What Is Science?

Science is not just a pile of facts in a textbook. Science is a careful way of finding out how the world works, and then building up a body of trustworthy knowledge over time. The whole purpose of science is to build knowledge and understanding of the world through observation, experimentation and analysis. That is the exact idea from the NSW syllabus dot point you are learning today (SC4-OTU-01).

Science IS:

• Based on evidence you can observe or measure, not on guessing or wishing.
• Testable. A scientific idea can be checked by an experiment or further observation.
• Open to change. If new evidence appears, scientists update their ideas. Barry Marshall changed what doctors believed about ulcers.
• Done by people from every background, all over the world, including right here in Australia.

Science is NOT:

• Just personal opinion. "I reckon" is not enough; you need evidence.
• A fixed set of unchangeable facts. Knowledge grows and gets corrected.
• Magic, luck or belief that cannot be tested.

So when Marshall and Warren noticed the same bacterium again and again, then tested their idea, then checked the data, they were doing real science. Believing something simply because it feels right is not.

Science builds knowledge using three main steps that feed into each other again and again. The syllabus calls these observation, experimentation and analysis.

• Observation: noticing and recording what is happening, using your senses or instruments. Everyday example: you notice the grass is greener after rain. Australian example: Barry Marshall observed the same bacterium in the stomachs of many ulcer patients.
• Experimentation: running a fair test to see what happens when you change one thing. Everyday example: you water one pot plant and not another to see which grows better. Australian example: Marshall ran an experiment by deliberately swallowing the bacteria to test whether they caused illness.
• Analysis: looking carefully at your results to work out what they mean. Everyday example: you compare the two pot plants and decide that water helped growth. Australian example: Marshall analysed his own test results and the patient data, and concluded the bacterium caused the ulcers.

These three steps form a cycle. An analysis often leads to a new observation, which leads to a new experiment, and so on. This is how science keeps improving our understanding.

Science is a huge field, so we split it into branches. The syllabus names four main branches you should know.

• Biology: the study of living things, plants, animals, fungi and tiny microbes. A biologist might study koalas in a Victorian forest, or the bacteria Marshall discovered.
• Chemistry: the study of substances, what they are made of, and how they react and change. A chemist might work out why a medicine cures an illness, or test water quality in a river.
• Physics: the study of energy, forces, motion, light and electricity. A physicist might design the radio receivers behind wireless internet; in fact Wi-Fi was developed using ideas from CSIRO scientists here in Australia.
• Geology: the study of Earth itself, its rocks, minerals, volcanoes and how the planet changes over time. A geologist might map mineral deposits in the Pilbara region of Western Australia.

Real problems do not fit neatly into one branch. The syllabus tells us that modern science is often interdisciplinary, which means it combines several branches at the same time. "Inter" means between, and "disciplinary" comes from discipline, another word for a branch of study.

An Australian example, the Great Barrier Reef: Scientists studying how to protect the reef have to use several branches together.

• Biology helps them study the corals, fish and other living creatures, and how warmer water makes coral go pale and die (coral bleaching).
• Chemistry helps them measure how carbon dioxide makes the seawater more acidic, which harms coral skeletons.
• Physics helps them track ocean temperatures, currents, and how sunlight and heat move through the water.

No single branch could solve the problem alone. By working across biology, chemistry and physics together, scientists build a much fuller understanding. This is why teams of scientists with different skills often work side by side. The CSIRO, Australia's national science agency, runs many projects exactly like this.

Not every claim that sounds science-like is actually science. It helps to tell three things apart.

• A scientific claim is supported by evidence and can be tested. Example: "These antibiotics kill the ulcer bacterium." You can test it and check the data.
• An opinion is a personal preference or feeling. Example: "Vanilla is the best ice cream flavour." It is not right or wrong, and there is no experiment that could prove it.
• Pseudoscience is a claim that pretends to be scientific but is not backed by real, testable evidence. Example: "This bracelet cures every disease using mystery energy." It uses science-sounding words but cannot be tested or shown to work.

The key test is simple: is there evidence, and could the claim be tested? If yes, it can be scientific. If a claim cannot be tested, or it ignores evidence that goes against it, then it is not science. Good scientists, like Marshall and Warren, follow the evidence even when it surprises everyone.