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When it comes to asking big questions, how big is space is the biggest one. To the best knowledge of astronomers, space is infinite. We can not observe a small portion of all of the universe. We are only able to see the tiny bite that has emitted light that has been able to reach us. What is even more daunting is the fact that the universe is still expanding; therefore, getting bigger as we speak.
The observable universe(measured by the cosmic microwave background radiation) is 13.7 billion years old. That might make you think that it space’s radius is nearly 14 billion light years. That is more than likely not true. It is hard to quantify the rate of expansion of space from the beginning until now. We have to consider the co-moving distance. Sorry, but we really do. The currently most quoted estimate of the minimum radius of the universe is 78 million light years. Less than that and light would have had time to circumnavigate the cosmos. Truthfully, no one has a clue.
Let’s try to do some math that would put it in perspective. In one year light will travel 9.46 trillion km. Multiply that by the age of the universe. Let’s see, that is 9.46 trillion multiplied by 14 billion years. Well, I called it simple math, but, obviously, I was not being serious. I had to stop doing the math before I passed out.
Astronomers learn more each day. As telescopes are improved and able to view deeper into space, we are able to see many light years farther away. Also, as emitted light reaches us our knowledge of things farther away come to light(pun intended). What we know about how big is space is nothing compared to what our knowledge will be in a mere 50 years.
We’ve recorded many episodes of Astronomy Cast, including one about Hubble. Check it out, Episode 88: The Hubble Space Telescope.