In his 1996 book The end of science, John Horgan claimed that scientists were close to answering almost all the big questions about our universe. Was he right?
Theoretical physicist Sabine Hossenfelder does not think so. As she points out, the Standard Model of physics, which describes the behavior of particles and their interactions, is still incomplete because it does not include gravity. Moreover, the measurement problem in quantum mechanics remains unsolved, and understanding this could lead to significant breakthroughs.
Ultimately, Hossenfelder is optimistic that progress will be made over the next two decades, given today’s advances in quantum technology and quantum computing.
SABINE HOSSENFELDER: Beginning in the 1970s and 1980s, many physicists became very optimistic that we were quite close to finding a theory of everything that would explain all the interactions in nature in a coherent whole. And string theory was one of the biggest candidates for this. And partly in response to this over-optimism, John Horgan wrote “The End of Science” in which he picks up several scientific disciplines and tries to argue that we are actually quite close to the end. And I must admit that is a very good question to ask. You can have the perspective that there is a certain period in human history where we make the great fundamental discoveries in nature, and that is just behind us. It is not going to happen that we discover another continent. And that’s a good question to ask. Like, is the same the case with science? Have we just discovered all the great things there are to discover? And Horgan is not saying that we should stop doing science or that we should stop doing research, but he is saying that there won’t be any new big discoveries. We just want to add a few bits to the stuff we already have.
And as someone who has worked in the foundations of physics, I have to completely disagree with him on his perspective of being close to a theory of everything. And I suppose this also puts me at odds with many of my colleagues in the foundations of physics. A theory of everything in the foundations of physics is a theory that combines all the fundamental forces of nature. We currently know four of these forces. It is the electromagnetic force, which almost everyone has heard of. Then there is the strong and the weak nuclear force. A strong nuclear force holds together the particles that make up atomic nuclei, and the weak nuclear force is responsible for nuclear decay. All these are quantum theories. And then we have gravity. This is the fourth force. And it is not a quantum theory. And this is part of the problem. It’s kind of the odd outlier. And a theory of everything would combine all four of these forces into a coherent whole. And I think we are nowhere near such a theory.
One of the reasons is that we still do not have a theory of quantum gravity that would combine the Standard Model with particle physics. And yes, string theory was a contender for this. But it has fallen out of favor. It’s not even clear that it would actually solve the problem it was meant to solve in the first place. And much the same can be said about other approaches to quantum gravity. So this case is still unsolved. But perhaps even more importantly, we have a much bigger problem in the foundations of physics, which is the measurement process in quantum mechanics. It has created some practical problems in how we analyze experiments. Physicists are just confused about what it means, that we have to do this measurement update. Exactly what is the measurement? What is needed to make a measurement? We do not know. The theory cannot answer this question. And I think an answer is needed. And indeed, when we find this answer, it will lead to a lot of progress. And it’s not just progress in our theoretical understanding, it’s also progress through new technology, because if you look at all the technological devices we use today, they’re all based on quantum mechanics. So if we can improve this theory of quantum mechanics by finally understanding how a measurement process works, I think this will also help us improve our technological gadgets and that will have a huge impact on the whole world.
So I don’t think we are anywhere near the end of science. Now I’m actually quite optimistic that we’ll be able to solve the measurement problem in quantum mechanics in the next one to two decades or so because it falls into an area, quantum technologies and quantum computation, quantum information, quantum optics where there’s a lot of technological progress at the moment. So sooner or later they will just stumble upon something new, something they cannot explain, and then they will call for theorists to explain this. And this is when a lot of progress is going to happen very suddenly.