Well hello Astronomy Cast,
My name is Joseph Stayton (stay-ton) and I am from and live in Tacoma Washington. In the Astronomy Cast episode titled “wave-particle duality,” I couldn’t help but notice that the description of the double slit experiment is described in two distinct manors, which are inconsistent. In one, the experiment is described in the same context that I have always understood. In another, Pamela describes the effect observed when a very precise light source is projected through a slit (through one slit only) producing an interference pattern from which a different interference pattern is observed when the same light is projected through two slits. She also agrees with Frasier when he states that two slits are needed for an interference pattern to be observed i.e. with only one slit there is no interference pattern observed. Pamela also describes a “diffraction pattern” being observed with only one slit, which I interpreted as another word for interference suggesting an interference pattern. Prior to listening to this pod cast, every description of the results observed from the double slit experiment that I have encountered describes interference patterns as being observed only when there are two or more slits. Pamela describes how anyone can set up this experiment at home by very precisely setting up four razorblades to construct two slits. If you have set them up properly, when a laser is projected through the latter slits an interference pattern will be observed. Now if one of the two slits is blocked the interference pattern, according to my understanding prior to this episode of astronomy cast, should disappear.
Because Pamela describes in one instance that an interference pattern will be observed when a laser is projected through one slit, which is in opposition to what I have come to understand of the double slit experiment , me and a friend went out and got a couple of lasers, some razor blades and set up the experiment. I was expecting to observe an interference pattern when we projected a laser through two slits but not when projected through only one. Nevertheless, no matter what adjustment we made to try and make sure that we only allowed light through one slit we always observed an interference pattern, and in fact when we examined the laser beam itself, we observed an interference pattern by simply pointing the laser at the wall without going through any slits at all, though it was noticeably different than either of the other interference patters we observed, it was still there. We tried all three instances with several different lasers set up in different apparatus’s and in all instances we observed interference patterns, however different they may have been. The only way we were able to observe the lasers on the wall without producing interference patterns is when we placed both the laser and the slits very close to the wall in comparison with the distances required for us to observe these interference patterns. Would it possible that the lasers we used are somehow causing these interference patterns, possibly because they were cheap and therefore not as precise of a light source needed to conduct this experiment? Also, are there other instances when this experiment has been conducted in which the experimenters observed similar results, if not, was it just an honest mistake when Pamela describes an interference pattern being observed when light is projected through only one slit? Pamela describing interference patterns being observed when light is projected through one slit caused some confusion, and that’s what motivated me and my friend to conduct this experiment ourselves, the results of which has further confused us. Is there any way you guys could possibly clarify this confusion?
Joseph A. Stayton