How To Look Into The Distant Past; And How Our Earth Is An Isolated Island

https://www.youtube.com/watch?v=6Uy6Q_kQnwI

Check out the video above, where I talk about one of my favorite subjects: The Universe!

Full Transcript

Hey guys! This is Jesse Charger here and in this video I want to talk about one of my favorite topics, which is ‘Outer space and the universe’. Because I am basically an ‘outer space and universe’ nerd, I might as well put out some videos about what I find cool about the universe – some cool tips that most people aren’t fully aware of.

One of the things that most people aren’t aware of is that, when you are looking at the night sky and you see all those twinkling stars up there, you are actually looking into the past. Because those twinkling stars are so far away it takes years for their light to travel through space to bounce off your eye to the point where you see it.

If there’s a star, that is 4 light-years away and the nearest star to Earth (i.e. not the Sun) is 4 light-years away, and you look at that start, you are actually seeing it 4 years in the past. There is going to be another star next to it that might be 20 light years away and another star next to that one that is 50 light years away. So you are looking at the stars at the various points in the past history. You are not looking at how they are right now.

Even our own Sun is so far away that it takes 8 minutes for the light to travel from the Sun to Earth where it bounces off your eye(the light) and you see the Sun. 8 minutes!!! So, if the sun just went supernova all of the sudden i.e. exploded, you wouldn’t even know anything happened until 8 minutes later. Because the sun that you are looking at in the sky is actually the Sun that existed 8 minutes ago and not the Sun that is there right now.

So if the Sun just exploded you would have 8 more minutes of peaceful bliss were you dint know you’re going to immediately die. So, that is a kind of a cool little factoid.

Looking Back At the Early Universe

Extending on that idea, scientists look in a very powerful telescope like the Hubble telescope at galaxies that might be a billion light years away or 5 billion or 10 billion light years away, they are actually looking into the deep past of the universe. Because when you look at a very distant galaxy that is 10 billion light years away you’re looking at that galaxy as how it was 10 billion years ago during the early universe (the early formation of the universe). That is one way that scientists can gather clues about how the early universe actually was and looked, by just some very distinct galaxies. They are looking at the universe shortly after the Big Bang happened.

One of the interesting things is that when you look at a very distant galaxy, that galaxy right now is not there anymore. It’s at 10 billion light years. It has moved to a different place or lot of the stars have probably expired or went supernova or probably has totally new stars in it or It is in a completely new location. So when you’re looking at a very distant galaxy 10 billion years ago the galaxy is not there anymore or has different stars. If there were any civilizations they are 10 billon years ago, they are probably gone.

It’s just a kind of a weird thing to think about that you’re actually looking into the past when you look up at the night sky.

Earth’s isolation

Now we know that the visible universe is about 13-14 billion years across. But there’s a problem. If you look at even more distant galaxies some 13 or 14 billion years across you can’t, because now you are going back to the point of the Big Bang. Any galaxy that’s farther away than that wall, the light just hasn’t had enough time to reach Earth yet.

Based on measuring the curvature of the entire universe and finding that it is pretty flat, scientist actually think that the universe has to be at least 14 trillion light years across, Not 13 billion, but 14 or 13 trillion light years across or about a 1000 times bigger than what we can actually see. So, you got other galaxies out there. Not just the hundred sextillion stars on our own visible universe but hundred sextillion stars times, a million times more volume or a 1000 times across farther that we just can’t see! Light has not had time to get to us yet. But because the universe space is actually also expanding most of those stars, that light, will never reach us. Also the fabric of space is expanding and that light would just never have the time to reach Earth.

So we are effectively cut off from most of the stars out there. We will never be able see them. We will never be able see the other galaxies out there, if there is other intelligence civilizations out there, lets say, in just a different quadrant of the universe, say a trillion light-years away from us, the light from our sun, the light from the Milky Way galaxy will never be able to reach them. They will never know that we are there. All they do is infer that the universe is probably big and there is a lot more stuff out there that will never be able to see. And with our current technology, we are never going to be able to see them unless there is some kind of revolution in physics, which probably isn’t going to happen, anytime soon.

Let’s wrap up…

It is just kind of cool that we are so cut off from most of what is out there in the universe. Even what we can see is actually long been dead. So if you look at a distant galaxy probably all the stars in it have died or generated new stars. So you are just looking at the past when you look at the night sky. The very near stars you might be looking at are 4 or 5 or 10 years in the past and more distant stars billions of years in the past. Most of the stars out there, most of the galaxies are so far away we will never be able to see them from Earth. So that’s today’s ‘outer space and universe’ video. Hope you enjoyed it. Hope you learnt something. And until next time Jesse is out!