The concept of the hypothesis is not something very new. It is a guide behind every scientific investigation. It is such a basic thing that we use it almost every time rather unknowingly.

**Every scientific investigation is a 5-step process:**

- Identification of the problem
- Literature study
- Formulation of hypothesis
- Experiment
- Observations, Analysis, and Conclusion

**Let us understand this by an example: **

Suppose that your supervisor asks you to make a polymer sheet that is strong enough to break under a given pressure range and is flexible. The very first thing you need to do is a literature study bearing some questions in mind:

- What sheets are available and how much stress they can bear?
- What are the factors that limit their stress-bearing ability?
- Have others tried to prepare the sheets with properties similar to yours?
- What are their compositions and methods?
- To what extent, were they successful in their endeavor?

Thereafter, collecting all this information, your start figuring out the ways to modify the sheet to get the desired results. Now suppose you come to know that adding nanoparticles of some material can provide considerable strength to the sheet.

And so, you collect more info on it and tend to arrive at a conclusion that if I add NPs of this or that material in my film, I will be able to get such and such results. This is what your hypothesis is!! It means based on your understanding you set a roadmap to your destination. Only thing is that you may or may not reach the desired destination.

## What is a ‘hypothesis’?

The hypothesis is basically assumptions that a researcher makes to solve a problem, what he expects out of his experiments, what property he/she wants to investigate, what method will let him probe his subject, what are the variables, and what are the possible relationships between the variables.

## How it should be?

A hypothesis should be clear and precise. It means it must clearly state the relationships between the variables and the outcomes of the experiments. The predicted outcomes of the experiments must have systematic explanations and should be supported by valid references.

### When the work of Ignaz was ignored…

For instance when Ignaz Semmelweis in the 1850s, a childbirth doctor, stated that if doctors wash hands before treating women for childbirth, the mortality rate can be reduced. He observed this and implemented it in his hospital. Thereby he was able to reduce the mortality rate in his hospital but no one paid attention to his work. He was tortured to death and the hospital threw back the practice of handwashing after his death. This lead to the surge in the mortality rate again. All this happened…why? Because he couldn’t explain the reason that why handwashing was effective as the concept of germs was unknown. This explains the importance of the support you need to provide to your statements.

## Two types of hypothesis

### Null hypothesis

The null hypothesis is the assumption or fact that wish to deny or disprove. During a scientific investigation, after formulating a hypothesis, the researcher first carries out the experiments in order to reject the null hypothesis. (It is not essential that the null hypothesis will be rejected, experiments must be carried out without any bias).

For example, if you wish to modify the formula to find out the potential energy of a stone placed on a high building, you will need to first disprove the fact that the current formula mgh calculates the P.E. of stone correctly to a given accuracy. This is your null hypothesis.

H0: the current formula mgh calculates the P.E. of stone correctly to a given accuracy

### Alternative hypothesis

An alternative hypothesis is a statement or assumption you wish to prove to be true. After the null hypothesis is rejected, now one gets on to prove the alternative hypothesis. For the problem outlined in the above example, an alternative hypothesis will be

Ha: My formula correctly predicts the P.E. of stone placed on high building to the given accuracy.

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