This perfectly captures the eternal confusion about mass versus weight versus density. The "Nooo, they weigh the same!" person is technically correct—100 kg is 100 kg, whether it's gold, feathers, or helium. Mass doesn't care about your feelings OR the material. But here's where it gets spicy: the bell curve crowd smugly pointing out that "100 kg of gold weighs more than 100 kg of feathers" are actually onto something if we're being pedantic about buoyancy. In air, helium (and to a much lesser extent, feathers) experience significant buoyant force from the surrounding atmosphere, which reduces their apparent weight on a scale. Gold? That dense boi doesn't care about a little air resistance. So technically, if you put 100 kg of helium on a scale in Earth's atmosphere, it would register LESS than 100 kg due to buoyancy, while gold would be pretty much exactly 100 kg. The galaxy brains on the ends of the curve understand that context matters in physics—are we talking about mass in a vacuum or weight in atmosphere? Meanwhile, the middle is having an existential crisis about whether a kilogram is actually a kilogram.