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. :-)
Colliding asteroids to blame for Earth’s meteors (Synopsis) - “Men of genius are often dull and inert in society; as the blazing meteor, when it descends to earth, is only a stone.” -Henry W. Longfellow When you look ...
1 day ago