Looking into the Past

Moving Towards the Past

Robert suggested, “Let’s back up for a minute. Interstellar travel is travel between one star and another. It’s not possible today because there are physical and technological limitations. When we discuss extreme distances, we have to use terms like ‘light years’ and ‘the speed of light’. I’m oversimplifying this but hang in there with me. The speed of light is 186,000 miles per second. An Earth second is based on the decay of Cesium which is a universal constant. A light year is how long light will travel in one Earth year. The nearest star is just over four light years away. Four years traveling at the speed of light,” he repeated. “So, this is why interstellar travel is not a possibility today. “Now, here’s where it gets a little crazy. When we talk about seeing something four light years away, it’s not exactly what it seems. We can only view events as light reaches us – those events that happened at the time equivalent of how long it took for that light to reach us. Viewing the light from a star four light years away means that whatever we’re seeing right at this instant is what took place four years ago. It would be impossible for us to see what happened a year ago on that star, because that light hasn’t reached us yet. It still has three years more to travel. That’s a limit of our current reality.”