Ideas and Evidence in Science
Science and scientific evidence
Watch the video below, ‘What’s in the box?’ then read on.
Were you able to work out what was in the box from the sounds? The ideas you suggested were not based on pure guesswork, were they? They were based on the evidence available to you.
Suppose you are now given another box but this time, the box is sealed. You shake it and it rattles. It sounds a bit like a couple of metal spoons, but then again, perhaps it’s three spoons … or a fork and spoon. Is there a way to know which theory is right? Suppose you’re now given access to an X-ray machine. Does that help?
Suppose you X-rayed the box and saw nothing inside but the box rattled when you shook it, what would that tell you?
Conclusive evidence
Sometimes, when you’re investigating different possibilities, the evidence for one theory or another becomes overwhelming and everyone agrees on the proper conclusion.
In science, this is often the way it seems to work. Mind you, there is a reason for this. The science you study at school tends to focus on the ideas that are now well established in science. Even with this said, science is a particularly good way to test theories. Here’s why:
Scientific evidence is evidence you can detect using your senses or sensors. The evidence must be objective which means that everyone can see it.
Suppose in contrast you stub your toe and begin to hop around the room, yelling in agony. “Oi!” says your unsympathetic friend, “Stop making a fuss about nothing.” In this case, the evidence is subjective. The pain signals that travel from your toe to your brain are felt only by you, so only you can decide how much it hurts.
Galileo: the father of modern science
Galileo is widely considered to be one of the greatest scientists who ever lived. He is said to be the first scientist who used experiments as a way to test theories.
In the video below, we see how he came up with one of his most famous theories. This idea was that all objects, regardless of their weight, fall with the same speed.
To test his theory, Galileo did a range of experiments. It is sometimes said that in one of these experiments, Galileo dropped two balls from the top of the leaning tower of Pisa. One ball was wooden and one was lead. Historians think this probably didn’t happen, although Galileo did, they say, suggest that this would be an exciting way to see his theory working in practice.
Air resistance changes how the balls fall. It is as if one ball has a parachute.
Interestingly, Galileo’s experiment was tried years later: Two balls were dropped from Pisa but the surprise was that the lead ball hit the ground first. Why? Galileo knew why. He had already predicted that this would happen. If gravity were the only force at work, the balls would have hit the ground together, but air resistance also plays a role.
A couple of hundred years later, a chance came for scientists to see this experiment without air.
In 1971, Commander David Scott (pictured right) from the Apollo 15 mission, put Galileo’s idea to the test. In front of a live television audience, in one hand, he held a hammer and in the other, a feather.
Scott dropped them at the same time … and scientists nodded with satisfaction. Just as Galileo had concluded hundreds of years before, it really is the case that all objects released together fall at the same rate.
So in science, physical evidence is used to support and test ideas. In other fields, such as in History and Religion, the conclusions are not so clear cut.