I originally wrote this on June 20, 2006, 3:54 p.m. Posted it in another forum that is mostly a place for friends to get together; they usually have little insightful contributions. When I start astronomy threads, they usually limit comments to, "Cool picture". I have spent the last eight hours or so here reading threads in astronomy, physics, and math. Posting here will be a new experience for me. I am used to being the most knowledgeable an articulate person wherever I go. I will not be that person here. SciForums has some heavy thinkers. I am still trying to wrap my mind around the run of black hole discussions we have had recently. Fortunately, my cat Bella has been helping me out. She likes playing with a shoelace. It does not matter where I put it; she will find it and drag it out again. If I throw it in the trash, she will be on it before the echo dies down, showing only her hindquarters and tail as she digs it out. After she has lost interest in the shoelace, it is no longer straight. Saying that the shoelace is not straight though does not really tell you much about it. She may have left it wadded up in a corner, draped over the armchair with one end dangling, or just left as a double strand wrapped around the table leg because she likes to carry it from the middle. In the same way, saying that a concentration of mass warps or bends space does not tell you much about the gravity. It does not tell you the shape of space after gravity has bent it. My own take on gravity is that it thins space in the concentric shells around a massive object. Any given shell will be thinner the next moment from now. Objects in that shell will then be closer to the massive object because the intervening space has decreased. The objects do not move through space so much as space carries those objects along with it as it contracts. In the same way, galaxies do not move through space as it expands, pushing the universe further apart.
Humor is one possible marker of intelligence. The subject is difficult to think about if you have not already spent some time there. Neurons take six weeks or so to mature and take an active role in new neural pathways. You will feel it when you try to think and your thoughts keeps sliding off the subject. That subject is the shape change to distance and time induced by gravity. Consider it, now and again for the next couple of months. Then when the better-educated people come back to it, some might have creative thoughts on it. They might agree with me, or they might point out how I am full of bean soup. But either way I will enjoy reading their thoughts.
Yes, it's a bit hard to think about these things. Our mind likes analogies, and our analogies are mostly Newtonian and probably aren't particulary valid in quantum physics and cosmology. Any way, if space is like a stretched membrane (such analogy has been used by scientists) and objects of mass sort of make an impression in the membrane, then gravity could be more like all objects of mass pulling the rug (space) towards each other using their mass. Please Register or Log in to view the hidden image! I'm just playing with ideas, my first thoughts on this subject.
Heh, yeah. No---the point is that GR can give us a qualitative picture (warped spacetime) or quantitative predictions (the perhilion of mercury, for exaple). So if you really want to know about the guts of the theory, you have to do some calculations. If you're not satisfied with the hand-wavy picture of space-time, then you have to get your hands dirty.
I couldn't agree more. But I wonder how many members here understand the field equations; or what a tensor is, even. How about you start a thread explaining tensors, in all their muck and slime, just as a warm-up? Or maybe I could, whatever, I am willing to try..... Or are tutorials frowned upon at this forum? I can't remember.
QuarkHead--- I don't know much about Einstein's equations, perhaps you would be better to lead such a discussion.
You found one of my worries. Gravity is supposed to stretch the membrane. The massive bowling ball on a sheet makes a dip which the marbles roll down into. However, if gravity does the stretching, what makes the marbles roll? It can't be gravity; you've already used that to stretch the sheet.
Couldn't it be the structure of the spacetime itself? Bad analogy here, but if you have marbles one a wooden plank and you change the angle of the plank, the marbles roll towards the strongest local gravitational pull - Earth. In this case the structure of spacetime is changed by the mass of the object in such a way that other objects gain momentum towards that object, i.e., gravity. So maybe gravity isn't the one which does the stretching, mass does it, what does the pull is the structure of spacetime and that movement we call gravity. p.s. I'm not a scientist, so take this as a wild speculation.
The question is better than wild speculation. I have watched BenTheMan on and off for months, and admire his logic. Howsomever, his position in this thread is less than satisfactory. Yes, numbers are what we use to accurately describe our world. But still, we need to understand what we are talking about before we assign a number to it. I am not convinced that we really understand what gravity is, so assigning it a precise number leaves me uncomfortable. As a related but slightly different issue, what is it about mass that causes gravity? Yes, you can throw a number at it. But unless you know why, and how, mass causes gravity, then your number will not mean much.
Interesting. This leads to an infinite regress, doesn't it? Of course, it's only an analogy and thus not really the problem that it appears to be. However, the real problem does remain and it's a doozy. What is gravity? We don't know yet. Maybe the new generation of particle accelerators will tell us if they don't kill us all first.
One of most significant results of relativity is, the objects are moving in spacetime along fastest path available, so called the geodesics. Doesn't such theorem sounds familiar for us? Of course, it's well known Fermat theorem, which basically says, the light is spreading in optical inhomogeneous material along the fastest way available. Note that the Fermat theorem is special case of Huyghens principle, which is furthermore the special case of principle of least action. Please Register or Log in to view the hidden image! Please Register or Log in to view the hidden image! This effectively renders the inertial motion in the gravitational field as a Hamiltonian flow without presence of external forces, i.e. in the realm of Newtonian mechanics, which is most apparent at the case of so-called the gravitational lensing. We can say, the Earth is moving in the gravitational field like huge overgrown photon droplet through optically inhomogeneous matter. And this is exactly, what the gravitational field is: it's a density gradient of Aether, i.e. the gradient of mass/energy concentration of the material stuff, forming the vacuum and the matter is a dense cluster of standing waves of it. Note that this concept can be generalized recursively, so we can consider the generalized version of Fermat principle: both energy, both matter is spreading along extremal path of curve integral through space-time, whose curvature at the long scale is caused by nested deformations at the Planck scale. From this model the Feynman's concept of path integrals follows, which connect the quantum mechanics with general relativity: the quantum phenomena can be considered as a results of super-gravitational lensing at the Planck scale. The Aether Wave Theory (AWT) explains this behavior by probabilistic character of Aether fluctuations spreading in the chaotic field. Furthermore, the analogy of Fermat principle at the water surface and the geodesics concept of 4D space-time leads to the general definition of space-time and time dimensions. By AWT the space-time is formed by Aether mass/energy density gradient to be able to serve for the energy wave spreading by the same way, like the density gradient at the water surface. And the time dimension is the direction normal to this gradient. After then the geodesics concept follows exactly the Fermat principle concept of inertial environment.
Indeed, the fabric starts to fray if the analogy is taken too far. (BTW, perhaps its better to think of the marble as being made from the `fabric`...? )
Indeed, but I don't like the allegories like the "space-time fabric" and "to fray", which can sound illustratively for someone, but you cannot derive nothing explicit from such "models". Because these models are not analogies, but homologies of reality, instead. After all, these parables are motivated politically, because they were designed to cover the fundamental misunderstanding of Aether concept by mainstream physics before years. Because the science is supposed to remain apolitical and as objective, as possible, it should adhere on the principles of scientific priority of concepts. So no new denominations for old concepts should be accepted, for scrambling of publicity the less. Only such approach can keep the semantic transparent and it can lead to the stable credit and trustfulness of science as such from long-term perspective. Please Register or Log in to view the hidden image! Please Register or Log in to view the hidden image! By AWT the space-time is chaotic field of density fluctuations, similar to those, which appears during condensation of every dense stuff, like the condensing supercritical vapor. They're formed by heavily compressed density fluctuations of vacuum, which is supposedly formed by interior of giant black hole. Such model gives us a much more explicit clue, what the space-time is without oversimplification and it remains completely physical. Please Register or Log in to view the hidden image! Of course, because such concept is infinitely recursive in the realm of AWT, under more detailed analysis we can see, every density fluctuation is formed by another nested fluctuations like the infinitely nested dynamic foam.
By AWT every particle is formed by standing energy wave of Aether foam, undulating at place. Because every foam gets dense during shaking, such wave is bouncing between internal walls of the dense blob, which is creating itself by its own motion - this keeps such standing wave conditionally stable. This is due the so called total reflection phenomena, which occurs at the place of every sufficiently sharp density gradient. From this insight the particle-wave duality follows (between others). The photons are such blobs too, but not sufficiently intensive and dense to promote the total reflection phenomena. Therefore they can move in one predefined direction only, not to bounce at place under normal circumstances like common particles. Please Register or Log in to view the hidden image! Please Register or Log in to view the hidden image! Please Register or Log in to view the hidden image! But every standing wave confined inside of its potential box exhibits so called tunneling or evanescent waves effects. It simply means, every standing wave is shaking its closest neighborhood slightly, thus making it less or more dense too, even if it remains confined well inside of its own boundaries. As the result, it creates the density gradient, which is additive and it becomes more pronounced with the increasing of the number of such wave packets (particles) cumulated at place. Furthermore, such gradient is behaving like weak lens and it has tendency to focus both free energy waves (photons), both another wave packets (fermions) into its neighborhood. Briefly speaking, it manifest itself as so-called gravitational field, which is formed by mass/density gradient of Aether foam, in fact. At the case, the density of wave packets at place becomes very high, whole cluster of such particles will start to move collectively as a single quantum wave, it will change itself into black hole, surrounded by density gradient, which reflects the internal energy less or more effectively into it (so called the event horizon). Just the subtle portion of internal energy of longest wavelength can violate the total reflection condition and its emanated as so called Hawking radiation. By such way, the AWT explains both quantum mechanics, both relativity effects as a classical optical phenomena, which occurs inside of strongly nonlinear inertial environment, i.e. the Aether foam. Note that every cluster of particles has its own upper and lower mass limits, above which it will not stable anymore (the sort of energy quantization effect manifests here). Therefore the AWT predicts, the very massive black hole will start to emanate its matter via radiation as so called quasar by the same way, like this very small one. This has a certain cosmological consequences, indeed.
LOL. The humor is subliminal joy of foreign bad luck. Therefore it's not so surprising, the cretins are laughing often.Please Register or Log in to view the hidden image!Please Register or Log in to view the hidden image!Please Register or Log in to view the hidden image!
A difference in the radiation pressure (leading to gravity) depends upon two essential factors; as in a low pressure storm known as a hurricane, the strength of the hurricane's winds depend upon the outer local atmospheric pressure as well as the strength of the low pressure within the eye of the storm. Thus, in essence, it is the difference in pressures between the surrounding "high" and the internal "low" that matters most! So, for there to be gravity in the pressure viewpoint, the strength of gravity must depend upon the average local vacuum radiation pressure as well as the amount of matter present. This quantity of matter can be measured by the strength of the "low" or the negative pressure associated with the mass in question. Therefore, gravity may depend upon the local average negative vacuum radiation pressure (call this P1) added to the negative pressure associated with the amount of matter present (call this P2). Hence, P1 + P2 can be understood to be the two subcomponents that compose what we call mass. Mass, therefore, must be equal to P1 + P2. Therefore, in the standard Newtonian equation for gravity given by: F = G x (M1 x M2) / d^2 This can then be rewritten as: F = G [A(P1 + P2) x B(P1 + P2)] / d^2 Where: F = The Force Of Gravity G = The Gravitational Constant (As Deduced By Experiment) "A" And "B" Are The Two Different Bodies P1 = The Average Local Positive Radiation Pressure Of The Vacuum (This May Be "Locally" A Constant). P2 = The Negative Radiation Pressure Of A Piece Of Mass (This Varies Only With The Amount Of Matter That Is Present). So, All Matter Of The Same Quantity Has The Same Negative Pressure And, Therefore, An Identical P2. d^2 = The Distance Between Bodies A And B Squared It can then be understood by substitution from Newton's equation that: M1 (or the mass of the first body) = P1 + P2 And: M2 (the mass of the second body) = P1 + P2 Since P2 varies negatively with the amount of matter present, the bigger is the mass, the higher is the value for P2. So, M1 and M2 can be different (and usually are) and this is reflected by the two different values of P2 for both A and B. It is interesting to note that P1 is a "local" pressure value for the vacuum. Thus, P1 may vary in different regions of the solar system, galaxy and/or throughout the Universe. So, gravity in this picture may vary. Hence, if P1 locally rises, this may give bodies the appearance of being more massive than they actually are. The force is, therefore, greater between any two objects. More about this below. The observed rotational difficulties of galaxies (now explained with dark matter) might be understood as the local vacuum radiation pressure environment of these galaxies being very (or even extremely) high. Therefore, all objects that exist in this high radiation pressure environment would tend to have a stronger gravitational attraction toward each other. Thus, galaxies may be allowed to rotate faster than the conventional Newtonian gravity allows. This is what is observed presently by astronomers. Thus, Newtonian gravity may vary when the local radiation pressure environment P1 is different in different regions. Our own solar system's radiation pressure environment must be comparatively low; creating the conditions necessary for our own existence. http://www.johnkharms.com/mass.htm
