is bond market expensive?

Valuation of Government Bonds

Does it make sense to invest in government bonds now? Current valuation of government bonds became expensive. In this paper, I compare the total return on the iShares 20+ Year Treasury Bond ETF (ticker TLT) with the real yield on the 10-year US treasury bonds. By investing in the long-term US government bonds when the real rates are negative, makes such investment speculative and risky.