Science and function of gravity

[PB666]

https://www.sciencenews.org/article/using-general-relativity-magnify-cosmos

The article is not too bad, it has a decent reference list at the end.

On the issue of gravitational lensing, when you have a situation where light is coming from four different directions around a lensing mass, how much can you actually trust.....as in reconstruct. The reason I say this is that have measurable temporal ofsets for events that occur behind the lense. At best you know what you are seeing are not simultaneous. But even more troubling here is that the paths are virtually the same distance. We are talking about lensing of objects 10 billion years ago about galaxies 5 billion years in the past, the deflection angles are small fractions of a degree. The cosine of these small angles are all but 1.