I'll wait for the For Dummies version of this one. Oh, that was the For Dummies version!?
To overcome the strong attraction of all the mass in the Universe and drive Inflation "there must be a certain substance that has negative pressure -- or equivalently, a repulsive interaction," Xin-zhou Li said. "In the past, people assumed a field referred to as the 'dilaton' or 'inflaton' played such a role." Unlike the tachyon, "the inflaton or dilaton is not derived from any known fundamental theory," Alexander Feinstein told UPI. "We do not know how to explain this field."
"It is always a spiritual embarrassment to answer such questions as why there is a dilaton field and where it is from," Li agreed.
Tachyons? Sorry, no evidence. Pure conjecture at this point.