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Comment by drewblaisdell | Hacker News Reader

Something has always confused me about the Drake equation.

The explanation I have heard repeatedly goes something like:

"This equation shows that there should be [massive number] of alien civilizations in the universe. But where are they?"

This seems to assume that, given the density of civilizations throughout the galaxy we can determine from [massive number], we should be able to observe other advanced civilizations. But is that true? If there was a civilization as advanced as we are somewhere in e.g. Alpha Centauri, would we be able to detect them?

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You are describing the Fermi Paradox: https://en.wikipedia.org/wiki/Fermi_paradox - there is a lot of interesting reading on that Wiki page.

The usual response I think is that the timescales and distances involved are simply still too big / spread out that we're still searching for the metaphorical needle in the haystack.

I think people tend to push way way too optimistic numbers into the Drake equation. I would gander the jump from "life" to multicellular organisms to be one in a million times that life forms.

It's also perfectly conceivable that we do just happen to be the first. Looking less likely with every advance in astronomy, but still possible nonetheless.

I work for the NRAO but I am not a radio astronomer, but my sense of it jibes with yours. Planets are mostly so close to their host star from our perspective that to distinguish signal between the two would require extraordinary sensitivity. But that sensitivity also means that you have to point very precisely. A less precise instrument can cover more sky at once but then you can't pick out individual sources as well and brighter sources (like stars) would swamp weaker sources like terrestrial radio/television signals.

I don't think we have enough information to tune the values in the Drake equation to make meaningful predictions. We'd need observations to do that, but the observations are, as you point out, difficult enough that we don't know if they're absent or we just can't see them yet.

If they use encryption it would be very hard to detect a sinal

UPDATE We have had computers for less than a 100 years, and with i2p we hav already created a technoligy that would hide us from other aliens

Encryption will make a signal look like noise, but first you have to be able to separate that source from the host star, and I think even doing that is difficult. I think that's the more fundamental problem.

Could be but first you have to find a candidate star. And with all radom noise where would you start

I think you're kind of missing the point. According to the Drake equation and what we know about exoplanets now, you start by pointing to any star, any at all. The problem is that you won't be able to distinguish signal from the planet(s) from signal from the star.

Of course, it may be that advanced civilizations, assuming they survive long enough, don't become expansionist or explorist. Imagine a post-scarcity homeworld. People would be happier on that world or in VR or whatever instead of breaking their backs mining some distant planet until their extinction event. Which scenario brings out the most personal satisfaction for hypothetical ET? Why would conscious beings who have reached a high technological development even bother with expansion? That's like asking a cush white collar person to mine coal on the weekends. It doesn't make sense. In his world, the heat comes in via electricity which is taken from a local nuclear power plant. That gives him the most utility and pleasure. Now imagine technology very much past that. Intelligent beings will move towards comfort and safety assuming all other things are provided. Actually considering near killing yourself from labor or risk in a far-off colony only happens when you don't have a satisfying life in your current place.

Its also worth mentioning that FTL travel probably isn't in the cards and even if we consider exploratory advanced civilizations working for billions of years, they most likely would not get far by the time they hit their extinction event anyway. Even an incredible case of E.T. exploring an entire galaxy would be an achievement without peer, but ultimately would leave 2 trillion other galaxies unexplored. Even that would be a stretch considering a galaxy is 100,000 long/wide and in 3 dimensions. Even if you could have a practical 1/10th lightspeed ship, you're looking at 1bn years right there. The universe is only 13bn years old so this civilization could explore maybe 3 or 4 galaxies at most considering inter-galaxy distances.

>Its also worth mentioning that FTL travel probably isn't in the cards and even if we consider exploratory advanced civilizations, they most likely would not get far by the time they hit their extinction event anyway.

Another possibility is that we've simply explored in the wrong directions.

    ___________________________________________
    |                               Us --> Exploring this direction
    |
    |     [Millions of lightyears of space between Us and Them]
    |
    |             Them
    |                 |                   
    |                 |                    
    |                 |
    |                 v
    |  Exploring this direction

Our galaxy is pretty much bounded. If any race started spread a few millions of years ago, they should be exploring (and exploiting) the entire galaxy already.

Did you mean universe? Our galaxy is a spec of dust. Our local galaxy cluster is also just a spec of dust. For how large the universe is - even a supercluster is a spec of dust. The universe is mind boggingly massive.

The observable universe has an estimated diameter of 93 billion light-years. A few million years might be enough to explore nearby galaxies. For example, to explore just our Local Supercluster you would need approximately 65,000,000 years [0]. Travelling at the speed of light.

E: Virgo is further than Ursa Major. Updated 55,000,000-->65,000,000.

E2: I always refer people to this video in regards to aliens, space, and time. I forgot to in this post, so here it is now: https://www.youtube.com/watch?v=HPl10L40pBM

[0] https://upload.wikimedia.org/wikipedia/commons/e/e2/Local_su...

It happens to people in Walmarts. They're a lot smaller. Certainly could happen with races looking for each other in space with the timescale that energy takes to cross it. Another thing that popped in my mind are the nuclear submarines looking for each other while emitting almost no sound or energy. It's just a void with a tiny piece of data here or there that must be assembled into evidence of others' presence. This can happen even when they're fairly close to each other.

> Why would conscious beings who have reached a high technological development even bother with expansion? That's like asking a cush white collar person to mine coal on the weekends. It doesn't make sense

What about the people who ride on ships from Southport to the Americas to plant crops or cotton?

But most expansion beyond the solar system would be inter-generational anyway, so it's more like people who are born on a spaceship and told by their parents they're a pioneer to an uninhabited world, and can't turn around.

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