I recently talked to a friend who said the century of physics is over. The 21st century is about biotechnology, it's about enhancing ourselves, it's about designing our children, it's about customizing our food.

Of course I disagreed. Not only do I think biotechnology will take quite a long time to be incorporated in our every day lives simply because it’s hard to do better than Nature. I also think the 21st century is going to be about the social sciences: To cope with the challenges mankind is facing, the scientific revolution has to be finished. It needs to be extended into those areas we use to organize our lives on this planet, most notably sociology, politics and economics. The natural sciences are ahead in rigor and successful integration of knowledge into our civilizations, but both areas, the social and the natural sciences, are necessary to successfully shape our future.

Nevertheless, it made me wonder, what is the future of physics, the field that I love and live for?

The Future of Physics

While the content of our research departs more and more from our immediate experience and experimental confirmation of hypotheses becomes increasingly difficult, speculations are thriving and unconstrained creativity is booming on the theoretical side. Science fiction writers find ideas for their stories on the arXiv, and in some cases the boundaries are blurring. Will the Higgs try to disable its own discovery by inducing a technical failure at the LHC? Will we all be reborn as Boltzmann Brains? Have alien civilizations rearranged the stars to leave messages for us?

Motivations are turning into constructed justifications for calling fantasy research. Besides the oldfashioned strive to explain recognized puzzles in data or to solve shortcomings of current theories, one can now excel simply through creativity and novelty, connection to Nature not required. New theories can be introduced just for the fun of brain exercise. The light that shines on your career path is trendleading. Thus, you better know the fashions of the day - currently it's phenomenology, so whatever you're speculating about you should call it “phenomenological”, make sure it's “falsifiable” and claim to have “testable predictions”. At the very least, write that in the abstract, whether it's true or not.

If I look at hep-th and gr-qc, I find it increasingly depressive. In the vast majority of cases it is a complete mystery to me why somebody would even be remotely interested in that topic if he wants to describe nature. And isn't that what physics is supposed to be about? Describing nature? If we go on like this, I see physics moving from science to science fiction, from explanations to equationized stories about the could-be.

Do we have too many physicists?

We can not plan progress.

I'm all in favor of fundamental research, and I strongly believe that unexpected spin offs arising from it are a crucial ingredient of progress. Scientific breakthroughs can not be planned and rarely be foreseen. That makes it necessary to have faith in the scientific community and to support non-directed research. Today however, research in theoretical physics is directed by financial possibilities and job opportunities that are too often bound to specific subfields. Experts in a field will promote their own research and try to ensure its survival by hiring more people and producing more papers. But are more people working on a topic always the right choice to foster progress? Or does a field have a certain topic-dependent complexity that is optimally examined by a limited number of people?

Given the tight budget in foundational research this question is sure to upset many of my colleagues who are competing for the few permanent positions, but still, I have to ask: do we have too many physicists? Do we really need this vast production of redundant papers that nobody reads? Has foundational research become a commercialized publication production because our societies value money over wisdom and that’s where the incentives are, and thus, grants and papers and a well-paid job has become how we define ‘success’ in research. It’s about the career, stupid.


But if you try to build a house, hiring more and more people won't make the construction go faster and faster. At some point you will have a lot of workers who don't know what to do. They will pretend to be useful by occupying themselves with carving the wood or painting the bricks or worse, they will attempt to add extensions here and there that nobody asked for and nobody needs.

Do more people necessarily imply faster progress? Can we push insight by distributing research to ever more researchers? Can scientific breakthroughs be speed up by community building? I think there are limits to this. Progress has a pace that is set by the time it takes to appreciate, digest and incorporate a new insight. It can't be accelerated arbitrarily, it is constrained by the capacity of the human mind to find and process input, to extract patterns, and to then express an idea in a rigorous and useful way. It is, in many aspects, a lonely task - at least until we find a way to share our thoughts without the need to express them in words and equations inbetween. I would certainly be in favor of just uploading part of my brain.

Improving the connectivity of the scientific community and finding better ways to manage information is helpful to improve collaboration, get knowledge faster where it needs to be, and to optimize the use of resources we have. But still, the thinking needs to be done by a human brain. Look at the billions of dollars that have been spent and the thousands of people that have dedicated their lives to cancer research. Yet, the long hoped for breakthrough couldn't be pushed despite all these efforts. Science is a community enterprise, research lives from exchange and discussion and gradually builds the body of our knowledge. Does anybody really believe the ingenious idea will come if only the pressure is high enough, if only the incentives are good enough, if only enough money goes into the right channels? Do you really think we can overcome the limits of the human mind that easily? We can not plan progress and all the pushing isn’t going to change that. (Sadly enough, many people seem indeed to believe this works which is the reason why they don’t take global environmental problems seriously: surely, if the situation gets only bad enough, the ingenious homo sapiens will come up with a solution. Everything's gonna be alright.)

Diffusing the frontiers of research to more people the outcome will only be that new results are superficially discussed, sloppily integrated, and insufficiently communicated. If a field has too many people it will just produce irrelevant output, fragment and specialize, and lose coherence. A process that unfortunately is greatly supported by the pressure to publish for the sake of the CV.

But calm down, if you read this blog frequently you should know I don't think there are too many physicists. However, the investment of time, financial and human resources is suboptimal and directs too many people in some construction areas whereas others have too few workers. The present organization also doesn't really encourage new construction areas altogether, and the management of knowledge in academic research isn't appropriate to deal with the changes in our information-infrastructure. One obvious way to alleviate this problem is to just hire workers, and not assign them to a certain construction zone. (For more about this, see my earlier post We have only ourselves to judge on each other.)

What the bleep can we know?

But let me pursue this line of thought one step further. We have seen that theoretical physics opens a playground for increasingly wild speculations, due to the growing difficulties in experimental accessibility. We have also seen that research areas can attract more people than would be necessary to investiage their promise. The problem is that due to the delayed testability, it’s not Nature that judges on our ideas when we put them on the archive - it’s our peers, and it remains our peers for a long time.

Especially the field of physics I work in has set its goal very high. Commonly referred to as the “holy grail”, researchers are looking for a fundamental theory that combines quantum field theory with classical gravity, or even gives rise to the standard model of particle physics.

“Phenomenology” is the word of the day, and sometimes I can't but wonder what if that fundamental theory - should it exist - indeed does not make any testable predictions. Just consider it for a moment: There is a fundamental theory, but it makes predictions only in ranges far outside what we can measure. With the focus on phenomenology, aren't we then potentially discarding the path to go? It is not even that I believe it to be the case that a theory of quantum gravity would not have observable effects, but that possibility certainly exists (and who cares what I believe). So then what? What can we know? Can we know what we can know? What will happen to physics? Would the pursuit of such a theory still count as science?

It doesn’t require much imagination to extrapolate the current situation based on the above. We might get stuck with several theories that make differing predictions only in ranges we can’t test. That’s when we still start to argue about the beauty, elegance or naturalness of one approach over the other. That’s when we will start to ask how much time is appropriate to investigate and solve shortcomings before we have to consider them ugly, that’s when we will start discussing personal taste, community likabilities, and the historical value of concepts underlying our speculations. And that’s when physics will turn from a science to philosophy.

Time discovers the Truth

However, though this is my extrapolation of the current situation, it certainly isn’t inevitable. I think that the biggest part of the problem is that theoretical physics is way ahead when it comes to explaining the world around us. Maybe we will have to wait for other areas to catch up. Maybe we will have to wait until we can measure graviational waves or the cosmic neutrino background. Maybe we will have to wait until we can extend our brains, or the internet finally becomes self-aware and overtakes the planet. Either way, I am optimistic that time will discover the truth.

“Veritatem dies aperit.”
(Time discovers truth.)

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If that was too much words for you, here are some questions to ponder, your comments are welcome:

• Can progress be accelerated by increasing the number of researchers or does scientific insight proceed on a pace eventually set by the capacity of the human mind and the complexity of the field?
• Do too many people on one topic eventually hinder progress by producing irrelevant reduncancies and speculative distractions?
• Do we have too many theoretical physicists?
• Might the fundamental theory only make predictions far outside any range potentially accessible to experiment in the long future?
• Might there be various consistent theories that agree in the observable range that we will be unable to test for their truth, and would the argumentation about these theories still count as science?
• If the right theory of quantum gravity indeed does not make testable predictions, is the present focus on phenomenology hindersome to progress?
• Will physics turn into philosophy?