How does gravitational lensing tell us about the mass of a galaxy cluster?

Newton's universal law of gravitation predicts how mass can distort light, so we can apply Newton's law to determine the mass of the cluster. ... The lensing allows us to determine the orbital speeds of galaxies in the cluster, so that we can determine the mass of the cluster from the orbital velocity law.

Explanation:

so here is the information for current research:

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