Tag Archives: PublicPerception

Don’t Trust the Experiments, Trust the Science

I was chatting with an astronomer recently, and this quote by Arthur Eddington came up:

“Never trust an experimental result until it has been confirmed by theory.”

Arthur Eddington

At first, this sounds like just typical theorist arrogance, thinking we’re better than all those experimentalists. It’s not that, though, or at least not just that. Instead, it’s commenting on a trend that shows up again and again in science, but rarely makes the history books. Again and again an experiment or observation comes through with something fantastical, something that seems like it breaks the laws of physics or throws our best models into disarray. And after a few months, when everyone has checked, it turns out there was a mistake, and the experiment agrees with existing theories after all.

You might remember a recent example, when a lab claimed to have measured neutrinos moving faster than the speed of light, only for it to turn out to be due to a loose cable. Experiments like this aren’t just a result of modern hype: as Eddington’s quote shows, they were also common in his day. In general, Eddington’s advice is good: when an experiment contradicts theory, theory tends to win in the end.

This may sound unscientific: surely we should care only about what we actually observe? If we defer to theory, aren’t we putting dogma ahead of the evidence of our senses? Isn’t that the opposite of good science?

To understand what’s going on here, we can use an old philosophical argument: David Hume’s argument against miracles. David Hume wanted to understand how we use evidence to reason about the world. He argued that, for miracles in particular, we can never have good evidence. In Hume’s definition, a miracle was something that broke the established laws of science. Hume argued that, if you believe you observed a miracle, there are two possibilities: either the laws of science really were broken, or you made a mistake. The thing is, laws of science don’t just come from a textbook: they come from observations as well, many many observations in many different conditions over a long period of time. Some of those observations establish the laws in the first place, others come from the communities that successfully apply them again and again over the years. If your miracle was real, then it would throw into doubt many, if not all, of those observations. So the question you have to ask is: it it more likely those observations were wrong? Or that you made a mistake? Put another way, your evidence is only good enough for a miracle if it would be a bigger miracle if you were wrong.

Hume’s argument always struck me as a little bit too strict: if you rule out miracles like this, you also rule out new theories of science! A more modern approach would use numbers and statistics, weighing the past evidence for a theory against the precision of the new result. Most of the time you’d reach the same conclusion, but sometimes an experiment can be good enough to overthrow a theory.

Still, theory should always sit in the background, a kind of safety net for when your experiments screw up. It does mean that when you don’t have that safety net you need to be extra-careful. Physics is an interesting case of this: while we have “the laws of physics”, we don’t have any established theory that tells us what kinds of particles should exist. That puts physics in an unusual position, and it’s probably part of why we have such strict standards of statistical proof. If you’re going to be operating without the safety net of theory, you need that kind of proof.

This post was also inspired by some biological examples. The examples are politically controversial, so since this is a no-politics blog I won’t discuss them in detail. (I’ll also moderate out any comments that do.) All I’ll say is that I wonder if in that case the right heuristic is this kind of thing: not to “trust scientists” or “trust experts” or even “trust statisticians”, but just to trust the basic, cartoon-level biological theory.

Facts About Math Are Facts About Us

Each year, the Niels Bohr International Academy has a series of public talks. Part of Copenhagen’s Folkeuniversitet (“people’s university”), they attract a mix of older people who want to keep up with modern developments and young students looking for inspiration. I gave a talk a few days ago, as part of this year’s program. The last time I participated, back in 2017, I covered a topic that comes up a lot on this blog: “The Quest for Quantum Gravity”. This year, I was asked to cover something more unusual: “The Unreasonable Effectiveness of Mathematics in the Natural Sciences”.

Some of you might notice that title is already taken: it’s a famous lecture by the physicist Wigner, from 1959. Wigner posed an interesting question: why is advanced mathematics so useful in physics? Time and time again, mathematicians develop an idea purely for its own sake, only for physicists to find it absolutely indispensable to describe some part of the physical world. Should we be surprised that this keeps working? Suspicious?

I talked a bit about this: some of the answers people have suggested over the years, and my own opinion. But like most public talks, the premise was mostly a vehicle for cool examples: physicists through history bringing in new math, and surprising mathematical facts like the ones I talked about a few weeks back at Culture Night. Because of that, I was actually a bit unprepared to dive into the philosophical side of the topic (despite it being in principle a very philosophical topic!) When one of the audience members brought up mathematical Platonism, I floundered a bit, not wanting to say something that was too philosophically naive.

Well, if there’s anywhere I can be naive, it’s my own blog. I even have a label for Amateur Philosophy posts. So let’s do one.

Mathematical Platonism is the idea that mathematical truths “exist”: that they’re somewhere “out there” being discovered. On the other side, one might believe that mathematics is not discovered, but invented. For some reason, a lot of people with the latter opinion seem to think this has something to do with describing nature (for example, an essay a few years back by Lee Smolin defines mathematics as “the study of systems of evoked relationships inspired by observations of nature”).

I’m not a mathematical Platonist. I don’t even like to talk about which things do or don’t “exist”. But I also think that describing mathematics in terms of nature is missing the point. Mathematicians aren’t physicists. While there may have been a time when geometers argued over lines in the sand, these days mathematicians’ inspiration isn’t usually the natural world, at least not in the normal sense.

Instead, I think you can’t describe mathematics without describing mathematicians. A mathematical fact is, deep down, something a mathematician can say without other mathematicians shouting them down. It’s an allowed move in what my hazy secondhand memory of Wittgenstein wants to call a “language game”: something that gets its truth from a context of people interpreting and reacting to it, in the same way a move in chess matters only when everyone is playing by its rules.

This makes mathematics sound very subjective, and we’re used to the opposite: the idea that a mathematical fact is as objective as they come. The important thing to remember is that even with this kind of description, mathematics still ends up vastly less subjective than any other field. We care about subjectivity between different people: if a fact is “true” for Brits and “false” for Germans, then it’s a pretty limited fact. Mathematics is special because the “rules of its game” aren’t rules of one group or another. They’re rules that are in some sense our birthright. Any human who can read and write, or even just act and perceive, can act as a Turing Machine, a universal computer. With enough patience and paper, anything that you can prove to one person you can prove to another: you just have to give them the rules and let them follow them. It doesn’t matter how smart you are, or what you care about most: if something is mathematically true for others, it is mathematically true for you.

Some would argue that this is evidence for mathematical Platonism, that if something is a universal truth it should “exist”. Even if it does, though, I don’t think it’s useful to think of it in that way. Once you believe that mathematical truth is “out there”, you want to try to characterize it, to say something about it besides that it’s “out there”. You’ll be tempted to have an opinion on the Axiom of Choice, or the Continuum Hypothesis. And the whole point is that those aren’t sensible things to have opinions on, that having an opinion about them means denying the mathematical proofs that they are, in the “standard” axioms, undecidable. Whatever is “out there”, it has to include everything you can prove with every axiom system, whichever non-standard ones you can cook up, because mathematicians will happily work on any of them. The whole point of mathematics, the thing that makes it as close to objective as anything can be, is that openness: the idea that as long as an argument is good enough, as long as it can convince anyone prepared to wade through the pages, then it is mathematics. Nothing, so long as it can convince in the long-run, is excluded.

If we take this definition seriously, there are some awkward consequences. You could imagine a future in which every mind, everyone you might be able to do mathematics with, is crushed under some tyrant, forced to agree to something false. A real philosopher would dig in to this corner case, try to salvage the definition or throw it out. I’m not a real philosopher though. So all I can say is that while I don’t think that tyrant gets to define mathematics, I also don’t think there are good alternatives to my argument. Our only access to mathematics, and to truth in general, is through the people who pursue it. I don’t think we can define one without the other.

Outreach Talk on Math’s Role in Physics

Tonight is “Culture Night” in Copenhagen, the night when the city throws open its doors and lets the public in. Museums and hospitals, government buildings and even the Freemasons, all have public events. The Niels Bohr Institute does too, of course: an evening of physics exhibits and demos, capped off with a public lecture by Denmark’s favorite bow-tie wearing weirder-than-usual string theorist, Holger Bech Nielsen. In between, there are a number of short talks by various folks at the institute, including yours truly.

In my talk, I’m going to try and motivate the audience to care about math. Math is dry of course, and difficult for some, but we physicists need it to do our jobs. If you want to be precise about a claim in physics, you need math simply to say what you want clearly enough.

Since you guys likely don’t overlap with my audience tonight, it should be safe to give a little preview. I’ll be using a few examples, but this one is the most complicated:

I’ll be telling a story I stole from chapter seven of the web serial Almost Nowhere. (That link is to the first chapter, by the way, in case you want to read the series without spoilers. It’s very strange, very unique, and at least in my view quite worth reading.) You follow a warrior carrying a spear around a globe in two different paths. The warrior tries to always point in the same direction, but finds that the two different paths result in different spears when they meet. The story illustrates that such a simple concept as “what direction you are pointing” isn’t actually so simple: if you want to think about directions in curved space (like the surface of the Earth, but also, like curved space-time in general relativity) then you need more sophisticated mathematics (a notion called parallel transport) to make sense of it.

It’s kind of an advanced concept for a public talk. But seeing it show up in Almost Nowhere inspired me to try to get it across. I’ll let you know how it goes!

By the way, if you are interested in learning the kinds of mathematics you need for theoretical physics, and you happen to be a Bachelor’s student planning to pursue a PhD, then consider the Perimeter Scholars International Master’s Program! It’s a one-year intensive at the Perimeter Institute in Waterloo, Ontario, in Canada. In a year it gives you a crash course in theoretical physics, giving you tools that will set you ahead of other beginning PhD students. I’ve witnessed it in action, and it’s really remarkable how much the students learn in a year, and what they go on to do with it. Their early registration deadline is on November 15, just a month away, so if you’re interested you may want to start thinking about it.

Breaking Out of “Self-Promotion Voice”

What do TED talks and grant applications have in common?

Put a scientist on a stage, and what happens? Some of us panic and mumble. Others are as smooth as a movie star. Most, though, fall back on a well-practiced mode: “self-promotion voice”.

A scientist doing self-promotion voice is easy to recognize. We focus on ourselves, of course (that’s in the name!), talking about all the great things we’ve done. If we have to mention someone else, we make sure to link it in some way: “my colleague”, “my mentor”, “which inspired me to”. All vulnerability is “canned” in one way or another: “challenges we overcame”, light touches on the most sympathetic of issues. Usually, we aren’t negative towards our colleagues either: apart from the occasional very distant enemy, everyone is working with great scientific virtue. If we talk about our past, we tell the same kinds of stories, mentioning our youthful curiosity and deep buzzwordy motivations. Any jokes or references are carefully pruned, made accessible to the lowest-common-denominator. This results in a standard vocabulary: see a metaphor, a quote, or a turn of phrase, and you’re bound to see it in talks again and again and again. Things get even more repetitive when you take into account how often we lean on the voice: a given speech or piece will be assembled from elementary pieces, snippets of practiced self-promotion that we pour in like packing peanuts after a minimal edit, filling all available time and word count.

“My passion for teaching manifests…”

Packing peanuts may not be glamorous, but they get the job done. A scientist who can’t do “the voice” is going to find life a lot harder, their negativity or clumsiness turning away support when they need it most. Except for the greatest of geniuses, we all have to learn a bit of self-promotion to stay employed.

We don’t have to stop there, though. Self-promotion voice works, but it’s boring and stilted, and it all looks basically the same. If we can do something a bit more authentic then we stand out from the crowd.

I’ve been learning this more and more lately. My blog posts have always run the gamut: some are pure formula, but the ones I’m most proud of have a voice all their own. Over the years, I’ve been pushing my applications in that direction. Each grant and job application has a bit of the standard self-promotion voice pruned away, and a bit of another voice (my own voice?) sneaking in. This year, as I send out applications, I’ve been tweaking things. I almost hope the best jobs come late in the year, my applications will be better then!

Why Can’t I Pay Academics to Do Things for Me?

A couple weeks back someone linked to this blog with a problem. A non-academic, he had done some mathematical work but didn’t feel it was ready to publish. He reached out to a nearby math department and asked what they would charge to help him clean up the work. If the price was reasonable, he’d do it, if not at least he’d know what it would cost.

Neither happened. He got no response, and got more and more frustrated.

For many of you, that result isn’t a big surprise. My academic readers are probably cringing at the thought of getting an email like that. But the guy’s instinct here isn’t too off-base. Certainly, in many industries that kind of email would get a response with an actual quote. Academia happens to be different, in a way that makes the general rule not really apply.

There’s a community called Effective Altruists that evaluate charities. They have a saying, “Money is the Unit of Caring”. The point of the saying isn’t that people with more money care more, or anything like that. Rather, it’s a reminder that, whatever a charity wants to accomplish, more money makes it easier. A lawyer could work an hour in a soup kitchen, but if they donated the proceeds of an hour’s work the soup kitchen could hire four workers instead. Food banks would rather receive money than food, because the money lets them buy whatever they need in bulk. As the Simpsons meme says, “money can be exchanged for goods and services”.

If you pay a charity, or a business, it helps them achieve what they want to do. If you pay an academic, it gets a bit more complicated.

The problem is that for academics, time matters a lot more than our bank accounts. If we want to settle down with a stable job, we need to spend our time doing things that look good on job applications: writing papers, teaching students, and so on. The rest of the time gets spent resting so we have the energy to do all of that.

(What about tenured professors? They don’t have to fight for their own jobs…but by that point, they’ve gotten to know their students and other young people in their sub-field. They want them to get jobs too!)

Money can certainly help with those goals, but not personal money: grant money. With grant money we can hire students and postdocs to do some of that work for us, or pay our own salary so we’re easier for a university to hire. We can buy equipment for those who need that sort of thing, and get to do more interesting science. Rather than “Money is the Unit of Caring”, for academics, “Grant Money is the Unit of Caring”.

Personal money, in contrast, just matters for our rest time. And unless we have expensive tastes, we usually get paid enough for that.

(The exception is for extremely underpaid academics, like PhD students and adjuncts. For some of them money can make a big difference to their quality of life. I had quite a few friends during my PhD who had side gigs, like tutoring, to live a bit more comfortably.)

This is not to say that it’s impossible to pay academics to do side jobs. People do. But when it works, it’s usually due to one of these reasons:

  1. It’s fun. Side work trades against rest time, but if it helps us rest up then it’s not really a tradeoff. Even if it’s a little more boring that what we’d rather do, if it’s not so bad the money can make up the difference.
  2. It looks good on a CV. This covers most of the things academics are sometimes paid to do, like writing articles for magazines. If we can spin something as useful to our teaching or research, or as good for the greater health of the field (or just for our “personal brand”), then we can justify doing it.
  3. It’s a door out of academia. I’ve seen the occasional academic take time off to work for a company. Usually that’s a matter of seeing what it’s like, and deciding whether it looks like a better life. It’s not really “about the money”, even in those cases.

So what if you need an academic’s help with something? You need to convince them it’s worth their time. Money could do it, but only if they’re living precariously, like some PhD students. Otherwise, you need to show that what you’re asking helps the academic do what they’re trying to do: that it is likely to move the field forward, or that it fulfills some responsibility tied to their personal brand. Without that, you’re not likely to hear back.

Stop Listing the Amplituhedron as a Competitor of String Theory

The Economist recently had an article (paywalled) that meandered through various developments in high-energy physics. It started out talking about the failure of the LHC to find SUSY, argued this looked bad for string theory (which…not really?) and used it as a jumping-off point to talk about various non-string “theories of everything”. Peter Woit quoted it a few posts back as kind of a bellwether for public opinion on supersymmetry and string theory.

The article was a muddle, but a fairly conventional muddle, explaining or mis-explaining things in roughly the same way as other popular physics pieces. For the most part that didn’t bug me, but one piece of the muddle hit a bit close to home:

The names of many of these [non-string theories of everything] do, it must be conceded, torture the English language. They include “causal dynamical triangulation”, “asymptotically safe gravity”, “loop quantum gravity” and the “amplituhedron formulation of quantum theory”.

I’ve posted about the amplituhedron more than a few times here on this blog. Out of every achievement of my sub-field, it has most captured the public imagination. It’s legitimately impressive, a way to translate calculations of probabilities of collisions of fundamental particles (in a toy model, to be clear) into geometrical objects. What it isn’t, and doesn’t pretend to be, is a theory of everything.

To be fair, the Economist piece admits this:

Most attempts at a theory of everything try to fit gravity, which Einstein describes geometrically, into quantum theory, which does not rely on geometry in this way. The amplituhedron approach does the opposite, by suggesting that quantum theory is actually deeply geometric after all. Better yet, the amplituhedron is not founded on notions of spacetime, or even statistical mechanics. Instead, these ideas emerge naturally from it. So, while the amplituhedron approach does not as yet offer a full theory of quantum gravity, it has opened up an intriguing path that may lead to one.

The reasoning they have leading up to it has a few misunderstandings anyway. The amplituhedron is geometrical, but in a completely different way from how Einstein’s theory of gravity is geometrical: Einstein’s gravity is a theory of space and time, the amplituhedron’s magic is that it hides space and time behind a seemingly more fundamental mathematics.

This is not to say that the amplituhedron won’t lead to insights about gravity. That’s a big part of what it’s for, in the long-term. Because the amplituhedron hides the role of space and time, it might show the way to theories that lack them altogether, theories where space and time are just an approximation for a more fundamental reality. That’s a real possibility, though not at this point a reality.

Even if you take this possibility completely seriously, though, there’s another problem with the Economist’s description: it’s not clear that this new theory would be a non-string theory!

The main people behind the amplituhedron are pretty positively disposed to string theory. If you asked them, I think they’d tell you that, rather than replacing string theory, they expect to learn more about string theory: to see how it could be reformulated in a way that yields insight about trickier problems. That’s not at all like the other “non-string theories of everything” in that list, which frame themselves as alternatives to, or even opponents of, string theory.

It is a lot like several other research programs, though, like ER=EPR and It from Qubit. Researchers in those programs try to use physical principles and toy models to say fundamental things about quantum gravity, trying to think about space and time as being made up of entangled quantum objects. By that logic, they belong in that list in the article alongside the amplituhedron. The reason they aren’t is obvious if you know where they come from: ER=EPR and It from Qubit are worked on by string theorists, including some of the most prominent ones.

The thing is, any reason to put the amplituhedron on that list is also a reason to put them. The amplituhedron is not a theory of everything, it is not at present a theory of quantum gravity. It’s a research direction that might shed new insight about quantum gravity. It doesn’t explicitly involve strings, but neither does It from Qubit most of the time. Unless you’re going to describe It from Qubit as a “non-string theory of everything”, you really shouldn’t describe the amplituhedron as one.

The amplituhedron is a really cool idea, one with great potential. It’s not something like loop quantum gravity, or causal dynamical triangulations, and it doesn’t need to be. Let it be what it is, please!

The Winding Path of a Physics Conversation

In my line of work, I spend a lot of time explaining physics. I write posts here of course, and give the occasional public lecture. I also explain physics when I supervise Master’s students, and in a broader sense whenever I chat with my collaborators or write papers. I’ll explain physics even more when I start teaching. But of all the ways to explain physics, there’s one that has always been my favorite: the one-on-one conversation.

Talking science one-on-one is validating in a uniquely satisfying way. You get instant feedback, questions when you’re unclear and comprehension when you’re close. There’s a kind of puzzle to it, discovering what you need to fill in the gaps in one particular person’s understanding. As a kid, I’d chase this feeling with imaginary conversations: I’d plot out a chat with Democritus or Newton, trying to explain physics or evolution or democracy. It was a game, seeing how I could ground our modern understanding in concepts someone from history already knew.

Way better than Parcheesi

I’ll never get a chance in real life to explain physics to a Democritus or a Newton, to bridge a gap quite that large. But, as I’ve discovered over the years, everyone has bits and pieces they don’t yet understand. Even focused on the most popular topics, like black holes or elementary particles, everyone has gaps in what they’ve managed to pick up. I do too! So any conversation can be its own kind of adventure, discovering what that one person knows, what they don’t, and how to connect the two.

Of course, there’s fun in writing and public speaking too (not to mention, of course, research). Still, I sometimes wonder if there’s a career out there in just the part I like best: just one conversation after another, delving deep into one person’s understanding, making real progress, then moving on to the next. It wouldn’t be efficient by any means, but it sure sounds fun.

Doing Difficult Things Is Its Own Reward

Does antimatter fall up, or down?

Technically, we don’t know yet. The ALPHA-g experiment would have been the first to check this, making anti-hydrogen by trapping anti-protons and positrons in a long tube and seeing which way it falls. While they got most of their setup working, the LHC complex shut down before they could finish. It starts up again next month, so we should have our answer soon.

That said, for most theorists’ purposes, we absolutely do know: antimatter falls down. Antimatter is one of the cleanest examples of a prediction from pure theory that was confirmed by experiment. When Paul Dirac first tried to write down an equation that described electrons, he found the math forced him to add another particle with the opposite charge. With no such particle in sight, he speculated it could be the proton (this doesn’t work, they need the same mass), before Carl D. Anderson discovered the positron in 1932.

The same math that forced Dirac to add antimatter also tells us which way it falls. There’s a bit more involved, in the form of general relativity, but the recipe is pretty simple: we know how to take an equation like Dirac’s and add gravity to it, and we have enough practice doing it in different situations that we’re pretty sure it’s the right way to go. Pretty sure doesn’t mean 100% sure: talk to the right theorists, and you’ll probably find a proposal or two in which antimatter falls up instead of down. But they tend to be pretty weird proposals, from pretty weird theorists.

Ok, but if those theorists are that “weird”, that outside the mainstream, why does an experiment like ALPHA-g exist? Why does it happen at CERN, one of the flagship facilities for all of mainstream particle physics?

This gets at a misconception I occasionally hear from critics of the physics mainstream. They worry about groupthink among mainstream theorists, the physics community dismissing good ideas just because they’re not trendy (you may think I did that just now, for antigravity antimatter!) They expect this to result in a self-fulfilling prophecy where nobody tests ideas outside the mainstream, so they find no evidence for them, so they keep dismissing them.

The mistake of these critics is in assuming that what gets tested has anything to do with what theorists think is reasonable.

Theorists talk to experimentalists, sure. We motivate them, give them ideas and justification. But ultimately, people do experiments because they can do experiments. I watched a talk about the ALPHA experiment recently, and one thing that struck me was how so many different techniques play into it. They make antiprotons using a proton beam from the accelerator, slow them down with magnetic fields, and cool them with lasers. They trap their antihydrogen in an extremely precise vacuum, and confirm it’s there with particle detectors. The whole setup is a blend of cutting-edge accelerator physics and cutting-edge tricks for manipulating atoms. At its heart, ALPHA-g feels like its primary goal is to stress-test all of those tricks: to push the state of the art in a dozen experimental techniques in order to accomplish something remarkable.

And so even if the mainstream theorists don’t care, ALPHA will keep going. It will keep getting funding, it will keep getting visited by celebrities and inspiring pop fiction. Because enough people recognize that doing something difficult can be its own reward.

In my experience, this motivation applies to theorists too. Plenty of us will dismiss this or that proposal as unlikely or impossible. But give us a concrete calculation, something that lets us use one of our flashy theoretical techniques, and the tune changes. If we’re getting the chance to develop our tools, and get a paper out of it in the process, then sure, we’ll check your wacky claim. Why not?

I suspect critics of the mainstream would have a lot more success with this kind of pitch-based approach. If you can find a theorist who already has the right method, who’s developing and extending it and looking for interesting applications, then make your pitch: tell them how they can answer your question just by doing what they do best. They’ll think of it as a chance to disprove you, and you should let them, that’s the right attitude to take as a scientist anyway. It’ll work a lot better than accusing them of hogging the grant money.

Is Outreach for Everyone?

Betteridge’s law applies here: the answer is “no”. It’s a subtle “no”, though.

As a scientist, you will always need to be able to communicate your work. Most of the time you can get away with papers and talks aimed at your peers. But the longer you mean to stick around, the more often you will have to justify yourself to others: to departments, to universities, and to grant agencies. A scientist cannot survive on scientific ability alone: to get jobs, to get funding, to survive, you need to be able to promote yourself, at least a little.

Self-promotion isn’t outreach, though. Talking to the public, or to journalists, is a different skill from talking to other academics or writing grants. And it’s entirely possible to go through an entire scientific career without exercising that skill.

That’s a reassuring message for some. I’ve met people for whom science is a refuge from the mess of human interaction, people horrified by the thought of fame or even being mentioned in a newspaper. When I meet these people, they sometimes seem to worry that I’m silently judging them, thinking that they’re ignoring their responsibilities by avoiding outreach. They think this in part because the field seems to be going in that direction. Grants that used to focus just on science have added outreach as a requirement, demanding that each application come with a plan for some outreach project.

I can’t guarantee that more grants won’t add outreach requirements. But I can say at least that I’m on your side here: I don’t think you should have to do outreach if you don’t want to. I don’t think you have to, just yet. And I think if grant agencies are sensible, they’ll find a way to encourage outreach without making it mandatory.

I think that overall, collectively, we have a responsibility to do outreach. Beyond the old arguments about justifying ourselves to taxpayers, we also just ought to be open about what we do. In a world where people are actively curious about us, we ought to encourage and nurture that curiosity. I don’t think this is unique to science, I think it’s something every industry, every hobby, and every community should foster. But in each case, I think that communication should be done by people who want to do it, not forced on every member.

I also think that, potentially, anyone can do outreach. Outreach can take different forms for different people, anything from speaking to high school students to talking to journalists to writing answers for Stack Exchange. I don’t think anyone should feel afraid of outreach because they think they won’t be good enough. Chances are, you know something other people don’t: I guarantee if you want to, you will have something worth saying.

“Inreach”

This is, first and foremost, an outreach blog. I try to make my writing as accessible as possible, so that anyone from high school students to my grandparents can learn something. My goal is to get the general public to know a bit more about physics, and about the people who do it, both to better understand the world and to view us in a better light.

However, as I am occasionally reminded, my readers aren’t exactly the general public. I’ve done polls, and over 60% of you either have a PhD in physics, or are on your way to one. The rest include people with what one might call an unusually strong interest in physics: engineers with a fondness for the (2,0) theory, or retired lawyers who like to debate dark matter.

With that in mind, am I really doing outreach? Or am I doing some sort of “inreach” instead?

First, it’s important to remember that just because someone is a physicist doesn’t mean they’re an expert in everything. This is especially relevant when I talk about my own sub-field, but it matters for other topics too: experts in one part of physics can still find something to learn, and it’s still worth getting on their good side. Still, if that was my main audience, I’d probably want to strike a different tone, more like the colloquium talks we give for our fellow physicists.

Second, I like to think that outreach “trickles down”. I write for a general audience, and get read by “physics fans”, but they will go on to talk about physics to anyone who will listen: to parents who want to understand what they do, to people they’re trying to impress at parties, to friends they share articles with. If I write good metaphors and clear analogies, they will get passed on to those friends and parents, and the “inreach” will become outreach. I know that’s why I read other physicists’ outreach blogs: I’m looking for new tricks to make ideas clearer.

Third, active readers are not all readers. The people who answer a poll are more likely to be regulars, people who come back to the blog again and again, and those people are pretty obviously interested in physics. (Interested doesn’t mean expert, of course…but in practice, far more non-experts read blogs on, say, military history, than on physics.) But I suspect most of my readers aren’t regulars. My most popular post, “The Way You Think Everything Is Connected Isn’t the Way Everything Is Connected”, gets a trickle of new views every day. WordPress lets me see some of the search terms people use to find it, and there are people who literally google “is everything connected?” These aren’t physics PhDs looking for content, these are members of the general public who hear something strange and confusing and want to check it out. Being that check, the source someone googles to clear things up, that’s an honor. Knowing I’m serving that role, I know I’m not doing “just inreach”: I’m reaching out too.