Re: The Quantum Gravity Problem

From: Dawn M. Wolthuis <dwolt_at_tincat-group.comREMOVE>
Date: Fri, 15 Oct 2004 16:44:26 -0500
Message-ID: <ckpgcp$5c2$1_at_news.netins.net>


"Kenneth Downs" <firstinit.lastname_at_lastnameplusfam.net> wrote in message news:n72pkc.f8h.ln_at_mercury.downsfam.net...
> Here is a little its-been-a-good-week Friday musing.
>
> I wonder if database theory is suffering from a version of what is going
on
> in Physics. In Physics for the past few decades they have had to struggle
> with the fact that the two fundamental theories of the twentieth century
do
> not play nice together. Relativity describes gravity well, but it is not
a
> quantum theory. Quantum theory is considered the most successful theory
> in history, but does not describe gravity. Since most physicists believe
> that the underlying truths are quantum in nature, everyone is searching
for
> a quantum theory of gravity, instead of searching for the relativistic
> theory of E & M and nuclear forces.
>
> So can we draw any useful analogy here, with perhaps the RDM being quantum
> and Hierarchies being Relativity? This choice is not arbitrary, it
implies
> that we can find a way to add hierarchies to the RDM before we will get
RDM
> into a hierarchical form.

Yes, yes -- I have used this analogy before. The fun thing about it is that the answer to how to combine the disperate theories is the same for both (physics theory of everything and database theory) -- one word: Strings. (OK, I know that is simplistic in both cases, but it could be more true than some might think on the database side).

> I'd suggest the analogy is useful more as a motivational tool than an
> instructional one. For instance, Einstein's disdain for quantum theory
> gave him the freedom to pursue and develop General Relativity, while the
> excitement that others felt for quantum led them to ignore gravity
> completely and pursue quantum. However, sooner or later the us-vs-them
> camps began to fade and the question became, how do we get these two great
> but incompatible theories reconciled?

Yes and there are some excellent contributers to this list who have that mindset.

> Still it seems the analogy goes further. Physics has progressed from a
> study of what was obvious and readily observable through to the more
subtle
> and yet more comprehensive truths. Perhaps the RDM and hierarchical
models
> stand as that which we could readily observe (Remember: "People understand
> tables just fine"), but we need to look for models that unify the two in a
> way that may not be so readily obvious. Hmmm, what would that be?
>
> So to wrap us this idle musing, is the suggestion that we could put
> relations into columns an effort to put hierarchies into the RDM, as in:
>
> CREATE TABLE hier_test (
> hier_id char(10),
> hier_id_parent char(10) ,
> hier_id_kids relation(hier_test as
> (select * from hierarchy where hier_id_parent = hier_id)),
> ...other columns...
> )
>
> I could then pull out a hierarchy with this command:
>
> SELECT * from hierarchy where hier_id_parent is null
>
> which would do the same as the WITH RECURSE join modifier.

Hierarchies are one thing, but navigating data is another challenge. Yes, if you HAVE all of the data, you can treat it as sets and similate navigation with joins and all, but I think we ought to be able to navigate data just as we navigate the web -- we don't have to have all of the web available in order to select an entire set before zeroing in on the page we want to go to. I didn't say that well (as usual), but hopefully that helps to show why I would suggest we are not talking about hierarchical vs relational, but about di-graphs vs relations. What's common to both? String, for one, but also functions. cheers! --dawn

> --
> Kenneth Downs
> Use first initial plus last name at last name plus literal "fam.net" to
> email me
Received on Fri Oct 15 2004 - 23:44:26 CEST

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