some remarks on VOEvent

[Rob Seaman]

On Jun 3, 2005, at 11:05 AM, Ed Shaya wrote:

> Hypothesis - One of several possible testable explanations
> Theory - Only known explanation that fits the observed  data.
> Postulate - statements of assumptions needed to continue the line  
> of reasoning.
> Axiom - a truth commonly accepted and in no need of proof.
> Fact -  Real world facts (New York is in the US) and Mathematically  
> or logically proven statements.

I'm concerned at an apparent emphasis here toward a "science fair"  
model of the scientific method.  Successful science is more often  
inductive, not deductive.  The difference between a fact and a  
hypothesis is one of degree, not absolute confirmation via theory.   
Theories are often only approximately correct - and approximation is  
often much more than good enough a foundation for drawing further  
inferences.

Postulates are extremely frequent in astronomy - axioms extremely rare.

> The VOEvent is different from  ast:Event because an instance of an  
> ast:Event is the event itself not claims about the event.    
> However, times, locations and measurements of the event do belong  
> in ast:Event. Once there is a theory of the event it can be  
> subclassed to the specific type of event that it is (ast:supernova  
> etc).

Which begs the question of the definition of "event".  We may know  
one when we see one - Tycho's SN was apparently hard to miss - but  
even the distinction between an "object" and a "process" is fuzzy.  A  
star can be viewed as a 10 billion year nuclear process.  Is an event  
simply a process with a big amplitude of short fuse?  Define  
"short".  Define "big".

I understand a VOEvent - I've had a hand in its definition.  I fear  
the entire astronomical community will never understand an ast:Event  
well enough to make it useful.  (Would be delighted to be proven  
wrong...)

To put it another way, the most interesting events are like UFOs -  
theories are hard to come by.  The benefit of ontologies and UCDs and  
other semantic "technology" is precisely to help us to winnow out the  
pie plates and weather balloons.  It is the UFO sightings that are  
left after all the current theories are exhausted that we are  
interested in.

The only reason to classify Snarks is to find Boojums.

Rob Seaman
NOAO