We often hear that we are living in an ‘age of information’. At any given moment, we have access to all of humanity’s collective knowledge at the palm of our hands and it is information that allows our species to move forward.



This information comes to us from all kinds of places. Be it the internet or the many different research facilities all around the world striving to gather new knowledge and insights into things we don’t know about. 



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But did you know that one source of information is the past itself? No, not the past we have been through as a species but the past way beyond that, even billions of years.



This is not some crazy theory, it is the truth. In fact, a lot of our understanding of the universe has been possible because we can look at its past. 



Light, The Ultimate Time Machine


So, how is it that we can look into the past of the universe? ‘Doesn’t that violate some kind of laws of physics or something?”, you might ask. Well, no. It’s because of the laws of physics that this is possible, actually.



So, lets talk light. We know that the fastest thing in the universe is light. It can travel at a speed of 299,792,458 metres per second. That’s insanely fast. But the universe is so unimaginably vast, that on that scale, even the speed of light seems like that of a tortoise.



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Also, light can travel forever in the vacuum of space (if it doesn’t hit anything along the way). Combining this fact, with the size of the universe, pretty much explains how we can see into the past of our universe.



The light created at one point in time and space, can literally travel for billions of years before hitting the eyes of an observer. To the observer, it would be like seeing in the past billions of years ago.



Let’s Take And Example

If you are still confused, let me explain by taking an example of our own sun. We know that our sun is 150 million kilometres away from us. Light covers this distance in about 8 minutes and 20 seconds.



So, what that means is that we are looking 8 minutes and 20 seconds into the past of the sun because it is light that enables us to ‘see’ the state of anything. So, if the sun were to suddenly disappear, we wouldn’t even notice it for 8 minutes!

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The same is true for more distant galaxies and the billions of suns in them. Everyday, light reaches Earth from trillions of stars in the universe. Some of that light is millions of light years old and some is billions of years old. In many cases, the stars are long gone and we won’t notice it for billions of years!



When we are staring at the night sky, a lot of the stars that we see aren’t even there. What we see as stars are mere images of the stars past, a ghostly presence, trying to tell the tale of what once was. In a way, we are getting messages from the past, all the time.