Let's imagine that via some contrived mechanism the cosmos entered a new inflationary era, starting right now: Space itself started to uniformly expand faster than the speed of light. Would the effects on Earth be immediate and catastrophic, or would we start to notice the phenomenon only some time later through observations of distant stars, galaxies, etc?
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$\begingroup$ Space is expanding faster than the local speed of light, already, but that expansion is always hidden by an event horizon. To us that event horizon is the earliest moment of the big bang, i.e. it surrounds us with a past that is a mere 300,000 years earlier than the CMB. $\endgroup$– CuriousOneJan 19, 2016 at 11:31
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It depends entirely on the magnitude of the cosmological constant.
Due to dark energy spacetime is already undergoing very, very slow inflation. The doubling time, i.e. the time taken for the scale factor to double due to dark energy, is in the range 10-20 billion years and this is far too slow to have any effect on gravitationally bound systems like the Solar System or indeed the Milky Way.
However during the inflationary period immediately after the Big Bang the doubling time was around $10^{-34}$ seconds. Expansion at this rate would not just immediately rip the Earth to pieces but it would also destroy even the atoms that the Earth is made from.
answered Jan 19, 2016 at 11:49
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$\begingroup$ OK, so I'm interested in the middle ground between our universe as it is today and total immediate destruction caused by hyper-inflation. What doubling time would lead to slight changes in electrically bound systems? Say, by perturbing atomic spectra on order of a few parts per million, for example. $\endgroup$– ybrettyJan 19, 2016 at 19:22