Podcast Appearances

Just a quicky. I’ve been doing a lot of podcasts lately, and I’d hate for you to miss them, especially since they have run the gamut from mind-bending to absurdist. I’ll post them as they come up, but over the last few weeks, we’ve had:



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I’m thrilled to announce that my most recent book, “The Universe in the Rearview Mirror: How Hidden Symmetries Shape Reality” has been shortlisted for the Phi Beta Kappa Science Book Award.

This is extremely competitive and very exciting. Past winners have included Nate Silver’s “The Signal and the Noise,” Neal Subhin’s “Your Inner Fish” (which features Drexel’s own Ken Lacovara), Briane Greene’s “The Elegant Universe,” and Jared Diamond’s “Guns, Germs, and Steel” (which also won the Pulitzer). We’ll find out the winner in early October, and should I win, there’s a gala in Washington in December.

In the meanwhile, please do show the other excellent shortlisted books some love:


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On Raising Daughters

She wants to be just like me!
This morning, over breakfast, I asked my 4 1/2 year old daughter if she wanted to see something cool. I showed her a news story about Maryam Mirzakhani, the Stanford Mathematician who is first woman to win the prestigious Fields Medal. Willa, my daughter, has only a cursory grasp of the world of higher learning, so I explained it to her (and with no disrespect meant to the other 3 laureates) by saying that Mirzakhani is the “best in the world in math,” (immediately followed by a ‘kids say the darnedest things’ moment when Willa replied, “I thought you were.”)

It’s incredibly important to me that Willa and her little sister, Lily, see prominent women in the sciences, but I struggle with trying to achieve a balance between “Of course there are lots of outstanding women scientists (and so it’ll be no problem for you to join their ranks),” and “There are still too few women in science (and I want you to break down some barriers).” I’ve gone with approach #1, because society is going to give them the latter all on its own.

Despite the progressiveness of their parents, Willa and Lily are awash in “traditional” examples of gender roles. Willa’s doctor is a man; the nurses are all women. I work outside of the home, while, for now, my wife, Emily, (an excellent Speech Language Pathologist, by the way) stays at home with Lily. The issue isn’t that we’re setting a bad example with how we’ve set up our home, but rather, that smart kids tend to extrapolate from what they see around them.

Willa doesn’t have to be a scientist, but it’s important that she decide to be a scientist (or a musician, or a shoemaker, or whatever) based on her preferences and abilities, not because she’s internalized the idea that certain roles are for certain genders. While I’m trying not to princess shame her, I’ve looked on with unease as Willa picks Elsa, Ariel, and Sofia the First as her role models. The heart wants what it wants, I suppose. We’ve at very least tried to mitigate things by pointing to bravery and kindness as the defining qualities of princesses, rather than beauty (and in a fair bit of subversion, we give her the option of having princesses marry other princesses in her fairy tales).

To some degree, we end up cherry-picking examples to give Willa a deliberately skewed state of affairs. We focus on Mirzakhani or Emmy Noether, or the occasional female doctor who sees Willa at the doctor’s office. The hope is that in 10 or 20 years, these won’t be the exceptions, but for now, the societal messaging produces awfully lopsided results. The most recent report from the American Institute of Physics, for instance, shows that only 14% of physics and astronomy faculty are women. The numbers are similar for women in undergraduate physics programs. This last year — and only through fairly Herculean efforts — we were thrilled to have an enrollment at Drexel that was slightly less lopsided, about 30% women. We still have a long way to achieve anything like real gender equity in most sciences.*

Right now, I’m operating in a very limited realm. I’m trying to give my daughters a sense of the possibilities in the world around them. This is, in some sense, just a stalling maneuver while I hope for (and try to help) the world to catch up. It’s dismal and disturbing that primitive attitudes prevail among some in my and the older generation. But I’m hoping that every positive example I show to my girls moves us one step closer to the world I’d like them to live in.


* It is a sad thought that both Emily and I were raised on Free to be…You and Me in the 70’s and early 80’s which, of course, preached the same message. Gender equality seemed pretty close at the time, but it’s not obvious that we’ve made that much progress since then.

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The 1st floor table at Barnes and Noble in Rittenhouse, yesterday.

Exciting news! The Universe in the Rearview Mirror is out in paperback as of yesterday! There will be a bunch of new interviews and columns, beginning today with a new “Ask a Physicist” on Emmy Noether.

I’m always looking for new questions, so by all means give me your best. As a reminder, topical is good, but not necessary. They should be broadly interesting, ideally quirky, and if they have a sci-fi tie-in, so much the better.

I also got word from my publisher yesterday that we’ve sold the Polish rights to Prozynski. They’re the same publishers who brought you this beauty:

Finally, a personal note. I have just been appointed associate dean for science research and graduate education for my college for the next few years. Just in case you were concerned that I wasn’t an actual scientist, but rather some raving lunatic in his garage.


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Ask a Physicist is back, baby!

After an unacceptably long hiatus, I’m back with new “Ask a Physicist” columns over at io9. Today, I have a piece up about PeV neutrinos, and tomorrow I’ll be doing one on Emmy Noether. Thereafter, I’ll be posting a bit more regularly, and I’m need of some good questions.

So send me some.

Send me some now.

Oh, and in case you were one of the three people who missed it, Annalee Newitz (io9’s editor in chief) broke the internet the other day when she interviewed various scientists about misused ideas in science. I contributed “Theory” and “Quantum Weirdness.” Check out the other entries as well.


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Arbitrary Rankings Corner: The Best of Sci-Fi

I got a fun email a few days ago from Time Out magazine. They’re asking contacting a bunch of writers, artists, and scientists including such luminaries as George R R Martin and, er, myself, and asking us for our top 10 science fiction films of all time. From this, they’ll compile a top 100. They left it to us to determine our own definition of sci fi. Here’s the one I went with.

For me, science fiction includes any film that uses either extragalactic life or as yet unknown technology to forward the plot, whether or not either element is at the heart the film. To be truly great sci-fi, I feel as though the internal rules of the world need to be well-established and most importantly, self-consistent. So, for example, “Back to the Future,” while a great movie, is a mess in terms of self-consistency of the time travel rules.

My list is, I think, diverse enough where it would be tough to rank them, so I’ve simply listed them chronologically. I will note that for my money, Terminator is the most outstandingly self-consistent time travel narrative out there (if you’re looking to have a “best of breed” for different types of sci-fi).

  • Planet of the Apes (1968)
  • Fantastic Planet (1973)
  • Empire Strikes Back (1980)
  • ET (1982)
  • Bladerunner (1982)
  • Terminator (1984)
  • 12 Monkeys (1995)
  • Wall-E (2008)
  • Inception (2010)
  • Her (2013)

In writing this, I was reminded of some of the goofier stuff that Jeff and I included in A User’s Guide to the Universe. In particular, our recap of the failings of sci-fi television:

and our “two-sentence time-travel summaries”:

which, continuing onto the next page reads, “Timecop (1994) (no stars). In 2004, time travel is illegal. Jean-Claude Van Damme is (predictably) a time cop who saves his (supposedly) dead wife’s life without changing the timeline.”

Feel free to comment on how I’ve entirely missed the point of science fiction.


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What should a physics major know?

It’s summer. In academia, it’s a time to get some real research done, take a little R&R with ones family, perhaps wait in breathless anticipation of the paperback release of ones book, and most relevant to today’s discussion, to think about the successes and failures of the previous year.

In addition to my regular duties as a professor, I am also the director of Drexel’s undergraduate Physics program. Each year I have the opportunity to meet with prospective students and parents, guide admissions and curricular policies, and keep an eye on our students to see how they’re doing and where they’re going. And for the most part, our students do great things and go on to great places. For many of them, going on to do great things doesn’t necessarily mean that they go on to be physicists.

Oftentimes, when asked to talk about the value of a physics degree, I focus on how a physicist can do just about anything: finance, engineering, computing, medical school. But these outcomes suggest that the degree that many students actually go to school for — Physics — serves as nothing more than a testament to the fact that they can survive a challenging environment. We could, I suppose, simply take the view that it doesn’t matter whether they go into physics. Research skills, programming, electronic design, data analysis, mathematical rigor and so forth are useful skills for everybody. Certainly, there is a national push for so-called STEM education, and a very real recognition that these skills make a graduate employable.

I think that physics should go beyond an elite STEM accreditation field. The degree matters, even for those students (most of them, actually) who don’t go on to become physicists. They should learn what the state of the science is; they should be prepared to interpret for the world at large, to bring science and subject-specific literacy into their and others’ lives. And what else?

I have a few thoughts on that.

  1. Physics education should not be “engineering light.”

    Let’s start with the introductory sequences. Pick up just about any high school or calculus-based college textbook and you’ll see physics presented in almost the exact order it was discovered. (As a sidenote, you’ll also see virtually identical tables of contents, making it particularly easy for lazy instructors who don’t want to alter their lecture notes one whit to change textbooks without doing any additional work.)

    Generally, there’s a first term in 17th century physics (Newton’s laws), and a second term on 19th century physics (electromagnetism), while a truly excellent teacher might spend a week or two at the end on the more esoteric chapters from the early 20th century (relativity up to E=mc^2 or quantum mechanics up to a vague description of the double-slit experiment). Anything more sophisticated than the bank of a racetrack or the trajectory of a basketball is generally ignored. Speeds above a few hundred mph are generally considered “fast.” This, while we have accelerators capable of accelerating protons to within a few parts in a billion of the speed of light.

    These texts are written with the assumption that everyone reading them is going to be an engineer. The fact that future politicians might also be dozing in the audience is generally of only passing concern (a concern typically dealt with by putting a volcano or a bullet train on the cover ostensibly to jazz things up). This means that the T and the E in STEM get virtually all of the attention, and assumes that the S will simply take care of itself. There seems to be a societal shift away from interest in “basic science,” with the assumption that anything that’s not immediately applicable to technology is simple navel-gazing.

    Introductory physics, at least for majors, but ideally for everybody else, should ideally talk about what’s going on today, with an absolutely minimal focus on pulleys and blocks on planes. Drexel’s intro sequence, we use the (imperfect, but innovative) Matter and Interaction, by Chabay and Sherwood, which focuses on 20th and 21st century physics from the outset.

  2. Most majors aren’t going to be Physicists.

    This is okay. It doesn’t represent a failure on the part of physics educators (though perhaps I’m being too forgiving to myself), but a reality of both people’s interests as well as the job market.

    We’ve always known that students are likely to go into other fields, and we’ve treated that as an excuse to make to sure that they have lots of other skills. While I’m not arguing that we should forgo general education requirements (the etymology of University stems from Unversis meaning “whole” or “entire,” from a desire to have a universal education — a sentiment with which I wholly agree), it’s worth considering that for most physics majors, this is the end of the road, all of the physics that they’re going to see.

    Degree programs that focus only on solving electric fields for configurations of charges or deriving Hamilton’s equations give students the tools of physics, but not the basis. This term I taught a “Standard Model” course for the first time. This was an advanced class officially listed for grad students, but open to undergrads which explored the basis for E&M, the weak and strong forces, open questions with regards to neutrinos, and so on, without requiring Quantum Field Theory. It was literally the most fun I’ve ever had teaching a course, and the students seemed to have a ball as well.

    The more I think about it, the more I think that this is exactly the sort of course that should be required at the advanced undergraduate level. If the BS really is the terminal degree for most of our majors, then by the time they finish, they need to really see how everything fits together. And yet, courses like this seem to be the anomaly. I was only able to cobble together the course from various Classical Field, QFT, and Particle Physics textbooks, even though we were, in essence, justifying the study of just about everything else they’d seen.

    In order to make a coherent (or semi-coherent) whole, I put together a set of ever-evolving course notes with the long-term goal to turn them into a textbook. If you’d like, please check them out, and be sure to send me any corrections and comments you might have. (Please be kind.)

  3. “Physicist” doesn’t just mean one thing.

    It never did, of course. There is an enormous push for “interdisciplinary” research and academic programs at the university level, and you’ll find few people as skeptical as me. Oftentimes, the push is made at the institutional level so that individual researchers will be eligible for federal grants that they might not be otherwise, occasionally at the cost of focus on disciplinary areas of research.

    That said, the boundaries between basic research in condensed matter and applied research in materials engineering is a narrow one, as are the boundaries between biophysics and biomedical engineering, biochemistry (and several other fields). A graduate of physics can be a physicist without following the same career trajectory as even a generation ago. One approach that we take (which, admittedly, is a bit ad hoc) is to allow a much more a la carte approach to completing the degree outside of the essentials (which I’ve taken a stab at above). Physics is far too large to imagine a degree focused around course subfields or core methodologies (theorist? computational “experimentalist”? instrumentalist? You’re all physicist here.)

    That said, I’d like to issue an unresolved word of caution. It’s very easy to suppose that there are no boundaries between disciplines and that a student with a particular career trajectory should simply pick and choose. Beyond the question of whether an 18 or 20 year-old is prepared to map out their future in that way, it’s worth remembering that undergraduate degrees are not a professional degree. Also, that even within those permeable membranes, there’s a lot about physics that is physics, and nothing else. And while I’d like to be able to offer a rigorous definition of what defines a physicist for the next generation, I’m afraid I’m left with Justice Stewart’s definition: “I know it when I see it.”

    Hopefully, some of you can do better.


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Best. Class. Ever.

Credit: me. A simple 1-d simulation of a complex scalar field in an electric field. You’ll find this more instructive after you’ve read the lecture notes. Click on the link if it doesn’t auto play in your browser.

This term, I’m teaching a new class on The Standard Model. It is, bar none, the most fun I’ve had with a course in just about forever. What’s especially novel about it is that we’re tackling just about everything classically, with only occasional recourse to quantum fields.

We’re doing everything from elementary group theory to GUTs, from the Higgs mechanism to neutrino oscillation, with just about everything in between.

Why am I telling you this (besides the fact that I can’t contain my excitement)? Because in designing this class, I couldn’t find exactly the right text, so I’m thinking of transforming my lecture notes into a book. As a first stab, here are:
The First 4 weeks of lectures!
Please excuse any typos, and the verbiage wasn’t originally meant for human consumption. This is in the same spirit as my previous lecture notes on probability. Like my previous notes, these are extremely technical, and the course itself is designed for an advanced undergraduate/grad audience.

The notes themselves are a work in progress, but if you think any big topics are missing, please let me know.

BTW, part 4 of the notes is on scalar fields and inflation, and I am especially indebted to this excellent post by John Preskill for providing such a nice demonstration of dimensional analysis.

I welcome all constructive comments, but please, keep it classy.


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By now, you’ve either seen the first episode of the new Cosmos or you’re not going to. The nerdverse has been breathless with anticipation for months now, and now that it’s here, the reviews are… pretty good. I don’t make it a point to be a culture critic, but as the Drexel University Relations department asked for my take on the new show, I thought I may as well give a reasonably thoughtful one. Below are my somewhat expanded comments.

There’s a lot to admire about the Cosmos reboot. Neil Tyson, for one, is one of the best evangelists for science we have right now. He’s incredibly knowledgeable, personable, passionate, and a dedicated public educator. That said, while the science in the show was generally very accurate, I do have a fear that there is an element of preaching to the choir. Much is made in the introduction about the rigors of science, and yet there’s no discussion of how the science is done. Dedicated fans of science will already know much of what is presented, and those who doubt the scientific method, or evolution, or the Big Bang model of cosmology, are unlikely to be persuaded by Tyson’s assurances.

Instead, there’s a clear effort to overwhelm the audience with special effects. To a certain sort of fan, Tyson’s authoritative intonation of the scale of the cosmos (the focus of the first episode) will genuinely evoke excitement. It is also potentially a great entryway for kids who are just learning about science for the first time. Sagan’s original packed a wallop in large part because people like me were kids at the time. It evoked curiosity and an excitement about science. There is the very real hope that Tyson’s version will do the same.

As of the first episode, most of the updates (apart from the host) are cosmetic. Certainly, we know the timescale of the universe a bit better than we did in 1980, but the biggest changes center around using computer graphics to project the earth into the future, or to draw Tyson’s spaceship. Some of these effects (and the rather gratuitous use of lens flares) are a little cheesy. But there is also some excellent footage from modern spacecraft that is integrated seamlessly into the narrative, especially of Mars.

The most significantly new discussion centers around Giordano Bruno, a Franciscan Friar who proposed the possibility of many worlds (and thus, many aliens, each with their own savior), who was ultimately killed as a heretic. Bruno is a somewhat more complicated figure than Cosmos makes out, but it was refreshing to see a usually overlooked thinker included in the discussion.

There were a few instances in which the visualization obscures scientific accuracy. For instance, as Tyson flies through the asteroid belt in his “Ship of the Imagination” (a ray-traced, Prius-esque reimagining from the original series), the animators make the typical science fiction mistake of putting the field so crowded that Tyson is barely able to squeeze through. In reality, the typical distance between asteroids is about a million miles, roughly 4 times the distance to the moon. While a realistic asteroid field would look dull, I feel as though the show missed a number of opportunities to realistically portray the true scope and emptiness of space.

There were several other occasions where “what if?” scenarios were played interchangeably with “This is what happened.” The most glaring of these occurred during a sequence in which we’re shown a particular asteroid nudged gravitationally in its orbit and then later that same asteroid is seen to commit mass dinocide. This is meant to be a hypothetical, but to the uninitiated (including, apparently, the folks on the Culture Gabfest at Slate), it isn’t clear that is not, in fact, a detailed model rather than a very vague guess.

Those concerns aside, we would have a far more science literate audience if the public at large internalized the content of the show. In many ways, the reboot is long overdue. There’s a great deal of mistrust and misunderstanding of science. One need only look at the public views of evolution, global warming, and the anti-vax community to be aware of the backlash against science — real science, as opposed to “geek culture,” like in The Big Bang Theory and elsewhere. This is why it is so important that Cosmos not only get the next generation excited, but also to explain not only what we know, but how we know it.

I want to close with an observation about the final scene — one which most reviewers found quite touching. Tyson shows us Carl Sagan’s appointment book from when he (Tyson) was a boy, and that Sagan made an entire day for him, signed a copy of his book, and generally took Tyson under his wing and mentored him. It took me a little while to articulate what bothered me about this scene, but ultimately I feel as though it smacks of predestination. It reminds me of that famous photograph in which a fresh-faced Bill Clinton met JFK as a boy. The implication, in both cases, is that there was a symbolic passing of the torch. The problem, of course, is that most kids aren’t going to have such an experience. If a kid isn’t marked by some great scientist or mentor very early on, do they simply lack the spark?

I realize that this isn’t what Cosmos was trying to say in the sequence. Tyson and the show were simply trying to convey the generosity of Sagan’s spirit, and I appreciate that. But given the cult of personality that has grown up around Tyson in the last decade, it’s very easy to see it in another light.


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Does it make sense?

A question from a reader:

My dad always told me, after finishing a math problem for homework, ‘look at the answer and ask your self ‘does this answer make sense'” So, my question is: do the answers we get from the Wave Function make sense? And, if they don’t, shouldn’t folks like you consider finding a function that renders sensible answers?

My response:

I take it from the question that you feel that it doesn’t. The universe, unfortunately, doesn’t always conform to our common sense. We evolved in a world where knowledge on macroscopic (non-quantum) scales, non-relativistic speeds, and weak gravity were the norm, so time dilation or wave-particle duality are not part of the intuition wired into our brain. One of the amazing things about scientific discovery is that we’re able to overcome our natural intuition. The wave-function makes perfect sense in that it predicts (with astonishing accuracy) the behavior of all elements on the periodic table, astrophysical objects like white dwarves and neutron stars, the double slit experiment, radioactive decay and on and on. “Sensible,” in the case, should mean “correct,” and by that standard quantum mechanics (wave functions and all) is the single most successful theory in the history of science.


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