ToK and the nature of science
Physics isn't just a list of facts and equations. It is a way of producing knowledge. Every topic page starts with a Knowledge and science box that links the physics to two big ideas in the IB Diploma: the Nature of Science (NoS) and Theory of Knowledge (ToK). This page explains what they are and how to use those boxes.
Nature of Science (NoS): how science works
NoS is about the methods of science: how scientists find things out, test ideas and share what they know. It runs through the whole physics course. In exams, some questions are linked to a general understanding of NoS, for example how a model's assumptions limit it, or how evidence supports a theory. You won't be asked to define the aspects, so understand them rather than memorise them. The IB describes NoS through these aspects:
| Aspect | In a sentence | A physics example |
|---|---|---|
| Observations | Science starts by looking carefully, with our senses or with instruments. Surprises can open whole new fields. | Radioactivity was discovered by accident when photographic plates darkened in a drawer. |
| Patterns and trends | Scientists look for regularities in data, and for things that don't fit. A correlation is not proof of a cause. | Spotting that the period of a pendulum depends on its length but not its mass. |
| Hypotheses | A provisional, testable explanation of a pattern. | "Heavier objects fall faster", which experiments then showed to be false. |
| Experiments | Controlled tests that produce evidence. New technology often makes new experiments possible. | Measuring g with light gates or high-speed video. |
| Measurement | Numbers are more objective than descriptions, but every measurement has an uncertainty. | Repeating timings and quoting g = 9.7 ± 0.2 m s−2. |
| Models | Simplified representations (diagrams, equations, simulations) that are useful, and always have limits. | Point particles, frictionless surfaces, the ideal gas. |
| Evidence | Claims must be backed by evidence that others can check. Claims that can't be tested aren't scientific. | Repeating a result in a different lab before accepting it. |
| Theories | Wide-ranging explanations that make testable predictions. A "law" describes and predicts without necessarily explaining. | Newton's laws of motion; the kinetic theory of gases. |
| Falsification | Evidence can show an idea is wrong, but can never prove it right for certain. All scientific knowledge is provisional. | Relativity showing where Newton's laws stop working. |
| Science as a shared endeavour | Science is collaborative and international. Agreed units and terms, and peer review, make that work. | SI units; huge collaborations like CERN. |
| Global impact of science | Science has ethical, social, environmental and economic consequences, some of them unintended. | Nuclear power and nuclear weapons; car safety design. |
Theory of Knowledge (ToK): how do we know?
ToK asks questions about knowledge itself: what counts as knowing, how certain we can be, and how different subjects produce knowledge. In ToK, the natural sciences are one of the areas of knowledge you compare with others, such as history, mathematics and the arts.
Where NoS asks "how does science work?", ToK steps back and asks "how good is that way of knowing, and what are its limits?" For example, peer review is a NoS idea. A ToK question might ask whether peer review really guarantees objectivity, and how other subjects check their own knowledge.
Knowledge questions
ToK is built around knowledge questions: open, debatable questions about knowledge rather than about physics facts. Good ones have no single right answer. Each topic page gives several, linked to the physics you are studying. Physics raises some recurring themes:
- Models and truth: can a model we know is simplified still count as knowledge?
- Certainty: if science can only falsify, how confident can we ever be?
- Intuition and imagination: what role do they play when evidence goes against "common sense"?
- Language and mathematics: can everything we know be expressed in symbols?
- Tools and technology: how do the instruments we use shape what we can know?
- Change over time: how can accepted knowledge be overturned (paradigm shifts)?
- Responsibility: what responsibilities come with scientific knowledge?
How to use the "Knowledge and science" boxes
- Read the box before the topic to see the bigger picture, then come back to it at the end.
- Pick one knowledge question and discuss it with someone. Try to argue both sides.
- Keep a list of strong examples from physics. They are useful for your ToK essay and exhibition. They also help with exam questions that draw on a general understanding of how science works.