论文标题
重力理论无法预测第二个时钟效应
Weyl gauge theories of gravity do not predict a second clock effect
论文作者
论文摘要
我们认为重力理论（WGT）是在局部庞加莱变换和局部规模变化下不变的。这些理论可以被解释为Minkowski时空中的量规理论，但是它们的引力相互作用通常是根据Weyl-Cartan时空进行的几何解释，然后任何物质领域都驻留。这样的时空是Weyl时空的直接概括，包括扭转。正如爱因斯坦（Einstein）首先提出的那样，据信韦伊尔时空表现出所谓的第二个时钟效应，从而阻止了实验观察到的尖锐光谱线的存在，因为（原子）时钟的速率取决于它们的过去历史。文献中普遍的观点是，这将WGT排除在外。与这个观点相反，我们表明，如果人们采用了在WGT的几何解释中鉴定出的自然协变量，则正确考虑了物理量的缩放维度，并认识到爱因斯坦的原始反对意见需要大量的物质领域来代表原子，观察者和时钟，那么WGT不能预测wgts，则不会效应。
We consider Weyl gauge theories of gravity (WGTs), which are invariant both under local Poincaré transformations and local changes of scale. Such theories may be interpreted as gauge theories in Minkowski spacetime, but their gravitational interactions are most often reinterpreted geometrically in terms of a Weyl--Cartan spacetime, in which any matter fields then reside. Such a spacetime is a straightforward generalisation of Weyl spacetime to include torsion. As first suggested by Einstein, Weyl spacetime is believed to exhibit a so-called second clock effect, which prevents the existence of experimentally observed sharp spectral lines, since the rates of (atomic) clocks depend on their past history. The prevailing view in the literature is that this rules out WGTs as unphysical. Contrary to this viewpoint, we show that if one adopts the natural covariant derivative identified in the geometric interpretation of WGTs, properly takes into account the scaling dimension of physical quantities, and recognises that Einstein's original objection requires the presence of massive matter fields to represent atoms, observers and clocks, then WGTs do not predict a second clock effect.
