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If it's 3 billion communication-years away, in order to see Earth they'd have seen it 3 billion years ago at the time of viewing. Therefore, for this signal to
by ccvannorman 10y ago
If it's 3 billion communication-years away, in order to see Earth they'd have seen it 3 billion years ago at the time of viewing. Therefore, for this signal to be targeted at Earth, they'd be targeting an Earth SIX billion years ago (we didn't even exist yet).
- mattmanser 10y agoYou haven't read Contact (or have forgotten some of the plot). He explicitly circumvents this in the book. Read it a few weeks ago. Pretty great, though the ending is a bit inconsistent and a bit 80s.