Paging Art Bell.
"Simple, for van Manderpootz! I use polarized light, polarized not in the horizontal or vertical planes, but in the direction of the fourth dimension -- an easy matter. One uses Iceland spar under colossal pressure, that is all. And since the worlds are very thin in the direction of the fourth dimension . . ."
Stanley G. Weinbaum, The Worlds of If, 1935.