The "happiness" sensor is placed on the surface of the human body or implanted in the human body, and the indicators of people's happiness can be measured through various indicators. No "happiness" sensor will be perfect, and it is not necessary. When the thermometer was invented It is also very imprecise, but over time, the design of thermometers has become more sophisticated and is now an indispensable commodity. Scientists believe that "happiness" sensors will follow a similar evolutionary process, although they will There will always be a certain degree of uncertainty, but wearable sensors are more low-key and easier to use than traditional tools for measuring happiness. What does this passage mean? ['No "happiness" sensor can be perfect.', '"Happiness" sensor will become an indispensable commodity.', '"Happiness" sensors will develop towards high accuracy.', 'Humans do nt need perfect happiness sensors.']