I am curious about something, How can you tell how fast you are going? I mean if you are on a bus that is going 20 MPH and you walk forward 3 MPH are you going 3 MPH or 23 MPH. This can be applied to C. If you are on a ship going as close to the speed of light as possible and you walk forward are you going faster than the speed of light? Or is it not even possible to walk forward on a ship that is going that fast? Also if you held out your arm would your blood be able to pump to your fingers? Because if it did than your blood vessels are going faster than the speed of light.

Edit: another thing, if you are on a bus and you can see that is the light inside the bus moving faster than the light outside the bus?