Flying over thunderstorms

I find thunderstorms fascinating. They terrify me. But when I think about them – about the physics of the storm itself – they delight me with their beauty.

From my present vantage, about 30,000 feet above the Earth in a Southwest Airlines flight, I have a unique perspective on one big storm between New Mexico and Texas. We’re skirting the storm on its southern side. The scale of the system is deceptive. From where I sit, the lightning flashes inside the clouds, or between the clouds, seem as flickering fluorescent lightbulbs in need of replacement.

Yet, each of those flashes represents the complete breakdown of air between two points in space, the molecules of water, nitrogen and oxygen ripped apart by the electric field filling the space between what will become the origin and destination of the lightning strike. Once pulled apart and stripped of electrons, the air becomes a plasma – a cloud of ions and one of nature’s most perfect conductors. This is the end for air – and a great burst of light erupts in the electric field as photons are sprayed during the ionization process. Photons, those quanta of the electromagnetic field, free stream from the clouds to my eyes, where they seem to be from but a distant and harmless flicker.

Some of the lightning strikes are muted flashes in the clouds, their ferocity cloaked by thick curtains of water vapor. Others are clear and jagged streaks in the sky, a naked wire hanging in space for a tenth of a second and glowing as bright as the sun. I can imagine the great magnetic fields generated by these lines of electric current, the interplay of Maxwell’s Equations written in the sky as moving electric charge generates magnetic fields. Those magnetic fields are touching the skin of our aircraft, inducing eddy currents in the plane’s surface. Current makes magnetic field, and changing magnetic field makes current. Faraday would be pleased.

The electric fields required to rip apart air and water are vast, and the energy released in the breakdown is immense. On the ground, such energy is capable of splitting whole trees in half as they seek the ground, on their way vaporizing liquid water in plants and blowing apart the cells that form the building blocks of the unfortunate tree. I am trying not to think about what such a strike would do to the engines of a jet.

The storm recedes behind us, its passing in relative motion behind us a harbinger of storms to come to West Texas, and perhaps even to Dallas. The fate of this weather system is hard to predict, depending on too many variables. Somehow, the complex interplay of water and ice that gave rise, through friction and the beautifully named “triboelectric effect”, to the show of lightning and thunder seems less difficult to understand than the dynamics and movement of this entire storm system. Either way, I am delighted to have seen it, and delighted that it’s behind us.

One year after Higgsdependence Day

Just over a year ago, the ATLAS and CMS experiments reported strong evidence for the existence of a new particle who was was about 126 times that of the proton. It was a boson; this meant that it carries an internal unit of angular momentum (“spin”) whose value is an integer multiple of Planck’s Constant (\hbar = 1.054 571 726(47)\times 10^{−34}\, \mathrm{J \cdot s}). Those were about the most honest and scientifically accurate statements we could make. We did not know for sure it’s actual spin; we were not positive if it was one particle or two, since different decay modes yielded slightly different masses that might indicate the presence of two closely spaced new particles.

One of the figures from the ATLAS paper entitled "Evidence for the spin-0 nature of the Higgs boson using ATLAS data." This plot summarizes some of the work that SMU student Tingting Cao contributed to the measurement of the spin and parity quantum numbers of the 126-GeV boson, now considered to be the Higgs Boson.
One of the figures from the ATLAS paper entitled “Evidence for the spin-0 nature of the Higgs boson using ATLAS data.” This plot summarizes some of the work that SMU student Tingting Cao contributed to the measurement of the spin and parity quantum numbers of the 126-GeV boson, now considered to be the Higgs Boson.

But since that time, a year has passed, and both experiments have been extremely busy. Yesterday, ATLAS submitted to the journal Physics Letters B a pair of papers that summarizes our belief, based on the scientific evidence, of the nature of this particle. Already, by earlier this year, ATLAS and CMS were saying that this was no longer a “Higgs-like” boson – it was probably the Higgs Boson predicted to exist in the 1960s. ┬áNow, by collecting the analysis efforts together and refining the techniques for assessing the properties of the newly discovered particle, we are ready to say (in print, and for peer review, for the whole community to review) that this is a spin-0 particle whose couplings to the known Standard Model particles are very “Standard-Model-like” – meaning that, for all intents and purposes, the data supports the hypothesis that this is the Higgs Boson of the Standard Model.

And with that assessment in hand, I think it’s time for high-energy physics to accept that the last great untested prediction of the Standard Model has been tested, and it’s time to elevate this grand description of nature to “The Standard Theory of Particle Physics.” For when a set of ideas so beautiful and powerful withstands the brutal an unending onslaught of experimental science that this one has, it is time to elevate it from “model” to “theory.”

The papers submitted on July 4, 2013, to Physics Letters B, are here:

“Measurements of Higgs boson production and couplings in diboson final states with the ATLAS detector at the LHC.” Submitted to Physics Letters B. Available for download at arXiv:1307.1427

“Evidence for the spin-0 nature of the Higgs boson using ATLAS data”. Submitted to Physics Letters B. Available for download at arXiv:1307.1432

Higgsdependence Day! Celebrate our freedom from symmetry.

Celebrate your independence from symmetry on Higgsdependence Day!

Today, we celebrate our freedom from symmetry – libertas ex symmetria. If the universe respected Electro-Weak symmetry, the fundamental building blocks of nature would have no mass. Thankfully, the massless oppression of that symmetry is broken in nature. As a consequence, subatomic building blocks of nature can possess mass through their interaction with the Higgs particle. One positive result? We exist at all.

The discovery of a new particle, consistent with the Higgs particle, was presented today by both the ATLAS and CMS Experiments. So let us together all celebrate our #FreedomFromSymmetry!

Let us also thank the outstanding physicists and engineers who conceived of, built, and operated these incredible machines. We should also celebrate the many Ph.D.s that have resulted and will result from the hunt for the Higgs particle and from all of the other fascinating physics topics that can be explored at multi-purpose collider-detector experiments like CDF and DZero (Tevatron), and ATLAS and CMS (LHC).

Many thanks to Joseph Tuggle for sharing the term “Higgsdependence Day” with me; I don’t know if he invented it or not, but am certainly grateful. Happy July 4th everybody!

My live blog of the results from the ATLAS and CMS seminars is available here:

http://blog.smu.edu/smucern/2012/07/04/live-blogging-release-of-atlas-and-cms-higgs-searches-with-2011-and-2012-lhc-data/