How can my friend get to see the double-slit experiment live?

See hed. He keeps bugging me, not that he doesn’t believe it, but that he thinks it would be cool.

It’s the single-photon shooter that’s hard.

You don’t need a single photon shooter just a light source.

The point of the experiment is that if light is a particle (Newton’s view) then you should wind up with 2 groupings of light. If light is a wave then you’ll have interference patterns.

If you want to see the long term development of the interference pattern based on a single photons I suppose you would have to both have a persistent recording mechanism and heavily attenuate teh light source.

What does he think he is going to see?

I think what he would see is something like the following. A closed apparatus that is left alone to “run” for some time. Eventually a photographic plate is removed (or a printout is checked, or something like that) and it shows a patten of light and dark stripes.

Like most scientific experiments, it is not going to be interesting, exciting or even meaningful without an intimate knowledge of not only the general theoretical background, but also a detailed understanding of the apparatus and how it works (together with relevant theory). Actually, for exciting and more than mildly or “historically” interesting, you really need to be in the problem-situation that the relevant scientists were in at the time the experiment was originally performed.

You need a coherent light source. Initially, this was done by first passing the light through one slit, then the two slits. Now, you can just use a laser.

I think Leo is probably thinking of the version of the experiment where you get an interference pattern despite the fact that you have reason to believe that the apparatus only ever has a single photon in it at one time, thereby revealing something of the paradoxical nature of wave-particle duality.