[0zelot]

Unfortunately, that video contained some flawed conclusions. I had left a comment back then. Alpha particles from natural sources like an uranium stone penetrate 50 micrometers of solid hard material at most. Let's give it maybe 100 micrometers of soft paper, but that's about it. What was most likely observed in that video is radon, which is a radioactive gas, slowly diffusing out of uranium or thorium stones. Since it's gaseous, it can circumvent the paper and then do its alpha decay just behind it. I wrote a few lines on those aspects in this article https://www.mdpi.com/1424-8220/19/19/4264

[polishdude20]

Oh that's pretty cool! I guess the best way to check would have been to have it in a paper box then?

[0zelot]

Yes, radon is pretty hilarious and spreads in very unexpected ways. Completely wrapping sources of radon like uranium or thorium minerals (or these bracelets containing some of that), only holds back the diffusion process for some time unless the shielding is really thick and very dense. That's why radon accumulates so well in household cellars, it penetrates concrete walls easily.

If you look closely in thought emporiums video (link below), the thick clouds - representing each the full paths of individual alpha particles (from the point of decay until full absorption in the air) - don't originate right at the surface of his shielding materials (paper, chicken skin... whatever). Instead, the alpha particle clouds stand by themselves in free space and can only really stem from radon that decided to decay at those positions somewhere outside of the shielding (transforming to "solid" polonium in that process and sticking itself to the next closest lump of molecules/dust). If the alpha particles would penetrate the shieldings (which they can't because of too much material/density), we would see clouds stemming directly from the shielding surfaces which I don't see happening:

https://www.youtube.com/watch?v=C7TwBUxxIC0&feature=youtu.be... You may find and like my comment there, maybe it helps to fight some misconceptions about natural radioactivity. ;-)

[polishdude20]

Awesome thanks!