What is the meaning of inferred absolute zero temperature? Why does the resistance temperature graph it is obtained from behave that way?

Question

Studying basic direct current circuits, I've come across the term inferred absolute zero temperature on computation of resistances that change due to temperature. Based on my readings, I understand it to be a predicted value as the word "inferred" means. It predicts the value of the absolute zero temperature based on using a segment of the graph that seems to have a linear slope through extending that line to where the temperature is zero.

Although that is my understanding, I decided to ask it in StackExchange because I've searched for an explicit definition of this term and no source has ever defined it in such a way. You have to go through a lesson of resistances changing by temperature, find the terminology and read the paragraph to get it. I mean, for such a common lesson I can't believe that I couldn't find any source that just defines the terminology in a friendly manner or even have a Wikipedia article that defines it as there it gets a little more clear and precise.

Can anyone confirm this concept for me and define it more explicitly? By explicity I mean that say that the term means this, and not focus on some other topic where I have to read and it is only implied and that the terminology is just put there.

I got the image from this website.

https://enjoy-electrical.blogspot.com/2014/09/inferred-absolute-zero-temperature.html

Is it also right to say that, resistance and temperature in actual testing do not have a clearly defined relationship? Then their relationship also looks like a curve where a segment in the middle seems to have a linear behavior, which is where the concept of getting the inferred absolute zero temperature came from? Why does the resistance temperature curve behave like that? It's just that for me it kind of feels convenient that the middle segment has a linear behavior.

Answer 1

I think you are making much ado about nothing. As stated in the website, they are approximating the behavior of the device with a straight line to make it easier to convert resistance into temperature. As a result, there is an error at the extremes of temperature because the actual resistance vs temperature departs from the straight line. They show that the approximation has an error when carried out to absolute zero which is expected since it is only an approximation. They use the word "infer" because they are using an approximation beyond its useful range. This is often done with a variety of sensors which behave linearly over only a portion of their range and there is nothing mysterious about it. As to why not all sensors are not linear is a subject for physics, not engineering.