To use a language as a scientific lingua franca can give advantages and disadvantages for the members of the scientific community on the basis of their culture and mother tongue. The status of a scientific or international language developed historically and not according to logical ideas and decisions on equal opportunity. I have tried to classify former scientific languages and some present candidates. I - as a European with my own experiences and preconceptions - have found Italian and German languages as the best fits. I am waiting for your opinion and reasons.
Characteristics of the ideal international scientific language
Grammar: easy
Vocabulary: well known
Script: easy
Pronunciation: easy
Giving equal opportunity: perfect = dead language
Strong cultural background: yes
Strong scientific background: yes
Strong economic/political background: none (= economy and politics do not influence the choice)
Characteristics of historical international scientific languages and candidates
Greek
Grammar: not easy
Vocabulary: well known
Script: not easy
Pronunciation: not easy
Giving equal opportunity? yes, one mother country
Strong cultural background: yes
Strong scientific background: historically yes
Strong economic/political background: none
Latin
Grammar: difficult
Vocabulary: well known
Script: easy
Pronunciation: relatively easy
Giving equal opportunity? perfect
Strong cultural background: yes
Strong scientific background: historically yes
Strong economic/political background: none
Arabic
Grammar: very difficult
Vocabulary: very difficult
Script: very difficult
Pronunciation: very difficult
Giving equal opportunity? too many native speakers
Strong cultural background: yes
Strong scientific background: historically yes
Strong economic/political background: too many countries
Chinese
Grammar: I do not know
Vocabulary: very difficult (for Europeans at least)
Script: very difficult
Pronunciation: very difficult
Giving equal opportunity? too many native speakers
Strong cultural background: yes
Strong scientific background: yes
Strong economic/political background: world power
English
Grammar: at the beginning easy, then difficult
Vocabulary: well known
Script: OK
Pronunciation: difficult
Giving equal opportunity? too many native speakers
Strong cultural background: yes
Strong scientific background: yes
Strong economic/political background: world power
French
Grammar: difficult
Vocabulary: well known
Script: OK
Pronunciation: difficult
Giving equal opportunity? one mother country
Strong cultural background: yes
Strong scientific background: yes
Strong economic/political background: none
German
Grammar: relatively easy
Vocabulary: well known
Script: easy
Pronunciation: easy
Giving equal opportunity? two mother countries (Switzerland has four official languages)
Strong cultural background: yes
Strong scientific background: yes
Strong economic/political background: none
Russian
Grammar: difficult
Vocabulary: not so easy
Script: easy
Pronunciation: easy
Giving equal opportunity? too many native speakers
Strong cultural background: yes
Strong scientific background: yes
Strong economic/political background: world power
Italian
Grammar: easy
Vocabulary: well known
Script: easy
Pronunciation: easy
Giving equal opportunity? one country
Strong cultural background: yes
Strong scientific background: yes
Strong economic/political background: none
Spanish
Grammar: not so easy
Vocabulary: well known
Script: easy
Pronunciation: not so easy
Giving equal opportunity? too many native speakers
Strong cultural background: yes
Strong scientific background: yes
Strong economic/political background: too many countries