Translation plays important role in any society. Most of the people around the world will realize and understand the folklore, cultural traditions, religions, believes, epics and … of other people in different countries by translation. In addition, translations transfer scientific information between scientists that can develop the welfare of humans during the passing of times. As a result of these facts, translators have great responsibility because of transferring accurate and unbiased truth and information between two languages. Translators should find the appropriate and accurate equivalent for the words of the Source language by attention to the political, cultural, social, economic and the norms of the Source and Target languages.
We have different kinds of translation which include:
1. Bilingual translation which occurs between two languages.
2. Monolingual translation that is inside of language such as the translation of poems and complex concepts and local words.
3. Franca translation that one language is the mediator between two languages.
4. Historical translation that translators may translate the historical texts which come back to million years ago between two languages or on language.
5. Sign translation which is related to the translation of the signs in every country such as traffic rules shape, American Indians' signs and …
6. Emotional translation in fact how we show the writer's feeling in our translation.
7. Code translation that is related to the decoding of symbols, code, and cryptogram and so on in wars such as World War II and the war of Iraq against Iran.
According to the above facts, translators are to be talented, hard working and more knowledgeable persons around the worlds. And finding proper and appropriate equivalent is the duty of every translator.
Thinking on equivalence in translation helps to deepen our understanding of the nature of translation. Equivalence, at the abstract level, is a rather necessary and important term in the field of translation studies (Edwin Gentzler 1993 p.58). Theoretically, according to him equivalence is attainable and equivalence takes the form of different subcategories that are realized at different layers of translation, because this term usually comes with modifier. Certainly, nothing but the abundant practice of translating and the study of obvious problems occurring in translation would be enough for a theory relating to equivalence.
Broek (1981 p.33) also redefines the term equivalence by the concept of "true understanding". Another scholar M. Mehrach (1997 p.44) also considers equivalence "an impossible aim in translation". He supports his saying by the idea that no two languages share the same linguistic structures, social or, cultural aspects. Instead, he proposes the use of the term 'adequacy' for the 'appropriate' translation, that is," a translation that has achieved the required optimal level of interlanguage communication under certain given conditions."
Hervey and Higgins (1995 p.75) believe that the principle that a translation should have an equivalence relationship with the source language text is problematic. For supporting their idea, they say that there are three main reasons that an exact equivalence or effect is difficult to achieve. Firstly, it is impossible for a text to have constant interpretations even for the same person on two occasions. According to them before one could objectively assess textual effects, one would need to have referred to a rather detailed and exact theory of psychological effect, a theory capable, among other things, of giving an account of the aesthetic sensations that are often important in response to a text. Secondly, translation is a matter of subjective interpretation of translators of the source language text. Thus, producing an objective effect on the target text readers, which is the same as that on the source text readers is an unrealistic expectation. Thirdly, it may not be possible for translators to determine how audiences respond to the source text when it was first produced.
According to Kong (2009 p.56) equivalence is at least a functional and effective term for us to describe and analyze translation or to tolerate the heated controversy in this field and find a way out of the complex dilemmas in the practical translating that is unresolved. And according to him the theory on equivalence actually did, do or will do offer us a theoretical basis to examine the variety of translation methods created.
Finding equivalences to convey the same meaning of a source language text is not always an easy task (Gimenez 2005). The difficulties related with the process of translation have been widely reported by scholars and professional translators, but they become highly famous when we pay attention to language students learning to translate into their native language.
The comparison of texts in different languages inevitably involves a theory of equivalence (Leonardi 2000). Finding equivalences in translation involves decoding the source language (SL) text and making an attempt to find an appropriate equivalent in the Target language (TL) text to encode whatever has been decoded in SL (Baker 1992).
Equivalence is a central concept in translation theory, but it is also a controversial one because theoreticians consider equivalence from different viewpoint in translation studies. Translators through finding equivalence leave some room for their readers to understand better the real meaning of texts (Kenny 1998).
Approaches to the question of equivalence can differ radically: some theorists define translation in terms of equivalence relations (Catford 1963, Nida and Taber 1969, Toury 1980, Pym 1992, 1995, Koller 1995).
While others reject the theoretical notion of equivalence, claiming that it is either irrelevant (Snell – Hornby 1988) or damaging (Gentzler 1993) to translation studies. Yet other theorists take a middle course: Baker says that the notion of equivalence ‘for the sake of convenience- because most translators are used to it rather than because it has any theoretical status' (Baker 1992, P.5-6).
Thus equivalence is variously regarded as a necessary condition for translation, an obstacle to progress in translation studies, or useful category for describing translations. Finding equivalence in translation of scientific texts plays important role in academic discourse (Swales, 1990). Therefore, many studies have been focused on the nature, interlingual and intertextual, empirical and theoretical notion of equivalence in recent years (Catford 1965, 1994, Pym 1992, Koller 1979, Toury 1980, Hutchins and Somers 1992, Arnold 1994). These studies have tried to show us the variation of finding equivalence across different disciplines.
The domain of equivalence covers linguistic units such as morphemes, words, phrases, clauses, idioms and proverbs (Baker 1992). Through using finding equivalence strategies, the translators also attempt to improve the chance of persuading their readers by making better their qualities of translation (Neubert 1985).
According to Leonardi (2000), finding equivalence is the most problematic stage of translation. She also believes that the translator should not always find one to one categorically or structurally equivalent units in two languages, that is, sometimes two different linguistic units in different languages carry the same function. Baker (1992) also believes that the choice of a suitable equivalent in a given context depends on a wide variety of factors such as linguistic and extra linguistic. She also said that non – equivalence often creates difficulties for the translator in translating of terminologies of scientific texts.
The neglect of the study on finding equivalence at word level in scientific texts in the past years is reported by Crystal (1995, p. 120) who attempted to shed light on the areas in English language studies which have not received attention. Despite its major role in translation of scientific texts, equivalence received most attention in the literary context (Nida and Taber, 1982). There have not been many cross – linguistic and cross – disciplinary studies on finding equivalence in translation of scientific texts. The limited numbers of studies which are conducted in this area have shown that there are some variations in the use of equivalence strategies across languages (Baker, 1992, Fawcett, 1997, Dorothy, 1998; House, 1997) and across disciplines (Carter and Macarthy 1988).
Koller (2000) has proposed to distinguish two concepts of equivalence: "As a theoretic- descriptive concept Equivalence designates the relation between a B text in language L2 (target language text, TL-text) and A text in language L1 (source language text, SL- text) which allows us to speak of B as a translation of A. Equivalence is then understood as a basic, constitutive translation concept. It is suitable for distinguishing translation from other forms of secondary text products (text related to a primary or source text)" (p.11) It is often said that the ultimate purpose of translation should be to achieve an "equivalent effect" (Bekku 1975, Newmark 1988).
In other words, a translator should achieve a similar effect on the target text receiver as the source text has on the source text receiver. However, between languages with greater cultural differences, it may not be easy to achieve this (Higashino 2001).