Present annual world energy consumption is about equal to the annihilation energy of 4 tons of matter.
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.
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.
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.
Antimatter is not a source of energy for us, it's a method of storing energy, compact but inefficient.
