... "causality doesn't appear to be violated"
Well, it's just... how could you tell? I mean, maybe the angel that told Colombo to sail west was a time-travelling hologram sent to avert the Tlaxcalan conquest of Europe.
An example would be faster-than-light neutrinos. It would be really damn hard to influence the past significantly with such neutrinos with nothing set up to catch them.
Well yes, I understand you probably couldn't use faster-than-light neutrinos from the future (FTLNFTFs) to effect changes in the year 1470 any more easily or precisely than, say, creating an equivalent neutrino burst to 10^10^9999 galaxies going supernova simultaneously one AU from Earth, presumably resulting in the planet melting or some such thing, I don't know.
However, elsewhere in this thread I suggested a method that takes advantage of a system that already exists and is set up to detect neutrinos (admittedly not FTLNFTFs specifically, though I don't know why that should matter). I still don't see exactly what prevents Eliezer_2831 from fiddling around with MINOS's or CERN's observations in a causality-violating but not-immediately-obvious manner.
Other than, you know, basic human decency.
Well, it's just... how could you tell? I mean, maybe the angel that told Colombo to sail west was a time-travelling hologram sent to avert the Tlaxcalan conquest of Europe.
We obviously can't with certainty. But we can say it is highly unlikely. The universe looks to us like it has a consistent causal foundation rather than being riddled with arbitrary causality violations. That doesn't make isolated interventions impossible, just unlikely.
...I still don't see exactly what prevents Eliezer_2831 from fiddling around with MINOS's or CERN's observations in
http://www.nature.com/news/2011/110922/full/news.2011.554.html
http://arxiv.org/abs/1109.4897v1
http://usersguidetotheuniverse.com/?p=2169
http://news.ycombinator.com/item?id=3027056
Perhaps the end of the era of the light cone and beginning of the era of the neutrino cone? I'd be curious to see your probability estimates for whether this theory pans out. Or other crackpot hypotheses to explain the results.