 The tendency for electrons to form interference fringes when you put them through two slits but arrive in little blobs Leads some people to describe them as having a wave particle duality as though they're confused But if we just give up the baggage of whether it's a wave or a particle an electron is an electron It is what it is and we're learning about its properties. Let's just think about those properties So in order to make an interference pattern It has to go through two slits at once if you cover up one of the slits You don't get an interference pattern in the end. You just get the blobs appearing in a smear if you cover up the other slit Same only when they're both open at the same time Maybe if you're only putting one electron through at a time That's the only time you get that interference pattern So somehow each electron is individually knowing about both slits, but they're also arriving in blobs So either we've got some kind of method of blobs knowing Mysteriously whether the other slit is open or it's actually traveling as a wave and then for some reason becoming a blob And if you look at which slit it's going through so if you just rather than covering up a slit You just look that turns out that also makes the interference pattern go away. And so the final Conclusion that we came to for quantum mechanics is that an electron is a wave But when you look at it that wave function collapses and gets very small and so you get a very small wave When you look at it and the tendency for things to change their behavior when you look at them makes a lot of people very Uncomfortable and if you're uncomfortable that idea you're in very good company