I have reasons to resent Sabine Hossenfelder. 1: She has criticized my end-of-science thesis. 2: She’s a free-will denier. 3: Scientists who write for non-scientists make it harder for mere journalists to make a buck. In December, she lectured at a physics conference in Germany, and then she reported on the conference in Forbes. Come on, how can journalists compete with that?
But I enjoy Hossenfelder’s brisk, blunt style too much to dislike her, even when her views diverge from mine. Born and educated in Germany, she got her doctorate in theoretical physics in 2003 and soon started writing popular articles as well as technical papers. She maintains a blog, Backreaction, and contributes to the Forbes column “Starts with a Bang.” She has also written for Scientific American, Physics Today and other publications. Now based at the Frankfurt Institute for Advanced Studies (after stints at the University of Arizona, the Perimeter Institute and elsewhere, see her bio here), Hossenfelder seems to be everywhere lately, chiming in on string theory, loop-space theory, multiverses, black holes and the physics of lightsabers, among other topics. We recently had the following email exchange:
Horgan: Why are you called “Bee”?
Hossenfelder: The last two syllables of my first name are pronounced like the German word for bee. You have to credit my mom for the nickname. But a tiny buzzing creature that stings and kills itself in that process seemed an apt blogger pseudonym.
Horgan: Why physics?
Hossenfelder: I originally studied math, not physics. I later switched to physics because I realized I was interested in mathematical truths only to the extent that they could teach me something about the real world. My main interest has always been in the structure of natural law, the question what makes the universe run this way. And physics is the discipline that delivers the sharpest answers to this.
Horgan: Do you ever regret your career choice? I hear physics might be ending.
Hossenfelder: No regrets. I have learned – am still learning – a lot about the fundamental nature of reality, and I don’t think this would have been possible in any other profession. I doubt physics will end any time soon. At some point maybe parts of it won’t be called physics any more.
And Harry Cliff… My summary of his talk would be that it might become more difficult for particle physicists to find jobs. But if he’d just say that nobody would invite him to give a TED talk about it.
Horgan: In 2002 I bet Michio Kaku $1,000 that no one will win a Nobel Prize “for work on superstring theory, membrane theory, or some other unified theory describing all the forces of nature.” Who’s going to win?
Hossenfelder: By 2020?! Of course you will win. I think though there will be a Nobel Prize for finding experimental evidence for quantum gravity in the next, say, 25 years.
Horgan: Okay, readers heard it here first. Ed Witten recently told me that string theory is still our best candidate for a unified theory. [See link below.] Agree?
Hossenfelder: Does “best” mean that the most papers have been written about it? Then I suppose he is right. Other than that, how do we know which theory is the “best” if there is no observational evidence that could distinguish between theories? (And yes, there are alternatives to string theory, such as for example asymptotically safe gravity.)
How to decide which theory is the most promising one is a pressing question in an area starved of data, and it was also the central question at the Munich workshop I attended in December. How can non-empirical arguments increase confidence in a theory?
The use of non-empirical arguments in theory development is nothing new, what is new is that its relevance is much larger now that it takes so long to test theories.
Theorists use non-empirical theory assessment all the time, when they decide what to work on or even what conference to go to. In principle that is reasonable, taking into account all knowledge that has accumulated about a theory, such as how well it’s been shown to be compatible with already confirmed theories or how many alternative explanations there are. But the problem is that this non-empirical assessment can, and almost certainly is, skewed by social and cognitive biases.
As you wrote recently, how many alternatives one has found depends on how hard one tried to find them. Tell me how this effort-counting in science is not affected by job opportunities and peer pressure.
If you want to rely on non-empirical assessment, you have to make really sure that scientists’ judgment is as objective as humanly possible. And the environment in academia presently is absolutely unsuitable for this. You just can’t be sure how much sociology affects judgment. And no physicist I know makes any effort to consciously address cognitive biases, such as wishful thinking, loss aversion, or the use of aesthetic criteria. It’s just not something that they pay attention to because it’s never been necessary before. As long as you have data for guidance, you’ll be swiftly corrected.
Horgan: Paul Steinhardt, an originator of inflation, is now a critic of inflation and of multiverse theories. Do you share his concerns?
Hossenfelder: Steinhardt’s argument in a nutshell is that inflation doesn’t solve the problem it was meant to solve because for all we presently know it (the potential) requires finetuning to fit current data. I don’t have a problem with fine-tuning. It’s fine by me. Consequently I don’t share this aspect of Steinhardt’s concern. It’s a model, it fits the data, all is good. I don’t really care what was the original motivation. The concern I share is that landscape arguments will just turn out to be a huge waste of time. But I don’t have a big problem with people who want to study the physics of the multiverse. I think it’s unlikely but maybe there is something to learn here.
Horgan: Do you ever suspect that black holes exist only in our imaginations?
Hossenfelder: I do on occasion suffer from a bout of solipsism in which I suspect that the whole universe is only my imagination. But on my better days I think black holes are a straightforward and plausible explanation for many astrophysical observations, and I consider their existence very well confirmed.
Horgan: Steven Weinberg recently told me that science will never explain why there is something rather than nothing.
Hossenfelder: I agree with him. It’s not a scientific question, or at least I don’t see how to make a scientific question out of it. Unless of course you want to reinterpret “nothing” as “quantum vacuum” as Lawrence Krauss does. I would argue though that even a quantum vacuum is still something.
Horgan: If physics can’t solve that problem, does that mean we’ll always be stuck with religious explanations?
Hossenfelder: Religious explanation is an oxymoron. Religion is what people draw upon if they don’t want to admit that they have no explanation. Will we always be stuck with problems to which scientists don’t have an answer? Yes, I think so.
Horgan: Do you believe in God?
Horgan: What is “the free will function”? And why doesn’t it persuade you that free will is real?
Hossenfelder: The free will function allows the universe to evolve in such a way that the future is neither determined by the past nor its becoming fundamentally random. If you want to hang on to the belief in free will, then you need to find a law for the universe’s evolution which is different from the laws in our current theories. This new evolution law must partly be based on a process that was neither random nor pre-determined. This process is what the free will function provides.
It doesn’t persuade me because the example that I constructed isn’t embedded into the current theories of nature and I don’t know whether it’s possible to do this. It is not a realistic construction – it is merely a proof of principle to demonstrate that is possible at all. And of course I am cognitively biased to believe in free will, so how much can I trust myself in my own argument?
Horgan: In this case, you should trust yourself. Can physics help solve the mind-body problem, as Roger Penrose and others have suggested?
Hossenfelder: Yes. Though, as I said above, at some point it might not be called physics any more.
Horgan: Has your popular writing harmed your career as a physicist?
Hossenfelder: Writing is what keeps me sane. I’m not sure whether that’s a career advantage in high-energy physics today.
Horgan: Nice! You recently said on your blog: “The biggest task of science bloggers--like Peter Woit, Ethan Siegel and myself--has become to clean up after sloppy science journalism.” Please elaborate.
Hossenfelder: I often find myself having to correct articles that mislead the reader about some recent research. The way much science journalism appears today, it is impossible for someone with no background in the field to tell how serious to take claims. Like, that new research shows black holes don’t exist, or that we will make contact with parallel universes, will soon test quantum gravity, or string theory, or that the information loss paradox has been solved (again!). And so on.
People don’t learn from this, they just get confused, doubt the trustworthiness of science, and it’s no good. I recently went to visit my mom and first thing she says after she opens the door is that she’s read the LHC proved we live in a multiverse and if I could please tell her what that is supposed to mean.
Yes, there is good science journalism. But then there are a lot of outlets that just seem to uncritically repeat press releases or what a scientist told them about their own research. And after one major outlet picked it up, it will appear in a dozen other places, each trying to make a bigger headline than the others. How come we still haven’t confirmed string theory if we’ve read two dozen times that it’s soon going to happen?
This statement you quote is just my observation that it often falls to bloggers to clarify what the research was actually about and what it means. If I come across a big headline in a field outside my expertise, I look for a blogger who puts things in context.
Horgan: Do you find philosophy useful?
Hossenfelder: Sometimes. I find philosophy useful to understand what it is that we really do in science, or at least the different ways to think about it. I would classify myself as an instrumentalist, but not all my colleagues are. And it’s good to know what their attitude is because it helps me put their motivations and interests into context.
For this very reason also I found the (above mentioned) workshop in Munich very useful. See, the non-empirical assessment is something theorists do constantly, but not really consciously, it’s just part of the practice. This discussion with the philosophers has helped me very much to structure my thinking, and also to pinpoint what aspects of non-empirical assessment are legit and which are questionable.
Horgan: What’s your utopia?
Hossenfelder: That we finally use scientific methods to restructure political and economic systems. The representative democracies that we have right now are entirely outdated and unable to cope with the complex problems which we must solve. We need new systems that better incorporate specialized knowledge and widely distributed information, and that better aggregate opinions. (I wrote about this in detail here.) It pains me a lot to think that my children will have to live through a phase of economic regress because we were too stupid and too slow to get our act together.