Why do Christians believe in the Resurrection of Jesus but not alien abductions?

[Jehanne]

I agree that interstellar space travel is not without its difficulties; clearly, any advance civilization undertaking such a venture would need to have developed some sort of controlled nuclear fusion, but if such a technology exists, then, yes, interstellar space travel would be possible.  And, also, you have to consider the effects of special relativity; if a space-faring civilization could reach speeds that are near the speed of light, time dilation would set in, and then, some sort of micro-regenerative cryogenics may be possible using some sort of nano-technology.  Who knows?!  Can you imagine a world without smartphones?

So there you are whizzing through space at light speed or greater.  Would your mass increase?  Would you affect space junk with your gravity field?  How would you avoid smashing into space junk?  How wealthy would your home world have to be in order to build and sustain a space-faring civilization?  And what would be its purpose?

From your perspective, your mass would not increase.  Another observer would, however, see your mass increase.  I am not talking, let advocating, FTL travel.  Even at "space normal" speeds (Ha!), ET could still, if they had developed nuclear fusion and advanced biotechnology, make such a journey.