This one is about as speculative as you get:
Suppose, just for fun, that we accept Posner’s $600 trillion estimate for the value of the Earth. What then is the value of the Universe?
…We could try to calculate the value of the Universe by estimating the number of planets with intelligent life and multiplying that by $600 trillion. It’s very hard to guess the number of such planets per cubic megaparsec. But since the Universe seems to extend indefinitely, the result is infinite.
That’s my best estimate: infinity!
But that’s not very satisfying. What if we limit ourselves to the observable Universe?
No matter what I say, I’ll get in trouble, but let me estimate that there’s one intelligent civilization per galaxy.
A conservative estimate is that there are 100 billion galaxies in the observable universe. There might be twice as many, but perhaps a lot of them are small or less likely to support life for various other reasons.
So, I get $600 trillion times 100 billion, or$60,000,000,000,000,000,000,000,000
as my estimate of the value of the observable Universe. That’s $6 × 1025, or $60 septillion.
That is from John Carlos Baez, via Benjamin Lyons. And to think it all cost nothing to produce…..the ultimate free lunch.