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Comment by _annum | Hacker News Reader

Can you unpack your reasoning here? The likelihood of civilizations occurring/existing in parallel leads me to a similar conclusion.

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Not OP, but I fully agree with them. Incoming ballpark figures I and hand waving. If, today, with our current technology, we decided to explore/colonize every star and planet in our galaxy, launching 3 ships per day that travel at single digits percent of c, we could investigate every planet in our galaxy in about a billion years. That's pretty much worse case technological scenario, because at some point in the next thousand or million years we'll have even more incredible technology to build more and fly faster. Probes that can constantly accelerate at 1g will reach other galaxies on the order of millions of years. If they self replicate, or have pioneers that can rebuild civilization on the order of a few thousand years and continue exploring, we're still within that 1 billion year limit to colonize at worst the entire galaxy, and realistically the entire universe. Earth has been around for 5 billion years, and the greater universe for 15. Humans have only existed for 10,000 years. ET should have been here long before we even came into existence.

We only have a few thousand years of reliable history and in many places, far less than that. It's perfectly reasonable in your scenario that ET was here long before we were, missed us by a couple of million years and left.

If you look at the history of human exploration, discovering new lands has not led to immediate settling or the establishment of long-term relationships with the locals.

Assuming they do not have a prime directive.

If the universe is infinite and life is possible ( as we know it to be), then life will occur an infinite number of times.

If we just look at the observable universe, number of stars, number of planets, and habitats we see even in our own solar system, there are a lot of shots on goal.

I don't think that's the right way to think about infinity. Just because the chances are infinite and you know goals are possible, it does not mean that there will be infinite goals. There are infinite numbers between 4.0 and 6.0 but only one of them is a prime.

> There are infinite numbers between 4.0 and 6.0 but only one of them is a prime.

Primality only applies to natural numbers, so there can't be primes between 4.0 and 6.0. There is one between 4 and 6, but that's a finite range.

The concept holds. Perhaps the example isn't great, I'm not sure - but since when does 'the set of numbers between 4.0 and 6.0' not include the natural number 5?

That's a set of real numbers, and primality is not defined for real numbers, so 5.0 can't be a prime. The whole concept is just not applicable unless were talking about natural numbers, in which case the set is finite.

Who said it's the set of real numbers? I don't remember adding any notation that specified the set must be real numbers.

But you can't score 4.1 goals. You can't take 5.9 shots on goal. Goals and attempts are integers. Ask Sheffield United.

I feel like this misses the point. Infinite outcomes != all outcomes.

What you stated is certainly true, but Infinite outcomes == all possible outcomes in infinite quantity, and we know that life is possible.

> infinite outcomes == all possible outcomes in infinite quantity

No it doesn't. This is a common misunderstanding of infinity. Infinite is absolutely not the same as all.

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