If you were on Earth monitoring a person in a rocket ship traveling away from Earth at a speed close to the speed of light, what changes would you note in his pulse? In his volume? Explain.

Solution 24E Introduction We will use the concept of time dilation and length contraction to explain what kind of changes we will observe. Solution Part 1 According to the special theory of relativity, the time will run slow in a frame of reference which is moving with respect to me. This is called the time dilation. The effect is noticeable if the object is moving at a speed close to the speed of light relative to me. Since the rocket ship is moving at speed very close to the speed of the light, there will be time dilation. Hence the pulse rate will be slower to the person monitoring from the earth. Part 2 Also since the rocket is moving very close to the speed of light, there will be length contraction. That is the length of the rocket will appear smaller compared to the earth bound observer. Now, if the length of the rocket decreases, the volume of the rocket will also decreases. So, to the observer from earth, the volume of the rocket will appear less.