According to the theory of special relativity, as formulated by Albert Einstein, an object with mass cannot travel at the speed of light. As an object with mass approaches the speed of light, its relativistic mass increases, requiring an infinite amount of energy to reach or exceed the speed of light. Therefore, it is not possible for an object with mass to travel at the speed of light.
However, let's assume for the sake of discussion that you could travel at the speed of light and then suddenly stop and turn around. In this scenario, some important principles of relativity come into play:
Time Dilation: According to time dilation, as you approach the speed of light, time would slow down for you relative to a stationary observer. This means that while you may experience a short amount of time, a significant amount of time would have passed for an observer at rest. However, even if you traveled at the speed of light, from your perspective, no time would have passed.
Relativistic Length Contraction: As you approach the speed of light, lengths in the direction of motion would appear contracted from your perspective. This means that objects in the direction of your motion would appear compressed.
Considering these principles, if you were somehow able to travel at the speed of light and then abruptly stop and turn around, from your perspective, you would not experience the passing of time during your journey. However, it is important to note that traveling at the speed of light violates the principles of special relativity, and this scenario is purely hypothetical.
As for whether everything behind you would have disappeared, it is difficult to say definitively. Since you would be traveling at the speed of light, relativistic length contraction would cause objects in the direction of your motion to appear compressed. However, the specific effects on your perception and the appearance of objects would be highly dependent on the details of the hypothetical scenario, which cannot be fully addressed due to the impossibility of surpassing the speed of light.