The universe is the name that we gave to the vastness of everything that we know and we don’t. When people could not define the boundaries of the heavens above them, they called it collectively. From the first time the word was used, the universe has had a lot of different meanings, dimensions and ingredients. Now we are at an age where we think we are in the most advanced stages of understanding the universe. We also think that we hold the most advanced technology to probe through the space with equipments to comprehend more than our ancestors did. So what really is the universe? How big it is and how vast it is in its extension? I don’t know how big it could be, but I think it is not as big as we think.
The key element that is used to measure the universe and its contents is the size of things. The distances between elements are so huge that we adapted to use the light years as the measurement units for distances. Everyone knows what a light year means; it is the distance that light could travel in a year. Light travels a little more than a second to reach the moon. There are exact figures and I don’t want to go too scientific so that the concept is being diverted into formulas.
There is one thing that everyone seems like missing in the measurements. The stars have an estimated lifespan. The lifespan of a star depends mostly on its solar mass. They could range from a several million years to a several billion years. If a star on the other side of the known universe did begin to exist, the light would have started travelling ever since. If we fix a life span for that particular star, then we can imagine when the light will stop being emitted from the star. We also would calculate the time it would take the light to reach us based on the distance between us and the star.
Let’s fix the lifespan of this particular star to 100 billion years. That means, after 100 billion years, the 英國留學費用 star is not there. Let’s fix a distance from the star to us. Let’s say it is a 100 billion light years. A hundred billion light years might seem like a huge distance but is a very normal distance in the universe. With these two assumptions, what we can know is that when the first lights of the star reaches our eyes or telescopes, we will see the primitive star but in effect, there is no star at all. When we see the brighter emissions of light due to the explosion of the star as it disintegrates, the star would have been extinct for a hundred billion years. Why? Because the light took a hundred billion years to reach us and when we see that light, it has been 100 billion years after the event has happened.
When we first saw the primitive star, then we should expect the light to be coming in continuously for the next 100 billion years because we know that the star’s lifespan is 100 billion years. After those 100 billion years; that is after we had seen the star exploding, the light would stop. If we continued to receive light from that particular star for more than a 100 billion years that would mean that the star has a higher lifespan. So the time limit for which we can receive light from a star is exactly the time limit of the lifespan of that star. If a star lived only a million years, then we cannot receive light from the star for more than a million years.
This is where it gets tricky. We have limitations to the lifespan of stars. There is a maximum time when a star could exist. The real problem is that we are receiving light from stars that are too far away so that the light took too longer than the lifespan of the star to reach us. This means, all the stars that are beyond a certain distance are not there!