Investors have a better chance of seeing a repeat of the past 40-years on the planet Mars than they do here on earth, says William Gross, manager of the Janus Global Unconstrained Bond fund (JUCTX).

In his recent Barron’s article, Gross argues that fund managers know they’ve had a great run given decades of high bond returns amidst low volatility. Even during significant bear markets (like the early 80’s), he notes, 30-year Treasury yields reached 15%. Stocks have followed a rockier trajectory, he says, but annual returns (including dividends) have still been over 3% higher than those of investment grade bonds. This is the way things should be, since higher volatility should be accompanied by higher returns.

The bottom line, Gross concludes, it that with interest rates at nearly zero (and now negative in many developed economies), the probability of double digit annual returns for stocks and 7% plus bond yields is slim at best. He asserts that history will not repeat itself, that asset returns of yore were “materially aided by declines in interest rates, trade globalization, and an enormous expansion of credit.” Today’s investor, he says, must understand that there’s a new normal in which returns will be low and risk will be high, and these conditions demand a different approach.