By Lori Ann White
In the series, "Where are they now?" we check in with KIPAC alumni: where they are now, how they've fared since their days exploring particle astrophysics and cosmology at the Institute, and how their KIPAC experiences have shaped their journeys.
Next up is Peter den Hartog, a postdoctoral researcher from 2009 until the end of 2014 who later went from studying pulsars at KIPAC to co-founding a Silicon Valley startup. We talk to Peter about data science, the real meaning of a Ph.D. in physics, and stumbling across the Bay Area's Dutch community while furniture shopping.
LW: Can you tell us a little bit about your academic background before you came to KIPAC?
PdH: I'm from the Netherlands and I studied first at Utrecht University, where I got two Master's degrees, in physics and astrophysics.
My Ph.D. is from the University of Amsterdam, and my thesis was on studying magnetars at hard X-rays but I did the work at SRON, the Netherlands Institute for Space Science. It's a research institute—like the Dutch NASA. They build instruments, like the X-ray lenses on Chandra [the Chandra X-ray Observatory] and the gratings on XMM [ESA's XMM-Newton X-ray observatory]. It's similar to KIPAC in that there are people who design the instruments and people who build them.
Above: SGR 0501+4516, illustrated here in an artist concept, is a member of a select class of neutron stars called magnetars. These stellar remnants produce the most intense magnetic fields in the cosmos. Only 15 have been observed thus far (all in our own Milky Way Galaxy). (Credit: NASA/Goddard Space Flight Center Conceptual Image Lab.)
LW: What brought you to KIPAC?
PdH: After my Ph.D. I knew I wanted to work with Fermi [the Fermi Gamma-ray Space Telescope]. That’s why I wanted to work here. Although the way I got my job here was very weird.
LW: You have to explain that!
PdH: The thing was there was no job when I wanted to work here.
In the Netherlands getting a Ph.D. is a little different than here. You have to decide when you're going to get your Ph.D. and set a date, and the reading committee has to accept all your papers and you have to publish your thesis as a book.
So as I was finishing up, I had two choices—I could postpone finishing my Ph.D. and spend time applying for postdocs or I could finish and then apply. In the meantime, Fermi was launched and all the jobs were handed out.
But my professor knew [KIPAC faculty member and head of the Fermi-LAT (Large Area Telescope) collaboration] Peter Michelson from the old days, and at his suggestion, I wrote Peter a letter. He decided he wanted me to come over, but 10 months passed between my first letter to Peter and getting the okay to come.
I heard from many people that's not the way you do it, but it's possible if you want it. (Laughs.)
LW: What did you do with your 10 months?
PdH: I did some work with INTEGRAL [ESA's INTErnational Gamma-Ray Astrophysics Laboratory], and traveled. A friend of mine asked, "Do you want to go to Antarctica?" I said 'Dude, I'm unemployed!" But a family tragedy taught me to take opportunities where they come, so—I went to Antarctica [a fairly popular destination among KIPAC folks, we might add, as this and this blogpost will attest.]
LW: And then you came to KIPAC and got to work.
PdH: (Nods.) Peter was my supervisor, and I worked a little bit with [KIPAC faculty member] Roger Romani.
LW: You said you knew you wanted to work with Fermi. Why?
PdH: Pulsars. Pulsars are a big part of Fermi. We didn't know that beforehand but after Fermi was launched it turned out to be the case—we knew of only seven gamma-ray pulsars before Fermi but now there are more than 200! Roger was one of the founding theorists for figuring out how the physics would work with gamma-ray pulsars.
The funny thing is, I studied very specific types of pulsars in the Netherlands called magnetars. They're the biggest magnets in the universe. But we didn't find magnetars with Fermi; remember, I studied them in hard X-rays. But I worked on other pulsar stuff, and if there was something interesting going on—such a great collaboration, so many interesting things to investigate! Sometimes your contribution is small, but it's still interesting. Always with cutting-edge science you find an answer and you get more questions, but all the big questions were answered fairly quickly. It was an amazing time.
Above: This plot identifies selected pulsars detected by Fermi's LAT. A pulsar is a type of rapidly rotating neutron star that emits electromagnetic energy at periodic intervals. A neutron star is the densest object in the Universe that has an actual physical surface and thus that astronomers can observe directly, crushing half a million times more mass than Earth into a sphere no larger than a city. Its matter is so compressed that even a teaspoonful weighs as much as a mountain. One pulsar shines especially bright for Fermi. Called Vela (seen in the above map within the galactic plane, towards but not fully all the way to, the right edge), it spins 11 times a second and is the brightest persistent source of gamma rays the LAT sees.
(Image credit: NASA/DOE/Fermi LAT Collaboration.)
LW: How did you go from a KIPAC postdoc to a Silicon Valley entrepreneur?
PdH: I thought a lot about the future during my postdoc, especially since I got married in the meantime. My wife told me to go for it, to go after whatever I wanted, but I realized I wanted a bit of security. But I'm also picky, and I wasn't convinced I could get a really top notch position. I couldn't really convince myself that the leads I had could get me where I wanted to go. So I made it a black/white decision—either I get what I really, really want or I stay here. We're in Silicon Valley! I would have opportunities.
I did some exploring entrepreneurial opportunities through Stanford Ignite and someone said something that stuck with me: "If you haven't found a company that you'd love, that would make you excited, you haven't looked hard enough."
As I was biking to a guitar class close to California Avenue—a bike ride of a couple of miles, max—I saw all these buildings with names that were probably tech companies and I had no idea what was in them. When I extrapolated, which is what scientists do, I realized he was probably right.
LW: But ultimately you didn't find one, you started one.
PdH: When I decided we were going to stay here I started sending out resumes but I was asked to found a company by another member of the Dutch community here.
LW: There's a Dutch community here?
PdH: Oh, yes, and in fact I connected with them right after I got here. I met a guy in the furniture store where I was buying a bed. He said, "Oh, you have an interesting accent. Where are you from?" I told him I was from the Netherlands, and he said, "That's interesting, she's from the Netherlands, too," and pointed to a woman who had just come in. There was a Dutch holiday coming up—Queen's Day [Note: Now King's Day, as Queen Beatrix has since abdicated in favor of her son, Willem-Alexander.] I asked her if there was any kind of get together, and that's how I found the Dutch community here in the Bay Area and met the person who's the CEO of our company.
LW: Which is?
PdH: HAL24K Data Intelligence Labs. We're both interested in the same thing—the internet of things. So when I was finishing up here I wrote him, and he told me that he was actually working on setting up a company but he wanted me to be the Chief Scientific Officer. We founded the company in Amsterdam.
Above: Peter with his company banner (Credit: P. den Hartog.)
LW: The internet of things covers a lot of area. Where does HAL24K fit in?
PdH: We're a data intelligence company that decided to focus on smart cities. Our company helps city governments collect and analyze data.
LW: Do you mean for policy decision-making?
PdH: (Nods.) Yes, collect data for policy decisions. Cities are big and they have problems, and the problems are only going to get bigger. There are five or six pillars of a city—crime, health, transportation, like that. All of them generate tremendous amounts of data. Data analysis is one tool city administrators can use to make better decisions.
We have a vision and we have goals—to make cities smart. But it's not going to be easy happen quickly because cities are government and government works slowly. There are issues like privacy issues and policies that are already in place. But we're working on it—we have some pilot programs underway to see if the way we want to solve stuff will work.
We're also getting more traction with businesses that want to take advantage of machine learning, data intelligence, AI, but don't yet have that capacity.
Ultimately, though, our goal is to make people happier in cities, that cities stay livable and clean and relatively crime-free.
LW: Given where you are now, do you think a Ph.D. in astrophysics was the right way to get here?
PdH: Of course! It's not only fun, it teaches you skills that are popular in industry. You have to push your way through tough spots when your research stalls. You can't just sit in a corner crying, you have to figure it out. Your network and supervisor can help but you're the expert because this is new.
LW: Is there anything you miss about KIPAC?
PdH: One thing that I liked is that KIPAC is very, very open. We work hard but we also have fun. I made a lot of new friends. We'd get together for dinner and guitar. People were willing to take adventures together—we'd drive off to Utah on Memorial Day weekend without a reservation for Bryce and Zion National Parks.
The whole campus breathes that. All of Silicon Valley is like that. If you don't talk to different types you can't get where you want to go alone, ultimately.