Did you know that the speed of light is around 3.00 × 108 m/s? For now, it is believed that there is nothing faster than the speed of light, which is why large astronomical distances are often denoted by light-years, the distance that light can travel in a year.
If we were to see a galaxy that is 100 million light-years away, we would actually be seeing how the galaxy was a 100 million years ago. The light from the galaxy would be light that traveled from that galaxy 100 million years ago and just reached our eyes. So technically, we would be looking at the past. Right now, in this very moment, the galaxy that we see would actually be 100 million years older than how we see it.
So if this is true, then isn’t everything we see in the past? Even objects that are much closer than 100 million light-years away still have some distance from our eyes. The infinitesimal distance that the light has to travel from these objects to our eyes is still greater than 0, meaning that everything we see has already happened.
It’s quite depressing to think of how insignificant human lives are. We will learn nothing about changes in the universe because by the time the updated light reaches our planet, humanity will most likely have already gone extinct. All we can do is peer out into the vast universe and simply oooh and ahhh at the marvelous sight.
Andy's Solar System Blog 
The point you made about how everything technically already happened by the time we see it was intriguing to me. When I look at the sky, it it is odd to now know the sunlight we see has taken about 8 minutes to reach Earth. Moonlight takes just over a second to reach us. We feel that this all happens instantaneously but we’ve been mistaken this entire time. I also share the same sentiment about how insignificant we are as humans in the vast universe we reside in. We often act as if the world is the universe and that it is all that matters. In reality, we’re the tiniest of tiny specks in the seemingly infinite universe.
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We can also view it as how special and unique we are as well. It takes the edge of the feelings of being a tiny speck!
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Hi Andy!
Before reading your blog, I’ve never really realized that everything we view, even things that are very close to us, are technically in the past. It’s interesting to think of it that way! I’m not ashamed to say that I stared at random objects in my room for far longer than I should have. 😆
Also, the sheer amount of time into the past that we see stars and galaxies that are far away from us is so large that I wonder how many of the stars we see at night are already gone. If nothing can travel faster than the speed of light, then I suppose that is the furthest in time that we are able to get information from those galaxies. It’s too bad that we have so many predictions that are so far into the future that we as a species might never be able to see come to fruition.
Our time on Earth is so incredibly minute compared to something like the Solar System forming, that I feel it’s unlikely that we will be able to see large changes in the universe. It’s as if humanity is living long enough only to see this snapshot of the universe, which is sad, but also, the fact that we are able to discover so much about our surroundings is already amazing.
I’m looking forward to what we might discover in astronomy in the future, using newer technologies!
– Vivian Li
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I agree that it is unlikely that we will be able to see large changes in the universe, but as technology improves, it is possible that we can see further out in the universe and see more events. So although we won’t be able to see the life span of a single galaxy, perhaps we can see the snapshots of several similar galaxies in different phases of its lifetime and eventually learn more about the universe!
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This is a very interesting idea! Since we will never truly be able to travel at light speed there is a chance that we will never be able to reach certain parts of the universe no matter how fast we can travel. All we’ll be able to do is observe what we can see.
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