Theory of Time Dilation / Twin Paradox and its Limitation

Washington DC, capital of USA, and Delhi, capital of India are situated at a time difference of 12/13 hours. If we travel this distance by a rocket with a speed of 10 mile/second it will take only 9/10 minutes. When we start at this speed from Washington DC to Delhi at 8 PM we will reach Delhi by 8:10 PM, Washington standard time. When we return back to Washington DC it will be 8:20 PM, Washington standard time. Only 20 minutes is gone by the coming and going process. Though it will be morning in Delhi. But this will happen in case of every short and long distance. No matter you travel at speed of, rocket, Light or more than the speed of light. If you travel at the speed of light for 2 years and when you will come back again to the earth; it will be passed-a total of 4 years; 2 years for going and 2 years for coming. Both the traveler and non-traveler will pass the same time. If the travelers are twin, they both will be older by 4 years more. There is no such thing as twin paradox will happen. Their look may be a bit different due to gravitational force on the earth.