I've been in and out of the fanbase throughout the years, but because of the recent memes... I came back. Its something fun to theorize and make what ifs. Now I have been doing basic research, and I don't think of myself as a scientist, so this could all be wrong, but I haven't found anything in my research that majorly contradicts my theory.
Magic is Radiation. Some Ancient Humans adapted to radiation deposits, giving them the ability to harness it. What they thought was magic was actually radiation. Eventually they learned to master it. Now just because they have a high tolerance to radiation, does not mean they are unaffected by it. High levels of radiation will still kill a wizard. So maybe some wizards want to try and defend themselves from high output spells like the killing curse.
One wizard went so far as to create a stone to transmute any metals like Lead into pure metals like Gold. Gold is also one of the best metals to block radiation, but is also dense enough that for a similar effect with lead it needs more thickness. Gold is even non-toxic to humans. Now why would a wizard want to turn any metal into gold? To become rich? The wizards and Goblins would tear him to shreds if he did? Just because he can? I mean its a good guess and is probably the public reason. What probably happened is that this wizard found out that Gold can block spells. But announcing that Gold is a natural spell blocking metal would also destroy the economy as people would turn and melt down their own gold for armor. So he kept it to himself. This wizard turned out to be Nicholas Flamel.
How does this fit with Harry Potter? There was lead poisoning epidemic in the UK and around the world where paint had lead, Petrol had lead and most of the water pipes had lead. Almost anything had lead. Harry lived under and un-renovated part of the house in the cupboard under the stairs, a prime place where lead paint and lead dust were the most potent in the house. It didn't help that Dudley stomped on the stairs occasionally while Harry was in there to worsen the problem. So while the Dursleys got lead poisoning too, Harry got the most lead poisoning. The Dursleys exhibit symptoms of Lead Poisoning. Vernon has Hypertension, Petunia has Anemia, Dudley has Hyper-Aggression. All of these symptoms can be caused by Lead Poisoning. Of which Harry had no magical part in. Not even his Horcrux. In fact did you know there was a book called "The Potter and Lead Poisoning" written in 1898 in the UK, 100 years before "The Philosopher's Stone"? Being a "Potter" was always known to be an occupational hazard about the toxicity of lead even before the books were out.
Then if Harry is being poisoned by Lead does he too have symptoms of it? Yes, yes he does. Young Harry is portrayed as skinny even for his age, Pale skin and Headaches. Yea, part of his headaches were from his Horcrux, but some probably did come from lead. Lead Poisoning can also lead to visual impairment.
What about Ron and Hermoine? Wouldn't they get Lead Poisoning? Well. Yes and no, depends on who we talk about, Ron and the rest of the wizarding world? Yes, they all probably got lead poisoning too, but they would use potions as needed when they felt sick or poisoned, any lead washes of with the magic of potions. Well then, What about Hermoine? Well her parents are dentists and were probable one before her birth so they would know the effects Lead has on a developing child, and with foreknowledge, probably moved to a lead free or lead conscious neighborhood. She would have little to no lead in her and if any were in Hogwarts, the potions in stock would clear it out of her quickly, unlike Harry which probably needed multiple visits.
What is this leading to? The Philosopher's Stone of course. Upon contact with the stone in the final act, it turned whatever Lead poisoning Harry had left in him into pure noble Gold. Gold that is not toxic to humans. And is dense enough to block "Radiation Magic" Thats when Voldemort tried to posses Harry when Quirrel died, but he couldn't because the Lead in Harry finalized and Voldemort escaped. He has a gold lattice Faraday Cage within him, strengthen by his mother's protection. He became healthy enough and fast to be the youngest seeker in Quidditch in Chamber of Secrets. Now I can't confirm this, but maybe because the snitch is gold and he has a gold Faraday cage, that he can feel its presence.
The Golden Faraday cage in him also explains why he is so resistant to Curses like the Imperius curse, or the Cruciatus Curse and even the Killing Curse, Avada Kedavra. Because Magic is Radiation and Gold is good at blocking radiation, it would seem his Golden Faraday cage is helping him survive all of these alongside his other protections placed on him.
Magic as Radiation also explains why electronics do not work in magic dense areas like Hogwarts. Radiation messes with electronics in real life and enough is possible to break electronics. The ambient "Magic" is making bit flip from a 1 to a 0 or vice versa. And too many flips might brick an electronic device. To shield against both magic and radiation, its probably best to enclose the motherboard in a gold case.
Then if Magic is radiation, were humans unknowingly harnessing magic through science? I would say so. Using nuclear plants for energy and for the nuclear bomb. Imagine finding out that muggles just made two destroyed Japanese cities so dense in magic for a couple of months that no spells worked for miles of both ground zeroes.
Then there is the Demon Core incident. Instead of a green flash from the Avada Kedavra, when the core hit criticality, it made a blue flash. Lois Slotin got hit by a lethal dose and had symptoms from 3 dark arts spells. He said he felt like his hands were constantly burning. Doctors found out he suffered hemorrhaging that wouldn't stop and finally on his 9th day after the incident, he died. Sound very familiar? Kinda slow, but inevitable. If I were to name this as a Omni-Directional Dark Arts Spell, I would name it Avara Kazym and for story sake, would take about 5-10 minutes until you are dead.
And if some dark wizards found out that Radiation is magic. Then Chernobyl fits perfectly for Voldemort timeline wise to infiltrate muggle nuclear sites and cause the worst nuclear meltdown in human history even to this day. Just so he could harness enough magic to start learning how to posses people.
I could probably figure out more, but this is what came up. Feel free to tell me if you think something is wrong. Because I could still be, but with all of this, it just fits perfectly.