question about space travel?

How long would it take to reach the nearest star (approx. 4,5 lightyears) if you accelerated at one G till you reached 99% of the speed of light maintained that speed and then decelerated at one G (creating artificial gravity for the occupants of the ship)?
Also would the theory of relativity suppose that there would be time dilation for the travelers? Would they feel 6 years and earth something dramatically different?

Well, if NASA succeeds in building the Anti-Matter spaceship which would be fueled by gamma rays, it would be a significant boost. Other advances in the meantime could make deep space travel a reality:

Dynamos made of Superconducting Rings from the new superconducting material (Iron doped with Arsenic), may one day block out "cosmic" radiation on other planets and moons in our solar system.

Phytoplankton, CO2, water and iron sulfate can be used to make "clouds" and Oxygen on planets and moons which don't have an atmosphere, to block out gamma, x-ray and uv radiation.

Boron, a mineral, can stop bone loss on deep space journeys, especially when combined with calcium, Vitamin D, magnesium and zinc.

Growing sprouts on deep space voyages will sustain its crew since it only takes 3-4 days to sprout all sorts of seeds, beans and nuts. Baby vegetables can also be grown with the AeroGarden Pro 100 or hydroponics in a matter of weeks. Hydroponically grown watercress is a complete food when combined with protein.

Frozen embryos of a pig, lamb, goat, etc. can be brought to term using a cow as the surrogate mother. This means farms, restaurants, and bakeries can be opened on other planets and moons in our solar system. Building Fischer Tropsch reactors will provide propane, burning the propane will yield water vapor and CO2.