Science and Modern Society

Fusion Confusion

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By now the word is widely out that Tuesday’s fusion announcement was less of a news flash (as I initially suggested) and more of a overheated news flicker. The politician-scientists who made the announcement that they’d put 2 Megajoules of energy into a pellet of nuclear kindling, and gotten 3 Megajoules out from nuclear fusion, … Read more

Fusion’s First Good Day on Earth

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The fusing of small atomic nuclei into larger ones, with the associated release of particles carrying a lot of motion-energy, is the mechanism that powers the Sun’s furnace, and that of other stars. This was first suspected in the 1920’s, and confirmed in the 1930s. Nuclear fission (the breaking of larger atomic nuclei into smaller … Read more

[Not] A Wormhole in a Laboratory

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Well, now…

  • Did physicists create a wormhole in a lab? No.
  • Did physicists create a baby wormhole in a lab? No.
  • Did physicists manage to study quantum gravity in a lab? No.
  • Did physicists simulate a wormhole in a lab? No.
  • Did physicists make a baby step toward simulating a wormhole in a lab? No.
  • Did physicists make a itty-bitty baby step toward simulating an analogue of a wormhole — a “toy model” of a wormhole — in a lab? Maybe.

Don’t get me wrong. What they did is pretty cool! I’d be pretty proud of it, too, had I been involved. Congratulations to the authors of this paper; the methods and the results are novel and thought-provoking.

But the hype in the press? Wildly, spectacularly overblown!

I’ll try, if I have time next week, to explain what they actually did; it’s really quite intricate and complicated to explain all the steps, so it may take a while. But at best, what they did is analogous to trying to learn about the origin of life through some nifty computer simulations of simple biochemistry, or to learning about the fundamental origin of consciousness by running a new type of neural network. It’s not the real thing; it’s not even close to the real thing; it’s barely even a simulation of something-not-close-to-the-real-thing.

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The Artemis Rocket Launch and Particle Physics

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A post for general readers:

The recent launch of NASA’s new moon mission, Artemis 1, is mostly intended to demonstrate that NASA’s incredibly expensive new rocket system will actually work and be safe for humans to travel in. But along the way, a little science will be done. The Orion spacecraft at the top of the giant rocket, which will actually make the trip to the Moon and back and will carry astronauts in future missions, has a few scientific instruments of its own. Not surprisingly, though, most are aimed at monitoring the environment that future astronauts will encounter. But meanwhile the mission is delivering ten shoe-box-sized satellites (“CubeSats“) which will carry out various other scientific and/or technological investigations. A number of these involve physics, and a few directly employ particle physics.

The use of particle physics detectors for the purpose of studying the not-so-empty space around the Moon and Earth is no surprise. Near any star like the Sun, what we think of as the vacuum of space (and biologically speaking, it is vacuum: no air and hardly any atoms, making it unsurvivable as well as silent) is actually swarming with subatomic particles. Well, perhaps “swarming” is an overstatement. But nevertheless, if you want to understand the challenges to humans and equipment in the areas beyond the Earth, you’ll inevitably be doing particle physics. That’s what a couple of the CubeSats will be studying, entirely or in part.

What’s more of a surprise is that one of the best ways to find water on the Moon without actually landing on it involves putting particle physics to use. Although the technique is not new, it’s not so obvious or widely known, so I thought I’d draw your attention to it.

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W boson mass too high? Charm quarks in the proton? There’s a (worrisome) link.

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Two of the most widely reported stories of the year in particle physics,

both depend crucially on our understanding of the fine details of the proton, as established to high precision by the NNPDF collaboration itself.  This large group of first-rate scientists starts with lots of data, collected over many years and in many experiments, which can give insight into the proton’s contents. Then, with a careful statistical analysis, they try to extract from the data a precision picture of the proton’s internal makeup (encoded in what is known as “Parton Distribution Functions” — that’s the PDF in NNPDF).  

NNPDF are by no means the first group to do this; it’s been a scientific task for decades, and without it, data from proton colliders like the Large Hadron Collider couldn’t be interpreted.   Crucially, the NNPDF group argues they have the best and most modern methods for the job  — NN stands for “neural network”, so it has to be good, right? 😉 — and that they carry it out at higher precision than anyone has ever done  before.

But what if they’re wrong? Or at least, what if the uncertainties on their picture of the proton are larger than they say?  If the uncertainties were double what NNPDF believes they are, then the claim of excess charm quark/anti-quark pairs in the proton — just barely above detection at 3 standard deviations — would be nullified, at least for now.  And even the claim of the W boson mass being different from the theoretical prediction,  which was argued to be a 7 standard deviation detection, far above “discovery” level, is in some question. In that mass measurement, the largest single source of systematic uncertainty is from the parton distribution functions.  A mere doubling of this uncertainty would reduce the discrepancy to 5 standard deviations, still quite large.  But given the thorny difficulty of the W mass measurement, any backing off from the result would certainly make people more nervous about it… and they are already nervous as it stands. (Some related discussion of these worries appeared in print here, with an additional concern here.)

In short, a great deal, both current and future, rides on whether the NNPDF group’s uncertainties are as small as they think they are.  How confident can we be?

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The Hunger for Power: Geopolitics and Particle Physics

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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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Relatively Confused: Is It True That Nothing Can Exceed Light Speed?

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A post for general readers:

Einstein’s relativity. Everybody’s heard of it, many have read about it, a few have learned some of it.  Journalists love to write about it.  It’s part of our culture; it’s always in the air, and has been for over a century.

Most of what’s in the air, though, is in the form of sound bites, partly true but often misleading.  Since Einstein’s view of relativity (even more than Galileo’s earlier one) is inherently confusing, the sound bites turn a maze into a muddled morass.

For example, take the famous quip: “Nothing can go faster than the speed of light.”  (The speed of light is denoted “c“, and is better described as the “cosmic speed limit”.) This quip is true, and it is false, because the word “nothing” is ambiguous, and so is the phrase “go faster”. 

What essential truth lies behind this sound bite?

Faster Than Light? An Example.

Let’s first see how it can lead us astray.

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News Flash: Has a New Axial Higgs Boson (Possibly Dark Matter) Been Discovered?

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No.

No, no, no.

I was tempted to blame the science journalists for the incredibly wrong articles about this, but in fact it seems entirely the fault of the scientists involved.

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