> Surprisingly, these particles were found decades ago by Alonzo Church, the inventor of Lambda calculus long before electronic computers even existed!!
John McCarthy has introduced his lambda notation in October 1958, being inspired by the work of Alonzo Church, but it had very little to do with Lambda calculus.
The essential innovation brought at that time by John McCarthy to programming languages was that, unlike in earlier programming languages like Fortran, where a function definition was a separate section of a program source file, where an identifier had to be bound to a function definition, a McCarthy function definition behaves just as a constant value, very similarly to a character string constant, integer constant or floating-point constant, so it can appear in any place where a constant can appear, it can be assigned to an identifier, but it can also be used directly as an argument in the invocation of another function.
Once the new semantics of a function definition was established, the syntactic notation for it was a minor detail. A possible notation would have been to enclose any function definition in a special pair of parentheses, like a character string constant that is enclosed in quotation marks. Because this was not feasible due to the limited character set that was available, the chosen syntax was that of a LISP special form, which needs a keyword, for which the choice was "lambda".
To distinguish in a function definition the parameters used for function invocation, Alonzo Church had enclosed them in a pair of special parentheses, where the leading parenthesis was a small Greek lambda character and the trailing parenthesis was a raised middle dot.
This provided the inspiration for the "lambda" keyword. Perhaps McCarthy was also inspired by Church's work to change the handling of function definitions to be like that of any other values, but that is the maximum extent of the relationship between Lambda calculus and LISP.
Nevertheless, the LISP "lambda" notation played an important role in attracting attention upon the work of Alonzo Church, so in the following decade there was much research in functional languages that was much more strongly influenced by Lambda calculus than LISP was.