Are we close to hitting the limits of what we can discover? Or can we keep pushing forward into the edges of the universe, atoms, genes and human societies? Are we nearing the boundaries in some fields like theoretical physics or macroeconomics? And what exactly shapes the current boundaries of what we can know? These are key unanswered questions, but the answers are often less mysterious than they seem. Recognising that progress in tools is what mainly drives progress in science—that spectrometers reveal the chemical makeup of distant planets, that x-ray crystallography uncovers the molecular architecture of complex compounds—gives us a new way to think about the barriers of science. Yet generally, researchers study the limits of science only through the lens of their own field; they point to what we are not yet able to explain: from dark matter in physics, to how life began in biology. Yet here we explain how our current scientific frontiers are shaped by five factors: our scientific methods and tools set the present limits of what we can observe, test and discover in most of science today, but our evolved mind shapes how we develop those methods—while the time and place we live in, our human perspective and our social context help shape what we study within these limits. What is key is that the incredible power of our new tools of discovery consistently break through these barriers, by reducing our human constraints and vastly stretching our scope of the world. Science's boundaries are not fixed, they are the shifting edges of a map we redraw with each major new tool. Still, there are many mysteries we cannot unlock with our current tools today: from the size of the universe and superstrings to how consciousness emerges and predicting the rise and fall of democracies. But there is a paradox: understanding what drives the current limits of science is the best way we have to expand and redefine these very limits.
We know the universe came into existence about 14 billion years ago. We know physical reality is governed by fundamental forces—gravity, electromagnetism, the strong force and the weak force. We know the chemical elements of the periodic table make up the world. And we know our genetic material is transferred through our DNA. These discoveries form central and reliable pillars of science—so solid that we are unlikely to replace them with fundamentally different breakthroughs and theories that are as remarkable. But does that mean we may be getting closer to the limits of science? The evidence shows that alone in the last few decades, we have made over a dozen groundbreaking discoveries that have reshaped entire fields. Think of the nobelprize-winning discoveries of CRISPR gene editing made in 2012 that rewrites life's code—it was sparked by a new method of differential RNA sequencing developed in 2010. Or take the existence of the Higgs particle also in 2012 that confirmed a missing piece of physics—it was detected by the large hadron collider built in 2008. Or the detection of gravitational waves in 2015 that illuminates the mysteries of black holes—it was achieved by the LIGO laser interferometer upgraded in 2015. Or other major non-nobel discoveries like mapping the human genome in 2003 that transformed personalised medicine today—it was driven by an improved genome mapping technique created in 2001. These discoveries did not just add details to what we know, they redrew the borders of genetics, physics and astronomy. Each time, new tools or methods were key in breaking through the scientific frontier. If we want to keep expanding our frontiers, we need to ask: what holds us back today? What limits our current tools to explore the world in new ways? The limits of our current tools tell us how far we have gotten and when we hit the borders of how we can presently do science. Many unsolved puzzles exist at the research frontier: what exactly makes up our universe? What are the evolutionary origins of stars and planets? How exactly did societies evolve? What exactly is the nature of memory in the brain? Can we not just understand cancer's causes but find cures that work for everyone? What parts of the scientific process can be best carried out by AI and machine learning methods? Then there is one of the most perplexing mysteries of all: consciousness. We have advanced tools to scan brains, map neural activity in real time, detect regions involved in decision-making and language, and mimic some aspects of human thinking with AI methods. But the enormous challenge of consciousness remains unsolved: how do the physical processes of neurons create the vivid, subjective experience of being alive and aware? Tackling the limits of science is crucial, because even though biology and medicine have drastically reduced deadly diseases and extended our life expectancy, we still do not have cures for many diseases, cancers and viruses. Physics and chemistry have fuelled vast technological and industrial advances that built modern society—from electricity to computers—but we have not yet solved the challenges they foster like climate change, pollution and the risk of advanced weapons. Yet scientists rarely study the boundaries of science in a systematic way, at times seeing them as too big, too abstract or not subject to scientific study. A keyword search of 'limits of science' and 'boundaries of science' in publications up to 2025 in the leading journals Nature and Science results in about 250 hits. Yet we have still not explained what actually drives the current boundaries of science and how we can expand them in an integrated way. Researchers do not focus on how we push our boundaries to discover entirely new phenomena; but rather generally focus on what phenomena are presently out of reach: puzzles in physics, unsolved mathematical mysteries, the bounds of our mind and philosophical aspects underlying scientific laws. The journal Science published a special issue What Don't We Know? exploring 25 of the biggest open questions in science. From physicists who explore questions such as what dark matter is made of, to biologists who investigate questions such as how life began on earth. Yet it helps to think beyond disciplinary borders. In an influential book, The End of Science, John Horgan offers a pessimistic outlook, claiming that science may be coming to an end as science is running out of big questions. But the last few decades have proven the opposite: major new breakthroughs have been achieved and many big open questions remain. Yet there is still no integrated framework that explains where our scientific boundaries lie or how we can best expand them. The best way to achieve this is by combining methods and evidence from different fields. Here we draw on methodology, cognitive science, social sciences and science of science—each contributes to capturing the larger picture. Whenever we run into a wall with our current tools—whenever we cannot see smaller, farther, faster or deeper than our tools allow—it means we are reaching the frontier of science. If we understand what holds us back and deliberately redirect our energy to tackle it, we can break through the frontier. Here is the key insight: scientific methods and tools set the current boundaries of what we can know and what discoveries are possible for most of science today, but our evolved mind also shapes how we create those methods—while where and when we live, our human perspective and social factors help shape what we study within these boundaries. Science is something we do, using our tools and our mind, within our niche of the world. So what factors shape the limits of science and the scope of discovery? Here we describe the five main factors: • Methods and tools : Today's major discoveries that break boundaries are only possible with advanced tools—cutting-edge statistics, computers, x-ray devices, MRI scanners. These massively expand how we see, think, reduce complexity and imagine. These tools set what we can measure, model and explain in the world—and what we cannot. They come with their own blind spots and limits— from resolution limits in microscopes to biases in AI models. That is why the real challenge—and opportunity—is finding ways to push beyond those barriers with ever more powerful tools. • Our mind: While our evolved cognition and senses shape how we observe, solve problems and reason, we vastly extend them and tackle our built-in blind spots with the tools we invent. We are able to uncover those discoveries that fall into our sensory range that we are able to perceive with our methods and tools that stretch our mind in extraordinary ways—from mapping neuron synapses to detecting distant galaxies. • Our place and time: We live within a specific century and in a limited pocket of the universe—on one small planet. That means we have to deal with the data we are able to gather: here and now. This shapes part of what we can discover. The further we study the past (like the origin of our planet or the Big Bang) or into the future (like the evolution of a virus, species or galaxy), the current limits of science are shaped by human limits—the boundaries of our methods and mind. But also by the increasing difficulty of collecting reliable data as we move away from the present. • Human perspective: We humans are the ones doing the science—and developing the tools that enable doing so. We focus on questions that serve our needs and wants: we care about curing disease, understanding human origins and building better human technologies. Even the way we define a 'problem' , 'solution' or 'sufficient evidence' is shaped by our human perspective—our human lens that drives incredible discoveries but also leaves blind spots in what does not matter to us as humans. • Social context : By pooling the method-making resources of many scientists, our scientific community spurs research at the frontier. Our institutions, funding and societal challenges—from pandemics to climate change—can influence some of our research priorities and tools we produce. Economies of scale, reward systems and science policy also help steer research directions, influencing some breakthroughs we chase. These five factors together set the limits of what we know, but there is one clear, unifying thread: our methods and tools. Through innovative toolmaking, we can push past the limits of our current tools but also our senses, mind and human perspective. Our tools are generally the factor we can most deliberately improve. And only a cutting-edge telescope, computer or sensor lets us see something we could not before. Science can only ever go as far in explaining nature as the tools we have developed so far can visualise, detect and measure it. Here, we tackle three questions: how did we, throughout history, expand the boundaries of science? How do these five factors actually shape our current limits of what we can discover? And how do the strengths and limits of today's most advanced tools largely define the edge of what is possible to uncover?
In the early 1500s, we viewed our physical world as geocentric and finite. But we developed extraordinary tools and methods in the 1600s like the telescope that enabled us to peer at distant planets, the barometer to measure air pressure and calculus to describe motion. These tools transformed how we thought by allowing us to explore and theorise about the world in new ways. By the end of that century, our physical world was no longer geocentric and finite but heliocentric and unimaginably vast. In the medical world, we were not able—in the mid-1800s—to link diseases to their causes and test treatments properly. But by the early 20th century, we developed systematic controlled trials using randomisation, blinding and placebos, powered by statistical analysis. This method revolution vastly improved how we experiment, turning medicine into a rigorous, evidence-based science. We were then able to measure what actually worked—the causal effects of medical treatments—cut deadly guesswork and extend human life. With randomised controlled trials transforming how we test what drugs, vaccines and public policies work best, we redefined and pushed T the limits of medicine but also psychology and the social sciences. These fields became in part redefined by the limits of this new method. The boundaries of science are not rigid but are the flexible edges of a map that we keep redrawing. When our tools stagnate, so does our progress. Just like the first telescopes forced us to revise and update what we know about our solar system, the size of the universe and our place in it, the first microscopes uncovered hidden microorganisms and eventually changed our understanding about disease and infection. Each new tool did not just add data but rewrote and redefined the very limits of physics and biology. These limits were no longer defined by the limits of our senses but became redefined by the limits of these new tools. These remarkable tools were continually improved and very successful up to the 19th century until we reached the blurred limits of their resolving power—and again the limits of science in different fields. Leading up to the 1930s, biologists and physicists were able to observe some but not other phenomena they thought could exist. A critical change came in 1933 with the invention of the electron microscope, bringing ever more minuscule phenomena into view and revealing more of the mysteries of cells, large molecules and crystals. It revolutionised fields from biology to materials science, and their limits became once again reset by the limits of this new instrument. The current edge of science is largely synonymous with the current edge of the tools we have created so far. Without progress in methods, major new discoveries are commonly not possible. Without launching improved space telescopes to search for ever better signs of new planets or even life on distant planets, we cannot ever find them (Chapter 1). The success of science is—at any moment in history—mainly a success story of the incredible tools we have in our hands, and invented and recombined up to now. What is striking is that we have not yet given enough attention to this fundamental fact: there is no general methods-driven theory of science and the limits of science. Instead, we have stretched the bounds of science in a surprisingly ad-hoc, piecemeal way—by individual researchers who happen to innovate a new tool enabling us to broaden our reach (Chapters 1–6). We have expanded the frontier without a science-wide understanding that our new tools are what trigger our major new advances. We have seen how six new groundbreaking inventions unlocked most major discoveries in the 17th century. Pioneers like Galileo, Hooke, Boyle and Newton each used at least one of the newly invented tools to uncover mysteries about life, the human body, mechanical physics, light and the cosmos. Strikingly, these tools, in updated forms, remain essential today. It is not by chance but by devising new tools that make the invisible visible and the complex understandable. Our greatest discovery may be uncovering that progress itself depends on constantly building better ways to observe, measure and test the world. Those remarkable inventions around the 17th century did not just explain nature—they planted the seeds of modern science. The roots of modern science stretch back and branch out through these few extraordinary tools (Chapter 7). Redefining our scientific limits with new methods and tools Method or tool developed LIGO detector, improved (2015) differential RNA sequencing (2010) spectroscopy, improved adaptive optics (2002) starch-column chromatography (1948) electron tube, improved (1913) x-ray crystallography (1913) spectrograph, improved (1859) discharge tube (1875) microscope, with silver staining (1873) leyden jar (1745) thermometer, mercury (1714) calculus (1675) statistics (1663) microscope, improved (1662) vacuum pump (1659) barometer (1643) telescope (1608) discovery it triggered observing gravitational waves (2015) method for genome editing – CRISPR (2012) supermassive compact object at the centre of our galaxy (2002) synthesis of polypeptide hormones (1953) structure of DNA (1953) atomic light signatures (1859) x-rays (1895) structure of nervous system (1873) nature of electricity (1752) oceans control global weather (1770) hydrodynamics (1734) field of demography (1663) cells (1665) Boyle's law (1662) Pascal's law (1647) Jupiter's moons (1610) Limits of science and our understanding of the world in the… future 2000s 1900s 1800s 1700s 1600s laws governing impact of electron on an atom (1913) Our scope of the world expands at the pace of our new methods and tools The major discoveries and the tools used to make them are based on nobel-prize and major non-nobel discoveries.