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A letter is from the future so we are talking about science fiction. It makes us think about science, but letter is for current time and also readers are of the current time. So whatever will happe...
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Source: https://writers.stackexchange.com/a/48974 License name: CC BY-SA 4.0 License URL: https://creativecommons.org/licenses/by-sa/4.0/
#2: Initial revision
A letter is from the future so we are talking about science fiction. It makes us think about science, but letter is for current time and also readers are of the current time. So whatever will happen to language in 2050, whether new slangs introduce, new acronyms, new phrases or even total English has been changed the main thing which you need to remember is that readers need to read that in English of the current era. Let's come to science, Natural Language Processing is an active research topic in the current computer science field. According to current research text summarization and machine translations are very popular. Also "Concept Search" is a popular term. So if we combine these technologies together (which is even valid for today, and hopefully will be at their fully functional form in 2050), we will get something like this " Son will write Mail in his/her own language(Maybe he/she moved to some other place rather then English, even if it is more Modern English then nowadays) and the computer program understand the "Concept of the letter" and also know the "History of the Person" (Becuase software will hold trillions of data or even larger), and that software will translate that "Conceptual Email" into a normal 2019 readable Email." But one more thing which will be fully Developed in 2050 is EEG communication, which is via thoughts, Researchers had found very useful results and hopefully they will be able to place a sensor on mind and computers will interact through thoughts of Person and maybe Idea comes to a Mind of the person in 2050 and no need to write a single word just by thinking the receiver of the Letter and "Concept of the Letter" will result into a 2019 readable Letter. (Depends on how much advance YOUR 2050 is :)