Once to light never back again

[WCOLtd]

I am no theoretical physicist, so please don't be too bothered by my lack of understanding.

I assume that things like atomic bombs can turn mass to light. But I have never heard of anything that can turn light back into mass. Does that happen in nature? Or is everything slowly turning into light as time progresses?

[ZapperZ]

Look up "pair production (http://hyperphysics.phy-astr.gsu.edu/hbase/particles/lepton.html)".

In many facilities, this is how antimatter such as positron is produced.

Zz.

[Dr Lots-o'watts]

Any element that is heavier that iron needs energy to be created (thus natural decay and radioactivity, which happen mostly with atoms heavier than iron, + isotopes of anything).

Yet, tons of elements heavier than iron are found in nature (gold, lead, uranium etc.)

These heavy elements, which are heavier than their separate constituents, were created naturally, by exploding stars.