Hepkat: Well, according to Newton, energy can neither by created nor destroyed. It can, however, be recombined to form other materials, and that's exactly what happens when our body dies.
Yes. But Einstein opened yet another path: Matter can be converted to energy (nuclear energy!) or energy to matter (presumably during the "big bang"). The famous e = mc^2 goes both ways (m = e/c^2).
CPDC10-30: In nuclear fission, heavy atoms are split into smaller elements. In fusion, two light elements are combined to create one heavy one (ie hydrogen to helium in the stellar core). So atoms can be destroyed and created. But the matter that the atoms are composed of (electrons, protons and neutrons) have not ever been split or combined...at least to my knowledge.
That´s the only purpose of most super colliders used by scientists: To break down those parts. And they get broken, alright. It just gets harder to "see" the fragments as they get smaller. That´s why the physicists constantly request even bigger toys...
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The current scientific view is that most atoms we´re made of have been "bred" in huge stars billions of years past, before they exploded as super-novae and spilled their material into space, where it later "congealed" into our solar system (sun, planets, "leftover" debris and gases). So we basically consist of "star ashes"...
Some of those elements are radioactive, which means they disintegrate over time (into smaller atoms plus radiation); Even the normally "stable" elements have radioactive variants (isotopes). C-14 is one example of that (a variant of "regular" and stable C-12 carbon). But the others seem to be quite durable. At least from a human point of view, they appear to be as good as "immortal". Individual chemical substances or biological systems are just different configurations of the same atoms.
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