> but black holes can suck in matter by becoming arbitarily more dense. This isn't possible for such sinkholes Correct but this is not the behavior which the s

> but black holes can suck in matter by becoming arbitarily more dense. This isn't possible for such sinkholes Correct but this is not the behavior which the sinkholes are mimicking. With out having read the article the behavior that is probably being mimicked by the sink holes is while the sink hole is active the sound waves can not escape, similar to how light does not escape the event horizon of the black hole. Their are laboratory experiments that mimic similar behavior in fluids to study such physical phenomena as well.