Special Relativity

Does anybody know why we can't get any mass to the speed of light by adding velocities?

For example if a ship is going 40 Miles per hour and the water is going 10miles per hour in the same direction, the ship will be going 50miles per hour.

Well.. if we can get inside something that moves 4/5 the speed of light and move 1/5 the speed of light in that moving object, can't we reach the speed of light? Or does the relation with time mess stuff up?

where : u is 4 /5* c and  v is 1/5*c

 now we have :

 

s= (4/5 *c + 1/5*c )/(1+(4/5c *1/5c)/c2 )

=1*c/ (1+ 4/25)

=0.862068965517241*c

Or, to answer your question in words;

Time changes for those in different reference frames. If you travel near the speed of light on a train, an observer watching the train go by would be seeing you move in slow motion. As a result, time increases for the motion to happen (to the observer) and so speed is decreased. If you were to run along the corridor of the train, to the observer you are still travelling slower than the speed of light in total. (To yourself, you are running at the speed you are running, irrespective of the speed of the train.)

Note: I just realised velocity would be a better word in this post. Pretend all 'speed' is 'velocity'!

thanks! that's interesting

I think that the equation is a little more complicated

@jbell35 : "Tell us this complicated equation , If exists "

These days, physicists are keen to avoid saying mass increases with speed. Instead, the energy of something increases with speed.  This is correctly approximated at low speed by the classical formula for kinetic energy:

K.E. = mv^2/2

I just wonder...when we talking about the speed of light...i always imagine a beam of light that travel into infinity...what puzzle me is that we view light with our eyes...if we couldn't see it(being blind), does it mean that we should study it?  Should we OnLy study things that that the MaJoritY of people view?  Have anyone considered that when you do travel at the speed of light, that light itself might become dim...I would think that the light would stop reflecting to the eye, and at that speed, it would just vanish, like mist!  How can we study something we cannot see? Perhaps reality stop, as soon as we cannot see light...perhaps our mind travel at a speed of light, cause whenever I close my eyes, there is darkness...perhaps our thinking process go fast, the way a light beam travel. My observation is that E=mc2, does not apply to blind people, so how can it be true to the world of some people, but not to that of all people??? Maybe, things should make sense to everyone...perhaps we have not found a place to stand on, from which we base our theories...would meat be preserved at the speed of light, honestly, i don't really know how it work. Mind my curiosity:)  Can it be that we are blind to other factors, that our eyes do not pick up on things,  that would leave blank spaces in our theories?

concerning, velocity...i would say that something gain velocity, only when it come into a gravitational pull of another object...light have particles...they travel at the speed of light...and when it go past an object with great gravity pull, the particles in that light beam, would be pulled to the side of the light beam...slowing it down at that side...perhaps bending the light, the way a prism, bent it...I wouldn't say that light have velocity on its own, it only come into play when there is gravitational pull, or at worst collision...mass would only appear in light, when it changes direction...but then gravity determine that...together with this, i must mention that its just an opinion, its just what I'm thinking based on a cyclone, where heavier particles move to the side in a liquid.