Is there any planet outside solar system that has almost same characters that of earth? If not found till now,will it be possible ever to shift the whole human race to a new planet,because as Stephen Hawkins stated,in the years to come the world will be unfit for living beings,and a need for a new planet to reside will come.So if it is so, is there any idea of how to shift humans to a new planet or is there no such ways at all?
$\begingroup$ See Are there any other Earth-like planets in the universe?, How Earth-like is “Earth-like”?, Are exoplanets in the habitable zone suitable for human colonization?... $\endgroup$– TildalWaveFeb 1, 2016 at 21:11
The Earth similarity index (ESI) is a way to measure how similar other planets are to Earth. Mars has similarity index or 0.7 (1 being Earth) and Kepler-438b 0.88.
ESI depends on planet's density, radius, surface temperature and escape velocity. A planet with high ESI value is not necessarily habitable (and there a there is some uncertainty of it's accuracy because some of the values going in might not be very accurate) but it stands to reason that if they are in the habitable zone of their star, there is a chance they are habitable.
That being said, those planets are light years away. Flying there with current technology will take thousands of years. To make this trip reasonable you have to reach a significant fraction of the speed of light (10% - 20% maybe) which would require a (very large) leap in propulsion technology.
Gliese 667 Cc is probably the best candidate at the moment similarity wise that's relatively close by - "mere" 24 light years away. https://en.wikipedia.org/wiki/Gliese_667_Cc
1$\begingroup$ Just adding, to make it more explicit, that 24 light years away means 240 years to get there if you manage to reach 10% of the speed of light, which is hundreds of times faster than the fastest spacecraft mankind has ever launched. $\endgroup$– jcaronFeb 1, 2016 at 23:26
$\begingroup$ @jcaron Correct. Plus some time for acceleration / deceleration. I once calculated how long it will take to get to the closest solar system ( ~ 3 light years or so away) at current speeds and it came out to something around 6500 years. $\endgroup$– ventsyvFeb 2, 2016 at 4:04
1$\begingroup$ And AFAIK current speeds aren't fast enough for any significant time dialation. 6500 years will still be about 6500 years for the crew. $\endgroup$– Joe L.Feb 2, 2016 at 4:37