Sexism Poisons Everything

That black hole image was something, wasn’t it? For a few days, we all managed to forget the train wreck that is modern politics and celebrate science in its purest form. Alas, for some people there was one problem with M87’s black hole.

Dr. Katie Bouman, in front of a stack of hard drives.

A woman was involved! Despite the evidence that Dr. Bouman played a crucial role or had the expertise, they instead decided Andrew Chael had done all the work and she was faking it.

So apparently some (I hope very few) people online are using the fact that I am the primary developer of the eht-imaging software library () to launch awful and sexist attacks on my colleague and friend Katie Bouman. Stop.

Our papers used three independent imaging software libraries (…). While I wrote much of the code for one of these pipelines, Katie was a huge contributor to the software; it would have never worked without her contributions and

the work of many others who wrote code, debugged, and figured out how to use the code on challenging EHT data. With a few others, Katie also developed the imaging framework that rigorously tested all three codes and shaped the entire paper ();

as a result, this is probably the most vetted image in the history of radio interferometry. I’m thrilled Katie is getting recognition for her work and that she’s inspiring people as an example of women’s leadership in STEM. I’m also thrilled she’s pointing

out that this was a team effort including contributions from many junior scientists, including many women junior scientists (). Together, we all make each other’s work better; the number of commits doesn’t tell the full story of who was indispensable.

Amusingly, their attempt to beat back social justice within the sciences kinda backfired.

As openly lesbian, gay, bisexual, transgender, queer, intersex, asexual, and other gender/sexual minority (LGBTQIA+) members of the astronomical community, we strongly believe that there is no place for discrimination based on sexual orientation/preference or gender identity/expression. We want to actively maintain and promote a safe, accepting and supportive environment in all our work places. We invite other LGBTQIA+ members of the astronomical community to join us in being visible and to reach out to those who still feel that it is not yet safe for them to be public.

As experts, TAs, instructors, professors and technical staff, we serve as professional role models every day. Let us also become positive examples of members of the LGBTQIA+ community at large.

We also invite everyone in our community, regardless how you identify yourself, to become an ally and make visible your acceptance of LGBTQIA+ people. We urge you to make visible (and audible) your objections to derogatory comments and “jokes” about LGBTQIA+ people.

In the light of the above statements, we, your fellow students, alumni/ae, faculty, coworkers, and friends, sign this message.

Andrew Chael, Graduate Student, Harvard-Smithsonian Center for Astrophysics

Yep, the poster boy for those anti-SJWs is an SJW himself!

So while I appreciate the congratulations on a result that I worked hard on for years, if you are congratulating me because you have a sexist vendetta against Katie, please go away and reconsider your priorities in life. Otherwise, stick around — I hope to start tweeting

more about black holes and other subjects I am passionate about — including space, being a gay astronomer, Ursula K. Le Guin, architecture, and musicals. Thanks for following me, and let me know if you have any questions about the EHT!

If you want a simple reason why I spend far more time talking about sexism than religion, this is it. What has done more harm to the world, religion or sexism? Which of the two depends most heavily on poor arguments and evidence? While religion can do good things once in a while, sexism is prevented from that by definition.

Nevermind religion, sexism poisons everything.

… Whoops, I should probably read Pharyngula more often. Ah well, my rant at the end was still worth the effort.

Happy Emmy Noether Day!

Whenever anyone asks me for my favorite scientist, her name comes first.

At a time when women were considered intellectually inferior to men, Noether (pronounced NUR-ter) won the admiration of her male colleagues. She resolved a nagging puzzle in Albert Einstein’s newfound theory of gravity, the general theory of relativity. And in the process, she proved a revolutionary mathematical theorem that changed the way physicists study the universe.

It’s been a century since the July 23, 1918, unveiling of Noether’s famous theorem. Yet its importance persists today. “That theorem has been a guiding star to 20th and 21st century physics,” says theoretical physicist Frank Wilczek of MIT. […]

Although most people have never heard of Noether, physicists sing her theorem’s praises. The theorem is “pervasive in everything we do,” says theoretical physicist Ruth Gregory of Durham University in England. Gregory, who has lectured on the importance of Noether’s work, studies gravity, a field in which Noether’s legacy looms large.

And as luck would have it, today was the day she was born. So read up on why she’s such a critical figure, and use it as an excuse to remember other important women in science.

Ridiculously Complex

Things have gotten quiet over here, due to SIGGRAPH. Picture a giant box of computer graphics nerds, crossed with a shit-tonne of cash, and you get the basic idea. And the papers! A lot of it is complicated and math-heavy or detailing speculative hardware, sprinkled with the slightly strange. Some of it, though, is fairly accessible.

This panel on colour, in particular, was a treat. I’ve been fascinated by colour and visual perception for years, and was even lucky enough to do two lectures on the subject. It’s a ridiculously complicated subject! For instance, purple isn’t a real colour.

The visible spectrum of light. Copyright Spigget, CC-BY-SA-3.0.

Ok ok, it’s definitely “real” in the sense that you can have the sensation of it, but there is no single wavelength of light associated with it. To make the colour, you have to combine both red-ish and blue-ish light. That might seem strange; isn’t there a purple-ish section at the back of the rainbow labeled “violet?” Since all the colours of the rainbow are “real” in the single-wavelength sense, a red-blue single wavelength must be real too.

It turns out that’s all a trick of the eye. We detect colour through one of three cone-shaped photoreceptors, dubbed “long,” “medium,” and “short.” These vary in what sort of light they’re sensitive to, and overlap a surprising amount.

Figure 2, from Bowmaker & Dartnall 1980. Cone response curves have been colourized to approximately their peak colour response.

Your brain determines the colour by weighing the relative response of the cone cells. Light with a wavelength of 650 nanometres tickles the long cone far more than the medium one, and more still than the short cone, and we’ve labeled that colour “red.” With 440nm light, it’s now the short cone that blasts a signal while the medium and long cones are more reserved, so we slap “blue” on that.

Notice that when we get to 400nm light, our long cones start becoming more active, even as the short ones are less so and the medium ones aren’t doing much? Proportionately, the share of “red” is gaining on the “blue,” and our brain interprets that as a mixture of the two colours. Hence, “violet” has that red-blue sensation even though there’s no light arriving from the red end of the spectrum.

To make things even more confusing, your eye doesn’t fire those cone signals directly back to the brain. Instead, ganglions merge the “long” and “medium” signals together, firing faster if there’s more “long” than “medium” and vice-versa. That combined signal is itself combined with the “short” signal, firing faster if there’s more “long”/”medium” than “short.” Finally, all the cone and rod cells are merged, firing more if they’re brighter than nominal. Hence where there’s no such thing as a reddish-green nor a yellow-ish blue, because both would be interpreted as an absence of colour.

I could (and have!) go on for an hour or two, and yet barely scratch the surface of how we try to standardize what goes on in our heads. Thus why it was cool to see some experts in the field give their own introduction to colour representation at SIGGRAPH. I recommend tuning in.


It Is Friday, After All

I was sitting down to write a weighty post about child separation, while reminding myself of another post I’d promised on the subject, and eyeing up which Steven Pinker post I should begin work on, all of which is happening as I’m juggling some complex physics and computational problems, and-

You know what? Here’s a video of someone dunking oranges in a fish tank, in an excellent demonstration of the scientific method. [Read more…]

The Total Package

Mano Singham and PZ Myers aren’t that interested in eclipses. I’m sort of the opposite, as a group of us drove 13 hours to reach totality, arriving only an hour and a half before the eclipse started… and departing for the return trip fifteen minutes after totality ended. Why the heck would anyone go to such extreme lengths for a few minutes of darkness?

The Corona

The solar corona is the hottest part of the sun we can see, far hotter than the surface, and we don’t know why that is. Despite being so hot, the corona is also very diffuse and thus the cooler chromosphere blasts out far more light than it does. This means you can’t see it if any part of the sun is visible, and the physics of choronographs means they block off significantly more of the corona than the Moon does during an eclipse.

While that’s all very nice and intellectual, there’s also something satisfying about looking up in the sky and seeing what looks like Albert Einstein being consumed by a black hole.

An image of the corona from "the Camera for Photographing Eclipse Photographic Collection."Mercury

The planet Mercury is likely the last visible-eye planet discovered. Because it clings so tightly to it, you need to blot out the Sun by exploiting sunsets and sunrises, and even then you need a view close to the horizon and the planet in a certain orientation. A solar eclipse accomplishes the same, only during the middle of the day. I’m not convinced I actually saw Mercury yesterday, as it was faint and appeared in the wrong spot too close to the sun, but oh well.

Sunsets on Every Horizon

I can verify this actually happens. The physics is pretty simple: the Moon’s shadow occupies a finite area. If you’re perfectly centred under it, every horizon is in the direction of a patch of earth which has at least some sunlight falling on it. That sunlight bounces back up into or scatters through the atmosphere, producing something that looks like a sunset. It is wicked cool!

Watching The Shadow

The shadow of the Moon is quite fuzzy, so if you’re expecting to see a sharp line you’ll be disappointed. The best view is definitely from space, though an airplane will do in a pinch; on Earth, I could spot the Eastern horizon getting gradually lighter even as we were in totality.

Shadow Bands

As NASA puts it, “Shadow bands are thin wavy lines of alternating light and dark that can be seen moving and undulating in parallel on plain-coloured surfaces immediately before and after a total solar eclipse.” Scientists aren’t entirely sure what they are, but the best guess is atmospheric cells warping light in a similar way to stellar flicker. They aren’t guaranteed to show up, but I insisted on laying out a white blanket to make them more visible. We missed seeing them as totality was approaching, but as the Sun started peeking back I strongly suggested everyone stare at the blanket. And we saw them!

A Chill In The Air

The Sun radiates a lot of heat our way, which is absorbed and scattered by the ground and atmosphere. Take away that source, and you’re just left with the radiation from said ground and atmosphere as it cools down. This is at its strongest during totality, and collectively we could feel the atmosphere was notably chillier just after the eclipse than it was in the lead up. I’m estimating the difference was about 5-10C.

People Losing Their Shit

My photos of the eclipse were pretty lousy, as I didn’t have any money to invest in the proper gear. Derek Muller of Vertasium was much luckier, but his video is more notable for the audio; he, and everyone around him, were losing their minds as they reached totality. You don’t get that from a partial solar eclipse.

Don’t listen to Singham or Myers. Total solar eclipses are the coolest, and if one happens to fall near you I recommend you take full advantage.

A Third One!

I know, I know, these are starting to get passé. But this third event brings a little more information.

For the third time in a year and a half, the Advanced Laser Interferometer Gravitational Wave Observatory (LIGO) has detected gravitational waves. […]

This most recent event, which we detected on Jan. 4, 2017, is the most distant source we’ve observed so far. Because gravitational waves travel at the speed of light, when we look at very distant objects, we also look back in time. This most recent event is also the most ancient gravitational wave source we’ve detected so far, having occurred over two billion years ago. Back then, the universe itself was 20 percent smaller than it is today, and multicellular life had not yet arisen on Earth.

The mass of the final black hole left behind after this most recent collision is 50 times the mass of our sun. Prior to the first detected event, which weighed in at 60 times the mass of the sun, astronomers didn’t think such massive black holes could be formed in this way. While the second event was only 20 solar masses, detecting this additional very massive event suggests that such systems not only exist, but may be relatively common.

Thanks to this third event, astronomers can set a stronger maximum mass for the graviton, the proposed name for any gravity force-carrying particle. They also have some hints as to how these black holes form; the axis of spin for these two black holes appear to be misaligned, which suggests they became binaries well after forming as opposed to starting off as binary stars in orbit. Finally, the absence of another signal tells us something important about intermediate black holes, thousands of times heavier than the Sun but less than millions.

The paper reports a “survey of the universe for midsize-black-hole collisions up to 5 billion light years ago,” says Karan Jani, a former Georgia Tech Ph.D. physics student who participated in the study. That volume of space contains about 100 million galaxies the size of the Milky Way. Nowhere in that space did the study find a collision of midsize black holes.

“Clearly they are much, much rarer than low-mass black holes, three collisions of which LIGO has detected so far,” Jani says. Nevertheless, should a gravitational wave from two Goldilocks black holes colliding ever gets detected, Jani adds, “we have all the tools to dissect the signal.”

If you want more info, Veritasium has a quick summary, while if you want something meatier the full paper has been published and the raw data has been released.

Otherwise, just be content that we’ve learned a little more about the world.