We consider Friedmann-Lemaitre-Robertson-Walker cosmological models in the framework of general scalar-tensor theories of gravity (STG) with arbitrary coupling functions, set in the Jordan frame. First we describe the general properties of the phase space in the case of barotropic matter fluid and scalar field potential for any spatial curvature (flat, spherical, hyperbolic). Then we address the question under which conditions epochs of accelerated and super-accelerated expansion are possible in STG. For flat models filled with dust matter (and vanishing potential) we give a necessary condition on the coupling function of the scalar field which must be satisfied to allow acceleration and super-acceleration. This is illustrated by a specific example.
The distance modulus determined from Carmeli's cosmology fits the accelerating universe data of the high-redshift type Ia supernovae without dark matter
Self-accelerating Massive Gravity: Superluminality, Cauchy Surfaces and Strong Coupling
大质量引力中的自加速解提供了明确的、可计算的例子，展示了超光度、柯西问题的适定性和强耦合之间的一般相互作用。对于三个特殊的类的真空解决方案，其中之一是新的这项工作，我们构造的保角图上的各向同性的应力-能量扰动传播的特征表面。除了一个例外，所有的解都必然具有类空特性，这表明微扰超光性。用这些曲面来划分时空，会给出一个病态的框架，在这个框架中，微扰的动力学项消失了，混淆了自由度的哈密顿计数。这种框架依赖性区分动力学项的消失，从强耦合的扰动或不适定的柯西问题。我们给出的例子中，类空特性做，不起源于一个点，微扰理论故障，类空表面做或不相交的所有特性在过去的光锥一个给定的观察者。时空的整体结构也揭示了双度规理论所特有的问题：在所有三类解中，闵可夫斯基基准空间都不能覆盖整个德西特时空，使得观测者的世界线在有限的真时终止于决定性奇点。特征与这些曲面相切，需要{ \it ad hoc}规则来建立跨奇点的连续性。
