The Hunger for Power: Geopolitics and Particle Physics

A few days after Russia invaded Ukraine (I will not call it a “war,” as that might offend Czar Vlad and his friends) for the nth time, my thoughts turned to the consequences for the CERN laboratory and for upcoming research at the Large Hadron Collider [LHC].   It was clear that Putin would blackmail Europe using his oil and gas supplies, leading to a spike in energy prices and a corresponding spike in CERN’s budget.

Of course I didn’t foresee the heat waves and drought that have swept Europe, or the maintenance problems at France’s nuclear plants, which have made the energy crisis that much worse.  (Even though global climate change is now quite obvious, and the trends are partially predictable, one can’t predict what will happen in any given year.)  I am not familiar with the budgetary consequences of these higher energy prices for CERN operations, but they cannot be good.

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Could CERN open a portal to… somewhere? (anywhere?)

For general readers:

Is it possible that the particle physicists hard at work near Geneva, Switzerland, at the laboratory known as CERN that hosts the Large Hadron Collider, have opened a doorway or a tunnel, to, say, another dimension? Could they be accessing a far-off planet orbiting two stars in a distant galaxy populated by Jedi knights?  Perhaps they have opened the doors of Europe to a fiery domain full of demons, or worse still, to central Texas in summer?

Mortals and Portals

Well, now.  If we’re talking about a kind of tunnel that human beings and the like could move through, then there’s a big obstacle in the way.  That obstacle is the rigidity of space itself.

The notion of a “wormhole”, a sort of tunnel in space and time that might allow you to travel from one part of the universe to another without taking the most obvious route to get there, or perhaps to places for which there is no other route at all, isn’t itself entirely crazy. It’s allowed by the math of Einstein’s theory of space and time and gravity.  However, the concept comes with immensely daunting conceptual and practical challenges.  At the heart of all of them, there’s a basic and fundamental problem: bending and manipulating space isn’t easy.  

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The Standard Model More Deeply: The Nature of Neutrinos

Earlier this week I explained how neutrinos can get their mass within the Standard Model of particle physics, either by engaging with the Higgs field once, the way the other particles do, or by engaging with it twice. In the first case, the neutrinos would be “Dirac fermions”, just like electrons and quarks. In the second, they’d be “Majorana fermions”. Decades ago, in the original Standard Model, neutrinos were thought not to have any mass at all, and were “Weyl fermions.” Although I explained in my last post what these three types of fermions are, today I want go a little deeper, and provide you with a diagrammatic way of understanding the differences among them, as well as a more complete view of the workings of the “see-saw mechanism”, which may well be the cause of the neutrinos’ exceptionally small masses.

[N.B. On this website, mass means “rest mass” except when otherwise indicated.]

The Three Types of Fermions

What’s a fermion? All particles in our world are either fermions or bosons. Bosons are highly social and are happy to all do the same thing, as when huge numbers of photons are all locked in synch to make a laser. Fermions are loners; they refuse to do the same thing, and the “Pauli exclusion principle” that plays a huge role in atomic physics, creating the famous shell structure of atoms, arises from the fact that electrons are fermions. The Standard Model fermions and their masses are shown below.

Figure 1: The masses of the known elementary particles, showing how neutrino masses are much smaller and much more uncertain than those of all the other particles with mass. The horizontal grey bar shows the maximum masses from cosmic measurements; the vertical grey bars give an idea of where the masses might lie based on current knowledge, indicating the still very substantial uncertainty.

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At a Workshop on Hidden Particles at the LHC

Cutting edge particle physics today:

I’ve been spending the week at an inspiring and thought-provoking scientific workshop. (Well, “at” means “via Zoom”, which has been fun since I’m in the US and the workshop is in Zurich; I’ve been up every morning this week before the birds.) The workshop brings together a terrific array of particle theorists and Large Hadron Collider [LHC] experimenters from the ATLAS and CMS experiments, and is aimed at “Semi-Visible Jets”, a phenomenon that could reveal so-far-undiscovered types of particles in a context where they could easily be hiding. [Earlier this week I described why its so easy for new particles to hide from us; the Higgs boson itself hid for almost 25 years.]

After a great set of kick-off talks, including a brand new result on the subject from ATLAS (here’s an earlier one from CMS) we moved into the presentation and discussion stage, and I’ve been learning a lot. The challenges of the subject are truly daunting, not only because the range of possible semi-visible jets is huge, but also because the scientific expertise that has to be gathered in order to design searches for semi-visible jets is exceptionally wide, and often lies at or beyond the cutting edge of research.

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Celebrating the 34th Birthday of the Higgs Boson!

Ten years ago today, the discovery of the type of particle known as the “Higgs Boson” was announced. [What is this particle and why was its discovery important? Here’s the most recent Higgs FAQ, slightly updated, and a literary article aimed at all audiences high-school and up, which has been widely read.]

But the particle was first produced by human beings in 1988 or 1989, as long as 34 years ago! Why did it take physicists until 2012 to discover that it exists? That’s a big question with big implications.

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A Big Think Made of Straw: Bad Arguments Against Future Colliders

Here’s a tip.  If you read an argument either for or against a successor to the Large Hadron Collider (LHC) in which the words “string theory” or “string theorists” form a central part of the argument, then you can conclude that the author (a) doesn’t understand the science of particle physics, and (b) has an absurd caricature in mind concerning the community of high energy physicists.  String theory and string theorists have nothing to do with whether such a collider should or should not be built.

Such an article has appeared on Big Think. It’s written by a certain Thomas Hartsfield.  My impression, from his writing and from what I can find online, is that most of what he knows about particle physics comes from reading people like Ethan Siegel and Sabine Hossenfelder. I think Dr. Hartsfield would have done better to leave the argument to them. 

An Army Made of Straw

Dr. Hartsfield’s article sets up one straw person after another. 

  • The “100 billion” cost is just the first.  (No one is going to propose, much less build, a machine that costs 100 billion in today’s dollars.)  
  • It refers to “string theorists” as though they form the core of high-energy theoretical physics; you’d think that everyone who does theoretical particle physics is a slavish, mindless believer in the string theory god and its demigod assistant, supersymmetry.  (Many theoretical particle physicists don’t work on either one, and very few ever do string theory. Among those who do some supersymmetry research, it’s often just one in a wide variety of topics that they study. Supersymmetry zealots do exist, but they aren’t as central to the field as some would like you to believe.)
  • It makes loud but tired claims, such as “A giant particle collider cannot truly test supersymmetry, which can evolve to fit nearly anything.”  (Is this supposed to be shocking? It’s obvious to any expert. The same is true of dark matter, the origin of neutrino masses, and a whole host of other topics. Its not unusual for an idea to come with a parameter which can be made extremely small. Such an idea can be discovered, or made obsolete by other discoveries, but excluding it may take centuries. In fact this is pretty typical; so deal with it!)
  • “$100 billion could fund (quite literally) 100,000 smaller physics experiments.”  (Aside from the fact that this plays sleight-of-hand, mixing future dollars with present dollars, the argument is crude. When the Superconducting Supercollider was cancelled, did the money that was saved flow into thousands of physics experiments, or other scientific experiments?  No.  Congress sent it all over the place.)  
  • And then it concludes with my favorite, a true laugher: “The only good argument for the [machine] might be employment for smart people. And for string theorists.”  (Honestly, employment for string theorists!?!  What bu… rubbish. It might have been a good idea to do some research into how funding actually works in the field, before saying something so patently silly.)

Meanwhile, the article never once mentions the particle physics experimentalists and accelerator physicists.  Remember them?  The ones who actually build and run these machines, and actually discover things?  The ones without whom the whole enterprise is all just math?

Although they mostly don’t appear in the article, there are strong arguments both for and against building such a machine; see below.  Keep in mind, though, that any decision is still years off, and we may have quite a different perspective by the time we get to that point, depending on whether discoveries are made at the LHC or at other experimental facilities.  No one actually needs to be making this decision at the moment, so I’m not sure why Dr. Hartsfield feels it’s so crucial to take an indefensible position now.

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5th Webpage on the Triplet Model is Up

Advanced particle physics today: Another page completed on the explanation of the “triplet model,”  (a classic and simple variation on the Standard Model of particle physics, in which the W boson mass can be raised slightly relative to Standard Model predictions without affecting other current experiments.) The math required is still pre-university level, though complex numbers … Read more

Long Live LLPs!

Particle physics news today… I’ve been spending my mornings this week at the 11th Long-Lived Particle Workshop, a Zoom-based gathering of experts on the subject.  A “long-lived particle” (LLP), in this context, is either a detectable particle that might exist forever, or a particle that, after traveling a macroscopic, measurable distance — something between 0.1 … Read more

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