Science is one of the ways that humans try to understand the physical world and make sense of it. In science, the aim is to understand the world by developing theories that can explain what happens, and what might happen in nature in the future (under various conditions).

An explanation in science is usually an answer to a ‘why’ question – such as “Why does the light from the streetlamps make everything look orange?”. A scientific explanation uses scientific ideas (such as theories) to answer questions. Theories are developed by scientists in response to their observations.

BEWARE

Whenever someone gives an explanation in science (such as an explanation about why street lamps produce an orange glow), it’s almost always possible to ask, “Yes, but why?” For some small children it even seems to be a game – “yes but why, but why, but why, tell me why …” A ‘complete’ explanation (if it is possible) could get very complicated.

Here’s another example. Think about the question ‘why does it rain?’ – a ‘complete’ explanation would involve changes of state, gravity, solar radiation, and many other scientific ideas. Usually when scientists ask for explanations there are many things they are expecting to ‘take for granted’! In order to make any progress, scientists normally have to focus on a limited aspect of a question at one time.

What’s a ‘Law’?

Information collected during observations and experiments are called data.  When scientists observe a regular pattern in the data, this is often labelled a ‘law of nature’.

Before scientists carry out an experiment to test a law, they already have an idea of what the relationship might be.

An idea about a relationship that has yet to be tested is called a hypothesis.  To test a hypothesis scientists must design an experiment and predict what the outcomes would be if the hypothesis is correct.  There are always lots of possible hypotheses that could explain any observation, so an experiment can never prove a hypothesis is the correct one.           

What criteria do scientists use when judging explanations?

In general explanations in science are expected to

be logical

be relevant (so they answer the actual question posed)

be consistent with available evidence

draw upon accepted scientific ideas (principles, laws, theories) about the topic

Scientists also tend to prefer explanations that are simple as possible, making as few assumptions as possible.

Unfinished work

An important aspect of science is that explanations in science can be challenged if new evidence comes to light or if someone proposes a different explanation which seems to fit better with the facts (observations). See what you think about the following two theories which were once thought plausible but have since been challenged and dropped …