Time travel is possible. The speed of light is as fast as is possible. The speed of light has been calculated to be 186,282 miles per second, or, in meters 300,000,000 meters per second. Devising a method of going faster than the speed of light will either go back in time or forward in time. Everything on the earth in the solar system and beyond is slowly going into the future second by second. For example, one hour after this article is written will be one hour in the future. The past is what happened before now; memories of the past are kept track of with present record keeping tools.
But time is a human concept. One year is the time it takes the earth to orbit the sun. One month is approximately the time it takes the moon to orbit the earth. It is often possible to repeat what was done in the past by writing down what was done and doing it again and improving what was done. We might be able to go into the future by guessing what will happen and doing it if it is a good idea.
If a person falls asleep for twenty years as the main character did in the book “Rip Van Winkle” written in 1917 by Washington Irving, he will be twenty years into the future. This is also what happens in the movie “Planet of The Apes”, but the spacemen go thousands of years into the future. It is too dangerous to try to sleep for long periods of time, however.
There are a few good science fiction books written on the subject of time. One is “The Time Machine” by H.G. Wells. In this book, written in 1898, an inventor invents a time machine in which he goes into the distant future. He finds a cannibalistic group called Morlocks who cannibalize on the Eloi. It is well written.
There is a very good movie that closely follows the book by H.G. Wells starring Rod Taylor and Yvette Mimieux with the same title as the book (“The Time Machine”). There are videos about time travel one can check out at a public library or school library. Most of science fiction is about the future.
The first three dimensions are length, width, and depth. Time is the fourth dimension; it should be the right angle to the x, y, z axes in the coordinate system. The x axis is the horizontal line (length), y axis is the vertical line (width), z axis is the line perpendicular to the x and y axes (depth). They are also the first, second, and third dimensions respectively. We can label the time axis in centuries, years, hours, minutes, seconds, etc.
Planets of the solar system and beyond could give us insight about time travel. Of course Einstein's Theory of Relativity predicted that time travel is possible using E=MC^2 (energy=mass times the speed of light squared) in the early twentieth century. The light from the stars takes thousands of years to get to us, so it is from the past. Also, trees live hundreds of years (a tree’s age is the number of rings in its trunk). The General Sherman Tree is the oldest living thing.
One simple way to prove that time travel is possible is to realize that as this article is being read, time is moving to the future. Only a few seconds per sentence, but time is moving toward the future.
There are more and more technological advancements each year with the numerous improvements to computers. Traveling to the past has been proven impossible, but everything has been in the past that exists now. And the past can be thought of as something that is humanly counted.
Taking a plane to New York City, New York from Los Angeles, California takes about four or five hours. The arrival time in New York city will be three hours in the future relative to the time the plane took off from Los Angeles. This means if the plane left Los Angeles at 9:00 a.m. it will arrive at New York at about 1:30 p.m. Los Angeles time. Since it was 12:00 p.m. when it was 9:00 a.m. in Los Angeles, it will be 4:30 p.m. New York time. The passengers have lost three hours. The International Space Station takes about one hour to circle the earth. It is above every time zone on the earth during that hour.