Inflation with negative potentials and the signature reversal symmetry
Audrey T. Mithani and Alex Vilenkin
Published 10 April 2013 •
© 2013 IOP Publishing Ltd and Sissa Medialab srl
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1475-7516/2013/04/024
We discuss recent papers by Hartle, Hawking and Hertog, which proposed that quantum cosmology could predict an inflating universe in models with negative scalar potentials. Here we show that this is a result of an underlying symmetry which is manifest in both classical and quantum theory. Moreover, we show that inflating solutions in such models generally develop tachyonic and ghost instabilities and are therefore unphysical in realistic theories.