Schmelzer
Valued Senior Member
The theory I want to present here can be, if one likes, classified as an alternative theory, but, given that it is published in a peer-reviewed journal, the classification "on the fringe" as well as the usual stuff posted there does not really fit (but if some moderator decides to shift it, no problem).
The paper presenting the theory is
I. Schmelzer, A generalization of the Lorentz ether to gravity with general-relativistic limit, Advances in Applied Clifford Algebras 22, 1 (2012), p. 203-242 and can be downloaded from http://arxiv.org/abs/gr-qc/0205035 A more popular introduction can be found at http://ilja-schmelzer.de/gravity/
The main properties: Mathematically, it is very close to general relativity. It contains two additional parameters, $$\Xi, \Upsilon$$, and, if above are set to zero, we obtain the Einstein equations of GR in harmonic coordinates. Even if they are nonzero, the additional terms have mainly cosmological character, become important only at very large, cosmological distances, and very close to the horizon of a black hole. The theory itself does not tell us anything about how large they have to be, they are free parameters, thus, they can be very small, and in this case, the theory is almost indistinguishable from GR by observation. Some principles of GR, like the Einstein Equivalence Principle, hold even exactly, and the theory is a metric theory of gravity.
On the other hand, the metaphysics are completely different from the spacetime interpretation of GR. We have a classical Newtonian absolute time and an absolute space, which is filled with an ether. This ether has classical properties - an ether density $$\rho=g^{00}\sqrt{-g}$$, and a velocity $$v^i = g^{0i}/g^{00}$$ as well as a stress tensor, and the usual classical continuity and Euler equations hold - which are equivalent to the harmonic equation for the preferred Euclidean coordinates of absolute space and time.
The main interest for laymen is that this ether theory of gravity shows that all the claims that relativity proves that there is no ether, and that the ether is incompatible with observation and modern physics in general are simply false.
The main interest for professional physicists is that all the conceptual problems of GR quantization disappear. We know that to quantize a condensed matter theory in a Newtonian spacetime is unproblematic. The proposed theory remains, of course non-renormalizable, but the very concept also tells us that it can be only an effective field theory, which has to be replaced, below a critical length (the atomic distance of the ether) by a different theory. And for effective field theories, non-renormalizability is a quite natural, expected property.
The paper presenting the theory is
I. Schmelzer, A generalization of the Lorentz ether to gravity with general-relativistic limit, Advances in Applied Clifford Algebras 22, 1 (2012), p. 203-242 and can be downloaded from http://arxiv.org/abs/gr-qc/0205035 A more popular introduction can be found at http://ilja-schmelzer.de/gravity/
The main properties: Mathematically, it is very close to general relativity. It contains two additional parameters, $$\Xi, \Upsilon$$, and, if above are set to zero, we obtain the Einstein equations of GR in harmonic coordinates. Even if they are nonzero, the additional terms have mainly cosmological character, become important only at very large, cosmological distances, and very close to the horizon of a black hole. The theory itself does not tell us anything about how large they have to be, they are free parameters, thus, they can be very small, and in this case, the theory is almost indistinguishable from GR by observation. Some principles of GR, like the Einstein Equivalence Principle, hold even exactly, and the theory is a metric theory of gravity.
On the other hand, the metaphysics are completely different from the spacetime interpretation of GR. We have a classical Newtonian absolute time and an absolute space, which is filled with an ether. This ether has classical properties - an ether density $$\rho=g^{00}\sqrt{-g}$$, and a velocity $$v^i = g^{0i}/g^{00}$$ as well as a stress tensor, and the usual classical continuity and Euler equations hold - which are equivalent to the harmonic equation for the preferred Euclidean coordinates of absolute space and time.
The main interest for laymen is that this ether theory of gravity shows that all the claims that relativity proves that there is no ether, and that the ether is incompatible with observation and modern physics in general are simply false.
The main interest for professional physicists is that all the conceptual problems of GR quantization disappear. We know that to quantize a condensed matter theory in a Newtonian spacetime is unproblematic. The proposed theory remains, of course non-renormalizable, but the very concept also tells us that it can be only an effective field theory, which has to be replaced, below a critical length (the atomic distance of the ether) by a different theory. And for effective field theories, non-renormalizability is a quite natural, expected property.