Time Travel

While transporting a human from 2019 to the age of the dinosaurs might be a little ways off in terms of technological development, there is another form of time travel that occurs every day and all it takes to appreciate is a glance at the sky.

One of the more thought-provoking aspects of the universe is its immense size and scale. Considering our minuscule place in the all-encompassing beauty of the cosmos, one might ponder about the reach of light and whether what we see if actually accurate. On Earth, the speed of light is fast enough that distance is largely inconsequential; however, as we look further outward this definite speed begins to factor in to our perception of distance celestial objects. One light year, the distance light can travel in one year (9.46 x 10¹² km), is typically used to refer to objects as they stand in space. Given the vast separation of even our galaxy, much of what we see in the night sky is distorted. For example, the closest star system to our solar system, Alpha Centauri, is about 4.37 light years away from Earth. Due to the speed of light, as we look at these stars we are actually seeing them as they were 4.37 years ago. This simple fact can be expanded and becomes even more consequential as objects are further and further from the center of our observable universe. Take the Andromeda galaxy, located 2.5 million light years away, if a major event in that galaxy were to occur in the last 2.5 million years, we would not become aware until the light from that instant travels throughout space to reach us. In this sense, as we look further into the depths of space, we catch a glimpse into the past.

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