Heads up! Literally! If you live between Georgia and Maine, and as far inland as Ohio, you’ve got a good chance of seeing the launch of a rocket off Maryland’s Wallops Island, currently scheduled for 8:15 Eastern time. In the New York area, look to the south and east.
ON November 19, 2013
Appropriate for General Readership
[Apologies: due to a computer glitch, the figure in the original version of this post was not the most up-to-date, and had typos, now fixed.]
On Tuesday, the New York Times Editorial page ran an Op-Ed about dark matter… and although it could have been worse, it could certainly have been better. I do wonder why these folks don’t just call up an expert and confirm that they’ve actually got it right, before they mislead the public and give scientists a combination of a few giggles and a headache.
Here is the last paragraph from the Times:
“This experiment is probing a major hole in the way we understand the cosmos. Roughly speaking, the force of gravity in the universe can be explained only by a corresponding amount of mass, or matter. Some undiscovered mass — dark matter — must exist in order to explain gravity, but no one has seen any traces of it. Those traces, when they are finally found, will be exotic particles left over from the Big Bang. In the tale we tell about everything we know, scientists have now brought us to the edge of the deep, dark woods. They, and we, are waiting eagerly to see how the rest of the story goes.”
Ok, out comes the professorial red pen.
First, a relatively minor point of order. “…the force of gravity in the universe can be explained only by a corresponding amount of mass, or matter…” This isn’t great writing, because mass and matter are not the same thing. Matter is a type of substance. Mass is a property that substance (including ordinary matter, such as tables and planets) can have. Mass and matter are as different as apples and applets. You can read about these distinctions here, if you like. The author is trying to evade this distinction to keep things simple: the more correct statement is that gravity (in simple circumstances) is a force exerted by things (including ordinary matter) that have mass.
But here’s the real offending remark: “Some undiscovered mass — dark matter — must exist in order to explain gravity, but no one has seen any traces of it.” Dark matter is most certainly not needed to “explain gravity” in some general way; there’s not one bit of truth in that remark. For instance, the gravitational pull of the sun on the earth (and vice versa), and the pull of the earth on you and me (and vice versa), has absolutely nothing whatsoever to do with dark matter, nor is dark matter needed to explain it.
What the author should have said is: since the 1960s we have known that gravitational forces on large astronomical scales seem to be stronger than we can account for, and so either our equations for gravity are wrong or there is matter out there, pulling on things gravitationally, that we cannot see with any type of telescope. The reason the latter possibility is taken more seriously than the former by most experts is that attempts to modify gravity have not led to a convincing case, while the evidence for additional “dark” matter has grown very strong over recent decades.
Here’s one of the several arguments that suggest the possibility of dark matter… the simplest to explain. Experts study the motions of the stars in our own galaxy — the star city known as the Milky Way — and also study the motions of stars in other galaxies. [The overall motions of galaxies themselves, inside giant clusters of galaxies which can be found in deep space, are also studied.] Now what we ask is this; see Figure 1. Supposing all of the matter that is out there in the universe is of a type that we can see in one way or another: stars, gas, dust of various types. Then we can figure out, just by looking with a telescope and doing simple calculations, roughly how much measurable matter is in each galaxy, how much mass that matter has, and where it is distributed inside the galaxy. We can next use that information to figure out how hard that matter pulls on other matter, via the force of gravity. And finally — crucially! — we can calculate how fast that pull will make the matter move, on average. And what do we find when we measure how fast the stars are moving? Our calculations based on the matter that we can see are wrong. We find that the stars in the outer edges of a galaxy, and the galaxies inside clusters, are moving much, much faster than our calculation predicts. (This was discovered in the 1960s by Vera Rubin and Kent Ford.) It’s as though they’re being pulled on by something unseen — as though the gravity on the stars due to the rest of the galaxy is stronger than we’ve guessed. Why is this happening?
One possibility is that there is matter out there that we can’t see, a lot of it, and that matter is inside galaxies and inside clusters of galaxies, exerting a pull that we haven’t accounted for properly. A huge “halo” of dark matter, in this view, surrounds every galaxy (Figure 2).
Clearly, this isn’t the only logical possibility. Another option is that there could be something wrong with our understanding of gravity. Or there could be some other new force that we don’t know about yet that has nothing to do with gravity. Or maybe there’s something wrong with the very laws of motion that we use. But all attempts to make sensible suggestions along these lines have gradually run into conflicts with astronomical observations over the recent decades.
Meanwhile, during those last few decades, a simple version of the “dark matter” hypothesis has passed test after test, some of these tests being very complex and subtle. For example, in Einstein’s theory of gravity, gravity pulls on light, and can bend it much the same way that the lenses in eyeglasses bend light. A galaxy or galaxy cluster can serve to magnify objects behind it, and by studying these lensing effects, we again conclude there’s far more matter in galaxies and in clusters than we can see. And there are other arguments too, which I won’t cover now.
So while an explanation for the fast motion of stars inside galaxies, and galaxies inside clusters, isn’t 100% sure to be dark matter, it’s now, after many years of study, in the high 90%s. Don’t let anyone tell you that scientists rushed to judgment about this; it has been studied for decades, and I can tell you from experience that there’s a lot more consensus now than there was when I was an beginning undergraduate 30 years ago.
“Those traces, when they are finally found, will be exotic particles left over from the Big Bang.” Will they? Will the dark matter turn out to be particles from the Big Bang? Not necessarily. We know that’s one possibility, but it’s not the only one. Since I explained this point last week, I’ll just refer you to that post.
Now here come the big meta-questions: should the New York Times be more careful about what it puts on its editorial page? Should its editors, who are not scientists, talk broadly about a subtle scientific topic without fact-checking with an expert? What are the costs and benefits when they put out oversimplified, and in some ways actually false, information about science on their editorial page?
ON November 7, 2013
Appropriate for General Readership
Last week, the LUX experiment reported its results in its search for the dark matter that (speaking roughly) makes up 25% of the stuff in the universe (see here for the first report and here for some Q&A). [See this article, specifically the “Dark Matter Underfoot” section, for some nontechnical discussion about how experiments like LUX work.] Shortly thereafter, a number of articles in the media made a big deal out of the fact that, simultaneously,
as though this was contradictory and mystifying. Actually, if you think about it carefully, this is perfectly normal and typical, and not the slightest bit surprising. But to make sense of it, you do also have to understand the levels of “happiness” that the LUX scientists are expressing.
The point is that whenever scientists do an experiment whose goal is to look for something whose precise details aren’t known, there are two stories running simultaneously:
Notice that humans have control over the first story. The wiser they are at designing their experiment, and the more skillful they are in carrying it out, the more effective their search will be. But they have no control over the second story. Whether their prey lies within their reach, or whether it lies far beyond, requiring the technology of the distant future, is up to nature, not humans. In short, story #1 is about skill and talent, but story #2 is about luck. Even a great experiment can’t do the impossible, and even one that doesn’t work quite as well as it was supposed to can be fortunate.
Of course, there is some interplay between the stories. A disaster in story #1 precludes a happy ending in story #2; if the experiment doesn’t work, there won’t be any discoveries! And the better is the outcome in story #1, the more probable is a success in story #2; a more thorough search is more likely to get lucky.
The LUX researchers, in order to make a discovery, have to be lucky in several ways, as I described on Thursday.
None of these things is necessarily true, given what we know about dark matter from our measurements of the heavens. And if any one of them is false, no detector similar to LUX will ever find dark matter; we’ll need other methods, some of which are already under way.
Now, in this context, what’s the worst thing that could happen to a group of scientists who’ve built an experiment? The worst thing that could happen is that after spending several years preparing the experiment, they find it simply doesn’t work. This can happen! These are very difficult experiments requiring very special and remarkable techniques, and every now and then, in the history of such experiments, an unexpected problem arises that can’t be solved without a complete redesign, which is usually too expensive and in any case means years of delay. Or something just explodes and ruins the experiment. Something like this is extremely depressing and often deeply embarrassing.
So if instead the experiment works, the scientists who designed, built and ran it are of course very relieved and reasonably happy. And if, because of a combination of hard work and cleverness, it works better than they expected and as well as they could have hoped, they’re of course enormously pleased, and proud of their work!
Now what could make them happier still — even ecstatic, to the point of staying up late drinking entire bottles of champagne? A discovery, of course. Discovering what they’re looking for, or perhaps something they weren’t even looking for, if it is truly novel and of fundamental importance. If that happens, then they won’t care as much if their experiment worked better than expected… because, if you’re an experimental scientist, there’s nothing, nothing at all, better than discovering something new about nature.
So with this perspective, I think the LUX scientists’ emotions (as conveyed during his talk by Richard Gaitskell of Brown University, the project’s leader) are actually very easy to understand. They are very happy because their experiment works better than they expected and as well as they hoped… maybe even better than that. For this, they get the high respect and admiration of their colleagues. But make no mistake: they’d certainly be a lot happier — overjoyed and humbled — if they’d discovered dark matter. For that, they’d get a place in the history books, major prizes (perhaps a Nobel, if the Nobel Committee could figure out who to give it to), lasting fame, and the almost unimaginable feeling of having uncovered something about nature that no human previously knew, and that (barring a complete collapse of civilization) will never be forgotten. So yes, they’re happy. But not nearly as happy as can be. They’re frustrated, too, just like the rest of us, that nothing’s shown up yet.
However, they’re also hopeful. Since they’ve built such a good experiment, and since they’ve only run it for such a short time so far, they’ll have another very reasonable shot at finding dark matter when they run it for about a full year, in 2014. Not only will they run it longer, they’ll surely also learn, from their experience so far, to be smarter about how they run it. So expect, at the very least, powerful new limits on dark matter from them in eighteen months or so. And maybe, just maybe, something more.
ON November 4, 2013
Appropriate for General Readership
Tomorrow there will be a solar eclipse (i.e., the moon will pass between the earth and the sun, blocking the sun’s light.) Those of us on the east coast of the United States who wake up to a clear sky at dawn will see the rising sun partially eclipsed, as much as half blocked in many places. [Don’t forget that in the US the clocks are changing tonight, so dawn is one hour earlier, as the clock tells it, than it was today; in New York City sunrise is at 6:30 am tomorrow.] Meanwhile, a substantial partial eclipse will be visible across most of Africa, and a less substantial one in parts of southern Europe. And a little sliver of central Africa will be fortunate enough to see one of nature’s most extraordinary spectacles: a total eclipse of the sun, where for a couple of minutes the sky suddenly goes almost dark, the stars come into view, and the pink prominences and silvery corona of the sun glow and shimmer in the darkness of the moon’s shadow.
Really, this ought to have been scheduled for Halloween. Because if you didn’t know to expect a total solar eclipse, and you didn’t know what was going on, there’d be nothing more terrifying.
Remember: Except in the truly dark heart of a total eclipse, looking at the sun for even a few moments can destroy your eyes; either use specially designed “eclipse glasses” (ordinary sunglasses are completely unsafe) or use a pinhole in a piece of cardboard to project the sun’s image onto a piece of paper or a wall. [As I described here, carefully placed binoculars pointed at a piece of paper or wall will work too — but do not look through them!!! just let the sun’s image go through.] For those watching at sunrise, if there is cloud or haze in the east that dims the sunlight, you can look for a few moments — but make it very quick!
ON November 2, 2013
Since the mainstream news media, in their reporting on the new result from the LUX experiment I wrote about Wednesday, insists on confusing the public with their articles and headlines, I thought I’d better write a short post reminding my readers what we do and don’t know about dark matter.
Scientists are, collectively, pretty darn sure, though not 100% certain. Certainly something is out there that acts a lot like a dark form of matter (i.e. something that gravitates and clumps, but doesn’t shine, either in visible light or in any other form of electromagnetic waves). There have been some proposals that try to get around dark matter, by modifying gravity, but these haven’t worked that well. Meanwhile the evidence that there really is dark stuff out there that really behaves like matter continues to grow year by year, and every claim that it actually isn’t there (such as this one I wrote about — see the second half of the article) has turned out to be wrong. Dark matter is needed to explain features of the cosmic microwave background, to explain how galaxies form, to explain why we see certain types of gravitational lensing, etc. etc. No one alternative can explain all of these things. And dark matter easily arises in many particle physics theories, so it’s not hard to imagine it might be created in the early universe and be a dominant player today.
No, that’s not certain. Particles would do the job, but that’s not a proof it is made from particles.
No. Dark matter could be WIMPs. Or dark matter could be made from a very different type of particle called “axions”. Or dark matter could be made from particles that aren’t of either of these types. This could include particles that only interact with ordinary matter through the force of gravity, which could make them very, very hard to detect.
As far as I can tell, most experts do not know what to think; some have a bias toward one idea or another, but when pressed admit there’s no way to know. Many scientists think WIMPs are a good candidate, but I’ve never heard anyone say they are the only one.
Partly because they can. Sometimes science involves looking under the lamppost for your keys. You look where you can because you can look there, and you may get lucky — it has happened many times before in history. That’s fine as long as you remember that’s what you are doing.
Not that WIMPs are the only things that people are looking for. They can also look for axions, and there are experiments doing that search too. Looking for other types of dark matter particles directly is sometimes very difficult. Some of these other types of particles could be found by the experiments at the Large Hadron Collider [LHC] (and people are looking.) Others could be found by experiments such as FERMI and AMS, through the effect of dark matter annihilation to known particles (and people are looking; there’s even a hint, not yet shown to be wrong). Still other possible types of dark matter particles are completely inaccessible to modern experiments, and may remain so for a long time to come.
Don’t ask me. Ask the editors at CBS and the BBC why their headlines about science are so often inaccurate.
The search for dark matter will end when some type of dark matter is found (or somehow shown convincingly not to exist), not before. The former could happen any day; the latter will not happen anytime soon. The only thing that is currently approaching its end is the search for WIMPs as the dark matter (and even that search will not, unfortunately, end as soon or as conclusively as we would like.) If WIMPs aren’t found, that just probably means that dark matter is something else on the list I gave you above: some other type of particle, or some other type of thing that isn’t a particle. Or it could mean that dark matter forms clumps, rather than being smoothly distributed through our galaxy, and that we’re unlucky enough to be in an empty zone. Certainly, if LUX and XENON1T and the other current experiments don’t find anything, we will not be able conclude that dark matter doesn’t exist. Only those who don’t understand the science will attempt to draw that conclusion.
Well, it’s important, but not amazingly important, because indeed, (a) they didn’t find anything, and (b) it’s not like they ruled out a whole class of possibilities (e.g. WIMPs) all at once. But still, (i) they did rule out a possibility that several other experiments were hinting at, and that’s important, because it settles an outstanding scientific issue, and (ii) their experiment works very, very well, which is also important, because it means they have a better chance at a discovery in their next round of measurements than they would have otherwise. In short: they deserve and will get a lot of praise and admiration for their work… but their result, unlike the discover of the Higgs particle by the LHC experiments, isn’t Nobel Prize-worthy. And indeed, it’s not getting a front-page spread in the New York Times, for good reason.
ON October 31, 2013
Two new ground-breaking measurements reported results in the last 24 hours! Here are very quick summaries.
A group of atomic physicists, called the ACME collaboration, has performed the best search so far for the electric dipole moment (EDM) of the electron. Unfortunately they didn’t find the EDM, but the limit
is 12 times stronger than the previous one. While this is still a billion times larger than what is expected in the Standard Model of particle physics (the equations used for the known elementary particles and forces), there are various types of as-yet unknown particles and forces that could easily produce a much larger electron EDM, through new violations of T symmetry (or, almost equivalently, CP symmetry). These effects could have been large enough to have been discovered by this experiment, so those types of possible phenomena are now more constrained than before. Fortunately, there’s more to look forward to; the method these folks are using can eventually be improved by another factor of 10 or so, meaning that a discovery using this technique is still possible.
This morning the LUX dark matter experiment reported new results, and knocked everyone’s socks off. They have understood their backgrounds from radioactivity much better and more quickly than most of us expected, using new calibration methods and a much better characterization of their backgrounds than has previously been possible. Although they have a detector only a bit larger than XENON100 and have only run the detector underground for three months, compared to the year or so that XENON100 ran previously, their limits on the rate for a dark matter particle to hit a Xenon nucleus beats XENON100’s results by a factor of 2 for a dark matter particle of mass 1000 GeV/c², increasing to about a factor of 3 for a dark matter particle in the 100 GeV/c² mass range, and soaring to a factor of 20 for a dark matter particle in the 10 GeV/c² mass range. Consequently, LUX pretty definitively rules out the possibility, hinted at by several dark matter experiments (as discussed in the second half of the article I wrote about this in April), of a dark matter particle in the 5 – 20 GeV/c² mass range. (See the figure below.) While XENON100 seemed to contradict this possibility already, it didn’t do so by a huge factor, so there were questions raised as to whether their result was convincing. But the sort of ~10 GeV/c² dark matter that people were talking about is ruled out by LUX by such a large factor that finding ways around their result seems nigh impossible. And again, there’s more to look forward to; by 2015 their results should improve by another factor of 5 or so… so they get another shot at a discovery, as will XENON1T, the successor to XENON100.
Congratulations to both groups for their spectacular achievements!
ON October 30, 2013
I spent the last two days at an extraordinary conference, “Dreams of Earth and Sky”, celebrating the life and career of an extraordinary man, one of the many fascinating scientists whom I have had the good fortune to meet. I am referring to Freeman Dyson, professor at the Institute for Advanced Study (IAS), whose career has spanned so many subfields of science and beyond that the two-day conference simply wasn’t able to represent them all.
The event, held on the campus of the IAS, marked Dyson’s 90th year on the planet and his 60th year as a professor. (In fact his first stay at the IAS was a few years even earlier than that.) The IAS was then still a young institution; Albert Einstein, John Von Neumann, Kurt Gödel and J. Robert Oppenheimer were among the faculty. Dyson’s most famous work in my own field was on the foundations of the quantum field theory of the electromagnetic force, “quantum electrodynamics”, or “QED”. His work helped explain its mathematical underpinnings and clarify how it worked, and so impressed Oppenheimer that he got Dyson a faculty position at the IAS. This work was done at a very young age. By the time I arrived to work at the IAS in 1996, Dyson had officially retired, but was often in his office and involved in lunchtime conversations, mostly with the astronomers and astrophysicists, which is where a lot of his late career work has been centered.
Retirement certainly hasn’t stopped Dyson’s activity. His mind seems to be ageless; he is spry, attentive, sharp, and still doing science and writing about it and other topics. When I went up to congratulate him, I was surprised that he not only remembered who I was, he remembered what I had been working on in 1992, when, as an unknown graduate student on the other coast, I had sent him a paper I had written.
By the way, it’s somewhat bizarre that Dyson never won a Nobel Prize. Arguably it is part of the nature of the awarding process, which typically rewards a specific, deep line of research, and not a polymath whose contributions are spread widely. Just goes to show that you have to look at the content of a person’s life and work, not the prizes that someone thought fit to award to him or her. Still, he has his share: Dannie Heineman Prize for Mathematical Physics 1965; German Physical Society, Max Planck Medal 1969; Harvey Prize 1977; Wolf Foundation Prize in Physics 1981; American Association of Physics Teachers, Oersted Medal 1991; Enrico Fermi Award 1995; Templeton Prize for Progress in Religion 2000; Henri Poincaré Prize 2012.
The thirteen talks and several brief comments given at the conference, all of which in one way or another related to Dyson’s work, were organized into sessions on mathematics, on physics and chemistry, on astronomy and astrobiology, and on public affairs. All of the speakers were eminent in their fields, and I encourage you to explore their websites and writings, some of which were controversial, all of which were interesting. For non-scientists, I especially recommend Stanford Professor Emeritus Sid Drell’s extremely interesting talk about nuclear disarmament (which he’s been working towards for decades), and a thought-provoking if disconcertingly slick presentation by Dr. Amory Lovins of the Rocky Mountain Institute on what he sees as a completely realistic effort, already underway, to wean the United States of its addiction to oil — with no net cost. Those with a small to moderate amount of scientific background may especially enjoy MIT Professor Sara Seager’s work on efforts to discover and study planets beyond our own solar system, Texas Professor Bill Press’s proposal for how to rethink the process of drug trials and approvals in the age of electronic patient records, Sir Martin Rees’s views on the state of our understanding of the universe, and Caltech’s Joseph Kirschvink’s contention that scientific evidence tends to favor the notion that life on this planet most likely started on Mars.
But really, if you haven’t heard about all the different things Freeman Dyson has done, or read any of his writings, you should not miss the opportunity. Start here and here, and enjoy!
Many happy returns, Professor Dyson; you have been an inspiration and a role model for several generations of young scientists, and may you have many more happy and healthy years to come!
ON September 29, 2013
I attended a conference this past week celebrating two great physicists (Steve Shenker and Renata Kallosh) whom I got to know pretty well during the early part of my career. Unlike most of the conferences I’ve attended in recent years, there were no talks at all about the Large Hadron Collider; the community of speakers was largely drawn from experts on quantum field theory, quantum gravity, string theory and cosmology.
Any one of the talks would require an extensive article, especially since the required background material isn’t currently explained on this website. So rather than get bogged down in details, I thought I’d try to give you more of the general flavor — reflective, perhaps, of the tenor of the field at the moment. I’ll cover a couple of the talks later, if time permits (though I’m a bit under the gun at the moment…)
If you like to put labels on people, you’d probably call most of the speakers “string theorists.” This is a useful label if you’re in a hurry and not very interested, or if you want to abuse people, but not so useful if you want to actually understand their research. Indeed, out of about 21 talks, there were 3 on string theory. That said, many of the speakers have in the past done some research in string theory, and many of the talks owe a debt to lessons that have been learned from string theory.
So what were the talks about? What are these people actually doing? (more…)
ON September 16, 2013
This week I’m at Stanford University, where I went to graduate school, attending a conference celebrating the illustrious careers of two great physicists, Renata Kallosh and Steve Shenker.
Kallosh is one of the world’s experts on black holes, supersymmetry, cosmic inflation (that period, still conjectural but gaining acceptance, during which the universe is suspected to have expanded at an unbelievable rapid rate), and “quantization” (i.e., on how to define quantum field theories and quantum gravity theories so that they actually make mathematical sense — which is not easy to do correctly). Much of her work concerns supersymmetry and its application to quantum gravity and to superstring theory. Her technical expertise and her inventiveness are legendary, as is her friendly enthusiasm. I’ve known her since I was a graduate student; she was one of a number of famous scientists from the former Soviet Union who came to the United States around 1988-1989. Aside from just interacting with her within Stanford’s small community of theoretical physics students, postdocs and faculty, I also attended two courses that she taught on advanced topics, one on supersymmetry and one on quantization.
Shenker is famous for a number of papers that significantly changed our understanding of quantum field theory, quantum gravity and string theory. His fame derives in part from his ability to extract deep insights about physics from just a few mathematical clues — often ones that only he recognizes as being clues in the first place. Shenker was a faculty member at Rutgers when I was a postdoctoral researcher there in the mid-90s. (He later moved to Stanford.) I cannot count the profound lessons that I learned during those years from him (and the other Rutgers faculty), both at our daily group lunch, and in the lounge where several of the faculty and other postdocs would regularly gather in the mornings. And I was even fortunate enough to write a paper (on black holes and their entropy) together with him and another then-postdoc, Dan Kabat. Aside from his down-to-earth no-nonsense style, and his strong support of young people and their ideas, one thing I remember well about Shenker is that it was perilous to say anything interesting to him while walking back from lunch on a bitterly cold day. He would stop and think… and the rest of us would freeze.
In the wider world of the public, and especially the blogosphere, Kallosh and Shenker would probably be labelled as “string theorists.” Such terminology would be somewhat crude, for it would fail to capture the range and depth of their careers. Appropriately, the talks at the conference so far have ranged widely, including general attempts to make some sense of quantum gravity, discussion of the information-loss problem of black holes (the so-called “firewall” problem), unexpected subtleties in how quantum field theory works (yes, we are still learning!), new ways of thinking about the physics of electrical conductors and insulators, and advances in our understanding of cosmic inflation. And there were even a couple of talks on string theory. (That said, the long shadow of string theory, and its direct and indirect influence on many other subfields, can be palpably felt at this conference. More on that subject another day.)
Since I’ve been so busy with Large Hadron Collider physics in recent years, and haven’t been following these subfields closely, it’s been a very educational conference for me. I’ll describe some of the talks later in the week.
ON September 11, 2013
I’m still early on in my attempts to explain the “naturalness problem of the Standard Model” and its implications. A couple of days ago I explained what particle physicists mean by the term “natural” — it means “typical” or “generic”. And I described how, at least from one naive point of view, the Standard Model (the equations we use to describe the known elementary particles and forces) is unnatural. Indeed any theory is unnatural that has a
But I didn’t actually explain any of this yet; I just described it.
Specifically, I didn’t start yet to explain what causes the Standard Model to be unnatural. This is important to do, because, as many attentive readers naturally complained, my statements about the unnatural aspect of the Standard Model was based on a rather arbitrary-sounding statistical argument, and story-telling, which is hardly enough for scientific discussion. Patience; I’ll get there, not today but probably the next installment after today’s.
To see why the argument I gave is actually legitimate (which doesn’t mean it is right, but if it’s wrong it’s not for a simple reason you’ll think of in five minutes), it is necessary to look in a little bit more detail at one of the most fundamental aspects of quantum field theory: quantum fluctuations, and the energy they carry. So for today I have written an article about this, reasonably complete.
Be prepared — the article runs headlong into the only naturalness problem in particle physics that is worse than the naturalness problem of the Standard Model (the one I wrote about on Tuesday)! I am referring to the “cosmological constant problem”. In a nutshell:
After you’ve read about quantum fluctuations and the cosmological constant problem, and have a bit of a sense as to why it is so hard to make it go away, we can go back to the Standard Model, and try to understand the naturalness problem that is associated with the Higgs particle and field. It all has to do with another aspect of quantum fluctuations — the fact that their energy depends on, and therefore helps determine, the average value of the Higgs field.
ON August 30, 2013
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