This section has some programs to perform the basic numerical computations regarding relativistic space travel.   They allow an idealized numerical view of how we would experience relative time (Earth vs. Ship time) on a very-long-term space voyage.

The experiences of relativistic space travel are somewhat counterintuitive with respect to the local type space travel we typically experience every day.

The theory of relativity predicts, and it has been repeatedly experimentally confirmed, that time goes relatively slower for a moving observer than for a relatively stationary one.   The space travelling we do today, travelling around the world, even trips to the ISS or Hubble space telescope or even the Moon, do not easily demonstrate the predicted effects of relativity without special high-technology aid to measure the extremely tiny effects.

However, if we travelled over extremely great distances in space and reached very high relative speeds, then returned home, the effects of relativity on our comparative experiences of time would become very evident.

Relative time is only one problem with interstellar space travel. If you leave on an interstellar voyage, to even a nearby star, then your current friends, family, even your children would have passed away from old age long before you return from your mission.   Under these conditions of relative time, we may wish to reconsider the practicality of humans making interstellar space voyages, since, for the crew, it would essentially mean saying goodbye forever to everyone they ever knew back on Earth whether or not the mission was a complete success.

It should be noted that to reach even the closest star would be a technological achievement of extraordinary proportions, considering the nearly impossible logistics involved in designing a reliable spacecraft engine to handle the task as described here and otherwise provision such a voyage.   Such voyages are still the stuff of science fiction, nevertheless, we can still do the computations that will tell us very closely what it will be like if and when we finally do achieve interstellar space travel.