>> guest: telescope building seemed to reach a limit, palomar was built in the second world war and it wasn't exceeded for decades. the russians exceeded it with the fixed rate in the 70s, a crappy mirror and still is. there was an optical, expensive and heavy and hard to move around and keep accurate in shape so one of my colleagues, recently retired, invented this way of making mirrors large, thin and very accurate and the way you do it, the trick is to put the glass in an oven and spin the oven while liquid takes the shape of a parabola and let it cool and take it out and you have a mirror that is really large, bigger than any mirror made in the us for half a century and not as expensive. >> host: what is the connection to the football field? >> guest: at the time, the only place where there was a big enough space to do this, you need a lot of vertical space, horizontal space and have to avoid game days. >> host: spinning mirrors on the football field. >> guest: under the angle in the big triangular space. the university had available space. >> host: why does it matter how big a tel