Cosmic horizon of 42-billion light-years?

[MACHO-WIMP]

I recently read the new Scientific American and in one of the articles it says that the observable universe can see a distance of 42 billion light-years away but my question is that the big bang is predicted to have occurred at approximately 14 billion years ago, so how can the observable universe be 42 billion light-years?

[edgepflow]

There is a well written FAQ on this:

http://physicsforums.com/showthread.php?t=506987

In mathematical terms, the radius of the observable universe is (REF: Introduction to Modern Cosmology, Eqn. A1.12):

ro = 3 c to

ro = radius of observable universe
c = speed of light in vacuum
to = age of universe

This formula will match your numbers.