Dictionary.com says a billion is "a cardinal number represented in the U.S. by 1 followed by 9 zeros, and in Great Britain by 1 followed by 12 zeros." It also seems it indicate that British definition is no longer used, although it's unclear on that.

Does a billion still represent two different numbers among scientists? If not, when did this change? Wouldn't older papers still use the old definition? Has this discrepency caused any practical problems in scientific projects--particularly in relation to astronomy and physics?

Cheers,

John