An observer holds a cup of coffee that is filled to the brim at the moment a gravitational wave passes by. Should the observer be worried about spilling coffee because of the gravitational wave? If so, could we estimate the maximum height that the observer can fill his cup to avoid spilling the coffee?

  • $\begingroup$ Related: physics.stackexchange.com/q/338912 and physics.stackexchange.com/q/168274 $\endgroup$
    – Charlie
    Aug 19 '20 at 18:16
  • $\begingroup$ Could you elaborate? I do not find a clear answer in the "related" posts. $\endgroup$
    – drandran12
    Aug 19 '20 at 18:22
  • $\begingroup$ They're not duplicates, but similar questions have been asked about roughly what a person would feel if a strong enough gravitational wave went past. $\endgroup$
    – Charlie
    Aug 19 '20 at 18:54
  • $\begingroup$ LIGO has detected 14 gravitational waves. None of them spilled my coffee. $\endgroup$
    – G. Smith
    Aug 19 '20 at 19:35
  • $\begingroup$ @G.Smith, Maybe you just weren't sitting close enough to the black holes. Maybe next time, pull up your chair to within a couple of light years of the stage, and see how your beverage fares then. $\endgroup$ Aug 19 '20 at 21:10

The passing wave will not spill your coffee. Simply because it transforms the cup including the coffee inside it in the same way. No movement of the coffee will be observed, no matter how strong the wave. Of course, if the wave has an enormous intensity, the cup will probably break, and all your coffee is spilled! So don't go living near two circulating black holes with masses comparable to the mass of the black hole in the center of most galaxies...

  • $\begingroup$ Great answer! Combined with the related questions, it solved my question. $\endgroup$
    – drandran12
    Aug 20 '20 at 16:32
  • $\begingroup$ @drandran12 I just finished eating. Great to hear this! Thanks! $\endgroup$ Aug 20 '20 at 18:05

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