Of Particular Significance

Author: Matt Strassler

Meanwhile, On the Other Side of the Planet

This week I’ve escaped the power outages, the gasoline shortages, the cold and the snow of my home town, and have been visiting warm and humid Hong Kong. Today I gave a colloquium (same one, more or less, as I gave last month at the University of Toronto, on-line here) at the physics department of the Chinese University of Hong Kong (CUHK). CUHK is one of three universities in Hong Kong that are banding together to try to establish a particle physics presence at the Large Hadron Collider (LHC) and beyond.

I’m in Asia because of next week’s Hadron Collider Physics Symposium (HCP 2012), a conference that will be held in Kyoto, Japan. Among other things, many new measurements using 2012 data from the LHC will be presented at this conference, along with updates of the measurements of the properties of the new Higgs-like particle whose discovery was announced in July. Stay tuned for posts on the new LHC results next week.

POSTED BY Matt Strassler

ON November 9, 2012

Another Storm Predicted

The greater New York region, having been broken into disconnected and damaged pieces by Hurricane/Nor’Easter Sandy, is still reassembling itself. Every day sees improvements to electrical grids and mass transit and delivery of goods, though there have been many hard lessons about insufficient preparations. Here’s an impressive challenge: over a million people and thousands of businesses lack electrical power; therefore many of them are running generators, to stay warm, keep food cold, and so forth; but the generators require fuel, typically diesel or gasoline; and so there is a greater need for fuel than usual; but a significant fraction of the petrol stations can’t pump fuel for their customers… because they lack electrical power and don’t have their own generators. These and other nasty surprises of post-storm recovery should be widely noted by policy makers and the public everywhere, especially in places that, like New York when I was a child, rarely experience disasters.

Unfortunately, another storm (a simple nor’easter) is now forecast for mid-week. While much weaker than the last, it is potentially still a dangerous situation for a region whose defenses are still being repaired. As was the case with Sandy, the new storm was already signaled a week in advance by the ECMWF (European Center for Medium-range Weather Forecasting), the current European weather-forecasting computer program or “model”. Confidence in the prediction has been growing, but still, predictions so far in advance do change. Also one must keep in mind that a shift in the storm’s track of one or two hundred miles or so could very much change its impact, so the consequences of this storm, even if it occurs, are still very uncertain. But again we are reminded, as we were last week, that weather forecasting has dramatically improved compared to thirty years ago; the possibility of a significant storm can now often be noted a week in advance.

What is this European ECMWF model? what is its competitor, the US-based GFS (Global Forecast System) model? And what about the other models that also get used? All of these are computer programs for forecasting the weather; all of them use the same basic weather data as their starting point, and all have the same basic physics of weather built into their computer programs. So what makes them different, and more or less reliable than one another? I asked one of my commenters, Dan D., about this after my last post. Here’s what he said, along with my best (and hopefully accurate) attempts at translation for less experienced readers: (more…)

POSTED BY Matt Strassler

ON November 5, 2012

Sandy: Amazing. Science: Amazing.

My neighborhood of New York City may remain without power for a few more days, but fortunately visible signs of damage are limited — none of the widespread destruction found along the immediate coast of the city and of nearby communities, where the sea rose and swallowed up land that had not seen salt water in many decades, even centuries. Many trees are down, and countless houses and businesses are wiped out by the sea’s wrath, even entire beach communities. The numbers of lost homes are surely in the thousands, if not more, with 100 houses alone destroyed in a runaway fire in the neighborhood of Breezy Point, cut off from firefighters by the storm’s high water.

Unfortunately, many people along the coast, lulled into complacency by the fact that last year’s Tropical Storm (formerly Hurricane) Irene was a bit less furious along the coast than was forecast, decided not to evacuate. Unfortunately indeed, because the forecast for Hurricane Sandy was worse than for Irene, and this time, there was no lucky break to make the reality of the storm significantly less severe than the worst-case prediction. I myself know of households who decided to evacuate at the last minute and almost didn’t make it out alive, and others who rode out the storm and found themselves in considerable danger. That so many people remained in harm’s way required “first responders”, as they are termed here, mainly members of the police and fire departments, to make many rescues, quite a few of which wouldn’t have been necessary had people heeded the warnings. For risking their lives to save so many others, the first responders are widely and justifiably hailed as heroes.

Also deserving of high praise, in my view, are some of the leading politicians and other civic leaders in our region’s states and cities. There are quite of few of them whom I don’t agree with politically and whom I personally don’t like very much, but on the whole they all seem very smart. And in this case they understood the risks, took them seriously, and made prudent decisions to order evacuations of areas in danger and to protect public property. They deserve a lot of credit for their non-nonsense approach.

But I feel that there’s an important story that the press is almost ignoring. There’s another group of people, little-mentioned in the media, who probably saved more lives and property than anyone else. I refer to the experts at the National Hurricane Center (NHC), and more generally the various branches of the National Weather Service (NWS) and its parent, the National Oceanic and Atmospheric Administration (NOAA). (more…)

POSTED BY Matt Strassler

ON October 31, 2012

Guest Post: Anand Gnanadesikan, Oceanographer

I know Anand Gnanadesikan, professor at Johns Hopkins University’s department of Earth and Planetary Sciences, from when we were both studying physics as undergraduates in college. He wrote something today that speaks with more authority than I could in my post earlier this morning, and it is a pleasure to make it available to you.

As Sandy approaches the coast I am very thankful for my former colleagues at the Geophysical Fluid Dynamics Lab who have spent decades trying to make better predictions of tropical cyclones. And the colleagues around the world who have spent decades developing the techniques of observing and modeling the physics of cyclones. Both the recurving of the storm and the high storm surge (currently already at major flood levels at a number of points between NY and DE) would have taken tens of thousands of people, at a minimum, by surprise. Kurihara’s first paper in the line of research that led to today’s prediction (http://www.gfdl.noaa.gov/bibliography/results.php?author=1061) was in 1965. It took him almost a decade to get to the first three-dimensional model of a hurricane and another couple of decades to improve the models to the point where they showed useful skill.

Just a little plug — it is important to remember that this kind of event, low-probability, high impact, is what well-run government is for. Putting together a storm-surge warning system for NY Harbor is not something that a private company is likely to do — the chances of it being used in any given 10-year period are so small as to make it a worthless investment. And the research that goes into making a forecast like this involves understanding of small-scale turbulence, understanding the transfer of radiation through the atmosphere and its interaction with multiple scatterers and absorbers, figuring out how to put weather satellites into orbit and keep them running, figuring out how to incorporate this information in computer codes, getting these codes to run reproducibly on large numbers of processors… almost all of this was accomplished by people working on the government dime.

Anand Gnanadesikan

POSTED BY Matt Strassler

ON October 29, 2012

North-East Winds A-Blowin’

The big storm of 2012 (at least, we hope it’s the biggest we’ll see this year) is approaching the New York City area, and though no one can predict in detail how bad it will be and for whom, there’s no question that with so much energy to play with, post-tropical quasi-hurricane quasi-nor’easter Sandy (also called “Frankenstorm” in honor of the Halloween holiday) is going to hit some of us very hard in the northeastern United States. Not that it will be a disaster everywhere in the region. With hurricane Irene last year, some areas just had a bit of wind and rain, while others had tremendous flooding that wiped out towns and roads and houses and history… and a few dozen lives, too. It will likely be the same this time.

How unusual is this storm? Several weather forecasters have been quoted as saying that their supercomputer-based forecasting tools, which predicted Sandy to strengthen and become a monster in size, were doing things they’d never previously seen them do. Right now, all you have to do is look at the weather map — the fact that there are tropical force winds extending over several hundreds of miles, and at the fact that the pressure of the atmosphere at the core of this storm is around 946 millibars and falling — to know there’s a lot of energy in this system that has to go somewhere, and is going to be taken out on somebody. Although this is a Category 1 hurricane in terms of its fastest winds, 946 millibars is what one expects for a strong Category 3 hurricane; 1000 is average atmospheric pressure, and the mid-800s is about as low as it ever gets. By comparison, the great blizzard of 1993 had a central pressure of about 960 millibars. The Perfect Storm of 1991 (also a nor’easter-hurricane hybrid, like Sandy) had a central pressure of 972 millibars. Anyone who thinks Sandy isn’t a dangerous storm hasn’t read enough history. (more…)

POSTED BY Matt Strassler

ON October 29, 2012

Shock, Foreshock and Aftershock in Italy

It’s hard to know quite what to say about the verdict in Italy convicting scientists — experts on earthquakes — for having… for having… well, what, exactly did they do? That’s the whole question. They made pronouncements that tried to state that risks of a big quake, following a swarm of smaller earthquakes in the L’Aquila area of Central Italy, were low, although of course not zero. But their wording and their calls for calm led to some people staying in their homes instead of remaining outdoors, and consequently losing their lives when, in fact, the big quake did take place soon after. The issue is not whether they failed to predict the quake — no one is arguing they could have done that. The issues are whether they did enough to make clear that there was a small risk of a big quake, and also, who is ultimately responsible — the experts, the government, or the public — for making the final cost-benefit analysis about the risks to individuals’ lives?

And of course, following the conviction, and a sentence of six years in prison for manslaughter, the next question is: even if this sentence is overturned on appeal, what scientist, or expert of any type, will dare to give advice to the Italian public in future, knowing that if the advice proves incomplete or unwise in retrospect, the result may be incarceration? Has Italy lost its wisest advisors? (Four members of the “Great Risks Commission” have already resigned, including one of Italy’s greatest theoretical particle physicists, and I doubt they’ll return without new legal protections.) Will other countries lose theirs?

The issue at stake is clearly not Italian earthquakes; it is expert advice. Sometimes I feel that we in modern society are forgetting how to be grown-ups and take responsibility for our own actions, and how to accept that bad things do just happen sometimes and it isn’t always someone’s fault. When we go and get advice from anyone — whether it be medical advice, financial advice, advice about the weather or advice about the risks from earthquakes — we need to remember it’s provided by a human being. Ideally that human being has access to the best information available and understands the odds, and will give us a recommendation based on the odds — on the probabilities for various things to happen. But even when it is the best available advice, it’s based on odds… on statistics. It’s an educated guess — yes, it’s educated, but also yes, it’s a guess.

And one thing that is dead certain, given that it is a guess based on odds, is that occasionally — rarely, perhaps, but not never — that guess will be wrong. It’s inevitable, even if the expert is making the best possible recommendation, based on the best available information and the most accurate possible assessment of the odds. When that bad guess happens, property may be lost, and people may die. It’s sad, but it is inherent in the nature of odds and probabilities. (more…)

POSTED BY Matt Strassler

ON October 25, 2012

Garisto’s Reply to Previous Post

Robert Garisto sent me a reply to my previous post; here it is. [A “vev” is shorthand for a non-zero value in the vacuum of space, what I call a “non-zero average value”.]

—

Matt – Thanks for your extensive reply to my comment! Of course I agree that a scalar field without a vev can have a hard mass term. And I do agree that how the Higgs boson gets mass is at least somewhat different than how the W does.

Let’s agree to define a Higgs as a scalar field with a vev. Then I think you agree that the mass of the excitation about the vev, the Higgs boson, is not a hard mass term, one obtains it by finding the minimum of the potential as you did above. Now if there are other scalars with vevs, the mass of the Higgs boson we are concentrating on can depend on those too. But isn’t it correct to say that the mass of such a Higgs boson goes to zero in the limit that all of those vevs go to zero? If so, I would say that the Higgs boson mass is provided by the Higgs fields (all scalars with nonzero vevs).

Anyway, the main reason I made the comment is that for the purposes of explaining to the public electroweak symmetry breaking, I think it makes sense to say that the Higgs boson mass comes from the Higgs field, because it is, in the SM, proportional to the vev. It’s also kind of neat, I think.

—

We disagree, that’s all there is to it. What Garisto says about the Standard Model is a simple consequence of dimensional analysis, not a fundamental relation that applies widely. And no, it is not correct to say that the mass of a Higgs boson always goes to zero in the limit that all vevs go to zero; there can be first order phase transitions in which, as the parameters change, the Higgs field’s vev jumps from non-zero to zero abruptly, and the mass of the Higgs particle is never zero. So I think to tell the public that the Higgs particle gets its mass from the Higgs field is to confuse them into thinking that the Higgs particle gets its mass the same way the other known particles do — which is false.

But in any case, we agree it’s not that big a deal. The thing which is important for the public to understand is that the Higgs field does not give mass to all massive objects — such as atomic nuclei and black holes. And the thing which it is important for particle physics students to understand is that the Higgs mass is not generically proportional to the vev of the Higgs field.

POSTED BY Matt Strassler

ON October 24, 2012

Does the Higgs Field Give the Higgs Particle Its Mass, or Not?

When I wrote my article last week about the relation between the Higgs and gravity, emphasizing that there really was no relation at all, I said that the Higgs field is not the universal giver of mass. I cited four reasons:

The Higgs field does not give an atomic nucleus all of its mass, and since the nucleus is the vast majority of the mass of an atom, that means it does not provide all of the mass of ordinary matter.
Black holes appear at the centers of galaxies, and they appear to be crucial to galaxy formation; but the Higgs field does not provide all of a black hole’s mass. In fact the Higgs field’s contribution to a black hole’s mass can even be zero, because black holes can in principle be formed from massless objects, such as photons.
There is no reason to think that dark matter, which appears to make up the majority of the masses of galaxies and indeed of all matter in the universe, is made from particles that get all of their mass from the Higgs field.
The Higgs field, though it provides the mass for all other known particles with masses, does not provide the Higgs particle with its mass.

Although it doesn’t matter too much to the main point of the Higgs-and-gravity article (since the first three points are not in question), the editor of a leading physics journal, Robert Garisto, took issue with the fourth point, arguing that I was making a statement that really wasn’t right, or at least is too strong. His argument has some merit, though in the end, I stick with my statement. I think it’s worth describing what he had in mind (as best I understand it) and why I feel strongly that one should think about it differently. There are some semantic aspects to the disagreement, but there are also some interesting and important subtle scientific points. I don’t want to suggest that this discussion is really that big a deal — the very fact that we can argue about whether the Higgs field does or doesn’t provide the Higgs particle with its mass distinguishes the Higgs particle from, say, the W particle, whose mass indisputably arises from the Higgs field. But there’s something to learn here about quantum field theory and how the Higgs mechanism works. (more…)

POSTED BY Matt Strassler

ON October 23, 2012

From the Higgs Field to the Higgs Particle

With my series of articles on Fields and Particles complete, I’m continuing my series of articles on How the Higgs Field Works. (These sets of articles require a little math and physics background, the sort you’d get in your first few months of a beginning university or pre-university physics class.)

The first article in the new series was an overview of The Basic Idea behind how the Higgs field works. (In these articles I’m mainly concentrating on the simplest type of Higgs, the Standard Model Higgs field and particle.) Then came an article about why and how the Higgs field becomes non-zero. And the newest article explains how the Higgs particle arises as the quantum of waves that oscillate around the non-zero value of the Higgs field, and how its mass is determined by the equation of motion of the Higgs field.

POSTED BY Matt Strassler

ON October 22, 2012

Colloquia Here and There

This Wednesday I was visiting the University of Massachusetts, in the currently colorful town of Amherst, where I gave a colloquium (an hour-long talk aimed at a physics department’s undergraduate majors, graduate students and faculty who are not themselves experts in particle physics) entitled The Quest for the Higgs Boson. It’s similar to the one I gave two weeks ago at the University of Toronto, which is available on-line now. There’s audio and there are slides, but no video, so I’m afraid you’ll have to figure out on your own how the slides and audio fit together; but I think it should be fairly obvious.

If, however, you’re not a physicist or physics student, but you have been following particle physics a little bit, perhaps by reading this blog or Scientific American articles or books for laypeople by, say, Brian Greene or Lisa Randall, then you might instead want to try listening to this lecture I gave recently, which is also in the form of an audio feed plus slides. It makes far fewer assumptions about what audience members are familiar with. And of course there’s always my [in]famous video clips from my March 2011 public lecture on the Large Hadron Collider; a bit out of date since they were made before the new Higgs-like particle was found, but still basically covering what you need to know.

Please note these presentations are under copyright.

POSTED BY Matt Strassler

ON October 19, 2012

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