The sun and its retinue of planets drift as a group through the vast gulfs of space that separate the stars.
The main problem here is not that we don't known how to contain antimatter, which we don't its that we don't know how to obtain it - in quantity.
The factor most ignored in discussing interstellar flight is the kinetic energy that must be invested in the ship to make its tons of matter move at a substantial fraction of the speed of light.
Present annual world energy consumption is about equal to the annihilation energy of 4 tons of matter.
No one can deny the excitement of visiting another world.
In the past, on Earth, it has largely been to exploit foreign resources and to expand the domestic territory.
The known methods of producing anti-protons require, for their formation, millions of times the energy they will release when they contact protons.
This allows us to believe that some-day, when our technology is up to the task, the cost of interstellar travel will drop dramatically.
The essential point we want to make is that interstellar travel, far from being easy, presents problems for which we do not have valid solutions.
If interstellar travel is as time- or energy- demanding as the above figures indicate, it is far from obvious what the motive for colonization might be.
Antimatter is not a source of energy for us, it's a method of storing energy, compact but inefficient.
It would be a pity if, frustrated by the price of travel, we elected to become a society that never made contact, that never gave SETI a fair chance.
Years of science fiction have produced a mindset that it is human destiny to expand from Earth, to the Moon, to Mars, to the stars.
Above all, I would not expect a wise race, at great expense, to set loose an army of self-replicating robots.