Note that different people have different research approaches. The two old ladies check that none of them can see herself and the problem is solved! ;-)
The other older lady makes an experiment with motion and rigorously determines that she is ... well ... unsichtbar. :-)
Messier Monday: A Spiral Sliver Headed Our Way, M98 (Synopsis) - “[L]ife is a luminous halo, a semi-transparent envelope surrounding us from the beginning of consciousness to the end.” -Virginia Woolf One of the only mem...
18 hours ago