Waaaayyyy fuggin' big; no one knows for sure how big. One estimate is 150 billion light years. Y'know what a light year is, right? The distance it takes light to travel in one year.
Light travels at 186,000 miles per second, okay? Multiply that by sixty seconds, and you'll get a light minute. Multiply *that* by sixty minutes, and you'll get a light hour. Multiply *that* by *24 hours,* and you get a light day. Multiply *that* by 365.25 days per year, and you'll get a light year.
Y'still with me?
Now, multiply *that* by 150 billion. And in all that space, with all those billions of planets and galaxies, nanoanalplug will tell you there is *no life ANYWHERE* but on our own little blue dot out here on the edge of the Milky Way.
In redneck terms, you'll never be able to skip a rock across it.
And you can't say that it's not.<quoted text>
Yes I know. It was one of them there rhetorical questions.
As far as ET goes, the fact remains that it hasn't been discovered, so no matter how "sure" about it abound is, they can't say it's definitely out there.
We *can* say that the chances for extra-terrestrial life are quite high.
An old joke: Do you know what the surest proof is of intelligent life out there in the universe? The fact that they have *not* tried to contact us.
"If we are alone in the universe, then it's an awful lot of wasted space." Dr. Carl Sagan