Though it seems impossible to colonize galaxy at sub-light speed but without FTL travel we can still colonise the universe at sub-light velocities[ using self replicating probes and Bioprograms which I've discussed recently], but the resulting colonies are separated from each other by the vastness of interstellar space. In the past trading empires have coped with time delays on commerce routes of the order of a few years at most. This suggests that economic zones would find it difficult to encompass more than one star system. Travelling beyond this would require significant re-orientation upon return, catching up with cultural changes etc. It’s unlikely people would routinely travel much beyond this and return.
Archive for the ‘Astrophysics’ Category.
The notion of time travel is rooted in the early 20th century physics of Albert Einstein. In the 1880s, two American scientists, Albert Michelson and Edward Morley set out to measure how the speed of light was affected by Earth’s motion through space. They discovered, to their amazement, that the speed of Earth made no difference to the passage of light through space (which they called the ether). No matter how fast you travel, the speed of light remained the same.
The Schwarzschild reference frame is static outside the Black Hole, so even though space is curved, and time is slowed down close to the Black Hole, it is much like the absolute space of Newton. But we will need a generalized reference frame in the case of rotating Black Holes. Roy Kerr generalized the Schwarzschild geometry to include rotating stars, and especially rotating Black Holes. Most stars are rotating, so it is natural to expect newly formed Black Holes to process significant rotation too.
You know how space time are intermingled? Euclidean relativity is another theory which explain our current perceptions regarding space and time. It is just a transformation of minkowskian invariant….below is space time metric in Minkowskian invariant