On Wed, October 31, 2012 12:37, Andries van Renssen wrote:
> doug foxvog on 30 oktober 2012 at 19:15 wrote:
>> On Tue, October 30, 2012 06:48, Andries van Renssen wrote:
>> > On 26 september 2012 at 19:50, doug foxvog wrote:
>> >> On Wed, September 26, 2012 11:44, Andries van Renssen wrote:
>> >> > John F Sowa on 26 september 2012 at 15:53 wrote:
>> >> >> On 9/26/2012 8:53 AM, Andries van Renssen wrote:
>> >> >> ...
>> >> >> > But the piece of land that is defined by that boundary is
>> >> >> > nevertheless a physical object, and it has a mass, although
>> >> >> > its value is unknown and not of interest. (01)
>> >> >> Space is physical, but it doesn't have a mass. An area is
>> >> >> a two-dimensional region. The political subdivisions only
>> >> >> specify coordinates that determine the area at the surface,
>> >> >> and they are silent about depth or height. (02)
>> >> > [AvR] I hesitate about the mass of a physical space, and whether
>> >> > the gas in a space is part of the space or just occupies the space. (03)
>> >> Occupies. (04)
>> > [AvR] Why? In geometry we make a distinction between
>> > a hollow sphere and a solid sphere. (05)
>> I'm just using the standard English definition. (06)
> [AvR] Ah, you use the definition of 'absolute space'.
> That is a valuable concept, but it seems to me a mathematical
> concept and not a physical concept. (07)
We can't get anywhere in designing ontologies unless we have clear
definitions of the terms in the ontologies. (08)
I just looked at OpenCyc. I am referring to Cyc's
#$SpaceChunk-Emperical -- an intangible three-dimensional contiguous
localized spatio-temporal thing. (09)
There are other types of intangible space: Non-localized atemporal
ones -- e.g., that of a Platonic solid. Ones fixed to a specific
coordinate system (geocentric, heliocentric, galactic-centric, etc.)
or to a specific object (the inside of _____). (010)
By "physical concept", if you mean "tangible" or "having mass/energy",
i agree it is not that sort of "physical concept". But, by being situated
in a physical system, and having relations with tangible objects, it is
a "physical concept" under a different definition; in this case, one could
call it an "intangible physical concept". (011)
>> > By excluding the content of a space from the definition of the space
>> > you seem to define a physical space as a hollow space, whereas
>> > I think that the analogy is more with the solid space, including the
>> > content. (012)
>> The concept of the English word "space" is that of a volume,
>> excluding the material in the volume.
>> This concept is of a spatio-temporal entity without mass.
>> It is not the hollow sphere -- which is a 2D surface curved in
>> 3-space. It is not something necessarily hollow
>> -- although spaces with holes in them can be defined. (013)
> [AvR] I appreciate the concept of absolute space which you describe.
> In physics and engineering it is difficult to use, because it is empty,
> although there are (always) things in it. Thus we have to
> 'think away' its content. But as an abstraction that's fine. (014)
One need not 'think away' its content. One merely uses relations
other than parthood relations to relate an intangible physical space
to its content. (015)
>> The concept of a volume including the matter present in it is also a
>> useful concept.
>> The first concept does not change as something moves into and
>> out of the Space, while the second concept does. (016)
> [AvR] The question is how is that second concept called? (017)
That needs to be decided. It seems that this concept was not
deemed by Cycorp to be worthy of defining. (018)
> From your text below, I understand that you call this 'physical space'.
> It seems that we are in violent agreement. (019)
I find that "disagreements" in creating ontologies normally arise
because various parties are considering different concepts, but
are using the same terms for them. The solution in such cases
is to carefully define each party's concepts and to come up with
an acceptable term for the concept that each party was actually
referring to. (020)
I selected your term, when trying to distinguish the various concepts
we were discussing. (021)
But i don't understand what is violent. 8)# (022)
>> >> > But if the space is
>> >> > not empty, the mass may be of interest such as in the interior of a
>> >> > balloon and a submarine. (023)
>> >> Sure. (024)
>> >> > ...
>> >> > I question whether a physical area is by definition two
>> >> > dimensional. (025)
>> >> I'm not sure what you mean by "physical area".
>> > [AvR] See below. (026)
>> I prefer a definition to guessing a meaning from an example. (027)
>> >> > Mathematical area's are two dimensional.
>> >> > But two dimensional area's in
>> >> > physical reality seem to be abstractions. They are at least curved
>> >> > in the third dimension. (028)
>> >> Fine. Math allows this. It also defines planar 2D areas. (029)
>> > [AvR] Which implies that two dimensional area's (which are abstract)
>> > do not belong to the physical domain, but to the mathematical domain. (030)
>> Mathematics works at two levels.
>> 1) A logical system of symbols and rules for their manipulation.
>> 2) Mappings of portions of the logical system to specify properties of a
>> system outside of mathematics (whether physical or not).
>> A description in 2) seems to me to be able to be partly in the physical
>> domain and partly in the mathematical domain.
>> Mathematical descriptions of the count, speed, location, volume,
>> etc. of something i would treat as being in
>> both domains. So i consider located 2D areas to be in both the physical
>> and mathematical domain. (031)
> [AvR] I see that as a trick to smuggle mathematical concepts in the
> physical domain. (032)
Trick? ... or treat? [sorry, but it was just Halloween in the US] 8)# (033)
That's what applied math is for -- describing the physical domain.
I find it useful to be able to use math to describe features of a
physical system. Physicists do, too. (034)
>> >> > But more important: if you walk on them, they compress
>> >> > under pressure and they provide an upward force on you. (035)
>> >> The areas don't compress. The physical surface does. (036)
>> > [AvR] In my view a (physical) surface is a kind of (physical) area. If
>> > a surface compresses, that implies that the area compresses. (037)
>> I find the name "physical area" for whatever you mean here
>> to be misleading. (038)
> [AvR] Not all area's need to be at an outside. (039)
I'm still guessing at what you mean by "area". ... a physical surface? (040)
>> >> > If you buy them (041)
>> >> You don't buy an area (or volume). You buy physical land or part of
>> >> a physical structure or rights to take certain actions within some
>> >> volume (spatial or physical). (042)
>> > [AvR] I don't understand what is wrong with the statement
>> > to buy an area. (043)
>> Although early definitions of "area" according to the OED are various
>> types of plots of land,
>> the word isn't used with such a narrow meaning any more.
>> A term such as "geographical region" would be more easy
>> to understand if a definition is not provided. (044)
>> > I make a distinction between two homonyms: (physical) area
>> > as a physical object with a shape (045)
>> I'm trying to figure out what a physical object without a shape
>> might be -- how it could be physical.
>> If this is your definition, why not use the term "physical object"? (046)
>> Or would you want a narrower definitition than "physical object with
>> shape" for "physical area" -- perhaps something to do with surfaces? (047)
> [AvR] Apparently you know what I meant. (048)
I prefer not play guessing games. I suppose that means i'm getting
closer. (049)
>> > and (property) area as an aspect (e.g. of a physical area),
>> > measured as a two dimensional integral of distance. (050)
>> This is a third and fourth meaning, neither of which we have been
>> discussing. (051)
> [AvR] No, my illucidation by mentioning the (typical) way of measuring is
> not defining a subtype. (052)
I didn't mention subtypes, just different meanings of the English word,
"area". (053)
>> Connected Abstract Space -- a connected massless volume defined by the
>> coordinates of its limiting abstract surfaces. (054)
> [AvR] Apparently space is a subtype of (abstract) volume in your view. But
> how is volume defined? (055)
Something 3D. Remove the constraints of being connected and massless.
It could be temporal or not. It would include your massive space and
my Connected Abstract Space. A volume would be defined by bounding
surfaces, could have temporal aspects or not (depending on the subtype)
and could include whatever matter/energy was in it or not (again depending
upon the subtype). (056)
>> Physical Space -- a Connected Abstract Space along with all the matter
>> within the space.
>
> [AvR] Is this an abstract thing 'along with' a real thing, or is the
> matter also abstract? (057)
I was trying to specify your concept. I'm not sure how matter could be
abstract. That certainly wasn't the intent in this case. (058)
> Does 'along with' specify a relation between the two components? (059)
Sure. (060)
> And what is the kind of relation between each component and the
> physical space? (061)
(whollyLocatedAt-Spatial <PhysicalSpace> <ConnectedAbstractSpace>)
(completePhysicalContents <PhysicalSpace> <Matter>) (062)
>> Physical Object -- a connected body of matter with a shape. (063)
> [AvR] Is a quantity of gas connected and how? And is a cloud connected? (064)
Yes. Spatially connected. (065)
> Or are they not physical objects? (066)
Yes, they are. (067)
> Is a ray not a physical object? (068)
If you mean electromagnetic radiation, i would classify it as an event.
I would also classify a beam of massive particles (subatomic or larger)
as an event. The particles themselves would be (069)
> Or do you have a special definition of connected? (070)
There are many ways of being connected -- including many physical
ways. (071)
>> Connected Area -- a connected two dimensional surface, which may be
>> curved in 3-space (072)
>> Area Quantity -- a quantity dimensioned as a distance quantity times
>> a distance quantity (073)
> [AvR] Seems to be a synonym of what I called the property 'area'. (074)
Fine. (075)
>> surface Area Of Object -- a property of a spatial object relating the
>> surface of that object to an Area Quantity. (076)
> [AvR] This seems to be a relation, whereas IMO the relation is not a
> property, but relation(ship) between an object and a property. (077)
Fine. (078)
>> > I discussed the first concept. You seem to argue on the basis
>> > of the second concept. (079)
>> I haven't discussed either the relation or the quantity. (080)
>> > My impression is that you do not make the distinction. (081)
>> My distinction is different -- that between something spatial and
>> massless and
>> something spatial that includes the mass within the space. (082)
> [AvR] Fine. Is the first concept of those two also energyless? (083)
Yes. (084)
> Does the second concept 'include' all the mass within the space or only
> some mass? (085)
Whatever you want. I thought your definition was that it included all
the mass within the space. (086)
> When is some of such mass 'part of' that space? (087)
When it is enclosed within the boundary of the space. (088)
-- doug foxvog (089)
>> >> > then you also possess a mass with volume below
>> >> > and a space above it, (090)
>> >> If you buy a physical object, then you own (a social property)
>> >> the mass that comprises that object along with associated
>> >> rights as defined by society. (091)
... (092)
>> >> > We are probably
>> >> > influenced by the abstract mathematical concept of dimensions.
>> >> > In practical physics, every physical point has a size that is non
>> >> > zero, although nearly infinitesimal. (093)
>> >> What do you mean by "physical point"? (094)
>> > [AvR] With "physical point" I means a volume of negligible
>> > small size, but not of zero size. Because things of zero size
>> > cannot be observed nor located (095)
>> They cannot be observed, but certainly they can be located. (096)
>> Are your "physical points" cubes/spheres/indeterminate shapes with
>> a size of the Planck distance? (097)
>> -- doug foxvog (098)
>> > and therefore do not belong to the physical domain.
>> > However, mathematical points with zero size do exist in the
>> > mathematical domain.
>> ... (099)
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