists and “household name” news sources described the inflated claims of the BICEP2 study as scientific fact.

But now the roof has caved in on this claimed breakthrough. Further analysis by the very large team of Planck scientists has found that the results of the BICEP2 team can plausibly be explained as being the result of ordinary dust and something called gravitational lensing, without imagining that the observations are caused by anything having to do with gravitational waves, the Big Bang, or cosmic inflation.

From the beginning there were lots of reason for suspecting that the BICEP2 study was on very shaky ground. The day after the study was released I released a very skeptical blog post entitled “BICEP2 Study Has Not Confirmed Cosmic Inflation,” pointing out some reasons for doubt. I followed this up in the next month with several other very skeptical blog posts on BICEP2. The reasons I discussed were out there in April 2014, but seemed to be ignored by most cosmologists at that time, who got busy writing lots of scientific papers about the implications of the supposedly historical BICEP2 study.

Now some cosmologists will point their fingers at the scientists of the BICEP2 team, and say, “Their error.” But the blame goes surprisingly wide and deep in this matter. We must also attach blame to the many other cosmologists who jumped the gun, and wrote scientific papers based on the BICEP2 claims, treating them as if they were all-but-proven. You can use this link to find the names of 125 scientific papers that have “BICEP2” in their titles. A great deal of these papers had titles such as “The Blah Blah Blah Theory in Light of BICEP2” or “Blah Blah Blah After BICEP2.” It seems that very many theoretical physicists took a good deal of time to write up papers discussing the profound implications of the BICEP2 study, the main results of which have now been declared “officially dead.”

How can we explain this embarrassing goof? It couldn't have been because our cosmologists are stupid. After all, they write these papers with lots of very hard math. Could it be this snafu occurred because no one warned them that the BICEP2 findings were preliminary, and needed to be confirmed by the Planck team? No, there were plenty of such warnings, and it was clear from the beginning the BICEP2 claims were in conflict with some of the Planck results.

In order to explain this gigantic goof, one needs to consider sociological factors. The group of scientists with one particular specialty is a small subculture subject to bandwagon effects, peer pressure, groupthink, group norms, group taboos, and other sociological influences. Given a proclamation by enough scientists within a field that a particular result is a “stunning breakthrough,” acceptance of that result becomes a group norm. Similarly, once a particular effect or result has been denounced by enough scientists within a field, then a taboo has been established, and rejection of that result becomes a group norm. Once a group norm or group taboo has been established in such a small subculture, it is rather like a buffalo stampede. Running with the herd is very easy, and running against the herd is very difficult. Every subculture imposes punishing sanctions on those within it who defy the group norms and group taboos. 

Peer pressure

For several months, acceptance of the BICEP2 claims was a group norm within the community of cosmologists, and so cosmologists fell in line, and followed the herd. A gigantic bandwagon effect was created. Using many dollars of taxpayers and universities, they wrote up lots of scientific papers that were based on the now-defunct group norm.

What lesson can we learn from this misadventure? One important lesson: make a judgment on the truth of something based on the facts and the evidence, not based merely on whether some consensus has been reached by a small subculture of scientists. That's because such a consensus may be heavily influenced by sociological factors and economic factors within the subculture: herd effects, groupthink, group norms, group taboos, bandwagon effects, and vested interests. Like politicians and judges, scientists like to imagine themselves as impartial judges of truth, judging only on the facts. But scientists are subject to sociological influences just like other people, influences that can decisively affect their pronouncements.

Let's Keep the Big Bang, but Dump the Cosmic Inflation Theory

The long-awaited dust analysis of the Planck team has finally arrived, and it's bad news for those who claimed last March that the BICEP2 study had produced evidence for cosmic inflation. Last March such people had claimed to have found a “smoking gun” that finally provided evidence for the theory of cosmic inflation: evidence of b-mode polarization caused by gravitational waves produced at the dawn of time. Subsequent studies suggested that the BICEP2 study was a false alarm, and that the results can be explained as being the result of ordinary dust. Now an analysis by a large team of scientists (using the Planck space satellite) shows that the “clean window” claimed by the BICEP2 team (a particular area of the sky where there's supposedly little dust) is more like a dirty window that has lots more dust than the BICEP2 team thought. It now looks like the “evidence for cosmic inflation” claimed by the BICEP2 study is no such evidence at all. The BICEP2 observations can be explained as being the products of dust and gravitational lensing, without any need for cosmic inflation. Yesterday Physics World summarized the situation with a story having the headline “BICEP2 gravitational wave results bites the dust thanks to new Planck data.”

This new Planck result will get a little coverage, but much less than the BICEP2 news coverage last March, when it seemed like almost every cosmologist was popping a champagne cork in premature self-congratulation. It was a huge orgy of unwarranted credulous enthusiasm over a study with quite a few problems, problems I pointed out in a very skeptical blog post the day after the BICEP2 study was released (at a time when I seemed like a rare doubter, with few others voicing similar doubts at that time). My skepticism about BICEP2 was apparently warranted. 
 
Given the new Planck result, it may be a good time to look at a basic question: should we actually believe in the theory of cosmic inflation? I will argue in this post that we should not.

The Difference Between the Big Bang Theory and the Cosmic Inflation Theory .

Before giving my case against the cosmic inflation theory, let me clarify the difference between the cosmic inflation theory and the Big Bang theory. No doubt many people get the two mixed up, because the concepts are fairly similar.

The Big Bang theory originated around the middle of the twentieth century. The Big Bang theory is the theory that about 13 billion years ago the universe originated from an extremely hot and dense state. It's basically the idea that the universe “exploded into existence” billions of years ago (or began to expand from a state so hot and dense that it was just as if the universe had exploded into existence). The theory was dramatically substantiated by the discovery of the cosmic background radiation around 1965, believed to be the “relic radiation” of the Big Bang. The Big Bang theory is also supported by the simple fact that the universe is expanding. When you “rewind the film” on an expanding universe all the way to the beginning, you are stuck with something like the Big Bang.

The cosmic inflation theory did not originate until about 1980. The cosmic inflation theory is actually a theory about a tiny fraction of the universe's first second. The theory maintains that when the universe was a fraction of a second old, the universe underwent exponential expansion, which is a type of expansion vastly quicker than the type of expansion we now observe. According to the cosmic inflation theory, this phase of super-fast exponential expansion lasted only a fraction of a second. The diagram below illustrates the cosmic inflation theory.

You can believe in the Big Bang theory without believing in the cosmic inflation theory, which is exactly what cosmologists generally did during the decade of the 1970's. However, you cannot believe in the cosmic inflation theory without believing in some form of the Big Bang theory.

The Reasons Many Cosmologists Believe in the Cosmic Inflation Theory .

The rationale given for believing in the cosmic inflation theory is that it supposedly solves some cosmic mysteries. The main such mystery is what is called the flatness problem. The flatness problem is a fine-tuning problem involving the Big Bang. According to cosmologists, when the universe began, it started to expand at just the right rate. If the universe had started to expand at a tiny bit faster rate, it would have expanded so quickly that galaxies would not have formed from gravitational contraction. If the universe had started to expand at a tiny bit slower rate, the gravitational attraction from the universe's matter would have caused the universe's matter to form into super-dense black holes rather than galaxies.

The physicist Paul Davies puts it this way:

For a given density of cosmic material, the universe has to explode from the creation event with a precisely defined degree of vigor to achieve its present structure. If the bang is too small, the cosmic material merely falls back again after a brief dispersal, and crunches itself to oblivion. On the other hand, if the bang is too big, the fragments get blasted completely apart at high speed, and soon become isolated, unable to clump together to form galaxies.

How finely balanced did this expansion rate have to be in order for there to be a universe like ours, in which galaxies exist? Scientists say that it had to be balanced to at least one part in 10 to the thirtieth power (1 part in 1,000,000,000,000,000,000,000,000,000,000). In other words, if the universe had expanded at a rate only .00000000000000000000000000000001 faster or slower, it would not have galaxies, and would not have life.

The calculation given here is not some oddball conclusion made by only one or two scientists.A statement like the statement above has been made in innumerable scientific books and papers.

The cosmic inflation theory was created mainly to solve this problem. It seems that if the universe underwent the exponential phase of expansion imagined by the cosmic inflation theory, the universe's expansion would not need to be so fine-tuned.

Another reason given for believing in the cosmic inflation theory is that it offers an answer for what is called the horizon problem, which is basically the problem of why opposite ends of the universe have identical thermodynamic attributes, as viewed in the cosmic background radiation.

A third reason given for believing in the cosmic inflation theory is that it solves some “missing monopole” problem, although this is not a compelling reason because the problem only arises for those who believe in some family of theories called grand unification theories (and there seems to be no particular necessity in believing in such a theory).

Why Cosmic Inflation is Not a Good Way of Explaining These Problems .

The theory of cosmic inflation offers a way of explaining the flatness problem and a way of explaining the horizon problem. But both of these problems are examples of more general phenomena. The flatness problem is an apparent case of cosmic fine-tuning, and the horizon problem is an example of cosmic uniformity. The weakness in trying to solve these problems with a theory of cosmic inflation is that we have many other apparent cases of cosmic fine-tuning and many other cases of astonishing cosmic uniformity – but the cosmic inflation theory only offers a solution to one of the many cases of cosmic fine-tuning, and only one of the many cases of cosmic uniformity.

Cases of apparent cosmic fine-tuning are discussed here and here (in a blog post that includes a handy color-coded chart). Among the many astonishing cases of cosmic fine-tuning are the flatness problem, the fine-tuning of the Higgs to 1 part in 100,000,000,000,000.000, the fine-tuning of the cosmological constant to 1 part in 10 to the sixtieth power (or 10 to the 120^th power, depending on how you look at it), the fine-tuning of the strong nuclear force, the fine tuning of atomic resonances, the fine-tuning of fundamental constants related to stellar nuclear reactions, and the fine-tuning of the proton charge and the electron charge (involving a match to one part in 1,000,000,000,000,000,000,000). There are also many similar cases. Now, how many of these cases of cosmic fine-tuning does the cosmic inflation theory claim to explain? Exactly one: the flatness problem. In this sense, the cosmic inflation theory is rather like a theory that tries to explain the origin of animal species, but only explains the origin of tigers rather than explaining the origin of the rest of the animals.

If we are to try to explain cosmic fine-tuning, we need a more general explanation – some particular principal or assumption that will explain all the cases (or most of the cases) of fine-tuning, rather than jumping on some “one-trick pony” that explains just one example of cosmic fine-tuning.

When we look at examples of cosmic uniformity, we find a very similar situation. There is not just one amazing case of cosmic uniformity (the horizon problem), but many others. Among the main cases of cosmic uniformity are the uniformity of fundamental constants in opposite regions of the universe. Scientists have determined that some fundamental constants such as the fine-structure constant are the same in opposite regions of the universe separated by a distance of more than twenty billion light-years (ten billion light-years in one direction, plus ten billion in another direction). This is particularly amazing because it is not just a uniformity over a vastness of space but also a uniformity over a vastness of time equal to almost the age of the universe. Other examples of cosmic uniformity are the uniformity of the universe's laws. The universe is like a vast machine that keeps on following the same set of rules (which we call the laws of nature), obeying those laws to the letter, with slavish obedience eon after eon.

If we were to list all of the cases of cosmic uniformity, it would be a long list. But how many on that list does the theory of cosmic inflation purport to explain? Exactly one: the horizon problem. Again, in this sense the cosmic inflation is like a theory of the origin of species that only explains the origin of tigers, without explaining the origin of any other species. If we are to start trying to explain cosmic uniformity, we need a more general explanation, rather than jumping on some “one-trick pony” that explains just one example of cosmic uniformity.

How the Cosmic Inflation Theory Robs Peter to Pay Paul .

The advocates of the cosmic inflation theory neglect to explain that as the price of explaining one example of cosmic fine-tuning (the flatness problem), the cosmic inflation theory requires its own fine-tuning, in not just one place, but multiple places. One has to imagine various types of fine-tuning to create a theory of cosmic inflation compatible with observations. You have to do fine-tuning so that the cosmic inflation can start at just the right instant, and more fine-tuning so that the cosmic inflation can end at just the right time (or else you end up with a universe that keeps inflating exponentially, which we know did not happen). It is not clear at all that when you add up all these types of fine-tuning needed for cosmic inflation to work, that you end up with less cosmic fine-tuning than if you don't believe in the theory. It's basically a case of robbing Peter to pay Paul.

The False Prediction of the Cosmic Inflation Theory

Before justifying my assertion that the cosmic inflation theory makes a false prediction, I must declare an interesting and important principle that is sometimes overlooked. This is the principle that we should never ignore the “gross predictions” of a theory, and never try to subtract counterfactual predictions, thereby judging a theory only on a set of “net predictions.”

Here is what some people think our procedure should be when evaluating a theory:

(1) Start with the “gross predictions” of a theory – everything it seems to predict, regardless of known facts.
(2) Subtract from these “gross predictions” anything known to be false.
(3) Then evaluate the theory on a smaller set of “net predictions.”

I think such an approach is badly mistaken. Rather than discarding “gross predictions” of a theory that are clearly counterfactual, we should in fact pay great attention to such predictions, because they are often very important indicators that the theory is false. It's rather like this: suppose a theory predicts that a factory makes only red phones, and you open a package from the factory, seeing a blue phone. What does the theory predict now? Exactly the same thing it predicted before you opened the package: that the factory makes only red phones.

So let's look at exactly what are the predictions are of the cosmic inflation theory, without discarding any counterfactual “gross predictions.” The predictions of the cosmic inflation theory are as follows:

(1) The universe is spatially flat, or very close to being spatially flat.
(2) There is a relatively small amount of what is known as cosmological non-Gaussianity.
(3) Our universe is a lifeless “small bubble” universe that is way too young and small for any galaxies to have formed in it.

The cosmic inflation theory actually makes the third of these predictions because it predicts that each universe that undergoes exponential expansion produces many other “bubble universes,” and that each of these bubble universes themselves produce many other bubble universes, and so on and so forth. According to the predictions of the theory, the number of these bubble universes too small to contain any galaxies (and any life) should be billions and trillions and quadrillions of times larger than the number of bubble universes large enough for galaxies to form. As cosmic inflation proponent Alan Guth describes here (in a discussion of this “youngness paradox”), “The population of pocket universes is therefore an incredibly youth-dominated society, in which the mature universes are vastly outnumbered by universes that have just barely begun to evolve.”

Given such a situation (in which small bubble universes vastly outnumber bubble universes large enough for galaxies to form), and given that predicting one thing is trillions of times more likely than another thing is equivalent to predicting the first thing, it must be said that the cosmic inflation theory predicts that our universe is one of those smaller, lifeless universes. It is not legitimate at all to subtract this counterfactual prediction because of some principle that we are allowed to subtract counterfactual predictions, reducing a set of “gross predictions” to a set of “net predictions.”

So how can an advocate of the cosmic inflation theory explain how we got lucky enough to be living in one of the rare life-compatible “bubble universes,” when it is almost infinitely more likely (under cosmic inflation theory) that our universe would be one of the young “bubble universes” too small for galaxies to form in it? He must resort to a “blind luck” explanation. But the luck needed is greater than the luck needed to have a successful universe without cosmic inflation. So nothing is accomplished, and the “miracle” of our existence is not made any less miraculous. In fact, the cosmic inflation theory seems to make our existence even more miraculous. How can such a result be described as scientific progress?

Cosmic Inflation: A “Cash Cow” for Lazy Cosmologists?

If the case for cosmic inflation is so weak, why do so many cosmologists support it? One answer can be found in groupthink effects, the tendency of modern cosmologists to travel in a herd because of sociological “go with the crowd” reasons. But another reason is that for decades the cosmic inflation theory has seemingly been an easy “meal ticket” for lazy cosmologists.

Producing a new paper on cosmic inflation is a cinch for a modern cosmologist. He merely has to write some new paper juggling some astrophysical numbers (perhaps thinking of some minor new speculative tweak), and doing the same type of calculations done by many earlier cosmologists. Since the cosmic inflation theory was introduced, cosmologists have published thousands of new papers discussing different flavors of the theory. A large fraction of this work has been funded by university grants or federal research grants. So for a cosmologist who is not particularly innovative, the cosmic inflation theory is a wonderful “cash cow.” Think of how easy it is: just produce “yet another cosmic inflation paper” (something like “cosmic inflation paper number 5,678”) without any real originality, and with zero risk that anyone will ever prove you wrong; and let the taxpayers or your university foot the bill. I'm reminded of the phrase in that Gershwin song: nice work if you can get it.

Given the existence of this convenient “cash cow” that pays well for easy speculative work, cosmologists are reluctant to bite the hand that feeds them, and admit how weak the cosmic inflation theory is. That would be like up ripping up their meal ticket.

Conclusion

There seems to be good evidence for the Big Bang and the expansion of the universe, so we should keep believing in such theories. There is no good evidence for the theory of cosmic inflation (the theory of exponential expansion in the universe's first second), and it should be dumped, in the sense of being relegated to a mere possibility rather than asserted as a likelihood. Scientists Ijjas, Steinhardt, and Loeb recently wrote a paper giving some powerful objections to the cosmic inflation theory.

Rather than embracing a theory that claims to explain only one case of cosmic fine-tuning (when there are many such cases to explain), we should look for a more general explanation. Rather than embracing a theory that claims to explain only one case of cosmic uniformity (when there are many such cases to explain), we should also look for a more general explanation. If scientists cannot think of such a more general explanation, they should simply say that they do not understand the explanation for the flatness problem and the horizon problem that originally motivated the cosmic inflation theory. It is an intellectual sin to claim to understand a cosmic mystery that you do not really understand. For 1000 years, astronomers embraced the Ptolemaic theory, and claimed to understand why the solar system behaves as it does, before they really understood that mystery. There's a lesson to be learned from such a long mistake: don't claim to understand a cosmic mystery based on some weak theory. Much better to simply candidly say: I don't understand this cosmic mystery.

The Groupthink Problem in Modern Cosmology and Physics

Two months ago in March 2014 the BICEP2 study was released, and almost all cosmologists seemed to hail it as compelling evidence for the theory of cosmic inflation (the theory that the universe underwent exponential expansion in its first second, not to be confused with the more general theory of the Big Bang). Even after a scientific paper was published in April casting grave doubt on the conclusions, cosmologists continued to assert that the BICEP2 study had provided strong evidence for gravitational waves produced by cosmic inflation. There seemed to be only a handful of skeptical voices about this matter back in March and April, including this blog (here and here), and the blogs of a few scientists (such as here).

But in May 2014 the situation finally changed, after the devastating presentation of Raphael Flauger at Princeton (and the rumors that arose from it). A flood of skeptical stories began to appear in the press. Doubts about the BICEP2 study now seem to be spreading dramatically. The scientific journal Nature just published an article citing two new scientific papers (including this one) indicating that the BICEP2 observations can be explained by ordinary dust and gravitational lensing (nothing special), rather than anything from cosmic inflation or the Big Bang. The journal quotes a scientist saying, “There’s no evidence for the detection of gravitational waves. It’s consistent with dust. “

Why did almost the entire community of cosmologists seem to throw themselves for at least a month behind a conclusion that is now regarded as being extremely doubtful? Why did cosmologists speak again and again as if a “smoking gun” of cosmic inflation had been discovered, when no firm evidence had been found, and there were from the beginning plenty of reasons for being skeptical? To understand this embarrassment, we have to take a candid look at groupthink problems in modern cosmology.

Anyone who has taken a sociology course may remember the phenomenon. Groupthink is the tendency of a relatively small group to produce unwarranted decisions, largely because of sociological reasons pertaining to conformity. Groupthink can occur when a person belongs to a small group that regards itself very highly, and when fitting in with that group is regarded as extremely important. Groupthink can occur when few or no people in the group challenge the decision of the group, because each person wants to fit in with the group, and no one wants to be regarded as an outsider who is challenging the group.

To visualize groupthink, imagine a buffalo herd all traveling in the same direction, partially because no buffalo wants to view himself traveling in one direction when the rest of the herd is traveling in a different direction. Such an image gives you a feeling of what goes on in groupthink.

A classic example of groupthink occurred when the United States decided to support the Bay of Pigs invasion of Cuba that occurred in 1961. Everyone who advised President Kennedy on the matter agreed that supporting the invasion was a good idea. But the invasion was a disastrous failure that created tensions leading to the Cuban Missile Crisis that put the world on the brink of nuclear war. President Kennedy later complained, “The advice of every member that was brought into advise was unanimous – and the advice was wrong!”

But is there reason for thinking that the groupthink problem occurs among modern cosmologists? Exactly such a claim has been made by Martin Lopez-Corredoira in his paper “Non-Standard Models and the Sociology of Modern Cosmology.” Although this paper may go a bit too far in a skeptical direction, this is a paper with some perceptive observations, and it should be required reading for every cosmologist.

Lopez-Corredoira describes a severe groupthink problem in modern cosmology. He illustrates his thesis with the following quotation from the late cosmologist G. R. Burbidge:

We all know that new ideas and revolutions in science in general come from

the younger generation, who look critically at the contemporary

schemes, and having absorbed the new evidence, overthrow the

old views. This, in general, is the way that science advances.

However, in modern astronomy and cosmology, at present, this is

emphatically not the case. Over the last decade or more, the vast

majority of the younger astronomers have been conformists in

the extreme, passionately believing what their leaders have told

them, particularly in cosmology. In the modern era the reasons

for this are even stronger than they were in the past. To obtain an

academic position, to obtain tenure, to be successful in obtaining

research funds, and to obtain observing time on major telescopes,

it is necessary to conform.

Lopez-Corredoira describes what he calls a snowball effect. When a particular theory is created, it is rather like a small snowball descending from the top of a mountain. The theory may die away like a snowball that hits a rock, or the theory may be like a snowball rolling down the mountain, getting bigger and bigger as it accumulates more snow. But the snow being added to the snowball as it rolls down the mountain need not be evidence for the theory – it may be simply the accumulated financial and intellectual investment that has been made in that theory. Every time a new scientific paper is written based on that theory, it's more snow on the rolling snowball. Every time an expensive new scientific instrument is built to look for evidence for a theory, the snowball gets a lot more snow. Every time a big conference is called to discuss the theory, it's more snow on the snowball. Eventually it may get to the point where the theory is almost unchallenged, not because there is good evidence for it, but because no one wants to be the person standing at the bottom of the mountain with his hand out to stop the giant rolling snowball.

 A theory benefiting from the Snowball Effect

To understand some of the psychological and sociological factors that may influence the thinking of a modern cosmologist, imagine yourself as a cosmologist who recently entered the field. You have worked long and hard to gain acceptance into this small group of scientists, which enjoys great prestige. You want very much to be accepted by this elite little group. You know that your colleagues have invested many years in writing many hundreds of scientific papers relating to the theory of cosmic inflation. You know that scientists have chewed up more than $365 million dollars in taxpayer money in an attempt to look for evidence of cosmic inflation with projects such as LIGO. What you want most is acceptance in your peer group, and you know that group favors this theory of cosmic inflation. Are you going to be the one who says, “There's no real evidence for this theory – let's move on to something else?” Or, are you going to conform to the group's accepted wisdom, which will make it more likely for you to get research dollars and your next job or assignment?

Faced with such a choice, groupthink sets in, and you will probably “get with the program.” You will probably “tow the line,” and run in the same direction the herd is running in.

Groupthink seems to occur not just in modern cosmology, but in physics as well. String theory has dominated theoretical physics during the past several decades, despite a lack of any evidence to support it. In his excellent book The Trouble With Physics, physicist Lee Smolin suggests that groupthink and sociological factors may help explain the mysterious popularity of this theory. Groupthink may also explain why a theory such as supersymmetry continues to be defended by many scientists, despite taking bullets from observational tests that conflict with it, and despite a lack of evidence to support it.

Understanding this groupthink problem, we can better understand what went wrong with how scientists reacted to the BICEP2 study. A group of very qualified physicists had a press conference, and their press release announced the “first direct evidence” of cosmic inflation. A few opinion makers in the scientific community gave their thumbs up. It seemed clear in which direction the buffalo herd was going to run in this matter (even though there were lots of reasons for being skeptical, including the fact that the BICEP2 study seemed at odds with results from the Planck space telescope). So with a very few exceptions the rest of the cosmologists fell into line, with almost no dissent for more than a month. It was a temporary triumph of groupthink. But thanks to Raphael Flauger and a few others, who have shown that the BICEP2 signals can be explained by ordinary dust and gravitational lensing, many scientists seem to be realizing they jumped on this bandwagon too hastily.

If the current trend persists, and it turns out (as I strongly argued the day after the BICEP2 study was released) that the grandiose “evidence for cosmic inflation” conclusions of the BICEP2 study do not hold up, then cosmologists need to take a good hard look at that great big rolling snowball, the theory of cosmic inflation, A cosmologist should ask himself – am I supporting this theory because there is any compelling evidence for it, or am I just running with the buffalo herd?

I have a serious proposal to fight the groupthink syndrome in modern science. In addition to spending hundreds of millions of dollars on studies designed to verify or support the prevailing scientific theories, ten million dollars in taxpayer dollars should be reserved for annual prizes that we might call the Rebel Awards. These prizes should only be given to scientists who advance a new theory or discredit an existing theory, in a way that defies conventional scientific thinking and upsets the generally accepted opinion of other scientists in the same field. Each award should have a matching research grant, to be used by the winner for any serious research project that he chooses. This would help correct today's situation, where it seems that 100% of the financial incentive is for scientists to conform and “tow the line.”

A Talk at Princeton Deflates the Grandiose Super-inflated BICEP2 Claims

In March the BICEP2 study announced observations that were hailed as a “smoking gun” proof of the theory of cosmic inflation, a theory that originated as an attempt to explain away various eerie problems of fine-tuning or “unnatural coordination” in the Big Bang (problems known as the horizon problem and the flatness problem). But this week rumors have been swirling that the findings of the BICEP2 study may not hold up. However, the supporters of the cosmic inflation theory have kept saying that the BICEP2 findings “remain robust.”

Today may be the day that BICEP2 goes from “robust” to “bust.” A scientist has just finished a talk at Princeton University which spells bad news for anyone thinking that BICEP2 has provided any evidence for the theory of cosmic inflation.

The talk was delivered by scientist Raphael Flauger, and the slide show from his talk can be downloaded here.

BICEP2 detected what is known as b-mode polarization, something that could be produced by cosmic inflation in the universe's first second, but which can also be produced by ordinary things that do not come from the Big Bang: gravitational lensing, synchrotron radiation and dust (all originating long after the universe was born). The question is: can the BICEP2 observations be explained by ordinary things like dust and gravitational lensing, or can they only be explained by assuming some super-special cosmic inflation in the universe's first second?

Flauger presents updated models of the combined effects of dust polarization and gravitational lensing, which he shows in the graph below (from page 39 of the pdf) :

The colored bands are the b-mode polarization effects we would expect to see from dust, other ordinary foreground effects, and gravitational lensing, according to Flauger. Notice that they overlap almost exactly with the BICEP2 observations. In fact, if one uses a combination of the BICEP2 observations and similar preliminary observations from a related team (Keck), then basically 9 out of 9 observations can be explained by assuming ordinary, run-of-the-mill things like dust and gravitational lensing (not the super-special cosmic inflation from the universe's first second).

This result is devastating to the grandiose, super-inflated claims of those claiming that BICEP2 has provided evidence for cosmic inflation. The Princeton presentation suggests the BICEP2 observations do not come from the Big Bang or the dawn of time. 

Flauger then uses another, different way of estimating the foreground contribution of dust and gravitational lensing, one based on what are called column densities. He gets the same result: a model indicating that all BICEP2 observations can be explained by the dust, gravitational lensing, and other ordinary foreground effects. In fact, Flauger gets the same predictions using two different techniques, which suggests he's on the right track. Below is page 52 of his presentation: 

Yesterday I published a blog post arguing for the same thing, that the BICEP2 observations can be explained by ordinary dust and gravitational lensing, not from some super-special cosmic inflation at the dawn of time. It is nice to have my conclusion supported the next day by a presentation at Princeton University.

It may not quite yet be the day for the fervent BICEP2 advocates to wave the white flag, but I would suggest that they at least get one ready (along with an explanation of exactly why they told us with such assurance again and again that some ambiguous observations were proof of something from the universe's first second).  Postscript: the Resonaances blog (written by a physicist) has just come out with a post which pretty much says the same thing I say in this post, commenting on the same Princeton talk, and suggesting that the BICEP2 result "will not stand."   

Post-postscript: After repeatedly writing as if it was a decided fact that the BICEP2 observations are gravitational waves from primordial cosmic inflation,  physicist Sean Carroll now tweets that it is merely "even money" that such is the case.   

Post-post-postscript. In this article in the scientific journal Nature, it is explained that two recent scientific papers have concluded that there is no significant evidence that the BICEP2 signals are from cosmic inflation or gravitational waves, with dust and cosmological lensing being an equally plausible explanation. 

Why a New Planck Paper Casts Grave Doubts on the “Epic” BICEP2 Study

In March the BICEP2 study announced observations of what is called b-mode polarization. The study was declared to be “direct evidence” for the theory of cosmic inflation, the theory that the universe underwent a period of exponential expansion during its first second. But in recent days rumors have been swirling that the study (hailed an an epic breakthrough) may not hold up. Today National Geographic published a piece entitled “Big Bang Discovery Comes Under Fire.”

Let me explain exactly why a new scientific paper by the Planck team throws grave doubt on the BICEP2 study, by making it seem rather likely that the “epic discovery” may be merely the observation of ordinary, run-of-the-mill dust. I will use scientific visuals rather than rumors.

First let us look at a graph from a scientific paper by another scientific team (POLARBEAR) that is doing studies very similar to the BICEP2 study. It is a graph with the same scale and legends as the key graph of the BICEP2 paper. The graph is below.

Graph 1, from the POLARBEAR scientific paper

The graph above shows some purple lines. The lower dark-dashed purple line shows b-mode polarization observations we would expect to see from galactic dust, if a parameter called the polarization fraction (represented by the letter p) is equal to 1.5%. The higher light-dashed purple line shows b-mode polarization observations we might expect to see from galactic dust, if a parameter called the polarization fraction (represented by the letter p) is equal to 10%.

Below is the key graph from the BICEP2 paper. Notice that this diagram and the first diagram are plotting the same thing on the same scale (the only difference being that the POLARBEAR graph goes down slightly lower on the scale).

Graph 2, from the BICEP2 scientific paper

Because these two graphs plot the same thing on the same scale, it is very easy to take the 10% dust polarization line from the first graph and move it to the second graph. When we do that, we get the following graph:

Graph 3, combining the BICEP2 graph with one line from the POLARBEAR graph

This graph should be very worrying for anyone who thinks that the BICEP2 observations are from the Big Bang or cosmic inflation. The graph shows that if there was dust polarization of about 10%, then that could explain the BICEP2 observations (as the purple line in the graph above cuts right through the black dots representing the BICEP2 observations). I don't have a graph showing 13% dust polarization, but that would be a purple line higher than the purple line above, and in such a case all of the BICEP2 observations could be explained from a combination of dust polarization and gravitational lensing, shown by the solid red line in the graph.

So the key issue is: how high is this dust polarization fraction? If it's only 1.5% then the BICEP2 team has little to worry about, but if it's 10% or 15% then all the BICEP2 observations can be explained by ordinary dust and gravitational lensing, and the claims of an “epic Big Bang breakthrough” would seem to crumble completely.

In the BICEP2 paper the scientists refer to a preliminary pdf which they apparently used in estimating the polarization fraction, a PDF with the following visual showing dust polarization fractions in various regions of the sky:

Graph 4, preliminary Planck map used by BICEP2

Notice the legend at the bottom that indicates the dust polarization fraction, which extends from 0% (deep blue) to 20% (red). The BICEP2 observations were from a region around the bottom middle of this map. Based on the map above, you might have estimated that there was a dust polarization fraction between about 5% and 7%. That would translate to a purple line uncomfortably close to the 10% line in my combined graph above (graph 3), but it would still leave a little breathing room.

However, in the past two weeks the Planck team has published a scientific paper that includes a revised version of the graph above. The graph (which excludes certain areas) is shown below:

Graph 5, the later Planck map published in a scientific paper

As you can see, this is basically the same graph as the previous graph, but there's one big difference. Many of the regions which used to be yellow are now red. This means many of the regions listed as having only about 10% dust polarization are now shown with a much higher level of polarization – a polarization of almost 20%.

The map above does not show the region at the bottom middle from which the BICEP2 observations were made. But the best guess one can make from these two maps (keeping in mind that the second one is the later and more accurate one) is that the polarization fraction in the area of the sky observed by BICEP2 is at least 10%. In fact, table 2 of the above Planck paper tells us that the average dust polarization fraction (considering all regions) is 19%.

Such a result casts very grave doubt on the pretentious cosmic claims of the BICEP2 team. If the dust polarization is greater than 10% in the area observed by BICEP2, it means the dust polarization line is even higher than the purple line I have drawn for graph 3. In such a case all the BICEP2 observations can be explained by ordinary dust and gravitational lensing, not something special that happened in the Big Bang.

It will be quite an irony if this turns out to be true. The scientists who thought they were seeing something extraordinarily special (an echo from the first second of the universe's creation) may really just have detected polarization from something as ordinary and common and lowly as the dust on your shoes.

3 Recent Studies Spoil Party of Cosmic Inflation Celebrants

In March the BICEP2 study announced observations of what is called b-mode polarization. The study was declared to be “direct evidence” for the theory of cosmic inflation, the theory that the universe underwent a period of exponential expansion during its first second. The theory of cosmic inflation (actually a large family of theories) is not the Big Bang theory itself, but a version of the Big Bang theory created to explain away certain “problems” of the Big Bang (remarkable aspects of the Big Bang which may or may not be things that should be considered as problems we need to get rid of, depending on your viewpoint).

The BICEP2 announcement was hailed as an “epic discovery,” and there was talk about scientists popping the corks of champagne bottles in a celebration. But in the past several weeks some scientific papers have been released which in various ways rain on the party of those who wanted to claim that the theory of cosmic inflation had been verified.

Almost immediately after the BICEP2 announcement, a scientific paper by Liu and others was released which casts severe doubt on whether the BICEP2 b-mode polarizations really do come from cosmic inflation or the Big Bang. The paper described a source of dust-related "galactic radio loop" radiation that may well account for the radiation detected by the BICEP2 team. The paper noted that the dust source of radiation “crosses the very region of the sky from which the BICEP 2 experiment has recently detected a B-mode polarisation signal,” and noted that this "galactic radio loop" radiation peaks at 120 to 130 gigahertz, which is almost the exact frequency used by the BICEP2 team (150 gigahertz). The paper also noted that this source of radiation was not accounted for by the BICEP2 team. The paper caused several science web sites to have stories such as this: The Big “Gravitational Wave” Finding May Have Actually Just Been Some Dust. See also this later paper by a much larger team mentioning the same source of radiation, described as "magnetic dipole emission from ferromagnetic inclusions within interstellar grains."

Another recent scientific paper raining on the party of the cosmic inflation celebrants is this paper by Hu and others. The BICEP2 findings conflicted with the findings of a much larger scientific team (the Planck team), in regard to something called the tensor-to-scalar ratio. In an attempt to resolve this discrepancy, the BICEP2 team trotted out a kind of farfetched theoretical contraption called the vanishing scalar index running model. But Hu's paper blows the whistle on this, like an NFL official throwing a flag on a football play. Hu's paper points out that when you sum up all the latest observations (from Planck, WMAP, and BICEP2) “the vanishing scalar index running model is strongly disfavored,” with a high three-sigma confidence level (a 99.7% confidence level). 

Hu's paper shows that the BICEP2 team's observations indicate a “blue tilt” in their polarization observations, and the paper notes that “this blue-tilt spectrum is not consistent with the prediction of the standard single field inflationary paradigm.” That's a big downer for the proponents of the cosmic inflation theory, as it seems to suggest that the BICEP2 observations contradict the main predictions of cosmic inflation theory, instead of confirming them. In fact, a few years back this scientific paper ended by saying, “More strikingly, if B-mode polarization is found and is shown to be due to gravitational waves, then if the spectrum is slightly blue one would have falsified the inflationary paradigm.” Such a slightly blue spectrum has apparently being found in the BICEP2 observations, an embarrassment for cosmic inflation proponents who are trying to wiggle their way out of this dilemma.

The BICEP2 B-Mode Signal: Slightly blue

Another problem for cosmic inflation advocates is a recent paper on a topic called primordial non-Gaussianity. Primordial perturbations are tiny little lumps in the cosmic background radiation, tiny little blips in the Big Bang believed to be like the seeds of future galaxies. Most versions of the cosmic inflation theory (and basically all of the simplest versions) have predicted that these primordial perturbations should be almost perfectly Gaussian, that is, having the shape of a bell-shaped curve or normal distribution. If, however, scientists find evidence that these primordial perturbations were non-Gaussian, it would almost seem to put the inflation theory on life-support. Primordial non-Gaussianity is like poison to the theory of cosmic inflation. If the cosmic inflation theory is Superman, then primordial non-Gaussianity is kryptonite.

The WMAP space satellite observed the cosmic background radiation for nine years. Quite a few scientific papers based on the data from that satellite did actually report evidence for primordial non-Gaussianity, as you can see by reading the papers here. But a team studying data from the Planck satellite reported no evidence of primordial non-Gaussianity. However, the confidence level in their study was low, only 68%.

But on April 1 of this year a team of scientists reported a study on primordial non-Gaussianity based on quasars. They found a significant degree of primordial non-Gaussianity (between 46 and 158), with a confidence of 95%, much higher than the 65% confidence level reported by the Planck team. These results are rather toxic for the theory of cosmic inflation. They suggest that the main prediction of the typical cosmic inflation theory – almost perfectly Gaussian primordial fluctuations – simply is not true. This paper has received almost no attention from the proponents of cosmic inflation, some of whom seem to fulsomely hail any study that may favor their theory, and pay little attention to studies that conflict with their theory. 

A distant quasar (Credit: NASA)

 

Double-Fudging Their Way to the BICEP2 “Breakthrough”

I like a double-fudged ice cream sundae, but I don't like double-fudged scientific studies, particularly when they claim to be of epic importance.

The BICEP2 study was released a few weeks ago to great fanfare. The press release for the study announced breathlessly that it was evidence for the theory of cosmic inflation, the theory that the universe underwent exponential expansion during a fraction of its first second.

But the study involved at least two big fudges – cases in which curves were squashed or stretched unnaturally and unreasonably for the sake of getting observations to fit in with the favored storyline that evidence had been found  for cosmic inflation. Before discussing each of the fudges, let me give a little background information.

The Difficulties of Looking for Primordial B-Mode Polarizations

The idea behind the BICEP2 study is to look for a particular type of radiation called b-mode polarization. Scientists predict that if a period of cosmic inflation had occurred in the universe's first second, it would have produced this type of radiation. But before the BICEP2 study many scientists commented on the extreme difficulty of finding evidence for cosmic inflation through such a process. The main problem is that quite a few other astronomical phenomena can produce this same type of b-mode polarization radiation. Among these other phenomena are: various types of dust, synchrotron radiation and gravitational lensing. 

The problem is illustrated by the graph below. The red line shows the b-mode polarization predicted to occur from synchrotron radiation. The blue lines shows the b-mode polarization predicted to occur from dust. The dotted green line shows the b-mode polarization predicted to occur from gravitational lensing. The solid green line shows the the b-mode polarization predicted to occur from cosmic inflation, using a version of that theory compatible from the most recent findings from the Planck satellite.

From the scientific paper here

The problem is that any lines that are higher-up in this graph are stronger signals that will drown out any signals that are lower in the graph (just as a 100-decibel sound of a passing motorcycle will completely drown out the 30-decibel sound of a child whispering). So if we use the curves in the chart above, there would seem to be basically zero chance of ever being able to confirm a theory of cosmic inflation by measuring b-mode polarizations (the technique used by the BICEP2 study).

To try to overcome such problems, the BICEP2 study resorted to some fudges I will now list.

Outrageous Fudge Number 1: Shrinking the Gravitational Lensing Model

The BICEP2 study has a graph showing a projection of the expected amount of b-mode polarization from gravitational lensing. But the projection is a shrunken, low-ball projection. It is nowhere near as high as the projections made by some previous scientists.

Here is the BICEP2 graph in which they project gravitational lensing (the solid red line):

You have to look closely at the little lines on this logarithmic graph to figure out two things: the assumption being made about where gravitational lensing starts, and the assumption being made about where it peaks. The assumptions being made by the BICEP2 study are these:

Starting point for gravitational lensing: 50 multipole ( l )

Peak of gravitational lensing: .05 (close to 10^-1).

The problem is that this is a shrunken estimate, an extreme low-ball projection. The first graph in this post (in which l is the multipole) gives a very different, much-larger projection:

Starting point for gravitational lensing: 2 multipole

Peak of gravitational lensing: .2

In fact, most of the estimates that you will find (made prior to the BICEP2 study) match this much larger estimate for gravitational lensing. Indeed, the most recent POLARBEAR observations support these larger estimates, by showing the peak of the gravitational lensing at a much higher point than the peak in the BICEP2 graph.

Why is this important? If the larger estimate of gravitational lensing is correct, then all of the BICEP2 observations can be explained by assuming gravitational lensing (not cosmic inflation) as the source of the radiation. For example, if the larger projection of gravitational lensing is correct, then we have a model of gravitational lensing similar to the green line below, which can explain all of the BICEP2 observations without requiring any cosmic inflation in the universe's first second.

To force their observations to fit a theory of cosmic inflation, the BICEP2 study chose to present a shrunken, low-ball estimate of gravitational lensing.

Outrageous Fudge Number 2: Shrinking the Dust Projection

When they estimated the amount of b-mode polarization produced by cosmic dust, the BICEP2 team almost admitted that they didn't have what they needed to make an accurate projection:

The main uncertainty in foreground modeling is currently the lack of a polarized dust map. (This will be alleviated soon by the next Planck data release.) In the meantime we have therefore investigated a number of existing models and have formulated two new ones.

The team then present a graph showing some models they selected, models that minimize the amount of dust, and suggest that dust is no big problem when trying to measure signals from cosmic inflation. The low-ball models selected are inconsistent with some previous estimates, which estimate that dust should be blocking all or most of any b-mode polarization produced by cosmic inflation.

See, for example, this scientific paper, which on page 2 predicts a level of dust polarization many times greater than the amount projected by the BICEP2 study (as does this graph from a scientific conference). The relevant graph is shown at the beginning of this blog post.

 

It was almost rather like this:

Previous scientists: How on earth can we find a signal from cosmic inflation with all this cosmic dust all over the places we're looking for the signal, dust that blocks what we're looking for?

BICEP2 scientists: Dust? What dust?

Of course, the BICEP2 study needed to shrink and low-ball the dust projections, to clear the field for their triumphant announcement of evidence for cosmic inflation, and to try to rule out dust as the source of their observations. This was another biased case of artificially stomping on a data curve to get observations to fit a favored explanation of the data.

In an attempt to rule out dust as the source of their observations, and bolster their case for cosmic inflation (in the universe's first second) as the source of their observations, the BICEP2 team ran some simulations (using lots of subjective, hand-picked inputs) that they say show that their observations have characteristics “atypical” of dust. That is very lame and unconvincing reasoning – rather like arguing that a particular light seen in the sky is an alien spaceship because it has characteristics “atypical” of an airplane. The graph of their simulations (Figure 8 in the study) still shows a perfectly decent chance that dust or synchrotron radiation is the source of their observations, not cosmic inflation.

The End Result: A Half Fit

We might expect with these two examples of curve fiddling that the end results would match the favored model exactly. But no: even with these heroic efforts, the BICEP2 graph below only shows 5 out of 9 data points matching the favored model, with several of the data points far off of the model. 

Can We Trust the Claimed Data Points?

When a study is based on simple data observations, you can trust the observer to record the observations correctly, unless you think he might be careless or prone to fraud. For example, if a scientist measures the temperature on a particular day, you pretty much have to trust him, unless you think he might be faking it. But in a case such as the BICEP2 study we have a very different situation. The scientists took raw data, and subjected it to an extremely complicated process of transformations, summaries, and modeling. The process was almost like the process shown in the visual below:

Source: wikiuniversity, Howard Community College

Can we be confident that the BICEP2 team got this extremely complicated process right, and that the data points shown in their final graph are correct? No, we cannot be. This is because it is rather clear from these examples I have shown that the BICEP2 team had a strong experimental bias. Evidently they wanted very much to make their observations match a storyline that the observations came from primordial cosmic inflation. Given this very strong partiality, there are any number of ways in which things could have gone wrong because of experimental bias. At any number of points in the incredibly complicated data transformation process, the scientists may have made decisions influenced by their desire to end up with results favoring a theory of cosmic inflation, decisions that more objective and impartial scientists would not have made.

We need studies like the BICEP2 study to be performed by objective, non-biased scientists without any favored agenda (scientists with an attitude of “let the chips fall where they may”), rather than scientists who seem determined to hammer square pegs into round holes, in order to fit some desired preconceived storyline.

Postscript: See this link for a National Geographic story on how the BICEP2 results may be due to dust, not cosmic inflation. I'm not accusing any on the BICEP2 team of deliberately misleading anyone. I merely think that their desire to have an inflation-related result (good for their own careers) has influenced their paper, leading to some presentation and interpretation decisions that might not have been made by a more impartial set of writers. 

Post-postscript: I didn't originally mention the pathetic way the BICEP2 paper handled the issue of synchrotron radiation.  Synchrotron radiation is a widespread phenomenon that produces the same b-mode polarization observed by BICEP2.  This type of radiation can be produced by many types of high-energy violent events inside and outside of our galaxy. Rather than making any substantial attempt to show that synchrotron radiation is not the source of their observations (which would require many pages), the BICEP2 paper (in sections 9.2 and 9.3) has the skimpiest treatment of the topic, using only 6 sentences to address it. This discussion calls section 9 of their paper "the most ridiculous handwave of all time in the whole history of physics."

Post-post-postscript:  Today a physicist has on his blog a post that says the BICEP2 team made some big error in their dust projection (an error along the same lines as I insinuate in this post). He says, "However, at this point, there seems to be no statistically significant evidence for the primordial B-modes of inflationary origin in the CMB [cosmic microwave background]."

Yet another postscript: see this post for a discussion of a talk at Princeton University in which a scientist gives a presentation that gives a devastating blow to the inflated claims of the BICEP2 study. The scientist gives projections of dust and gravitational lensing which show how such common phenomena (not from the Big Bang or cosmic inflation) can explain the BICEP2 observations.