Quasars with a Double-Image Gravitational Lens Could Help Finally Figure out how Fast the Universe is Expanding

How fast is the Universe expanding? That’s a question that astronomers haven’t been able to answer accurately. They have a name for the expansion rate of the Universe: The Hubble Constant, or Hubble’s Law. But measurements keep coming up with different values, and astronomers have been debating back and forth on this issue for decades.

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I wonder if it expands evenly/same speed everywhere or large gravitational masses can slow it down

Cymek said:

I wonder if it expands evenly/same speed everywhere or large gravitational masses can slow it down

Golly. I haven’t thought about that in 40 years.

Thinking about it now, I don’t know the answer offhand.

If the expansion was even slightly nonuniform then it would show up in the cosmic background radiation. It does show up in the cosmic background radiation. So I suppose the expansion isn’t uniform. The effect of large gravitational masses would be largest where and when the density is highest. In the very early universe and where space is warped near black holes.