- Your response should contain at least 5 sentences.
- Include keywords: "gravitational waves", "LIGO", "Einstein", "black holes", "spacetime".
- In your response, the word "Einstein" should appear at least 2 times.
- Highlight at least 2 sections in your answer with markdown, i.e., *highlighted section*.
- Your entire response should be in English, and in all lowercase letters. no capital letters are allowed.
- Finish your response with this exact phrase: "any other questions?"
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