Research disagrees, you can measure happiness of other people. Much like you can test for depression even if the difference is not subjectively obvious.
>Subjective: based on or influenced by personal feelings, tastes, or opinions.
There are no objective biological tests for depression (or happiness), the psychiatric diagnosis relies exclusively on subjective observations (i.e. asking the person about their feelings).
>"psychiatric diagnosis still relies exclusively on fallible subjective judgments rather than objective biological tests."
The idea of happiness as a purely material objective phenomenon has been complicit in the exploitation and destruction of the Amazon and its inhabitants over the past centuries.
It's common to order blood tests when people show symptoms of depression. Hypothyroidism is the most common medical condition associated with depressive symptoms, but there are others.
Depression is considered when people have a null result on those tests, therefore there are physical tests for depression. Just not in the way testing is normally thought of.
