Mathematically;
a light year is the distance light travels in a year.
Since light travels at 299 792 458 m / s
And there are 60*60*24*365,25 = 31557600 seconds in a year (note that once every four years there are 366 days and therefore there are (366+365+365+365)/4 = 365.25 days in a year)
A light year is about 299 792 458*31557600 = 9.46 × 1015 meters
Since you're going 120 times as fast, your final speed is 120*9.46 × 1015 = 1.135*10^18 meters per second
That's more than 1 quintillion 135 quadrillion meters per second!
Now we go to the physics though.
einstein thought of the both praised and cursed formula E = mc2. The effect of this formula is that once an object tries to travel near the speed of light it's mass will heavily increase. If an object would be able to travel at the speed of light, it would have infinite mass and the energy required to move it would also be infinite.
This is the part where we meet the real sci-fi.
NASA is experimenting with methods to travel faster than light.
How?
You'll have to think in 4 dimensions.
Suppose you have a pen travelling across a paper, then there's a speed limit to how fast the pen can move. But what if we were to move the paper aswell? Then the pen wouldn't travel faster than the speed limit, but it would get faster from point A on the paper to point B.
Now in our world, the idea is that it is possible to create a certain 'bubble' of the space which makes the 'ship' go faster from one side of the bubble to the other. Therefore, inside the 'bubble' the ship won't be faster than the speed of light.
The whole theory hangs on the idea of the existance of negative energy, which is needed to create the bubble. Anyway, there's still a chance we might one day see the other end of the universe!
Here's where you can read about it;
http://www.nasa.gov/centers/glenn/technology/warp/ideachev.html
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