What is quickest way to travel in the space?

We always talk about space travel and lots of films about outer space and all. But how much our science has achieved till now? With known methods how much time would we really take to reach to nearest star? What are known obstacles?

with known methods we can already reach the closest star with no obstacles save for food, waste and air.
The Sun is our closest star ;)

That aside, I assume you mean closest neighboor star... current technology will never get us there. We'd need cyrogenics and whoever goes will never be able to contact earth again due to the distance problem... plus the fact that we're limited to conventional fuels like nuclear or ion...

how about we settle the moon first, THEN we think about how to get somewhere interesting?

there are ion engines being developed which travel at super high speed and deliver continous thrust to reach hundreds of kilometers per second unlike the present gravitational sling which is very slow and reaches only about 5km/sec and also in the future nuclear engines will be develop which will allow us to travel near to the speed of light!

Currently, our space ships are chemically propelled and burn a lot of fuel just to get out of Earth's tight grip of gravity!

The spaceship needs to get over 7 miles a second to break free, which NASA and their Russian counterparts have been capable of doing for nearly half a century!

Once free of gravity, these chemically operated vehicles can really pick up speed with very little additional fuel. However, acceleration does require fuel, and fuel requires large and heavy tanks! And so, missions seldom travel much faster than escape velocity once they are well away from the Earth, as seen in the old Apollo missions.

A good way of attaining increased velocity is to use the gravity of large mass objects such as the moon and planets, to sling shot into the desired directions.

Ion propulsion systems are being experimented with and nuclear powered ships are not a new concept.
Perhaps the most romantic and atavistic future concept spaceship is the sail-craft. It is not much unlike a sailboat, but instead of Earthly winds, driven by the sun, it relies on the direct winds of our sun!

If a space ship were to leave Earth on a trip to the nearest star (after our sun of course) and cruise at a constant velocity of 10 miles a second (about 50% faster than escape velocity) it would take about 80 thousand years to get there.

Better step on the gas! Or better yet, use a constant accelerating system where a comfortable and familiar 32 feet per second per second is maintained. This would shorten the transit time dramatically!

The most powerful propulsion system yet designed is that of using nuclear bombs and a push-plate. Basically you drop a bomb out of the back of the ship and you have a very strong shield facing the bomb. The bomb them pushes you away with it's shock wave. Radiation is not an issue in space.

It's not possible to reach any star other than Sol within a human lifetime with current propulsion technology. You could reach another star by simply having a self-sustaining ship that would support multiple generations of astronauts. You couldn't reach your destination, but your decedents could if you started the trip.

As far as a self-sustaining ship though we're still quite a ways off from that as well, but it's certainly something that will be reached much sooner than a new propulsion system capable of nearing light-speed.

NASA and the rest of the world do not seem to be interested in that technology at all though so you can forget about an ETA.

Mini-Magnetospheric Plasma Propulsion or also known as M2P2 designed by Dr. Robert Winglee of the University of Washington is probably the best way to travel to the another solar system, read these links to find out more and what it can do.

http://www.space.com/businesstechnology/technology/m2p2_winglee_010621.html

http://science.nasa.gov/newhome/headlines/prop19aug99_1.htm