What's the Fabric of space made out of?

One thing Phatt asked was "How do we know that it's still there?"While we can calculate an objects path based on current and past observations and projecting those into the future, is there actually any way to tell is something we observe is actually there at this time from our frame of reference? Are we relying on the fact that those things we can see at extreme distances are not individual objects but rather conglomerations so that the collection is likely to still exist even though individual elements may have be destroyed or added?

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Aslan is not a Tame Lion

jar Here is where things get tricky.Since we cannot judge the location of an event in spacetime except by our local frame of reference,we can only speak of the temporal quality we define as now in our frame of reference.The object we view has a different frame of reference locally and a different now which is defined by that local frame of reference.There is no absolute frame of reference to which we can attach a meaningful now that is coincidental with both locations.
Since the postulate that the laws of physics are universal is consistent with observation and the predictions of theory we are able to express the confidence that the object is located at a given area of the sky based on the distance in light years and the proper motion of the bodies through space.

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And since you know you cannot see yourself,
so well as by reflection, I, your glass,
will modestly discover to yourself,
that of yourself which you yet know not of

To keep this simple, let's assume a frame of reference at the time of observation and location of the observer.When we look at a distant object are we seeing it as it was in the past?

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Aslan is not a Tame Lion

buzsaw says: Sylas says: Webster says: According to the definition of geometry, Sylas, geometry is not a property of space, so your answer to my question is wrong. In an unbounded total space vacuum, there would be no binding properties, no gravity or other forces, and nothing to measure geometrically. Thus, my ongoing contention that there are no properties to space/vacuum to measure or cause expansion. Only when something is introduced into unbounded space/vacuum can anything be observed. Therefore it is only matter, particles and forces, et al which occupy space that can be observed or perceived as expanding, curving or any other activity.Geometry is an examiner or calculator of space/vacuum relative to that which has been introduced into space so as to occupy space.Edited to add bold emphasis to dictionary quote.This message has been edited by buzsaw, 03-23-2005 11:46 AM

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The immeasurable present is forever consuming the eternal future and extending the infinite past. buzsaw

jar We will take you standing in a field under dark skies {Lots of that in Texas} and looking up to view the andromeda galaxy. The light you view has travelled for 2.9 million years.This message has been edited by sidelined, Wed, 2005-03-23 09:53 AM

buzsaw Buzsaw,stand beside one wall in your house,stretch out a tape measure and go to another wall and take a reading of the length.What is it between those walls that is being measured? Is it not the space between them?Now picture in your mind a dust mote frozen in a shaft of sunlight.To determine its location you need to measure 3 dimensions from a reference point.You are measureing the 3 space dimensions commonly known as length width and depth.If the object is in motion you must include time as well in order to specify the event at a given instant.

I guess I'd answer in this way. About the Bible, Webster says: And so I'm free to conclude that the Bible is not inerrant and is not the Word of God, because Webster doesn't say so.Is any more discussion about the inadequacy of dictionary definitions for specialized fields necessary?Space *does* have a geometry. This is from http://www.wfu.edu/~brehme/space.htm: I suggest reading the entire article. It's pretty much what Sylas has been telling you.--Percy

Okay.Sticking with the same reference point, the Andromeda Galaxy is a composite of many objects and it is difficult to resolve down to individual units. If we had the capability of resolving individual units, and we returned 2.9 Million years from now, would we find that some of the individual objects were missing, and that there were new objects that we did not see in the initial observation?

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Aslan is not a Tame Lion

jar{qsIf we had the capability of resolving individual units, and we returned 2.9 Million years from now, would we find that some of the individual objects were missing, and that there were new objects that we did not see in the initial observation?[/qs]That is likely yes.

Okay. Thank you. Hate to bother you with this but my syns apsed.

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Aslan is not a Tame Lion

This, from your link: (italics mine)There are no points in space until something is introduced into space. Therefore the points, imo, should not be regarded as properties, i.e. consistency/makeup of space itself, but a means of geometric measurement of things in space. The above statement is surrealistic and illogical whereas I'm being logical and realistic.

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The immeasurable present is forever consuming the eternal future and extending the infinite past. buzsaw

buzsawHey buddy I posted some time back to see if we could get your common sense take on this. Perhaps you would let me know how this can work from a stance of logic you are working from.

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And since you know you cannot see yourself,
so well as by reflection, I, your glass,
will modestly discover to yourself,
that of yourself which you yet know not of

There are not even points in space then. A "point" is an abstraction, not a thing, used for convenience to talk about space. All our natural laws and mathematics and so on are abstractions, used to help give a description of how the world works.Here is a fact of life. Anyone who measures the speed of a light in a vacuum gets the same result, no matter where the light comes from or in which direction it is going, or how fast they are moving.Do you think this is "logical"?This is very different to what we normally expect. For example, if am standing beside the traintracks, and I throw a baseball at the train (and perpendicular to the tracks) at 120 km/hr, then I measure the ball moving perpendicular to the track at 120 km/hr.But if there is a train moving at 90km/hr along the track, then an observer in the train sees the ball travelling diagonally to the track at 150 km/hr.On the other hand, if I shoot at a spaceship in a vacuum with a laser beam, then it does not matter how fast the spaceship is going, or in what direction. I and the spaceship both see the photons moving at 299,792,458 km/sec.We express this a general law about all velocities; and velocity is an abstraction... a useful one.This very unintuitive discovery is a basis of special relativity. Let me know if you can accept this as a fact of life. If so, we'll go on to consider a fact about general relativity.Cheers -- Sylas

Hi, I have only gotten to this post so far in the thread, but isn't this the book where Brian Greene talks about "space tearing flop transitions?" So maybe the poster that stated that space doesn't stretch or tear was wrong? We are told all the time that one of the ramifications if general relativity is that space bends in the presence of matter and that "straight" trajectories become "curved" trajectories. Space has to be "something" to me if it can react to the presence of matter (unless matter is a wrinkle in space itself) and also have energy (the vacuum energy).

My apologies, my friend. There's so much to get posted and so limited the time to do it. I hadn't forgot you and some others who need responses. Thanks for being patient as you have. Of course, the parabola is the correct path. But your analogical parabola has a logical cause and effect. The parabolic path the ball takes on it's journey happened in space/area in which the event took place. The space/area itself in which this happened was exactly as it was before the ball dropped. The only factors in this was the speed of the train which existed in space and the drop of the ball which existed in space. Space did not curve. By definition, there's nothing difinitive about the property of space that has the energy to curve. Your analogy, imo, had everything to do with matter and energy existing in space and nothing to do with the property of the space/area in which the event took place.

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The immeasurable present is forever consuming the eternal future and extending the infinite past. buzsaw