Scientists still know very little about how early embryos develop, due to their small size (the width of a hair) and inaccessibility in the womb. (flipboard.com)
These extra dimensions would be imperceptible in our macro world but might have a detectable influence on gravity at scales of less than the width of a hair. (discovermagazine.com)
However, our eyes can not see something much less than the width of a hair (about a tenth of a millimeter) without the aid of a magnifying device. (discovermagazine.com)