Ever have the experience of feeling that no one is listening to you, and so, to make yourself heard, you yell really loudly? And then discover that one of the key people you were trying to reach is standing right behind you?
That’s a bit how I feel after my recent post about Tuesday’s article in the New York Times on the search for the Higgs particle at the Large Hadron Collider [LHC]. My readership is minuscule compared to Dennis Overbye’s, so I shouted. But Mr. Overbye, to my surprise, read the post. Clearly I could have made my points more gently, and for the unnecessary stridency of my tone, Mr. Overbye, I apologize.
I also believed the NY Times article contained an error, and said so. Mr. Overbye defended himself in a comment to my post, saying that the phrasing he chose was meant to imply the correct situation without going into too much detail. I accept this was his intent; I do understand that squeezing these complex ideas into very short articles is a huge challenge, one that he and his colleagues often do very effectively.
Still, in this case, the phrasing chosen could easily lead to an unfortunate and problematic misunderstanding in the wider public — negating the otherwise admirable features of the article. And the risk of causing this particular misunderstanding is the hot button issue on this website. I’ll explain why in a moment.
Before I go into detail, let me balance my negative comments, in the interest of fairness. As a commenter noted, Mr. Overbye carefully avoids referring to the Higgs particle (or “Higgs boson”, as most physicists call it [what's a boson? just a particular type of particle -- click here to read more]) as the “God particle”, a term invented purely to sell a book, and detested by most physicists I know. Thank you, Mr. Overbye, for setting a high standard here. And Mr. Overbye successfully evokes the current mood of extremely high excitement in the field — that 2012 is a very, very big year, in which huge questions bothering particle physicists for decades are finally coming to a head.
But what precisely are those questions? And why do I think it matters?
I do think it’s useful to look at why Mr. Overbye’s phrasing could be disturbing to some particle physicists. First off is the notion that the upcoming conference called ICHEP is “the boson’s last stand”.
In disagreeing with this statement, I am not (as some commenters thought) making a statement of theoretical prejudice. This has nothing to do with what I believe about nature, or what anyone else believes. I am making a simple logical point.
What is the “Standard Model”? It is the set of equations used by particle physicists to describe all known particles and forces at the LHC, along with the simplest possible Higgs particle. [Sometimes this is called the Minimal Standard Model.]
What the LHC experimenters are doing right now is an exhaustive search for this `simplest Higgs’. This search is nearing completion. (Caution: completion may not come at ICHEP. The limited data available so far means that ambiguities may still remain, due to statistical flukes. In that case we’ll have no choice but to wait for the end of 2012.) When the search is done, either a Higgs particle will have been found (perhaps a simple one, or perhaps a more complex one uncovered more or less by accident) or the simplest Higgs will have been ruled out.
Suppose indeed the simplest Higgs is definitively excluded by the data. Which of the following conclusions follows logically?
- The simplest Higgs particle does not exist in nature.
- The (Minimal) Standard Model is not a complete description of nature.
- There is no Higgs particle in nature.
The first two conclusions are logically correct, as well as scientifically spectacular. The third would be even more spectacular, but does not follow. But in saying that ICHEP is “the boson’s last stand”, Overbye gives the strong impression that the third conclusion will follow.
What is actually having its last stand, now or soon, is the Standard Model, [or Minimal Standard Model if you prefer that name] and its simplest Higgs. Professor Higgs and the others — Brout, Englert, Guralnik, Hagen and Kibble — will be disappointed if the Higgs doesn’t show up in its simplest form, but will have no reason to give up hope.
Why is this such an important distinction? Because a non-expert reading the phrase “the boson’s last stand” might naturally conclude that if no Higgs particle discovery is announced at ICHEP, it’s all over… that we know there is no Higgs particle in nature, and the search for the Higgs is done. And the natural next question for many people will be: “ok, but then what do we need the LHC for?” And for others, “so you mean to tell me that theorists said for 50 years there’d be a Higgs particle, and we paid for this 9 billion dollar machine, and the Higgs isn’t there?!” Personally, I do not want to see the New York Times creating these sorts of very dangerous misunderstandings, at a time of severe economic crisis. (Anyone who thinks no dangers lurk here should consider the last two decades of history carefully.) And that’s why I reacted so strongly to Mr. Overbye’s article.
According to Mr. Overbye, he was trying to convey this distinction. I realize these things are very hard to do, but, with respect, I think in this case it wasn’t done clearly. And that’s partly because he added the statement that “theorists will have to go back to the drawing boards” — which implies that theorists will all be so astonished and befuddled if the Higgs doesn’t turn up at ICHEP that they’ll all have to go back to square one.
Will the demise of the (Minimal) Standard Model and its simplest Higgs send theorists back to the drawing board? No. Theorists have not been idle over the past decades. They’ve been at the drawing board the whole time; it’s their job not to be satisfied with the conventional wisdom. It’s not the drawing board but the library and the desk drawer and the computer archive to which they will turn. And in those places you will find dozens and dozens of sensible alternatives to the simplest Higgs, many of which are harder to find than the simplest one and will still be worth searching for, well beyond 2012. And you will find numerous papers, by famous and less famous scientists, showing how nature can have a Higgs field but no Higgs particle; this situation (usually omitted by science journalists, because it is admittedly very hard to explain in a few words) always comes with other scientific opportunities for the LHC. [I've written about this here, if you want to learn more; see section 6 -- the article is out of date in its details but not in its scientific points.] [Experts: by "Higgs field" I specifically mean any effective field whose would-be Nambu-Goldstone bosons provide the longitudinal components of the W and Z particles. You may prefer a different terminology, but I hope you do not disagree with the science. The example I have in mind is technicolor, and its various cousins.]
If late this decade there’s still no Higgs particle and still nothing else unexpected in the LHC data, then you’ll find most of us at the drawing board.
I should note that a few commenters stated their opinion that if the simplest Higgs, or something like it, doesn’t show up in the current search, then they will be sure there is no Higgs particle in nature, because “nobody believes” these alternatives to the simplest Higgs. First, their opinion is one of theoretical prejudice, not logic; and if scientists’ beliefs were always right, experiments would be a lot less important than they are. And second, the point is not that anyone believes a particular alternative; I don’t “believe” in any specific one myself. The point is that there are so many, and so easy to create. It would be foolhardy to dismiss the possibility that nature might hide the Higgs from our initial searches.
Also, there is an unfortunate public perception (partly due to physicists cutting corners in public statements) that theoretical physicists said that “there is a Higgs particle in nature” and that the experimental physicists built the LHC to find it. This is too glib. As I have written in more detail elsewhere, what theorists said (collectively) is that “there is a Higgs field in nature” — a Higgs particle being likely but not a certainty. The LHC was built to help us understand the Higgs field, and was designed to handle both the cases where a Higgs particle would be found early on, and the cases where it would not be found early, or at all. In short: particle physicists have come to this point fully prepared.
And we need the news media to convey this. Having provided several billion dollars for this machine, taxpayers and politicians around the world rightly expect particle physicists to do a first-rate job with the money. We have a reputation to uphold. If the media, directly or indirectly, leads the public to view us unfairly as bewildered, stunned, unprepared, or otherwise incompetent, this would be very damaging. And so I feel that cannot sit idly by if a New York Times article, even unintentionally, could imply to many readers that not finding the Higgs by ICHEP would mean that nobody in the field would have any idea what to do next.
I myself write to explain science, mainly particle physics, to the public, and I know that science journalists everywhere have a very tough job. Mr. Overbye, in his position at the NY Times, can have huge influence on scientific understanding and science policy in the public, and consequently he has responsibilities that make his job even tougher. His contribution to public excitement about the current moment in particle physics is more than welcome. But isn’t there some way, in a few words, also to convey the decades of careful preparation by the particle physics community, not just for the conventional wisdom but also for the broad range of alternatives? And not just for this critical moment, but for the decade of LHC studies that lies ahead?
For even if we see strong evidence of a Higgs-like particle at ICHEP, the correct understanding of that particle — in particular, determining whether it is or isn’t a `simplest Higgs’ — may take many years. And we’re prepared for that.