Introduction to Scientific Method

In 1928, halfway through an experiment with bacteria, Scottish scientist Alexander Fleming went on vacation. Good-for-nothing that he was, he left a dirty petri dish in the lab sink. Petri dish  is a shallow transparent lidded dish that biologists use to culture cells, such as bacteria, fungi or small mosses.When he got back, he found bacteria had grown all over the plate, except in an area where mold had formed. That discovery led to two things: First Penicillin and Second Mrs. Fleming hiring a maid.

Fleming once remarked about this accidental discovery for which he received Nobel Prize:

One, sometimes finds, what one is not looking for. When I woke up just after dawn on September 28, 1928, I certainly didn’t plan to revolutionize all medicine by discovering the world’s first antibiotic, or bacteria killer. But I suppose that was exactly what I did.

If invention as important like penicillin can happen accidentally , is there a Scientific Method preferred by scientists? In reality there is no Scientific Method. But there are common features in the way scientists do their work.

This all dates back to Fifteenth Century Italian physicist Galileo Galilei and the English philosopher Francis Bacon. They broke free from the methods of the Greeks, reaching conclusions about the physical world by reasoning from arbitrary assumptions called axioms.  The modern scientist works first examining the way the world actually works and then building a structure to explain findings.  But there are some common ways most scientists carry out their work, which can be summarized as Scientific Method. Let us understand the steps involved in this method of investigation.

First step  is to recognize a question or a puzzle-such as an unexplained fact.

A scientific question is a question that may lead to a hypothesis and help us in answering the reason for some observation. Asking a scientific question is a part of the scientific method 

Let us ask a question ,say. Do all substances dissolve in water?

For answering this question, we may make an educated guess-a hypothesis-that might resolve the puzzle.

Let us make a guess .All substances cannot be dissolved in water. This hypothesis may be either correct or wrong .A scientific hypothesis must be testable.  When we are able to find  atleast one substance which cannot be dissolved in water we can prove this to be correct.

But there is a much stronger requirement that a testable hypothesis must meet before it can really be considered scientific. This criterion is called “falsifiability”. What falsifiability means is that if something was false, then it is possible to demonstrate that it is false.

We cannot experiment with all substances available in the universe to disprove the substance statement : All substances cannot be dissolved in water.  Thus a better hypothesis could be :  Out of talcum powder,  sugar and common salt  only talcum powder does not dissolve in water.

This hypothesis is testable as well as falsifiable. Hence is a Scientific Hypothesis.

Once we have a scientific hypothesis, we have to predict consequences of the hypothesis.

To predict the consequences of the hypothesis one has to perform experiments or make calculations to test the predictions.

While performing the experiment one has to ensure that all possible conditions that can impact your experiment be kept constant through out the experiment.

A teaspoon of each substance can be mixed with equal amount of water in the jars,  only adding one substance per jar. Stir it up! Observe whether or not each dissolves and record the findings,

Finally one has to formulate the simplest general rule that organizes the three main ingredients: hypothesis, predicted effects, and experimental findings.

In our experiment, It can be observed that sugar and salt dissolve and the talcum powder will remain intact. Hence we can conclude that all substances do no dissolve in water. This process of inquiry through experimentation may continue. Others will try to experiment under different conditions. It may also happen in certain experiments that we have to refine the hypothesis and conduct new experiments to check the consequences.

To conclude Scientific Method starts with a question or a puzzle, followed by a hypothesis- a statement which should be testable and falsifiable.  Then one has to predict the consequences of hypothesis and conduct experiment to test them and  come out with a generalized statement or rule at the end.

Although these steps are appealing, much progress in science has come from trial and error, experimentation without hypotheses, or just plain accidental discovery like Penicillin  by a well-prepared mind.

The success of science rests more on an attitude common to scientists than on a particular method. This attitude is one of inquiry, experimentation, and humility-that is, a willingness to admit error. In our next podcast, we will dwell upon this important aspect of scientific investigation.


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