Phases Of The Scientific Method
Phases Of The Scientific Method
Introduction
The experimental sciences as the Physics and the Chemistry, use him/it denominated experimental scientific method, whose main phases will analyze to proceed, using us of a real case. For so much, we propose that you imagine as if it already went a scientist and he/she had as incumbency to give an explanation to a natural phenomenon as, for instance, the rainbow.
How would you plan his/her activity and what steps would give until finding answer to all the questions that involve the phenomenon of the rainbow?
In elapsing of that text we will try guide him for that road where you will be the main protagonist.
The observation of the phenomenon
Once defined the study phenomenon, the first thing to do is to observe his/her event, the circumstances in that is produced and their characteristics.
This observation should be reiterated (it should be accomplished several times; it should be repeated), meticulous (he/she should try to appreciate the largest possible number of details), rigorous (it should be accomplished with the largest possible precision) and systematic (it should be made in an orderly way).
In what circumstances he/she does appear the rainbow?
The reiterated observation and systematic of the phenomenon it will allow to verify him/her that the rainbow appears when it rains (you will later be able to simulate a rain, in laboratory, and he/she won’t need more to be awaiting ‘to rain’) and, besides, that there is sun (later, in the laboratory, a good lamp will simulate the Sun). The same sequence of observations will do with that you notice that the rainbow will only be visible when you be placed between the sun and the rain, of backs for the Sun. You will write down in his/her field notebook: “The rainbow is not seen of any place that I am and, when I see him/it, I am of backs for the Sun between the sun and the rain.” In the illustration above, where should you be? Where is the Sun?
Which is the form of the rainbow?
The form of the acquaintance rainbow is the one of a circumference arch. However, you should not write down just that in his/her field notebook. Also write down: Will it “be that observed of the high of a mountain the size of that arch increases? do decrease? Does the medium ray of the circumference lose temper? If
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I was in an airplane would have him, still, the form of an arch?”
What colors him in the display and in what order they do appear?
You can observe (just using their eyes) that exists seven different colors in the rainbow and that they are, from within outside of the arch: violet, anil, blue, green, yellow, orange and red.
In search of information
You are not the first person to observe a rainbow, with certainty. Like this, as following step and with the objective of to confirm and to reaffirm the made observations, it should be consulted books, encyclopedias or scientific magazines that they already describe something on the phenomenon that is being, once again, studied. Don’t forget that in the books meet the accumulated scientific knowledge through the history. For that reason, the search of information and the use of the existent knowledge they are indispensable in every scientific work.
Do the information that he/she found coincide with those obtained during their observations?
The consultation of any book of Elementary Physics will confirm him/her that the conclusions the one that arrived through their observations are correct. Or be:
the) THE rainbow only appears and it can be seen when it rains and, besides, there is sun.
b) THE rainbow always presents the same colors and those they are happened in the same order.
He/she assists for the fact that that book elementary text didn’t give answer their ace logged doubts in his/her field notebook; maybe other books give them.
What other information could be gathered in the consulted books?
The consultation of books and magazines can inform him/her that, for instance, per times, they appear two arch-iris, although one of them is well more tenuous than the other and, therefore, more difficult to be seen.
The formulation of hypotheses
After observing the phenomenon and of gathering enough documentation about observations already made for other, the scientist should look for an argument to allow to explain and to justify each one of the characteristics of such phenomenon. As first step of this phase, the scientist begins to do several conjecture or suppositions starting from the ones which, later, by a series of experimental proofs, she will choose as explanation of the phenomenon the more you/he/she completes and simple, the one that better you/he/she is adjusted to the general knowledge of the science in the moment. That explanation rational, reasonable and enough is called scientific hypothesis.
Is the rainbow a luminous phenomenon?
He/she seems that yes, put that is only produced when a luminous (the Sun) source exists. Does his/her existence have to do something with water?
The answer is also affirmative, position that the rainbow only appears when it rains. Is a reflection phenomenon or of refraction?
He/she seems that, at first, we can discard the reflection, position that the emergence of the phenomenon is not observed in any body opaque reflector. For his/her time, we can propose the hypothesis that the rainbow is a phenomenon of refraction of the light and that his/her emergence feels because of the decomposition of the solar light when that raisin through the drops of water of the rain. It is a reasonable hypothesis.
The experimental proof
Once formulated the hypothesis, the scientist should prove that this is valid in all of the cases and, for so much, you/he/she should accomplish experiences more faithfully in which reproduce the possible the natural conditions in which the studied phenomenon is verified. If under such conditions the phenomenon happens, the hypothesis will have validity, in other words, it will be a true proposition in the stipulated conditions. How will we do to reproduce the conditions of emergence of the rainbow?
Let us begin by simulating a rain and, for so much we should have water falling in drops. It is
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not difficult to do that, it is enough to catch a hose of to water the garden and to press the exit extremity with the way hands to do a fine and wide jet. Machines of washing, electric, they allow the adjustment of that flow with easiness. Drive the jet upward and give their backs for the Sun. Ready, you reproduced with fidelity the indispensable requirements for the emergence of the rainbow; he/she simulated a rain, there is sun and you were put between both. What will happen he/she when you to accomplish that experience?
It was followed all of the steps described above, it can prove that in the horizon of the ‘rain’ he/she will appear a small rainbow. Can we admit how valid the formulated hypothesis?
Everything indicates that yes, because with the same conditions that feel in the Nature, however in reduced (everything of smaller size) scale, we got to obtain a rainbow.
Working at the laboratory
One of the main activities of the scientific work is the one of accomplishing measures on the several variables that intervene in the phenomenon that is studied and that are susceptíveis of they be measured.
If we arrest ourselves to the experiment described above difficultly you can remove some measured, for that, it is convenient to repeat the experience in an appropriate place where that can be made, in other words, in a laboratory. These experiences accomplished at the laboratories are called ’scientific experiences’ and they should accomplish the following requirements:
the) they should allow to accomplish an observation on which can be extracted data.
b) they should allow that the different factors that intervene in the phenomenon (brightness, temperature etc.)
they can be controlled individually.
c) they should allow her to accomplish (to repeat) so many times as necessary and for different
operators.
Habitually, in experimental sciences, the laboratory works allow to establish models, that are situations or theoretical suppositions by which he/she occurs an analogy (formalizao) (equivalence) among the phenomenon that happens in the Nature and the experiment that we accomplished.
How will we explain the one what happened?
When the strait bunch of white light reaches the area [THE] of the balloon and gatecrasher in the water he changes of direction enlarging the opening of the bunch (observe the area interns of [THE] for [B]). When arriving in the area [B], when leaving the water, again it happens other direction change and new enlargement of the opening of the bunch — it is the phenomenon of the refraction that she make to accompany of the decomposition of the white light. The coming colored lights of that decomposition reach the screen. Each drop of the rain, in the mentioned conditions, has that behavior. Owed the those thousands rain drops that participate in that decomposition is that if it turns possible to see the rainbow in the horizon.
Besides that important observation, the experiment allows to measure the different angles of deviation of each one of the colors in relation to the strait initial incident bunch. It is a scientific experiment, filling out the basic requirements.
Like this, he/she is proven that the formation of the rainbow can be explained by the laws that govern the refraction of the light.
The treatment of the data
The measures made about the factors that intervene in a certain phenomenon should allow to find some type of mathematical relationship among the physical greatness that characterize the phenomenon in study. For the to arrive that mathematical relationship the scientists tries to follow two previous steps: the analysis of the pertinent factors and the construction of tables and graphs.
1 analysis of the factors
The study in depth of a phenomenon requests, in first place, the determination of all the factors that in him intervene. So that that study takes place in a simpler way,
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he/she notices a series of greatness that you/they don’t vary (controlled variables) and it is studied the way as it varies a given greatness (dependent variable) when a variation of another greatness (independent variable) is produced. Like this, if thankfully 10 factors exist intervening in a die phenomenon, they notice the values of 8 of them, we varied one of the remaining two deliberately (in way very well certain) and he/she is determined, by careful measures that variation suffered that remaining factor. That repeats ciclicamente until draining the whole series.
Here is a practical example: we want to study the prolongation that a spring that has one of their fixed extremities tries, when we put ‘checked weights’ in the other extremity. There is a group of greatness that, at the beginning, they can be considered with invariable (temperature of the enclosure where it is made the experiment, the barometric pressure inside of the same, the relative humidity of the air etc.) values, that correspond controlled variable ace. In that case, the measure of the deformation of the spring (his/her prolongation) will be the dependent variable and it ‘I weigh’ (checked mass or massor) that put in the free extremity will be the independent (we chose the values of those weights) variable.
2 the construction of tables and graphs
The construction of tables consists of ordering the numeric data obtained for the dependent variable in correspondence with the numeric data of the independent variable. We should always specify the units with which those two variables are measured in game. They are usually used of par磪ntesis in continuation to their names.
The graphic representation consists of transferring the data of the measures (equal orderly) for a system of axes Cartesian ortogonais where, usually, the independent variable she make to correspond to the axis X (axis of the abscissas) while the dependent variable makes to belong together to the axis Y (axis of the ordinates).
We denominated ‘it adjusts of the graph’ to the procedure by which is determined which the best line than it goes (that is adjusted) by all of the points (or for most of them) of the graph, representative of the orderly pairs. In most of the cases, the graphs that is obtained are straight lines, what indicates that the relationship among the represented physical greatness is in the way Y = k.X, where k is a constant. See illustration above.
In other cases, the relationship among the greatness can be of the type ‘parabolic’, what mathematically will be represented by Y = k.x2, or of the type ‘hyperbolic’, whose expression will be in the way X.Y = k.
The conclusions and the communication of results
The analysis of the data and the proof of the hypotheses take the scientists to emit her/it their conclusions, that can be empiric, in other words, based on the experimentation or deductive, in other words, obtained by a reasoning process of which breaks of a truth known (true premise) to á explanation of the phenomenon to arrive.
Once well it solidifies those conclusions, these should be communicated and published for the remaining of the scientific community so that they serve as starting point for other discoveries or as foundation of a practical technological application.
Which done the road tread for á explanation of the formation of the rainbow to arrive?
The first scientist that studied in a rigorous way the decomposition of the light was Isaac Newton (1642 – 1727) and thei
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r publications served so that, later, the formation of the rainbow could be well explained. Further on still, the technology took advantage of the phenomenon of the refraction of the light and numerous optical instruments were invented, as cameras, projectors etc. in whose operation intervenes that phenomenon.
The elaboration of Laws and Theories
The scientific study of all of the aspects of a natural phenomenon takes á elaboration of laws and theor
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ies.
* A scientific law is a hypothesis that has been proven his/her validity.
* A scientific theory is a group of laws that you/they explain a certain phenomenon or group of them.
Like this, for instance, the proven hypothesis that the rainbow is formed due á refraction that the white (solar) light tries when crossing the rain drops, it is an integral law of a group of laws that you/they govern other luminous (reflection, dispersion, diffraction etc.) phenomena. That group is known as the Theory on the light.
As much the laws as the theories they should accomplish the following requirements:
the) they should be general, in other words, they should not just explain cases peculiar of a phenomenon.
b) they should be proven, in other words, they should be alavancadas (endorsed) (corroborated) (seated)
for the experimentation.
c) they Owe, when possible, to be ‘matematizadas’, in other words, can express by mathematical functions.
The scientific theories have validity until that they are unable to explain certain facts or phenomena, or until that some proven new discovery if it opposes them. Starting from then, the scientists begin to elaborate other theory to explain those new discoveries. The Science is evolutionary knowledge and no stationary.
The one what conclusion would you arrive if he/she came to see a rainbow in one day without rain?
In agreement with what up to now was studied, the theory of the light demands that, for the rainbow to be produced it is necessary that rains, so that the drops of water can decompose the solar light in their seven colors. If in the atmosphere there is not water, we will have to rethink on her mentioned theory and to try to complete her/it with other arguments (new hypotheses, new proofs) that start to explain the observed phenomenon. If such it is not possible every theory will fall for earth.
By: carlosduarteca
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