Departament de Matemàtica Aplicada I, Universitat Politècnica de Catalunya, Diagonal 647, 08028 Barcelona, Spain.
Phys Rev Lett. 2013 Feb 15;110(7):071104. doi: 10.1103/PhysRevLett.110.071104. Epub 2013 Feb 14.
Different models of universes are considered in the context of teleparallel theories. Assuming that the universe is filled by a fluid with an equation of state P=-ρ-f(ρ), for different teleparallel theories and different equation of state we study its dynamics. Two particular cases are studied in detail: in the first one we consider a function f with two zeros (two de Sitter solutions) that mimics a huge cosmological constant at early times and a pressureless fluid at late times; in the second one, in the context of loop quantum cosmology with a small cosmological constant, we consider a pressureless fluid (P=0⇔f(ρ)=-ρ) which means there are de Sitter and anti-de Sitter solutions. In both cases one obtains a nonsingular universe that at early times is in an inflationary phase; after leaving this phase, it passes trough a matter dominated phase and finally at late times it expands in an accelerated way.
在等效原理的框架下，考虑了不同的宇宙模型。假设宇宙充满了具有状态方程 P=-ρ-f(ρ)的流体，对于不同的等效原理和不同的状态方程，我们研究了它们的动力学。详细研究了两种特殊情况：在第一种情况下，我们考虑了一个具有两个零点的函数 f（两个德西特解），它在早期模拟了巨大的宇宙常数，在晚期模拟了无压力流体；在第二种情况下，在具有小宇宙常数的循环量子宇宙学背景下，我们考虑了一个无压力流体（P=0 ⇔ f(ρ)=-ρ），这意味着存在德西特和反德西特解。在这两种情况下，都得到了一个非奇异的宇宙，在早期处于膨胀阶段；在离开这个阶段后，它经历了一个物质主导的阶段，最后在晚期以加速的方式膨胀。
