Tests for the existence of black holes through gravitational wave echoes

  title={Tests for the existence of black holes through gravitational wave echoes},
  author={Vitor Cardoso and Paolo Pani},
  journal={Nature Astronomy},
The existence of black holes and spacetime singularities is a fundamental issue in science. Despite this, observations supporting their existence are scarce, and their interpretation is unclear. In this Perspective we outline the case for black holes that has been made over the past few decades, and provide an overview of how well observations adjust to this paradigm. Unsurprisingly, we conclude that observational proof for black holes is, by definition, impossible to obtain. However, just like… 

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