Satgen 527 Now you see it ? by GM4IHJ (BID SGEN527) 1999-05-01 A generally useful description of a human being is contained in the phrase " An ape designed not to fall out of trees". Indeed, in order to perform this feat, we are equiped with excellent three dimensional sensory perception. Perception which allows us to accurately locate any object in space , relative to a 3 axis grid using any or all of our senses of sight, hearing, smell or touch. But , is the universe really limited to 3 dimensions. Or , are we limited to 3 dimensional perception in a universe of more than 3 dimensions , where we cannot see/sense the whole picture. Carl Gauss started this line of thought 170 years ago when he privately expressed concern , that Euclidean geometry does not answer all the questions science posses for us. Carl Riemann then took the questioning much further in his studies of multidimensional geometries But it was not until Einstein proposed his General Theory of Relativity that anyone suggested an experiment which might give us some facts. Einstein offered no practical proof himself, but the British astronomer Eddington showed in a practical experiment during a solar eclipse that star light coming past the Sun was bent , ie the Sun itself, was bending the space around it. A situation which could not be easily explained if we insist on a universe limited to only 3 dimensions. Several geometric theories have been advanced to try to describe a space of more than 3 dimensions. With Kaluza and Kleins proposals seeming to answer some, but not all, of the questions. But we have not really got much futher than that. Our present space shuttle rocket technology is stuck in a groove. So we are presently nowhere near being able to proceed, via " Warp 4 Mr Solo", or, A.C Clarke's multidimensional Stargate for the astronaut of Odyssey 2001. It is true that several experiments have improved on Eddingtons demonstration of space curvature . Very large base line interferometry has narrowed down the value of amount of space curvature created by the Sun. Which result has has been further refined by a neat signal travel time experiment using the Viking Mars space craft. While more recently a set of measurements using the extremely successful European Hipparcos astrometry satellite has gone even further. Indeed Hipparcos is so sensitive it has shown the extent of curvature far from the sun. So we must accept that what we see in the night sky , or what radio observations reveal by night or day is neither the whole truth or anything like the truth. For years ,we have known that the typical galaxy we see 3 million light years from earth , is not where we see it. We see it by light taking 3 million years to get here and in those 3 million years it has moved a long way from where we see it. Now we must also accept that in addition to this " it is not where you see it effect " caused by light travel time, every star is curving space and the great gas clouds and galaxies of stars are curving space even more . So perhaps it is better that our poor brains do not have to image a multidimensional universe.