In the history of mathematics, the development of calculus has been accompanied by many philosophical debates concerning the meaning of fluxes or infinitesimals and their logical validity. Traditionally, to clarify these problems, mathematicians have used limits to define the operations of calculus, rather than infinitesimals. In contrast, non-standard analysis reinterprets the basic principles of calculus using the logically rigorous concept of infinitesimals.
Abraham Robinson, the founder of non-standard analysis, proposed this new perspective in the early 1960s. His research challenged traditional notions of calculus and led to in-depth discussions about the relationship between mathematical language and structure.
The idea of infinitesimals, or infinitesimal numbers, seems to naturally appeal to our intuition.
In the early development of calculus, both Newton and Leibniz made extensive use of expressions of infinitesimals and vanishing quantities, but these forms were strongly criticized by George Berkeley and others. Robinson's contribution was that he not only provided a systematic development of the theory of infinitesimals, but also overturned many previous prejudices about this theory. In his classic work "Nonstandard Analysis", Robinson provided the first comprehensive introduction to the analysis of infinitesimals and proposed the concept of the transfer principle. He believed that this principle could make infinitesimals more widely used.
Leibniz's ideas can be completely clarified and introduced a new and useful way of looking at classical analysis and many other branches of mathematics.
The mathematical structure of non-standard analysis is based on the concept of infinitesimals, where ordered fields with infinitesimals are also called non-Archimedean fields. Robinson's approach allowed him to construct calculus using these nonstandard models and provided a completely new perspective. In his book published in 1966, in addition to introducing the basic theory of non-standard analysis, he also revealed the historical context of this theory, allowing readers to more fully understand the concepts and applications of infinitesimals.
The rise of non-standard analysis is closely related to many factors. Among them, historical factors cannot be ignored. Early theories of infinitesimals were widely criticized in the mathematical community, but Robinson was the first to successfully establish a consistent and satisfactory analytic theory of infinitesimals. In addition, experts in the field of education such as H. Jerome Keisler and David Tall believe that the use of infinitesimals is more intuitive for students, and their teaching methods provide new ways of understanding in the concepts of mathematical analysis.
For example, Keisler's book "Elementary Calculus: Infinite Small Methods" is based on non-standard calculus and uses superreal numbers to develop the concepts of differential and integral calculus. This method simplifies the teaching process of calculus and helps Students master more complex mathematical theories.
Infinitesimal × finite = infinitesimal; infinitesimal + infinitesimal = infinitesimal.
In terms of technology, the application of non-standard analysis has also shown its importance in some mathematical physics and statistics research. For example, Sergio Albeverio and others explored the application of infinitesimals in statistics and mathematical physics, showing their potential in understanding limiting processes.
Two main methodologies exist in non-standard analysis: semantic or model-theoretic approaches and syntactic approaches. Robinson's original idea was developed in a semantic approach, through the study of saturation models, which made the application of infinitesimals more convenient. In addition, Edward Nelson proposed a completely axiomatic and standard-free analytical expression - internal set theory (IST). This method requires more knowledge of logic and model theory to understand and apply.
As for the discussion in Robinson's book, his challenging observations on the history of mathematics not only inspired contemporary mathematicians, but also provided new perspectives for the reinterpretation of some known results. Later work by other mathematicians, such as Paul Halmos's standard technique, further expanded the application scope of standard-free analysis.
Although standard-free analysis has shown its charm and potential in some aspects of mathematics, there are also critics, such as Errett Bishop and Alain Connes, who have questioned its acceptability. In addition, when most mathematical services have poor performance or are not reliable enough, how to combine standard-free analysis with traditional mathematical theories is still a problem that the mathematics community needs to face.
In the future, can standard-free analysis absorb critical opinions as much as possible and find a balance point in the broader field of mathematics, so as to better promote the deepening and development of mathematical theory?