Next to the favored general relativity, there is another theory of gravity that currently agrees with experimental results.

Brans-Dicke theory was formulated in the 1960's. Like general relativity, Brans-Dicke is formulated using the metric tensor, and describes gravity (partly) as the curvature of space-time due to the metric tensor. However, Brans-Dicke predicts that a scalar field is also partly responsible for gravitational interaction. Unlike general relativity, which is formulated using using a 1/G constant(G being the gravitational constant), Brans-Dicke theory replaces this constant with a scalar field that varies from place to place and with time.

Brans-Dicke theory predicts the precession of orbits as well as the bending of light, as does general relativity.

Are there any supporters of Brans-Dicke on this website?

- Nautilidae

I have yet to see any convincing reason to adopt the additional complexity.

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Unless it correctly predicts an experimental result which GR fails to predict, I don't see any reason to abandon the elegance of GR. So no, not me.

twistor59 wrote:Unless it correctly predicts an experimental result which GR fails to predict, I don't see any reason to abandon the elegance of GR. So no, not me.

What exactly makes Brans-Dicke less elegant than general relativity? I am not saying that I disagree with you, but I wish to see your reasoning.

Nautilidae wrote:

twistor59 wrote:Unless it correctly predicts an experimental result which GR fails to predict, I don't see any reason to abandon the elegance of GR. So no, not me.

What exactly makes Brans-Dicke less elegant than general relativity? I am not saying that I disagree with you, but I wish to see your reasoning.

Well, elegance is of course subjective, so people are welcome to disagree, but it just seems to me that the quantities appearing in GR - the curvature tensor and various contractions thereof - are incredibly "natural" objects of differential geometry. The extra scalar field as far as I know isn't.

Maybe it more naturally belongs to the side of the equation with the energy momentum tensor (I honestly can't remember the first thing about it), but then why not just stick with the Einstein and energy momentum tensors ?

twistor59 wrote:
Well, elegance is of course subjective, so people are welcome to disagree, but it just seems to me that the quantities appearing in GR - the curvature tensor and various contractions thereof - are incredibly "natural" objects of differential geometry. The extra scalar field as far as I know isn't.

Maybe it more naturally belongs to the side of the equation with the energy momentum tensor (I honestly can't remember the first thing about it), but then why not just stick with the Einstein and energy momentum tensors ?

I think that what attracts people to Brans-Dicke is that it gives rise to more solutions. All solutions of the Einstein field equations are solutions of the Brans-Dicke equations, but there are some solutions of Brans-Dicke that are not solutions of Einstein's equations.