How big our universe actually is, a mystery

• The universe has been expanding continuously since the Big Bang, but at what rate? The answer to this question may reveal that everything we know about physics may be wrong.

• Let us begin our discussion by saying that the universe is very vast. When we look in any direction, the distance to the farthest visible regions of the universe is about 46 billion light years. Its diameter is 540 sextillion (or 54 followed by 22 zeros) miles. But that's really just our best guess. No one knows how vast the universe is.

• This is because we have known the journey of light (or more accurately, microwave radiation since the Big Bang event) since the beginning of the universe. Since the universe came into being about 13.8 billion years ago, it has apparently been expanding ever since. But since we cannot definitively determine the age of the universe, it becomes difficult to figure out how to measure the distance between objects we cannot see.

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