steve wrote:
Martin wrote:
steve wrote:
...
You say that physical “real life” measurements of curved space are indeed made. Made by who? Which scientific test was done to do this? Someone actually measured the curve of space, or are you just making this conclusion from math equations?
The results of the measurements? Where did you get these results? Are you saying someone measured curved space and got real results (measurements)
There's been a century of observations and experiments confirming gravity's curvature of space-time, beginning with the so-called "classical tests of general relativity" that Einstein proposed in 1916:
1. The precession of the perihelion of Mercury (verified by Einstein in 1916);
2. The deflection of light by the sun (first observed by Eddington in 1919);
3. The gravitational redshift of light (initially established by Adams in 1924).
1. This was an observation by man that a planet has a peculiar orbit, it does not show that this orbit is without a doubt caused by a thing in space that is being bent by a mass.
The precession was known for many years. The only explanation was (and is) that it is a result of the effects of gravity. However, the amount of the precession predicted by Newtonian mechanics was not consistent with the amount actually observed; the amount predicted by General Relativity was.
As far as "without a doubt" is concerned: No scientific theory ever is "without a doubt."
If this space-time thing were a real entity
What do you mean by "real entity?"
it would have a mass and a location in space.
Oh? Would that also apply to, say, the electromagnetic field?
If mass warps this space-time thing then it would bend this thing in 360 degrees around the whole mass thereby making a space-time bubble, and objects would have the ability to move in any orbit around a large mass.
According to whom?
Why is it that all of these objects that are orbiting larger masses only orbit in one plane and not freely orbiting in any direction?
The orbits followed by orbiting masses are solutions to the equations that express laws of physics.
Is it that these large masses are resting on this thing called space-time? It seems so convenient that in all of the diagrams used to represent the idea of space-time bending, the mass is shown moving down into this space-time thing. Why only down? Is something pulling it down?
I suspect that you are referring to the "bowling-ball-on-a-trampoline" type diagrams, which are nothing more than 3-dimensional analogies for envisioning the behavior of large masses in 4-dimensional space-time. They are meant to be helpful, not literal.
2. The deflection of light is an appearance. Per wikipedia on Sir Arthur Stanley Eddington it states: “According to the theory of general relativity, stars near the Sun would appear to have been slightly shifted because their light had been curved by its gravitational field.”
The stars did not move, they just appeared that way. this appearance does not show why it appears this way. An observation of light being bent does not prove empirically that this can only be caused by the existence of a thing floating in space that is bent by mass. Besides where is the scientific data that shows how mass bends space-time. What is the correlation between the amount of mass and its warping of space-time. Einstein never gets into that.
Mass is indeed correlated—intimately correlated—to the warping of space-time via Einstein's Field Equations, the solutions of which predicted the results that Eddington measured.
Mass is a term used to describe the amount of force that is exerted on a body by gravity.
That would be "gravitational mass." There is also "inertial mass." The fact that the two happen to be equal always puzzled physicists. This equality was a key ingredient in Einstein's development of General Relativity.
So gravity pulls mass into this space-time thing?
Has anyone explained what the mass of an object has to do with bending space? No, we are just told that it occurs, with no explanation of how.
Nonsense. After developing the Special Theory of Relativity—an achievement that in and of itself likely would've provided him perpetual fame—Einstein spent another 10 years developing the General Theory. The details of his efforts—his thought processes, arguments, analyses and results—are well documented. Even then, the physics community didn't accept his "pronouncements" on face value. Relativity went through—and continues to go through—significant "peer review" and experimental testing. Although there is periodic debate regarding how some of the details of the theory should be interpreted, laboratory experiments and astronomical observations continue to provide increasingly precise supporting evidence. (However, I fully expect that the theory eventually will be modified (or replaced) to accommodate quantum mechanics—and vice versa.)
Here is a typical definition of space-time from the Essential Dictionary of Science:
“The general theory of relativity describes how space-time is distorted by the presence of material bodies, an effect we observe as gravity.”
Really? The theory of general relativity describes how space-time is distorted. O.k. lets look up a definition of general relativity to see how space-time is distorted.
Definition from same dictionary on general relativity: “The geometrical properties of space-time were to be conceived as modified locally by the presence of a body with mass.” Still no explanation of how.
Lets try a different scientific dictionary. The Dictionary of Scientific Literacy states that the definition for general theory of relativity is:
Einstein's theory views gravity as a property of space rather than force between bodies. As a result of the presence of matter, space becomes curved, and bodies follow the path of least resistance among curves.”
Still no mention of exactly how this “real” thing happens. All definitions I have read just state that this action occurs with no mention of exactly how. Also why would a body in
motion change course unless acted upon by an outside influence, what is the influence?
Do all of these smaller bodies roll along this space-time thing and than fall into the dent made by the larger mass? What pulls this smaller mass into the dent?
Look, I could go on and on about how this space-time thing is just part of a theory and all of the explanations of exactly how and why this space-time thing bends are vague. No mention of what created this thing. Is it flat? if so then what is above it, below it. In what medium does it exist?
If an object is curved its structure is cuved in a medium of some sort. Space is curved in relation to what?
There is straight flat space and curved space? Space actually changes shape so that points on it are moved to a different location in space. The whole thing is absurd, and hard to accept as fact.
I'm not sure what the source of your difficulty is. Is it that you find the notion that matter "bends" space-time (or even the notion of space-time itself) hard to accept—harder to accept than, say, the notion that matter attracts matter by some unexplained, almost magical "action-at-a-distance" force? You seem to be wanting to see some kind of "absolute proof" that matter bends space-time. There is no such proof, nor will there ever be. The same statement applies to every scientific theory that ever was—and that ever will be. (If that's not the source of your difficulty, then perhaps your difficulty is as simple as a lack of understanding of precisely what it means to be a scientific theory.)
The solutions to the Einstein Field Equations are essentially descriptions of the geometry of space-time. These solutions (which provide the "how" space-time is curved—i.e., how it differs from Euclidean ("flat") space-time)—depend upon matter (mass and energy—the "what" that causes the curving); these solutions also determine how matter reacts to the curving it created. To again quote John Wheeler, "Matter tells space-time how to bend, and space-time tells matter how to move."