The universe may be infinitely large. And even if it isn’t, it’s probably so big it could be infinite. But we see only a tiny fraction of that extent—a bubble known as the observable universe.
What we see is limited by the speed of light – 670 million miles per hour. That’s fast. But it is not infinite. So light can only travel so far in a year, or a century, or a billion years. Since the universe was born 13.8 billion years ago, we cannot see further than light can travel in that time – 13.8 billion light years. The most distant galaxies and quasars we’ve ever seen are almost that far away.
Or were they that far. We see these objects as they appeared more than 13 billion light years away. But keep in mind that the universe is expanding. So today there is much more space between us and these early objects. In fact, today the limit of the observable universe is about 46 billion light years.
Assuming Earth is still around, tens of billions of years from now we’ll see what these objects look like today. And the limits of the observable universe may eventually reach about 60 billion light years. But the universe is expanding so fast that we’ll never be able to see beyond that – confining us to a bubble of space and time in a possibly infinite universe.
We’ll have more on the observable universe tomorrow.
Screenplay by Daymond Benningfield
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