> What's particularly neat about this is I can construct a pyramid of interests so [the foundation is fairly broad ... and narrows to the specialization](https://thoughtstreams.io/jtauber/journeyman-of-some/10772/) I'm interested in as you go up.
James, may we risk saying that **cosmology** generates one of your **principal ideal**s?
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Well, the irony is ring theory isn't part of the constructed background of interests for cosmology :-)
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Actually, I'm wrong, my constructed background *does* include the course "Groups, Rings and Modules" at Cambridge.
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BTW, huge points to [Dave](https://thoughtstreams.io/Dave/) for suggesting the light-cone as a more useful analogy in the context of cosmology.
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if speaking in terms of [Principal Ideals](https://thoughtstreams.io/jtauber/response-to-dave-about-principal-ideals/) is inconsistent, we could always press the cosmological background-cone into service.
Consider the interval between, eg **cosmology**, and any other concept: we can classify these intervals according to the following schema:
- consequential: one background cone contains the other.
- inconsequential: the background cones fail to intersect, or do so only partially.
- tangential: one concept occurs on the boundary of the other's background cone.
I hope a trichotomous classification of intervals *is* consequential with regard to cosmology? :-)
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I love the idea of saying that, for example, "Vector Calculus is in the past light-cone of cosmology".
To more precisely relate his trichotomy to light-cones, I think you have:
* subject A is in the past light-cone of subject B
* subject A and B both have subject C in their past light-cone
* subject A and subject B are space-like