Step #4:

The experiment is gathering additional observations to test the hypothesis.  At this point, it is important to distinguish science from non-science. Science is not out to prove anything. The procedure of science is simple to TEST ideas, not prove them. Thus all scientific ideas, hypotheses or theories are falsifiable.

It is essential to emphasizes that experimentation tests both hypothesis (H1) and null hypothesis (H0) simultaneously. A scientist does not set out to "prove" his favorite hypothesis, but is willing to discard a favorite hypothesis if shown to be falsified by the data.

It is unfortunate that in so many instances, people in high positions of political, religious, economic or military power will stop at nothing to pressure others into accepting their favorite hypothesis without proper and rigorous experimental testing. They will often proclaim that their favorite hypothesis is so logical and so reasonable that it must be correct, therefore no further evidence is necessary. They then proceed to convert and even coerce others and before long the whole world is convinced and rejoices in their absolute truth.

But then the kill-joy voice of a scientists is heard like a voice in the wilderness:

"Where is the evidence?"

Under these circumstances, as seen in past historical events, the general public often responds by executing or imprisoning the scientist rather than changing an emotionally fixed public opinion. Such historical events have occurred many times in the past and involve such scientists as Galileo, Copernicus, and Darwin.

Even now, such coercion and repression of scientists occurs today, but with more disastrous possibilities for the future of humanity. Unresolved questions by scientists are still met with resistance by political, religious and military leaders, and the confusion, misunderstanding, and resistance is reflected in general public opinion. Consider the problems of toxic wastes, increased buildup of carbon dioxide in the atmosphere, the disappearing ozone layer, genetic engineering, uses of atomic energy, and the world human population explosion. For each of these pressing problems there are ignorant people in powerful positions whose influence may result in devastating and horrifying results.

"Too often, leaders are willing to accept the products of science,
but will reject its methods." (Carl Sagan)

Probably one of the most potent statements to counteract such coercion and deceit by people in high positions is

"Question Authority"

Perhaps if all peoples of the world would question all authority, the doors of progress could be opened very wide indeed.

The experiment is the most difficult step in science. Here, the most demanding requirements must be met for the results to be valid. In an experiment, rigor must be applied to every aspect. Rigor means that bias must be eliminated as much as possible, that measurements taken must be exact to the full limit of any instrument used, that many, many observations be made repeatedly in order to fully substantiate that the observations are not made in error. In addition, the experimental conditions must be correctly set up in such a manner that the experiment will be appropriate to test the hypothesis. Furthermore, a control or parallel experiment must be performed to rule out causes which were not expected and were not part of the original hypothesis. One difficulty with biological experiments is the health of the organisms being tested. Sick or stressed organisms may not function normally under artificial experimental conditions and may lead to incorrect interpretations.

If a scientist wanted to test the hypothesis that smoking cigarettes caused lung cancer, merely studying one individual who smokes would not reveal valid results. If the smoker lived to be 105 and died of an automobile accident, nothing could be decided with respect to cause and effect. If the same person died at age 33 of lung cancer, there still could not be a valid interpretation. Perhaps the next 100 people who smoked heavily would live a long life and never get cancer. However . . . suppose 1,000 people living in Nebraska (not in cities) who smoked cigarettes were compared to 1,000 people also living in Nebraska (not in cities) who never smoke anything (control group). If the results yield many more smokers developing lung cancer than non-smokers, then valid interpretations can be made.