Difference between Hypothesis, Theory and Law.
Updated: Jun 7, 2020
The three words- hypothesis, theory, and law are the most acquainted word in the scientific community but, still, many of us do not clearly understand the meaning of them. Let us understand in the easiest possible way.
A scientific hypothesis is a possible explanation of an event that is enunciated with the help of a set of observations. Scientists propose a hypothesis during or after their initial data collection from the field. For example, A team of geologists finds a crater in a region. They propose two hypotheses for the natural landscape found by them, either from a volcanic eruption or a meteorite impact.
Since a hypothesis is no more than an idea that can be either wrong or right. Thus, scientists have to scrutinize the hypothesis with the set of tests to see whether it works or not. Let’s go back to the example. The Geologists in the field found mineral Stishovite- high-pressure polymorph of Quartz and the most characteristic feature of a meteorite impact i.e. shatter cones (both the italicized words will become more clear in the upcoming articles). But they were unable to find features related to volcanic explosions i.e. rocks formed by solidification, tephra, or ash. What they found in the field was compared to the published observations made at other sites with the known geology and the process responsible for its occurrence. And this is how testing of the hypothesis was made for the found crater.
Theories are those scientific ideas that are supported by abundant evidence. They have passed many tests and have failed none. There is more confidence in the correctness of a theory than a hypothesis. For our example, continued study of the rocks and minerals found in the field provided so much evidence for the impact hypothesis so that it was viewed as a theory. Successful theories withstand so many tests and are supported by numerous observations that they become part of the subject’s foundation. However, there may be possibilities for some theories to be disproven and replaced by new as more and more study is made and new observations are noted.
In a few cases, scientists devise concise statements that completely describe a specific relationship or phenomenon. Such statements are called Scientific Laws. They might not explain the cause for their existence but they, for sure, explain the phenomenon. For example, the law of gravity does not explain why gravity exists but it surely explains the resultant phenomenon. Newton’s law explained why the apple fell from the tree but could not explain why it happened.
Let's understand this with an exquisite example of Lonar Lake.
Lonar crater is the only terrestrial crater excavated in basalts in the world. This is one unique crater among the 120 recognized craters on the Earth. Recognized, as the surficial process pitied it, and we, fortunately, have it unmodified by erosion. It has a circular plan developed in the Deccan basalt, erupted around 65 Ma, during Quaternary and unrelated to Deccan Volcanism. But how do we know it was formed in Quaternary when it has a crater morphology and that too standing out fairly in a Deccan basalt. Was it not the center of eruption?
Image credit: NASA Earth observatory
Well, in the beginning, there was speculation on whether the crater was formed due to explosive volcanism, land subsidence, or meteoric impact. Now, here, all three are different hypotheses. But for one of them to be true, the other two have to be falsified. For this began researches in the region. Researchers found the presence of lava channels/ tubes, volcanic debris, and red tuff in the vicinity of the crater and pointed out for the correctness of the Explosive Volcanic eruption theory. And, this was, even, for a time, accepted to be the origin of this crater. However, soon investigations, like a detective, by the Geological Survey of India revealed shock ejecta scattered as far as 600 m away from the crater. The presence of shock breccia, scatter cones, and brecciated basalt at a depth of 335 m was revealed by drilling. Plagioclase has been converted to maskelynite by the impact. All these features suggested a valid impact origin of Lonar Crater.
Lonar crater is situated in the Buldana District of Maharashtra and is one of the National Geological Monuments. It hosts a saline lake in its center.
Wait, Wait...there's more!
So the most important thing to remember after this article is to understand the difference between the three words. They do not mean the same and cannot be used interchangeably. Hold on to something tight because from the next article we will be starting our tour from 13.7 Ga to present.