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Originally Posted by ICER
Well, Rangsk. I would have to disagree with your assessment. Although you explained it quite well. So allow me to recap and you can tell me why I should have studied all this before I replied 
As I understand your post, the reason why we can't travel at the speed of light, is because we could not (cannot) measure the distance we are traveling. Hence the closer we get to that point, the farther we are from it ( since the faster it gets, the slower time gets for it)
The reason why I disagree (if I understand the post correctly) the person inside the craft would not be able to tell if they had reached light speed because (to him) he is not going very fast at all. But to someone on the outside. They should be able to determine the proper speed. Because they would be able to tell the distance and the time it’s taking them to cover it.
Or is that to literal? |
This is incorrect.
The reason why we cannot travel at the speed of light is because we have rest mass.
Any object which has rest mass cannot travel at the speed of light.
The faster you travel, the larger your apparent mass becomes. The larger your apparent mass, the more energy is required to increase your speed. At near the speed of light (say 99.9999%), your mass become so large, it requires more energy than exists in the entire universe to accelerate you.
What Rangsk is saying, is a rehash of the way that Lorentz transformations are derived. The idea being that since anything traveling at the speed of light must have the same velocity in all reference frames, the normal frame transformation (galilean transformation) must be incorrect. The correct transformation is one in which an object traveling at c has the same speed in all frames. The transformation that achieves this, is called the Lorentz transformation. This allows use to transform four-vector coordinates (3 space coordinates, and one time coordinate) from one frame to another frame.
Now that we can transform four-space coordinates, we can derive how to transform velocities. From velocities, we can transform momentums. Now we can calculate energiers. Anyways, we pretty much rederive our understanding of physics from the simple Lorentz transformations. One of things that we find out, is that objects with rest mass cannot travel at the speed of light. Light can travel at the speed of light because it has no rest mass. It can only travel at the speed of light. If it traveled at a speed lower than light, then it would have zero energy, and would cease to exist.