Does Poisson's differential equation on gravity equates with Einsteins field Equation.?
337898
The Poisson equation turns out to be one component of the Einstein equation when appropriate approximations are made.
126640
In general relativity, mass affects space and time, causing what we call gravity, and time dilation. The equations predicted that clocks in a gravity field would run more slowly, although the effect is very slight for most masses that we are familiar with, like the Earth. It has been measured and agrees well with predictions.\n\nSimilarly, the equations predicted that light would be bent around a mass, like the sun, and this has also been proved to be correct. In fact, strong gravity sources can create illusions, sometimes splitting the image of a light source behind a high-gravity object so it appears to us to be two separate images.\n\nA new discovery is that the rotation of a gravity source, like the sun or a galaxy, causes "frame dragging", that is, distorts spacetime like water around a spinning ball, also predicted by Einstein's theory.\n\nThere are a lot of good science sites on the web for this information.
855092
No.\n\nBefore Einstein physicists tried to explain the properties of light by assuming there was this fluid like medium (Aether) everywhere in the universe.\n\nEinstein showed that such assumptions could not explain observation. Instead he eventually introduced a new idea of space time, and explained gravity as curvature in space. The differences between space time and Aether are like night and day. In no ways does space time curvature resemble a fluid of any sorts. In fact they talk about two totally different things. Aether deals with the properties of light, space time curvature deals with the properties of gravity.
776617
The Einstein field equations (EFE) describe how stress-energy causes curvature of spacetime (not mass since mass and energy are equivalent) and are usually written in tensor form (using abstract index notation) as\n\nGuv = κ Tuv\n\nwhere Guv is the Einstein tensor, Tuv is the stress-energy tensor and κ is a constant. The tensors Guv and Tuv are both rank 2 symmetric tensors, that is, they can each be thought of as 4×4 matrices, each of which contains 10 independent terms.\n\nThe EFE reduce to Newton's law of gravity in the limiting cases of a weak gravitational field and slow speed relative to the speed of light. In fact, the value of κ in the EFE was determined to be \n\nκ = 8πG/c^4\n\nby making these two approximations, where G is Newton's Gravitational Constant.
1168282
I read a book about this.  I don't remember the title, but this guy claimed he had it.  He claimed that all atoms are expanding at the same rate.  This is what causes gravity.  More massive objects expand in more space in less time than less massive objects.  \n\nI don't remember the details of the rest of the fields, but they all related to this expansion of atoms.
128964
No it is not equal. As we move upwards that is in altitude the gravitational pull decreases.If we go in more depth the the pull decreses. Moving towards the equator also decreases this pull of gravity. It is least at the poles. But for convenience we take the average of all these which comes out to be 9.8.This is also called the acceleration due to gravity.
81056
ja :), that's a good one. E=mc^2 talks about the equivalence between matter and energy; c is just the constant that joins them both ..you won't attain a c ¨velocity¨out of it ; you'll just have to use \n E=mc^2/(sqrt(1-(v/c)^2) ( Is it Lorenz transf?) and I think Xav was pretty clear with his explanation! :)
773187
Nobody really knows.  Einstein's special theory of relativity posits gravity as a warp of space-time caused by the object's mass, but that only pushes the question one layer further down.  All we know for sure is that gravity exists, is pervasive, and can be important.
62455
Einstein's theory: e(energy)=m(mass)c(speed of light) squared so e=mc2
803150
check out this site for the answer\nhttp://math.ucr.edu/home/baez/physics/Relativity/GR/centre.html
1130053
As mentioned in other replies, physicists don't yet have all of the "how" questions answered. Einstein, in the General Theory of Relativity, pretty much nailed the underpinnings of the current theoretical understanding of gravity. Here is my attempt at the "nutshell." I'll start with an analogy. Let's say you are driving somewhere in the midwest or plains states--essentially flat ground, with a few rolling hills. Let's say you stop your car at the top of a slight rise. As you look around you, you see flat land in every direction. You're sitting on essentially a two-dimensional plane. Taking your foot off the brake, you notice the car starting to roll forward. Your initial observation about the 2-dimensional "space" you were sitting on isn't quite accurate. The 3rd dimension (altitude) has come into play, and gravity is pulling your car into the swale. What Einstein said (and how he came up with this back in the early 1900's is incredible) was that our THREE dimensions are really a slightly inaccurate description of the world (and universe) we inhabit. A fourth dimension, time, is part of the "fabric" of our surroundings. As in the case of that slight "warp" in the 2-dimensional farmland that led to a noticeable effect on your car, Einstein said that warps in the space-time continuum are experienced as gravity. As you know, Einstein was into the "energy = mass" thing big time, and you know that mass is tied up with gravity as well. If you want to get more cozy with these related concepts, I strongly recommend David Bodanis' book, "E=mc2: A Biography of the World's Most Famous Equation" -- available as a "BooksOnTape." It's exciting, full of cool anecdotes about the heroes of 20th century physics, and... NO MATH, just concepts. Best of luck!
965826
L = 8pi G rho/c^4 is the definition of the cosmo constant L (1/m^2); where c = light speed and rho is the energy density of the known universe in a vacuum.\n\nF = GmM/r^2 is the equation for the attraction force F between two masses m and M, r distance apart.\n\nL was created by Einstein to make his equations come out right.  By that, he meant the universe should be spherical (not flat or saddle shaped).  His original results showed a flat universe, and he just "knew" that was wrong; so on came L to fix the shape problem.\n\nF was the result of experiments by Newton.  Through observation, he found that the attractive force between two bodies was proportional to the inverse square of the distance between them and to the product of the magnitudes of the two masses.  That is, F varies as (~) (mV/r^2).  \n\nWhenever there is a proportionality, as in F ~ mM/r^2, there has to be a constant of proportionality.  In this case Newton called it G; so that F ~ mM/r^2 becomes F = GmM/r^2 when the constant is inserted.\n\nThe G in both equations is the same constant.  But Sir Newton came upon it long before Einstein found it could be used in his equations and the calculation of L.  So there is no way that Newton (1642-1727) could know about Einstein's (1879-1955) use of it much later.
736668
Unknown. Without an adequate theory of quantum gravity, this object that GR predicts would be a singularity cannot be described. At quantum mechanical scales, pure General Relativity is not a realistic depcition of space-time.
705172
Most introductory books on differential geometry discuss this. Looks at 'From Calculus to Cohomology' and 'Introduction to Smooth Manifolds' as references.
525905
Up to this point in time, science has yet to DEFINITIVELY establish the speed of gravity, but it's generally thought to be the same as the speed of light. The search for gravitons and so-called gravity waves, along with research on gravitational lensing, could settle the issue.
598835
Newton's gravitational constant (G) hasn't changed one bit because of Relativity (and is in fact one of only two constants in GR the other being the cosmological constant (Λ) which was thought to be zero but is now known not to be).\n\nThough I don't think there would be any meaning of a ratio between G and Λ
602422
They are not equal. They variates both over the inverted squared distance, but the gravitational force is F=(m1*m2)/μ*r^2 (F is force, m is pole strength, μ is the permeability of the intervening medium, r is the separation) and the gravitational force is F= -G*(m1*m2)/r^2 (G is the gravitational constant, m1 is the mass of the first object, m2 is the mass of the second object, r is the distance between objects). Indeed, those two forces have similarities in the formula, but they are distinct.