## Extreme Gamma Rays

The highest-energy gamma ray photon ever recorded was recently observed by the Large High Altitude Air Shower Observatory (LHAASO) on Haizi Mountain, Sichuan province, China, during its first year of operation.

1.42 ± 0.13 PeV

That is 1.4 petaelectronvolts = 1.4 × 1015 eV! The origin of this fantastically energetic photon hasn’t been localized, but possible candidates are the Cygnus OB2 young massive cluster (YMC), the pulsar PSR 2032+4127, or the supernova remnant candidate SNR G79.8+1.2.

How much energy is 1.4 PeV, actually?

We can calculate the frequency of this photon using

$\textup{E}=h\nu$

where
h = Planck’s constant = 4.135667696 × 10-15 eV·Hz-1
ν = the photon’s frequency
E = the photon’s energy

Solving for ν, we get

ν = 3.4 × 1029 Hz

Next, we’ll calculate the photon’s wavelength using

$c=\lambda \nu$

where
c = the speed of light = 299792458 m·s-1
λ = the photon’s wavelength

Solving for λ, we get

λ = 8.9 × 10-22 m

To give you an idea of just how tiny 8.9 × 10-22 meters is, the proton charge radius is 0.842 × 10-15 m, so 1.9 million wavelengths of this gamma ray photon would fit inside a single proton! An electron has an upper limit on its radius—if it can be said to have a radius at all—between 10-22 and 10-18 m. So between 1 and 2000 wavelengths of this gamma ray photon would fit inside a single electron.

Using Einstein’s famous equation E = mc2 we can find that each eV has a mass equivalent of 1.78266192 × 10-36 kg. 1.4 PeV then gives us a mass of 2.5 × 10-21 kg. That may not sound like a lot, but it is 1.5 million AMUs (Daltons), or a mass comparable to a giant molecule (a protein, for example) containing ~200,000 atoms.

This and other extremely high energy gamma ray photons are not directly detected from the Earth’s surface. The LHAASO detector array in China at 14,500 ft. elevation detects the air shower produced when a gamma ray (or cosmic ray particle) hits an air molecule in the upper atmosphere, causing a cascade of subatomic particles and lower-energy photons, some of which reach the surface of the Earth. It is the Cherenkov photons produced by the air shower secondary charged particles that LHAASO collects.

References
Conover, E. (2021, June 19). Record-breaking gamma rays hint at violent environments in space. Science News, 199(11), 5.
https://www.sciencenews.org/article/light-energy-record-gamma-ray

Z. Cao et al. Ultrahigh-energy photons up to 1.4 petaelectronvolts from 12 γ-ray Galactic sourcesNature. Published online May 17, 2021. doi: 10.1038/s41586-021-03498-z.

## Retirement Challenges

I retired from my full-time position on May 21, and am now working three hours a day, Monday through Friday, for the same company, 100% remote. It is intense work, but at least it is only 15 hours per week now, and the pay is good.

There are a lot of potential projects that present themselves for an encore career, but I’m finding that I live in the wrong place to do any of them. Some are going to be impossible to do without substantial help from others.

One thing I’ve learned, especially during the pandemic, is that I need to be with people in the work that I do. A 100% remote interaction with others is unsatisfying, and I certainly don’t want to spend the rest of my life doing that.

The project I am most excited about is Mirador Astronomy Village. Nothing like it has ever been done in the United States before.

Mirador would be a residential community that is astronomy-friendly, and the majority of that residential community would be permanent residents (in other words, not vacation homes for the wealthier among us). Mirador would have no dusk-to-dawn lighting, and no one living there will ever have to worry about a neighbor putting up a light that trashes their view of the night sky or shines into their home. Mirador would have a public observatory and provide regular astronomy programs. Mirador would also have private observatories for research, astrophotography, and visual observing.

Ideally, Mirador would be located where it is clear most nights and winters are mild. New Mexico, Arizona, and West Texas immediately come to mind.

The challenges? Mirador is going to need a land donation and a group of people who can take some financial risk to build it without jeopardizing their personal economic stability. Astronomy is such an important part of my life that I am willing to move, even to a remote location, for the opportunity to live in an intentional community of astronomers and astronomy enthusiasts. What I don’t know is whether there are even 20 others in the entire United States who would make the move for such an opportunity. Running a classified ad in Sky & Telescope for a year accomplished nothing other than “great idea, let me know when you get it built.” Well, even though I have passion, knowledge, and leadership skills to make this project a success, I do not have financial resources beyond providing for myself and my family. I can’t personally fund a development.

Many other projects and activities interest me. None of them can I do in Dodgeville, Wisconsin.

• Provide astronomy programs at a public observatory
• Volunteer at a classical music radio station, perhaps even hosting my own classical music program, or at least providing recordings and commentary
• Volunteer for a symphony orchestra
• Bring the best music of new and neglected classical composers to a wider audience
• Passenger rail
• Develop a comprehensive outdoor lighting code/ordinance that has support, will get enacted, and will be enforced

One current activity related to classical music is necessarily 100% virtual. Back in April, I created a groups.io discussion group called Classical Music Little-Known Favorites. I posted a note about it to the hundreds of people I am connected to on LinkedIn and Facebook, and that garnered only a single subscriber. Since then, I’ve been working diligently to find interesting and accessible classical music to feature. I am pleased with the results so far, only no one else is posting anything. Still only one subscriber besides myself. There must be at least 20 people in the entire world who have a passion to seek out and champion the best classical music that is not yet commercially available. How do I reach them?

Currently, my astronomical work is focused on stellar occultations by minor planets for IOTA. I spend about 20 hours per week running predictions, recording the events from my backyard observatory, analyzing the data, and reporting the results. My backyard observatory is wholly dedicated to this work. Wherever I end up living, I would like to continue these observations. This adds the complication that I will need access to a dedicated observatory for occultation work—either my own or one that I share with other occultation enthusiasts. That observatory should be within walking distance of where I live.

I would like to live closer to my daughter and her family in Alpine, TX. Even though I would prefer to live somewhere not too far from civilization (thinking quality health care, mostly) with a unpolluted night sky, I am beginning to consider moving to a larger city like Tucson or Las Cruces where I can better pursue my classical music interests in addition to astronomy. Tucson has direct Amtrak access to Alpine (a huge plus), but Las Cruces has no connection to Amtrak. The Sunset Limited needs to come to Las Cruces (between the El Paso and Deming stops), or at least there needs to be a bus that takes you directly to and from the train station in El Paso.

I am concerned about the direction this country is heading, and that is entering into my future plans, too. I am a non-religious progressive who believes that local, state, and federal government should be strong, competent, and efficient. There can be no higher calling than a life dedicated towards public service. I am pro-government, pro-tax, pro-education, pro-science, and anti-gun. I wouldn’t want to live anywhere where Trump got the majority of the vote in 2020. If the current Republican insanity continues (and they have most of the guns), we progressives may be forced to consider forming our own country. Or moving out of this one. Before things get any uglier. Living in an enlightened and compassionate society requires giving up some of your liberty and freedoms for the health and well being of everyone. That’s a given.

## James Clerk Maxwell

Today we celebrate the 190th anniversary of the birth of Scottish mathematician and physicist James Clerk Maxwell (13 Jun 1831 – 5 Nov 1879). Between 1864 and 1873, Maxwell developed four important mathematical equations that describe the behavior of electric and magnetic fields and their interrelated nature. He showed that any oscillating electric charge produces an electromagnetic field, and that this electromagnetic field propagates outward from the oscillating charge at the speed of light. He then correctly deduced that light itself is an electromagnetic phenomenon, and proposed that since electric charges can oscillate at any frequency, there should be a whole spectrum of electromagnetic waves of which visible light is only a small part. We now know that the electromagnetic spectrum does include many other types of “light”, namely gamma rays, x-rays, ultraviolet, infrared, microwave, and radio waves. They are all exactly the same phenomenon, differing only in their properties of frequency, wavelength, and energy.

Like many of you, I have more than one email address. One of those email addresses I use as a catch-all for nonprofits, political organizations, and commercial entities.

Over time, the volume of email I’ve received at that address has increased exponentially. Many senders subscribe me without my having ever opted in, and many senders send multiple emails a day (or per week)—and they don’t always give you the option to opt down. I unsubscribe from many every month, but the emails I receive daily keeps on growing.

I’m tempted (often), to unsubscribe from everything, but every once in a while I get an email that is important enough or useful enough that I’m glad I got it.

What to do? I am making a conscious effort to cut all of the insidious time wasters out of my life (this becomes much more important as we get older), freeing up precious time for what is most important. Email is one of the worst offenders.

Many online discussion groups have a “daily digest” option with all of the posts for the day being assembled into a single email, with a topical index at the top. I would like the ability through my email service provider to batch together emails from a variety of senders into a single daily email. It would work something like this:

1. Create a list of email domains that you want batched (facebookmail.com, ewg.org, onefairwage.org, etc.)
2. Activate the digesting service so that all emails coming from these domains gets batched into a single daily email with the subject line and sender of all the emails listed in the top section, followed by the full contents of the emails in sequence below that.

You’d have the option to receive the email sorted by time received in either ascending or descending order. You’d also be able to add or remove email domains from your list at any time.

Sure, it is going to be one long email for many of us, but it would go a long way towards reducing the clutter in our inboxes.

Another option would be to have an email service provider (unfortunately, digest.com is already taken) that will provide you with a pass-through email address that does this digesting for you, then forwards the daily email to the email address of your choice. You would update your senders with the pass-through email address. Let the digesting begin!