RichA wrote:
Earth-like? I'd believe it when they get there. Here's the travel time:

-Current rocket technology (if a large enough one could be built): 120,000mph.
25,000 years to get there.

-Project Orion 10,000 ton class ship: 80% speed of light peak speed.
14 years.

http://www.cnn.com/videos/world/2016...d-orig-nws.cnn



Project Orion was originally designed for solar system travel. It could get
to Proxima but no chance of 0.8c. Even 0.2c would probably be impossible
with fission bombs. .8C would need to cope with relativistic impacts
producing mechanical and much more importantly radiation damage needing
many metres of shielding and/or magnetic shielding which would be fatal to
human life. these problems may eventually be overcome but probably not
without antimatter propulsion. Even them a lot of radiation contamination
is likely.