A Journey Closer to the Hot Zone (C+66)

“Don’t forget your mask.”

I haven’t been in a place where people are actually expected to gather since March 6. I have so much to remember as I re-enter the world.

I have to remember to get all my keys. Where are all my keys? My car keys are on my dresser. One of my house keys is loose; it’s been off its ring since March because I take it with me when I go out running.

I haven’t been out running since the weather got hot. It’s routinely in the 80s, 90s, and even low 100s now. With humidity, it’s intolerable outside. The loose key has been sitting for weeks on a ledge by the front door, unused except for an occasional ill-conceived walk in the heat.

I gather up the keys. I pocket my phone. I get my face mask from the container in the kitchen. I say goodbye to Jodi. (“Don’t forget your mask!”)

My throat clutches a little.

I’m heading to a medical center, which is literally one of the last places I want to be right now. In the best of times, a medical building makes me twitch. During a pandemic, it makes my skin positively crawl.

The trip to my doctor, nestled in Dallas, in a county that has seen record-breaking rises in COVID-19 cases for weeks, is a journey to the edge of the hot zone. In my mind, I picture the majors hospitals of Dallas – Parkland, UT Southwestern, Baylor, Texas Presbyterian – as bright glowing red embers where the sickest of the sick flow in … and some never come out. Highway 75 weaves through most of these hospitals, and while I am going to a small medical center away from one of the main hospitals, I feel nervous heading into a county slowly being overrun by the infected.

Of course, my home county hasn’t been spared this pandemic. We have more cases every day, using the 7-day rolling average, than we ever had in April. It gets worse every week. We broke our own record today: 186 new cases in one day. (previous record: 140) The positive test rate is hovering around 10%, double what it was a month ago. Testing is slowly going up, but so are case numbers.

Going from Collin County to Dallas County is like going from the urgent care clinic to the emergency room: it will be more crowded and more people in your immediate vicinity are going to be sicker than where you came from.

My skin crawls.

It’s irrational. But the embers of infection in Dallas and fuel of my concerns are fed by the oxygen of incompetent leadership and bad public policy. When Texas abandoned its people to SARS-CoV-2 66 days ago, on “C-Day,” the current situation was obviously inevitable. Anyone with a basic working knowledge of the germ theory of disease and an appreciation for how poor human behavior gets when there is no guidance or expectations could see this coming. The epidemiologists certainly saw this coming, but any kid with 10th-grade biology and a measure of common sense could have figured out that taking the brakes off public health measures during pandemic will only make things worse.

As I drive down 75 to my appointment, my skin crawling, what is truly sad is that I am actually relieved to be doing this instead of what I had been doing: taking required online teacher training mandated by my university.

I’m not opposed to teacher training.

I’m not opposed to making a distinction between online and in-person teaching.

I’ve spent years exploring the balance of these very two things in my own teaching. What frustrates me is who has been forced to take this 20-hour online course: only faculty who opted to teach remotely in the fall.

Since June 1, there have been 32 cases of COVID-19 identified in people on my institution’s campus. And students aren’t even back on-campus yet.

Why doesn’t this mandated training make sense? Why does it frustrate me? Two reasons.

  1. Standards: Why is my institution only now requiring faculty to achieve some minimum level of certification? Never before has my university expected me to carry any teaching certification of any kind. Why aren’t ALL faculty required to do this?
  2. Inequity: Why are faculty who opt out of in-person teaching burdened with this responsibility? Faculty are only allowed to opt-out of in-person teaching at my institution if they have a legitimate medical concern aligned with CDC guidelines. At least, when I applied for this exception those were the rules. I was only granted this option because we are (a) in a pandemic and (b) there is a serious increased risk of death or severe consequences from SARS-CoV-2 in my household. Why, then, are the most vulnerable – or those whose loved ones are deserving of this protection – given an undue burden to prove their value and merit? Basically, the assumption has been made that faculty who need to teach remotely don’t know how to teach at all.

What really made me upset about this teacher training was its mix of technical instruction (valuable for the fall) with teaching theory (arguably deserving of a separate optional course). The two are actually separable, but are made inseparable in the course. You have to wade through 40 years of information about teaching theory just to get to the exercises and finally the quiz. The course spends a lot of ink trying to explain why requiring rote memorization in students is only testing the lowest level of learning – “knowledge”. But then the exams are all 25- or 50- question tests based on regurgitation of rote memorization. (true/false, fill-in-the-blank, and multiple answer – precisely the thing 40 years of teaching research are not the best ways to assess learning)

So instead of suffering my way through one more quiz testing whether or not I know when to use the word “student” or when to use the word “learner,” I was actually looking forward to going to a doctor’s office … in the hot zone.

When medically necessary and consistent with the Centers for Disease Control (CDC) guidance, testing to diagnose COVID-19 will be available for students, staff and faculty…

From the institution’s fall reopening plan

I arrive at the doctor’s office and remain in my car. I call to check in. I am told to wear a mask inside and someone will meet me at the office door. I am ushered through reception and into a room. A quick patient intake is done. The main exam is delayed about 10 minutes while the doctor finishes up with other patients. When the doctor arrives, it’s a quick inspection and a brief conversation. I tell them just to guide me through what they want; I tell them I haven’t really been in a public place since March 6. We get on the conversation of how school’s like mine reopening in the fall. The doctor starts going on about “as long as they have lots of testing to catch cases before they get out of control…” I tell them no such plan is in place – rather, my university will only allow people to get tests for whom it’s “medically necessary” – no snapshot testing.

Since June 1, there have been 32 cases of COVID-19 identified in people on my institution’s campus. And students aren’t even back on-campus yet.

The doctor doesn’t really know what to say to that. We seem to agree that the plan in place for now is going to simply lead to outbreaks and then having to shut down in-person teaching.

The delivery of high-quality, on-campus classroom instruction will continue … providing our students with valuable in-person interaction with faculty members and with each other. Additionally, high-quality remote instruction – often in tandem with in-person classroom instruction – will provide the University with the flexibility necessary to support social distancing while encouraging the use of innovative and creative technologies.  

From my institution’s reopening plan.

And what then? When all those faculty who opted to teach in-person (because it’s necessary for their class, or perhaps because they don’t want to take a 20-hour online teacher training course just to be allowed to teach remotely) are forced to go online because the campus closes under the strain of rampant SARS-CoV-2 spreading… will they have to take this course? Of course not! Who will have time in the fall … in the middle of an unfolding pandemic on campus?

Of course, who has time in the summer? I am paid in the summer to do research. June and July, my salary is paid by the American taxpayer via the U.S. Department of Energy. This is so I can be devoted to basic research with the potential to transform human knowledge. The taxpayer is NOT paying for me to take a 20-hour online teacher training course. I technically shouldn’t be required to take such a course until August, when I would normally prep for fall teaching anyway.

Many college faculty are not as lucky as me, especially lecturers and adjuncts: they are only paid when they teach; no teaching, no pay. Expecting those faculty to conduct university business when they are not paid in the summer is somewhere in the land of unethical… I’m just not sure where exactly. It make my skin crawl.

All of us who were granted remote teaching have to complete the training by July 31. So, I am forced to either take the class at night, on my personal time (uncompensated by my university), or take time away from vacation to do the course. I opted for the latter. I’m on vacation right now. I haven’t had a break since December, but I nonetheless burned two of my vacation days taking this teacher training.

We are looking forward to delivering the unique academic experience that defines [our institution], and to rekindling the energy our students bring to campus.

A message from our university leadership in April, 2020 and updated June 29, 2020.

This is faculty life right now. Like many college faculty, I am being told that I am expected to be on campus in the fall to “preserve the on-campus experience”. We know how to provide an education, regardless of the setting, so why pick the most dangerous setting?

Coronavirus doesn’t give a fuck about the on-campus experience, except in-so-far as 18-22-year-olds crammed into the same dorm assignments as before (seriously … not making that up) and not practicing the necessary social distancing and mask wearing will provide a perfect means to spread the virus. And while 18-22 year-old students don’t tend to suffer the worst consequences of the virus, people 40 and older do… those, of course, are the faculty and staff.

The University will open with standard housing occupancy driven by student choice.

From my institution’s fall reopening plan.

So to preserve the on-campus experience (the COVID-spreading experience), we will expose the most vulnerable to a large population of the most-effective spreaders.

Let that sink in. Higher education administration, folks.

Since June 1, there have been 32 cases of COVID-19 identified in people on my institution’s campus. And students aren’t even back on-campus yet.

But to avoid this nonsense and teach online, I have to take a course when, at no previous point in my decade here, has anyone ever cared this much about how I teach. To avoid the disease, I have to prove something no in-person university teacher is asked to prove. To be honest, I am not sure what makes me more mad: the lack of teacher certification at the college level, or the inequity of this policy in the middle of a pandemic.

Take your pick. Heck… pick both.

I tried not to touch anything in the medical center. I got into the hot car, roasting in the midday Texas sun in an open-air parking lot, and popped off the mask. I sanitized my hands again. I started the car. I went home. There, I took a full Silkwood shower and sanitized my mobile phone.

And then I spent another 90 minutes finishing the online teacher training course. Afterward, I was angrier and sadder and more frustrated than I have been in a long time.

Since June 1, there have been 32 cases of COVID-19 identified in people on my institution’s campus. And students aren’t even back on-campus yet.


Many clear-thinking universities have accepted the reality of the pandemic recently. University of Southern California reversed course a few days ago and decided to abandon their in-person fall teaching model for online-only instruction, even if a fraction of students return to campus. Harvard, Yale, and Princeton just announced the same basic plan: online instruction even with a determined but modest population of students on-campus.

We wait for a sensible decision to be made on our own campus.


  1. https://blog.smu.edu/coronavirus-covid-19/smu-cases/ – cases on-campus.
  2. https://www.smu.edu/News/2020/COVID-19/Plans-for-fall-semester-2020
  3. https://blog.smu.edu/coronavirus-covid-19/2020/04/30/we-intend-to-be-open-in-fall-2020/
  4. https://news.harvard.edu/gazette/story/2020/07/harvard-to-bring-up-to-40-of-undergrads-to-campus-this-fall/
  5. https://news.harvard.edu/gazette/story/2020/06/fas-dean-confirms-teaching-to-remain-online-for-2020-21/
  6. https://yalecollege.yale.edu/get-know-yale-college/office-dean/messages-dean/plans-fall-2020-yale-college-courses-june-22
  7. https://www.princeton.edu/news/2020/07/06/princeton-announces-plan-fall-2020-guidelines-undergraduates-returning-campus
  8. https://www.latimes.com/california/story/2020-07-02/usc-will-move-most-undergraduate-classes-online-cancels-reopening

The vegetable aisle

We are taking our home garden a bit more seriously this year. The pandemic, and poor health practices by shoppers at the local grocery store, have made it more important to offset time spent in the aisles by planting at home. If C-day was the day Texas’ leadership abandoned its people, unarmed, to a new viral enemy, then this would be the resurrection of the small victory garden.

Some of the leafy greens in our small vertical garden.

For me, this started back early in the lockdown in March. I had already been told to remain away from my university campus starting March 6; I had just returned from CERN and my university had, earlier that week, banned all international travel. This gave me a small head-start on thinking ahead about what we might need during a longer lockdown, which came a couple of week’s later in Texas. At the time, I experimented with growing potatoes indoors. Two of those potato plants took off like weeds. The others I spent too long before planting, and they’re never sprouted actual plants.

Wilma, the first of my blue potatoes to sprout. The original potatoes were a gift from Jodi’s cousin, who has a beautiful and extensive garden in Wisconsin. Who knew they would become the seeds of our own little Texas garden?

The leafy greens took off fast outdoors. The potatoes indoors should be ready to harvest soon. I’ll keep some of the potatoes for new seed and replant the plants if they are still viable. We’ll have a small portion of food to eat and a little more freedom from spending too much time in the presence of average Texans who cannot be neighborly, nor show the empathy for a fellow person that is the hallmark of simple mask-wearing.

Scenes from Collin County, TX

One of my daily activities in the last 20 days (or so) has been to scoop up the COVID-19 case and death data for my county from the Texas Department of Health’s (DSHS) information center [1]. I’m not an epidemiologist; I’m a physicist. I’m not trying to make predictions; I’m making observations, assuming the data from DSHS is accurate (given under-testing and under-reporting, it’s most likely a suppressed count on both cases and deaths, but I can’t correct for that).

COVID-19 reported cases (black) and deaths (red) in Collin County, TX. Data taken from the Texas Department of Health and visualized using open-source tools (Python, Matplotlib, Seaborn, SciPy,NumPy). The green arrow indicates the date on which Collin County imposed social distancing requirements on individuals, but deemed all businesses as “essential” and allowed all to remain open. It was on March 31 (cyan arrow) that this part of the order was rescinded, and businesses were no longer all deemed “essential.”

Collin County began social distancing on March 24, 2020. At the time, we were in the middle of what would become the first major phase of exponential growth of COVID-19 cases in our County. The first case was reported to DSHS 37 days ago; by March 24 (19 days after the first case), our county had about 35 cases. At that time, the doubling time for cases was about 2 days. If we had remained on that climb, which presumably represents a doubling-time scenario before social controls over spread, then…

  • By March 26, 2 days later, we would have had 70 cases;
  • By March 28, 4 days later, we would have had 140 cases;
  • By March 31, 6 days later, we would have had 280 cases;
  • By April 2, 8 days later, we would have had 560 cases;

You get the idea. By today, 38 days after the first reported case, if you run the math we would have had almost 9700 cases. Let that sink in. If the trend that emerged between about March 19 and March 27 (inclusive) had persisted, we would be approaching something in the neighborhood of 10,000 cases alone in Collin County right now.

(Of course, the exact numbers should not be taken strictly literally; there is statistical error on each count, and in addition to that there is an unknown systematic error from under-recording of cases – likely, the above are underestimates, and so can be considered a best-case situation.)

The rapid increase in cases is the direct result of how unchecked diseases spread: exponential growth. However, about one week after social distancing measures went into effect in the county, the doubling rate slowed. Instead of doubling every 2 days, we entered a period (where we still are now) where the doubling rate changed to 7.5 days. It lengthened (a good thing!) by just over a factor of 3. That change in slope began around March 28.

What this meant was that as of April 10, instead of the almost 9700 cases we might have had on the old doubling trend (when we were doing no appreciable social distancing), we instead have reached only 400 cases using limited social distances (businesses were finally not all deemed “essential” on March 31, and we should be expect to see the effects of that in the next weeks).

Social distancing is working. The data backs this up, even in a segment of America like Collin County. But we have not peaked. We have not peaked. We’ve slowed the spread, but we have no stalled nor reversed it. This is no time for complacency.

We are in a world war. The actors are not nations, the prizes are not borders. Every place is vulnerable. The prize is living through this without succumbing to a nasty virus. Every new infection is a victory for the virus. Every person who avoids the virus is a victory for humanity.

We humans are both the soldiers and the battlefield. Each of us is the weapon and the target. Right now, the best medical tactic is to hunker down in our trenches, spread out, and try not to be easy pickings for the respiratory bombs deployed by the Coronavirus.

But we need an offensive plan. We need a coordinated strategy. We need a team of generals to fight a war on multiple fronts: developing tactical weapons against the enemy (vaccines, anti-viral drugs), developing new defensive strategies (deployments of medical equipment), and developing strategic campaigns to cut the enemy off from its supply of resources (e.g. rapid testing, contact tracing, and targeted quarantine).

But we have no leaders. Not really. So for now, we soldiers must run the fight. For us, that means we hunker down in our trenches, isolated and in modest safety. It is a safety threatened if we are suddenly ordered by the loud lunatics to “charge!” without weapons, without armor, without a strategy.

Keep distancing and carry on.


[1] https://dshs.texas.gov/news/updates.shtm#coronavirus

A View from the Shadows: Lighthouse on the Cosmic Shore

I found myself recently standing on the shores of Lake Michigan, reflecting on the connections between these human spaces and the most vast spaces of the cosmic shores. 

The Lighthouse at Cana Island on Lake Michigan in Wisconsin.

The lighthouse on Cana Island in Door County, Wisconsin stands on the shores of Lake Michigan. At a height of 87 feet, the tower is host to a fixed light focused and beamed out into the lake by a third-order Fresnel lens. Ships on Lake Michigan will know this is the Cana Island light by the fact that it has no periodicity. As part of the light house network along the shores of this great lake, this beacon provides important navigation information to ships that may otherwise wander too close to shore, or become lost in poor weather while moving between ports on this vast body of water.

The Crab Nebula, whose gases are whipped into a fury by the pulsar at the center.

In the ocean of the cosmos, there are also lighthouses. These are built, not by engineers and masons and carpenters and lensmakers, but by the violent deaths of stars that started out a little too heavy, burned a little too bright and too fast as a result, and died in a terrific collapse. These cosmic beacons are Goldilocks corpses: not too big to collapse all the way to black holes, and not too small to simply puff off their outer atmospheres and die quietly as a white dwarf. These are the neutron stars, stellar corpses spun so fast by the uneven collapse of the star that once birthed them that they pulse rhythmically and regularly for millions of years as they slowly spin down. No two spinning neutron stars – “pulsars,” as they are also known – spin at quite the same rate when born. As a result, like the lighthouses that line coastal waters, pulsars that dot the cosmos and broadcast their periodic songs provide a kind of “cosmic carte des phares (lighthouses map)” that might, one day, allow ships capable of sailing the stars to know where they are.

A Tale of Light and Glass

People visiting historic lighthouses might be doing so for a wide variety of reasons. Few people likely realize that each of these structures represents the end of a long chain of technological marvels, the culminations of many competitions among nations to be the best, to go further with science and technology than other nations, and in doing so to preserve both blood and treasure.

One competition that lies at the heart of the Cana Island lighthouse is the battle of national secrets and the struggle between scientists to perfect optical glass. This story is partly told in the most recent “Cosmos” TV series (2014), especially in the episodes “Hiding in Light” (Episode 5) and “The Electric Boy” (Episode 10). While not central to the story arc of the TV series, peripheral mentions are made of the German perfection of optical glass under the direction of Joseph von Fraunhofer, a brilliant scientist who, among other things, observed that light spectra (the rainbows of color achieved by splitting white light into its constituent colors) are not continuous, but rather possess “gaps” or “missing colors.” These are the fingerprints of atomic structure. He would not come to understand the meaning of the observation of these dark spots in spectra – that would be left to a later generation of physicists – but Fraunhofer’s discovery was a step on the way to our modern picture of the universe and its structure. German optical glass, his own perfection, was the envy of Europe. A scientific power that wanted to rival Germany would have to unlock the secrets of such glass-making.

The French managed to make quite excellent optical glass, though it was not the better of the Bavarian glass whose secrets Fraunhofer largely took to the grave when he died in 1826 at the age of 39. In fact, the glass-making of the French, while adequate, was significantly challenged by the goal of the French state to deploy a serious and advanced network of lighthouses along French territorial coasts. What was it about this plan that provided such an obstacle to French glassmakers?

Portrait of “Augustin Fresnel”
from the frontispiece of his collected works (1866). This work is over 100 years old and is in the public domain in the country of origin.

In short, the answer is Augustin-Jean Fresnel. Fresnel was brought into the French Academy of Science thanks to his remarkable (and unpopular) ideas about describing light as a wave. Since the time of Isaac Newton, the “corpuscular” theory of light – the notion that light is made from little packets or particles – had taken hold in many scientific circles. To challenge it was to court heresy. But Fresnel had developed an extremely rigorous mathematical framework to describe that patterns of light and dark that are observed when light was shone past a sharp boundary, such as the edge of a razor blade or through a very narrow slit. Only Fresnel’s wave ideas, and especially the advanced application of calculus he developed to make calculations and predictions much easier, even for complex shapes, explained these patterns.

At the height of scientific challenges to Fresnel’s ideas, others noted that he had failed to calculate what light would do when shone down on a circular disc. When they ran the math, his framework predicted that a bright spot should appear at the center of the shadow cast by the disc. A bright spot dead center in a shadow? The idea seemed ludicrous. But an experiment staged for the benefit of the French Academy showed that Fresnel’s equations were, in fact, correct: the shadow of a circular disc contained a minute bright spot at its center. Fresnel’s equations predicted a phenomenon never before observed, and when looked for, it was found.

Fresnel’s larger story is that of a man tasked with boring engineering jobs who longed instead to play with light. He had a job to do for the French state, one which he took every opportunity to avoid doing in pursuit of his theory of light. However, the two jobs intersected when Fresnel became convinced that the way to improve lighthouses, making new ones to rival those of the English, was to switch from using reflectors that beam the light out to sea to using refractors to do the same job. Using his new theory of light, Fresnel did the math and convinced himself that a superior optical device could be constructed that, instead of letting light bounce off it and focus out to sea (losing half the light in the process of bouncing), instead could channel and bend light through a clear medium. This would make a powerful lens, with a short focal length, and would be required to have much less weight than a traditional curved lens. His idea is now known as the Fresnel Lens.

The third-order Fresnel Lens of the Cana Island Lighthouse. This lens was installed by the time the lighthouse made “first light” in 1870, and came from France.

The Fresnel Lens required very pure optical glass. Fresnel spent years before his own death micromanaging French glass makers and wrestling with their product to achieve a reliable means to cast the right glass pieces to assemble into these lenses. When he died of tuberculosis in 1827 (also at age 39, and just a year after Fraunhofer’s death… an interesting symmetry), he left behind many scientific and engineering challenges to those, including one of his own brothers, who would carry on the lighthouse project. Ultimately, those challenges would be overcome and what started as a handful of demonstration lighthouses in the “Carte des Phares” (Lighthouses Map) devised by Fresnel for the French state would blossom into the greatest optical technological advance of the 19th century. Lighthouses of significant brightness and reach prevented dozens of shipwrecks a year, evidenced by the French state’s own accounting of shipwrecks off French coasts before and after the installation of Fresnel lenses in lighthouses. Lighthouses built after this technological revolution in glass making and lens constructions demanded French-made Fresnel Lenses.

The Cana Island Lighthouse sports a Fresnel Lens that dates back to around 1869 or so. It was installed in the lighthouse and the facility achieved first light in 1870. The lens is a “third-order” Fresnel lens, which means it’s the third most powerful lens of the designs created by Fresnel before his death in 1827. While this particular lens is too young to have been crafted by Fresnel himself (who, as I mentioned, felt compelled to micromanage the construction process owing to the sense that others lacked the kind of attention to detail and precision needed for this art), nonetheless it bears the hand of the master.

It’s one of his “catadioptric” designs, with prisms at the top and bottom to internally reflect and refract light as if guided by a mirror, with central glass prisms to refract the light light a standard lens. In fact, if you stare carefully at the close-up photo below of the light coming out of the catadioptric prisms at the top of the lens, you’ll see the lake horizon and waves; that’s because the light you see was originally reflected off the waves of Lake Michigan before being totally internally reflected inside the prism and directed down toward the camera lens of my phone.

A close-up view of the catadioptric aspects of the top of the third-order Fresnel lens in the Cana Island Lighthouse. Both reflection (total internal reflection) and refraction are at play here. Light that bounced off Lake Michigan and should have missed my camera lens (because I am not aimed at the lake) is reflected and refracted inside the prism, ultimately directed down toward my camera. You can see the waves of the lake and the horizon in the distance.

Lighthouse Fresnel Lenses represent the technological might of 19th century physics and engineering. A deeper understanding of light’s wave nature allowed for the imagining and design of a lens with significant focusing power but light-weight design. Once the technological challenges were overcome, the parabolic reflecting mirrors of the previous generation of lighthouses were tossed aside in favor of this new French revolution: the Fresnel Lens.

Networks of lighthouses appeared on every major body of water, constructed over decades to aid ship navigation and improve safe passage on rough waters or during inclement weather. Countless lives were saved by this optical marvel, and countless commerce made more profitable by its employ. What made possible this advance? It wasn’t the then frontier of French optics and lighthouse engineering when Fresnel took on the challenge of the Carte des Phares. It also really wasn’t French glass-making; that was adequate but not up to the task when Fresnel needed it for his ideas. Rather, it was the idea that light could be described as a wave, an idea pushed hard by Fresnel’s mathematical confidence, that drove this particular revolution. Without Fresnel’s basic insights into light and his passion for light itself, reflectors may have ruled the design of lighthouses for many more decades and that particular revolution might have been delayed until much later. The Cana Island Lighthouse, lit in 1870, may instead have sported a dated and inefficient parabolic reflector rather than the gem of a Fresnel lens that it holds today.

Lighthouses in a cosmic sea

Our passion, as a species (dotted with intellectual lights), for understanding actual light, in all its forms, has driven many other technological revolutions. We are living through one right now: the revolution in personal, cheap telecommunications. This revolution was pushed not only by the development of small, miserly radio antennas, but also powerful but compact computers and, behind the scenes, a revolution in optical fiber communications (again, optics!) that made possible the packing of more information into the same space.

But our hunger for light in all its forms also made possible the detection of cosmic lighthouses, those stellar corpses we know as “pulsars.” The first pulsars were detected by radio astronomer Jocelyn Bell in 1967. As a young graduate student, she observed a regular repeating radio signal that appeared to originate from a non-terrestrial source. It was originally labeled “LGM-1”, standing for “Little Green Man – 1.” This was a temporary name in honor to the biased notion that such a regular, repeating radio signal must come from some intelligent origin. 

A photo of Jocelyn Bell from 1967. By Roger W Haworth – Flickr, CC BY-SA 2.0, https://commons.wikimedia.org/w/index.php?curid=37003823

Today we recognize these regular signals, as well as other kinds of light, are originating from rapidly spinning “neutron stars.” If a heavy star, much heavier than our own sun, experiences a runaway collapse at the end of its life, it is possible for the remnant to form a neutron star. This happens so long as the core of such a star, the seed left over after blowing off its atmosphere, is not much lighter than about 1.5 times our sun’s mass and not much heavier than about 3 times our sun’s mass. In that sweet spot, that “Goldilocks zone,” the core of the dead star will live out its days as a neutron star.

The collapse and death of a heavy star is not pretty, nor pleasant, nor without violence and drama. This leaves a toll on the neutron star, often (it seems) in gifting the stellar corpse with an incredibly fast rotation speed. Imagine an object that is spherical in shape and about the size of a major city, like New York City, but rotating more than 1000 times each second. This dense stellar corpse also emits an unfathomably large magnetic field, and as it also spins at an equally unfathomable rate, the result is an electromagnetic whip that tears at the atoms in the surrounding space – those recently cast off by the death of the star itself. Pulsars create incredible maelstroms not visible to the human eye, but visible in radio and x-ray light.

Their regular spinning results in regular pulsing in, for instance, radio. They are light cosmic lighthouses, sweeping out a beam of light for those with the right “eyes” to see. Large radio receivers will do the trick. No two pulsars spin at quite the same rate, owing to the details of their original mass (what star they came from) and how, exactly, that star died. Therefore, much as as ship at sea can know its location near a coast by the pattern of lighthouse flashes it sees in the distance, some cosmic traveler with the right radio antennas can know where in the Milky Way galaxy they have stumbled by listening to the pulsars within their radio horizon. The first such ships would have to map these cosmic shoals, but for all the ships that came after, this Carte des Phares Cosmiques would let a captain choose the next destination… or find their way to a home thought lost long ago.


This article is part of a wider series, “A View From The Shadows,” that I began writing as a follow-on to our book, “Reality in the Shadows (or) What the Heck’s the Higgs?”, published in 2017 by YBK Publishers in New York, NY and available from fine booksellers such as Amazon.com.

“Reality in the Shadows (or) What the Heck’s the Higgs” is meant to help a new audience come to discover a love of science and especially physics, or to welcome to the frontier those who already discovered that love a long time ago.