What does 'sphere of [something]' mean?

Question

Reading a journal article, I encountered these terms:

• customer sphere of privacy
• customer sphere of security
• privacy sphere of implementation
• security sphere of implementation

I know the rough meaning is: privacy connected with the customer, and so on. But what's the exact meaning of sphere here? And what's the pattern for the use of this kind of sphere?

Answer 1

I can see why this might be tricky, even after consulting a dictionary. The OED lists 11 meanings for the word sphere, but the one that applies here is Meaning #7:

The whole province, domain, or range of some quality, thing, etc., esp. of action, activity, operation, etc.

When the word sphere is used in this way, probably the most common usage is in the phrase sphere of influence. As Darryl Davis¹ wrote:

It's called a sphere of influence because it consists of a circle of people you know, who know other people, who in turn know other people, and so on.

I'm assuming your journal article had something to do with computer security. In this case, the system, its firewalls, and its users might all have certain roles and responsibilities for maintaining security and ensuring privacy. Conceptually, a customer's sphere of privacy might consist of all the data we would expect to be protected in such a system, and security sphere of implementation might be all the components that protect the system from a security standpoint, but it's hard to say for sure without seeing how the authors^2? used (and perhaps defined) those terms.

The word sphere have have been used simply because a security model used circles to depict the boundaries of such system roles and responsibilities, as was done in one tome³, or it could be because system security – much like people who know people who know people – can be modeled as concentric circles⁴:

As a side note, these are not common terms. I ran a few Ngrams, just to illustrate how predominant the phrase sphere of influence is, compared to, say, sphere of privacy. Notice how the results for sphere of privacy, sphere of security, and sphere of implementation all flatline, as sphere of authority and sphere of influence are added to the query:

Answer 2

Wikipedia has a lengthy Public sphere article that addresses some aspects of your question in detail. The article contains sentences like the following:

The public sphere can be seen as "a theater in modern societies in which political participation is enacted through the medium of talk" and "a realm of social life in which public opinion can be formed".

The public sphere mediates between the "private sphere" and the "Sphere of Public Authority", ...

More generally, sphere has long had the primary sense of a ball or a body of globular form. "Heavenly spheres" refers to spherical surfaces containing planetary orbits. Since the 1600's sphere has had as one of its senses "The region in which something or someone is active; one's province, domain". That's the sense being used in your four examples. I find it difficult to tell what the meanings of sphere of privacy, sphere of security, and sphere of implementation are, so will instead discuss a more-common phrase, sphere of influence. This phrase has technical meanings in astronomy and astrodynamics, but is more commonly heard in reference to the range of people and groups someone or something influence. For example, if you say "Columbia has fallen within X's sphere of influence", you are saying that X's influence has spread to the point that it is felt in Columbia.