Of Particular Significance

Author: Matt Strassler

Day 2 At CERN

Day 2 of my visit to CERN (host laboratory of the Large Hadron Collider [LHC]) was a pretty typical CERN day for me. Here’s a rough sketch of how it panned out:

1000: after a few chores, arrived at CERN by tram. Worked on my ongoing research project #1. Answered an email about my ongoing research project #2.
1100: attended a one hour talk, much of it historical, by Chris Quigg, one of the famous experts on “quarkonium” (atom-like objects made from a quark or anti-quark, generally referring specifically to charm and bottom quarks). Charmonium (charm quark/antiquark atoms) was discovered 40 years ago this week, in two very different experiments.
1200: Started work on the talk that I am giving on the afternoon of Day 3 to some experimentalists who work at ATLAS. [ATLAS and CMS are the two general-purpose experimental detectors at the LHC; they were used to discover the Higgs particle.] It involves some new insights concerning the search for long-lived particles (hypothesized types of new particles that would typically decay only after having traveled a distance of at least a millimeter, and possibly a meter or more, before they decay to other particles.)
1230: Working lunch with an experimentalist from ATLAS and another theorist, mainly discussing triggering, and other related issues, concerning long-lived particles. Learned a lot about the new opportunities that ATLAS will have starting in 2015.
1400: In an extended discussion with two other theorists, got a partial answer to a subtle question that arose in my research project #2.
1415: Sent an email to my collaborators on research project #2.
1430: Back to work on my talk for Day 3. Reading some relevant papers, drawing some illustrations, etc.
1600: Two-hour conversation over coffee with an experimentalist from CMS, yet again about triggering, regarding long-lived particles, exotic decays of the Higgs particle, and both at once. Learned a lot of important things about CMS’s plans for the near-term and medium-term future, as well as some of the subtle issues with collecting and analyzing data that are likely to arise in 2015, when the LHC begins running again.

[Why triggering, triggering, triggering? Because if you don’t collect the data in the first place, you can’t analyze it later! We have to be working on triggering in 2014-2015 before the LHC takes data again in 2015-2018]

1800: An hour to work on the talk again.
1915: Skype conversation with two of my collaborators in research project #1, about a difficult challenge which had been troubling me for over a week. Subtle theoretical issues and heavy duty discussion, but worth it in the end; most of the issues look like they may be resolvable.
2100: Noticed the time and that I hadn’t eaten dinner yet. Went to the CERN cafeteria and ate dinner while answering emails.
2130: More work on the talk for Day 3.
2230: Left CERN. Wrote blog post on the tram to the hotel.
2300: Went back to work in my hotel room.

Day 1 was similarly busy and informative, but had the added feature that I hadn’t slept since the previous day. (I never seem to sleep on overnight flights.) Day 3 is likely to be as busy as Day 2. I’ll be leaving Geneva before dawn on Day 4, heading to a conference.

It’s a hectic schedule, but I’m learning many things! And if I can help make these huge and crucial experiments more powerful, and give my colleagues a greater chance of a discovery and a reduced chance of missing one, it will all be worth it.

POSTED BY Matt Strassler

ON November 12, 2014

Off to CERN

After a couple of months of hard work on grant writing, career plans and scientific research, I’ve made it back to my blogging keyboard. I’m on my way to Switzerland for a couple of weeks in Europe, spending much of the time at the CERN laboratory. CERN, of course, is the host of the Large Hadron Collider [LHC], where the Higgs particle was discovered in 2012. I’ll be consulting with my experimentalist and theorist colleagues there… I have many questions for them. And I hope they’ll have many questions for me too, both ones I can answer and others that will force me to go off and think for a while.

You may recall that the LHC was turned off (as planned) in early 2013 for repairs and an upgrade. Run 2 of the LHC will start next year, with protons colliding at an energy of around 13 TeV per collision. This is larger than in Run 1, which saw 7 TeV per collision in 2011 and 8 TeV in 2012. This increases the probability that a proton-proton collision will make a Higgs particle, which has a mass of 125 GeV/c², by about a factor of 2 ½. (Don’t try to figure that out in your head; the calculation requires detailed knowledge of what’s inside a proton.) The number of proton-proton collisions per second will also be larger in Run 2 than in Run 1, though not immediately. In fact I would not be surprised if 2015 is mostly spent addressing unexpected challenges. But Run 1 was a classic: a small pilot run in 2010 led to rapid advances in 2011 and performance beyond expectations in 2012. It’s quite common for these machines to underperform at first, because of unforeseen issues, and outperform in the long run, as those issues are solved and human ingenuity has time to play a role. All of which is merely to say that I would view any really useful results in 2015 as a bonus; my focus is on 2016-2018.

Isn’t it a bit early to be thinking about 2016? No, now is the time to be thinking about 2016 triggering challenges for certain types of difficult-to-observe phenomena. These include exotic, unexpected decays of the Higgs particle, or other hard-to-observe types of Higgs particles that might exist and be lurking in the LHC’s data, or rare decays of the W and Z particle, and more generally, anything that involves a particle whose (rest) mass is in the 100 GeV/c² range, and whose mass-energy is therefore less than a percent of the overall proton-proton collision energy. The higher the collision energy grows, the harder it becomes to study relatively low-energy processes, even though we make more of them. To be able to examine them thoroughly and potentially discover something out of place — something that could reveal a secret worth even more than the Higgs particle itself — we have to become more and more clever, open-minded and vigilant.

POSTED BY Matt Strassler

ON November 10, 2014

Science, Technology and Modern Forms of Evil — Linked. (In.)

Readers are probably wondering what’s become of me, and all I can say is that career challenges are occupying 120% of my time. I do miss the writing, and hope I will get back to it soon, though it seems unlikely it will be before December. So it is all the more unfortunate that today’s post has almost nothing to do with science at all. It is an apology.

Which is weird. I have nothing to apologize for, and yet I have to apologize to everyone on my contacts list for the unsolicited invitation they received to become my contact on LinkedIn. Or rather, LinkedIn needs to apologize, but they won’t, so I have to do it. (more…)

POSTED BY Matt Strassler

ON November 4, 2014

Why did so few people see Auroras on Friday night?

Why did so few people see auroras on Friday night, after all the media hype? You can see one of two reasons in the data. As I explained in my last post, you can read what happened in the data shown in the Satellite Environment Plot from this website (warning — they’re going to make new version of the website soon, so you might have to modify this info a bit.) Here’s what the plot looked like Sunday morning.

What the "Satellite Environment Plot" on swpc.noaa.gov looked like on Sunday. Friday is at left; time shown is "Universal" time; New York time is 4 hours later. There were two storms, shown as the red bars in the Kp index plot; one occurred very early Friday morning and one later on Friday. You can see the start of the second storm in the "GOES Hp" plot, where the magnetic field goes wild very suddenly. The storm was subsiding by midnight universal time, so it was mostly over by midnight New York time. — What the “Satellite Environment Plot” on swpc.noaa.gov looked like on Sunday. Friday is at left. Time shown is “Universal” time (UTC); New York time is 4 hours later at this time of year. There were two storms, shown as the red bars in the Kp index chart (fourth line); one occurred very early Friday morning and one later on Friday. You can see the start of the second storm in the “GOES Hp” chart (third line), where the magnetic field goes wild very suddenly. The storm was subsiding by midnight Universal time, so it was mostly over by midnight New York time.

What the figure shows is that after a first geomagnetic storm very early Friday, a strong geomagnetic storm started (as shown by the sharp jump in the GOES Hp chart) later on Friday, a little after noon New York time [“UTC” is currently New York + 4/5 hours], and that it was short — mostly over before midnight. Those of you out west never had a chance; it was all over before the sun set. Only people in far western Europe had good timing. Whatever the media was saying about later Friday night and Saturday night was somewhere between uninformed and out of date. Your best bet was to be looking at this chart, which would have shown you that (despite predictions, which for auroras are always quite uncertain) there was nothing going on after Friday midnight New York time.

But the second reason is something that the figure doesn’t show. Even though this was a strong geomagnetic storm (the Kp index reached 7, the strongest in quite some time), the auroras didn’t migrate particularly far south. They were seen in the northern skies of Maine, Vermont and New Hampshire, but not (as far as I know) in Massachusetts. Certainly I didn’t see them. That just goes to show you (AccuWeather, and other media, are you listening?) that predicting the precise timing and extent of auroras is educated guesswork, and will remain so until current knowledge, methods and information are enhanced. One simply can’t know for sure how far south the auroras will extend, even if the impact on the geomagnetic field is strong.

For those who did see the auroras on Friday night, it was quite a sight. And for the rest of us who didn’t see them this time, there’s no reason for us to give up. Solar maximum is not over, and even though this is a rather weak sunspot cycle, the chances for more auroras over the next year or so are still pretty good.

Finally, a lesson for those who went out and stared at the sky for hours after the storm was long over — get your scientific information from the source! There’s no need, in the modern world, to rely on out-of-date media reports.

POSTED BY Matt Strassler

ON September 15, 2014

Auroras — Quantum Physics in the Sky — Tonight?

Maybe. If we collectively, and you personally, are lucky, then maybe you might see auroras — quantum physics in the sky — tonight.

Before I tell you about the science, I’m going to tell you where to get accurate information, and where not to get it; and then I’m going to give you a rough idea of what auroras are. It will be rough because it’s complicated and it would take more time than I have today, and it also will be rough because auroras are still only partly understood.

Bad Information

First though — as usual, do NOT get your information from the mainstream media, or even the media that ought to be scientifically literate but isn’t. I’ve seen a ton of misinformation already about timing, location, and where to look. For instance, here’s a map from AccuWeather, telling you who is likely to be able to see the auroras.

Don't believe this map by AccuWeather. Oh, sure, they know something about clouds. But auroras, not much. — Don’t believe this map by AccuWeather. Oh, sure, they know something about clouds. But auroras, not much.

See that line below which it says “not visible”? This implies that there’s a nice sharp geographical line between those who can’t possibly see it and those who will definitely see it if the sky is clear. Nothing could be further than the truth. No one knows where that line will lie tonight, and besides, it won’t be a nice smooth curve. There could be auroras visible in New Mexico, and none in Maine… not because it’s cloudy, but because the start time of the aurora can’t be predicted, and because its strength and location will change over time. If you’re north of that line, you may see nothing, and if you’re south of it you still might see something. (Accuweather also says that you’ll see it first in the northeast and then in the midwest. Not necessarily. It may become visible across the U.S. all at the same time. Or it may be seen out west but not in the east, or vice versa.)

Auroras aren’t like solar or lunar eclipses, absolutely predictable as to when they’ll happen and who can see them. They aren’t even like comets, which behave unpredictably but at least have predictable orbits. (Remember Comet ISON? It arrived exactly when expected, but evaporated and disintegrated under the Sun’s intense stare.) Auroras are more like weather — and predictions of auroras are more like predictions of rain, only in some ways worse. An aurora is a dynamic, ever-changing phenomenon, and to predict where and when it can be seen is not much more than educated guesswork. No prediction of an aurora sighting is EVER a guarantee. Nor is the absence of an aurora prediction a guarantee one can’t be seen; occasionally they appear unexpectedly. That said, the best chance of seeing one further away from the poles than usual is a couple of days after a major solar flare — and we had one a couple of days ago.

Good Information and How to Use it

If you want accurate information about auroras, you want to get it from the Space Weather Prediction Center, click here for their main webpage. Look at the colorful graph on the lower left of that webpage, the “Satellite Environment Plot”. Here’s an example of that plot taken from earlier today:

The "Satellite Environment Plot" from earlier today; focus your attention on the two lower charts, the one with the red and blue wiggly lines (GOES Hp) and on the one with the bars (Kp Index). How to use them is explained in the text. — The “Satellite Environment Plot” from earlier today; focus your attention on the two lower charts, the one with the red and blue wiggly lines (GOES Hp) and on the one with the bars (Kp Index). How to use them is explained in the text.

There’s a LOT of data on that plot, but for lack of time let me cut to the chase. The most important information is on the bottom two charts. (more…)

POSTED BY Matt Strassler

ON September 12, 2014

Will the Higgs Boson Destroy the Universe???

No.

The Higgs boson is not dangerous and will not destroy the universe.

The Higgs boson is a type of particle, a little ripple in the Higgs field. [See here for the Higgs FAQ.] This lowly particle, if you’re lucky enough to make one (and at the world’s largest particle accelerator, the Large Hadron Collider, only one in a trillion proton-proton collisions actually does so) has a brief life, disintegrating to other particles in less than the time that it takes light to cross from one side of an atom to another. (Recall that light can travel from the Earth to the Moon in under two seconds.) Such a fragile creature is hardly more dangerous than a mayfly.

Anyone who says otherwise probably read Hawking’s book (or read about it in the press) but didn’t understand what he or she was reading, perhaps because he or she had not read the Higgs FAQ.

If you want to worry about something Higgs-related, you can try to worry about the Higgs field, which is “ON” in our universe, though not nearly as “on” as it could be. If someone were to turn the Higgs field OFF, let’s say as a practical joke, that would be a disaster: all ordinary matter across the universe would explode, because the electrons on the outskirts of atoms would lose their mass and fly off into space. This is not something to worry about, however. We know it would require an input of energy and can’t happen spontaneously. Moreover, the amount of energy required to artificially turn the Higgs field off is immense; to do so even in a small room would require energy comparable to that of a typical supernova, an explosion of a star that can outshine an entire galaxy and releases the vast majority of its energy in unseen neutrinos. No one, fortunately, has a supernova in his or her back pocket. And if someone did, we’d have more immediate problems than worrying about someone wasting a supernova trying to turn off the Higgs field in a basement somewhere.

Now it would also be a disaster if someone could turn the Higgs field WAY UP… more than when your older brother turned up the volume on your stereo or MP3 player and blew out your speakers. In this case atoms would violently collapse, or worse, and things would be just as nasty as if the Higgs field were turned OFF. Should you worry about this? Well, it’s possible this could happen spontaneously, so it’s slightly more plausible. But I do mean slightly. Very slightly. (more…)

POSTED BY Matt Strassler

ON September 10, 2014

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Author: Matt Strassler

Day 2 At CERN

POSTED BY Matt Strassler

Off to CERN

POSTED BY Matt Strassler

Science, Technology and Modern Forms of Evil — Linked. (In.)

POSTED BY Matt Strassler

Why did so few people see Auroras on Friday night?

POSTED BY Matt Strassler

Auroras — Quantum Physics in the Sky — Tonight?

POSTED BY Matt Strassler

Will the Higgs Boson Destroy the Universe???

POSTED BY Matt Strassler

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