The authorities are now looking for anything that might have been part of the explosive devices - bits of metal or sharp objects that they might be able to trace back to its owner or owners.

BBC: Forensics investigators decode the Boston bombings

With a quantum theory of gravity, we may be able to trace the Big Bang expansion back to its very beginning, and understand precisely how our universe arose, presumably from nothing.

CNN: Higgs and the holy grail of physics

It can be difficult to link all these addresses and trace them back to the origin.

BBC: 'Fresh proposals' planned over cyber-monitoring

All this production capability might still be affected by potential parts shortages that trace back to the Japanese earthquake.

FORBES: Apple's Ability to Produce iPad 2s

The typical Viennese coffee house -- an elegant institution with high ceilings, marble-top tables and a stack of newspapers to make one linger over an impeccable black brew with a customary glass of water -- may be more famously known than its Ukrainian cousin, but to trace back the origin of the communal coffee space, you have to go to Lviv, a Medieval city in western Ukraine.

BBC: Tracing the coffee house revolution to its Ukrainian roots

And, Farai, it could be called a miracle by most because I was able to go back to the doctors and there was no more trace of cancer.

NPR: Battling Back from Breast Cancer