If they had that level of understandings, why didn't they invent atomic bomb?
Well, the scripts talk about Bhramastra, which would have a similar effect. Of course no other details can be found so it'd be up to us to believe or not. If you go strictly by Science, you need more proof than mere mention of the term, hence I really don't believe it. But they allegedly keep on bringing other "evidences" like this one :
http://veda.wikidot.com/ancient-city-found-in-india-irradiated-from-atomic-blast