Visualize Pac man in his video game world maze, clearly 2D. Pass a 3D item (anything, let's say a baseball bat) perpendicular to his game plane world right in front of his path. Pac Man could discern the length and width of the bat, but not the height, which is incomprehensible to him. All he'd "see" is a line changing in length as the baseball bat passes through his world and then disappearing.
It's said that the 4th dimension is time, which I agree and don't agree depending on how dimension is defined. We are visually 3D creatures, who, like pac man, are not capable of visually comprehending anything beyond. You can define dimensions mathematically, which makes perfect sense, and by other specifications, means. BUt, I like to think of a visual dimension beyond our comprehension as seeing something strange appear out of nowhere and vanish in the same way Pac man does above. Maybe this is theorically the means of getting around astronomical distances.

• GREAT! - mrfuji235 - October 22, 2003 - 17:32 UTC