Stacy McGaugh Profile picture
Feb 11, 2018 19 tweets 4 min read Twitter logo Read on Twitter
Interesting perspective. It is now over 30 years since I published my first referred paper “An investigation of the efficiencies of various buffer gases in Na-Xe spin exchange”, which has never been cited, even by me.…
It did perhaps contribute in a tiny way to making the world a better place as an incremental part of a larger project that ultimately led to useful medical imaging technology. Not that I appreciated that potential at the time; we were just trying to figure out how things worked.
Alkali and noble gas atoms can form weak van der Waals molecules in vapor. In terms of electron shell structure, the alkali is basically a noble with an unwanted electron. Temporary molecules form in which two elements like Sodium and Xenon share the electron like a hot potato.
Turns out that the wavefunction of the electron has a big overlap with the nucleus of the noble. By optically pumping the Sodium D line, we could spin polarize the electrons. Some of this would be transferred to the nucleus, providing a mechanism to spin polarize lots of nuclei.
Spin polarized nuclei light up an MRI imager. By breathing in a chemically inert noble gas with spin polarized nuclei, it enables an MRI to make a detailed image of the lungs, mostly empty soft tissue that is otherwise impossible to image in such detail.
Hence an obscure physics experiment helped in a small way to lead to a useful technology.

As a grad student assigned to do this work, I had zero appreciation for this possible outcome.
All it did was persuade me that I was less interested in table top experiments than the remote laboratory that is the astronomical observatory. So I switched. I left physics grad school, and went into an astronomy program where I knew I could get lots of telescope time.
This turned out to be a better path for me.
I will cop to entering astronomy with a bad attitude. Coming from a rigorous physics background, I assumed this astronomy stuff was trivial and I’d pick it up like a snap. I was very put out that my new grad school wanted me to do two years of grad course work. #beentheredonethat
It was only after those two years of course work, along with doing some serious astronomical research, that I had the epiphany that astronomy was not a trivial sub-field of physics. There were good reasons, historically, technically, and culturally that they were distinct fields.
I mention this in part because I recognize the same attitude in others. On the one hand, I’m glad that many physicists have recognized that there is interesting science to be done from studying the sky, and some fundamental physics to be gleaned from the workings of the universe.
How could I not be pleased by this? They’ve had the same realization I had. But on the other hand, as subjects like cosmology and dark matter became acceptable fields of study rather than fuzzy topics of dubious merit, it became possible to study them within the echo chamber.
Once enough physicists became interested in these topics, there was no need to confront the baseless assumption that the field that started them was inherently inferior. I frequently encounter physicists who still wallow in the bad attitude that I had started with in grad school.
Not all of them, of course. But it is very common now for physicists who work on dark matter to express dismay and contempt for the notion that astronomers could have anything important to say on the subject. Never mind that 100% of the evidence for dark matter is astronomical.
Not 90% or 99% or 99.9%. 100%. Yet the attitude persists, “thanks for the data, let us with the Big Brains take it from here.” I have lost count of the number of physics talks I’ve heard that have a slide acknowledging astronomical data as motivation, then goes off on... whatever
Whatever ill-motivated dark matter model the speaker fancies. Models that could usually be discard immediately with a dash of basic knowledge. Like the Milky Way having an excess of DM clumps from its merger history. But that would thicken the disk! The what? The. Thick. Disk.
The first slide of these talks always shows (1) flat rotation curves and/or (2) the bullet cluster/(3) the CMB. Usually I’m the only person in the audience who has written referees papers on all of those topics. But we’re sure what it means. It is Known, Khalesi.
My point is that there is a lot to learn about the universe. It is a big place. There is lots about it that seems absent from the knowledge base of physicists who are actively working on the subject. This shortcoming can be traced directly to the bad attitude I had in grad school
A bad attitude that still pervades physics. I don’t know where we pick it up as physics students, or how it rubbed off on me personally. It isn’t formally taught. Yet it remains pervasive to this day.

It is socially ugly and is an active drag on the progress of science.

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More from @DudeDarkmatter

Aug 28, 2018
What we have here is a failure to communicate.
Over and over I see statements from esteemed colleagues - genuinely brilliant people - that are simply incorrect, for simple lack of fact checking. Like “using only two out of 10 pieces” of evidence. How does one count? Or “MOND doesn’t and dark matter does.” Does what, exactly?
I understand their attitude. I had the same reaction when I first encountered MOND. Indeed, when I first realized that MOND made specific predictions about low surface brightness galaxies, my immediate thought was “Good. I have the data to falsify this stupid theory.”
Read 15 tweets
Aug 19, 2018
Strange choice of headline for a mission that was planned to run for 3 months but ran successfully for 14 years.
This is a skilled and subtle form of propaganda. By putting the price tag up front (how is this relevant to the story?) the immediate and natural reaction is to scoff “What a waste!” when by the standards of space missions this was incredibly successful and long-lived.
Ironically, NASA tried to kill it several times. The bureaucratic side of NASA hates it when missions run long. They have to continue paying pennies to continue to operate what they invested millions to build and launch.
Read 4 tweets
Aug 19, 2018
Minor astronomical mystery last night. Looked out just before bed & noticed the first quarter moon was... dimmer than usual. This was pronounced enough that I went out to look. Indeed. Even a slight shade of red. Also fewer stars than usual. But no clouds in the sky, nor cirrus.
Woke up this morning; still no clouds. The color of the sky seemed off though, and the sun a bit orangish even once well above the horizon. What the heck? Then I remembered all the wildfires in the west, and decided to look up a smoke map at @NOAA
Yep. My house is under one of those big red blobs.
Read 6 tweets
Jul 31, 2018
Came across 1954 classic “Them” on TCM. Apparently standard issue for New Mexico State police back then included sub-machine guns. Hollywood hype? Or just ahead of their time?
I mean, you meet a freakish giant ant in the desert. Pistol fire doesn’t phase it. So the state trooper runs back to the patrol car for extra firepower. Smart move. I’m expecting a shotgun, maybe a rifle. But dude comes back with a sub-machine gun. WHY is that in the trunk?
Fer snakes & such?

Entire prairie dog towns?

I mean, it’s the middle of the New Mexico desert in 1954. Ain’t a lot out there to be needing a sub-machine gun for.

Except giant ants, of course.
Read 8 tweets
Jul 27, 2018
Ethan Siegel has made it clear that he hated MOND. Over the years he has made it a personal crusade to persecute the heretics who dare speak of such things. Because nothing says scientific rationality like as hominem attacks.

Mostly I ignore him.

Here he crosses a line, accusing yours truly of cheating. This is an unjustifiable ad hominem attack. It has no place in science.

The issue is not one of cheating, but of interpretation, and how to weigh various contradictory lines of evidence.
Read 16 tweets
Jul 23, 2018
I like the starting point: “collapse [at] z<10+”
The “+” makes it. Collapse could happen any time. Redshift less than 10. Or redshift greater than 10. Whenever.

I really empathize with Simon here. This is a problem I’ve often faced as an observer. How do I express the predictions of a theory that makes no [agreed] prediction?
It induces a flashback. At the Maryland conference in 1998, a some of us were discussing the epoch of galaxy formation over lunch. Amid suggestions that galaxies might be present at [then] surprisingly high redshift, Carlos Frenk declared “There are no galaxies before redshift 7”
Read 17 tweets

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