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The Fermi Paradox

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Re: The Fermi Paradox

#101

Post by IndianAstronaut »

danieltillett wrote: post #73
bdamm wrote: post #30

Earlier quoted context omitted.

This model assumes that interstellar travel is profitable. There is no evidence that this is the case, even if we had Star Trek technology. If it isn't profitable, then it turns into a drain on the home planet. That isn't sustainable.

Profitability is not an explanation for many activities that take place here on Earth (today is one). There are many reasons that would allow non-profitable expansion to occur. If the cost is low compared to the wealth of the society and the society is not a hive mind, then some individuals within that society would undertake it purely for non-profit reasons. For example, if I could send a problem to Sirius for $1000…

>if I could send a problem to Sirius for $1000 that would beam back pictures of system in 18 years time I would do it right now

The only way that is going to happen is if a company with profit motive is willing to invest in r and d to bring down the costs.

NASA is incredible, but it isn't moving towards bringing down space exploration costs.

Re: The Fermi Paradox

#102

Post by maaku »

danieltillett wrote: post #56
maaku wrote: post #10

The "we are the first" argument seemed less convincing than it could have been. A better argument from that perspective is the observation that Type III civilizations expand at an alarming rate. Whatever the motivation for expansion[1], basic simulations and back of the envelope calculations show that even with technology we could imagine building in the not so distant future, humans could expand into the cosmos at >…

I actually posted about this very topic a few days ago here. Once you have von Neumann machines spreading they will take over each new star system pretty much as soon as they reach it. Assuming the von Neumann machines are small and are being powered by an energy source (i.e lasers) from their origin star system they will spread through the galaxy at close to the speed of light. This spread method creates an interest…

Another testable variation of this is the gravitational effect of voids. Voids[1]are regions of the universe devoid of visible matter (stars), as far as we can tell. These are predicted by the inflationary model as regions of low energy distribution in the early universe. But if we find a void that appears to have gravitational effects on its neighbors, what an astronomer might call "a concentration of dark matter", that could be a Type III civilization. I'd look around the edges and see if we can find any half-eaten galaxies...

[1] https://en.wikipedia.org/wiki/Void_%28astronomy%29

Re: The Fermi Paradox

#103

Post by Udo »

ZanyProgrammer wrote: post #8
Udo wrote: post #3

Earlier quoted context omitted.

Of course no one can now right now , it's not one of these things that can be solved by theoretical work alone. At some point - assuming we don't go extinct before reaching it - we will know. But it's still open to useful speculation, as there might be something we still need to consider in order to avoid said extinction. The Fermi Paradox is one of the more thought-provoking signs that something might be amiss (at l…

"The Fermi Paradox is one of the more thought-provoking signs that something might be amiss (at least in our part of the galaxy), and especially because our culture is predisposed to not take anything happening on the interstellar stage very seriously this provides an impetus for reflection that would otherwise not happen." A hypothetical observer in North America, circa 1500, would have no idea that Asia and Europe…

I'm not sure how your argument applies to what you cited of my post, but you are not wrong. You don't even need to consider exotic FTL communication, it could just be low-power directional radio traffic.

In fact, if a full clone of Earth with exactly the same culture and technology as ours was located just a dozen light years from here, chances are we would not be able to detect that civilization.

The media is always talking about our expanding radio sphere, but in reality this signal gets very weak and jumbled, very fast, with increasing distance. The means all the misinformed derps who believe aliens are coming to take our resources (a group which includes Stephen Hawking for some reason) can sleep pretty well at night knowing that we have not really advertised our existence yet.

Re: The Fermi Paradox

#104

Post by maaku »

DavidSJ wrote: post #27
maaku wrote: post #10

The "we are the first" argument seemed less convincing than it could have been. A better argument from that perspective is the observation that Type III civilizations expand at an alarming rate. Whatever the motivation for expansion[1], basic simulations and back of the envelope calculations show that even with technology we could imagine building in the not so distant future, humans could expand into the cosmos at >…

I had this idea recently myself and to the best of my knowledge you're the only other person who's mentioned it. The closest I've found is the "galactic preemption" hypothesis published in the 80's, but that's more an explanation for why only one civilization would exist in a single galaxy, rather than for why a newborn civilization such as our own would look at the sky and see no signs of civilization in the whole u…

No, but I haven't read any science fiction since my teenage years. (Sadly, because I would like to... just don't have the time.)

I actually don't remember reading this anywhere, it just seemed an obvious idea. The idea that humanity would expand into a Type III civilization and near light speed is very old, probably dating to the work done by the British Interplanetary Society on interstellar travel. I don't have citations handy, but I remember reading a critique of generation ships which basically boiled down to "if you travel less than 0.9c, you can expect someone else to leave after you do but arrive sooner." Applying the same logic to other civilizations just seemed like common sense...

Re: The Fermi Paradox

#105

Post by maaku »

bdamm wrote: post #30
maaku wrote: post #10

The "we are the first" argument seemed less convincing than it could have been. A better argument from that perspective is the observation that Type III civilizations expand at an alarming rate. Whatever the motivation for expansion[1], basic simulations and back of the envelope calculations show that even with technology we could imagine building in the not so distant future, humans could expand into the cosmos at >…

This model assumes that interstellar travel is profitable. There is no evidence that this is the case, even if we had Star Trek technology. If it isn't profitable, then it turns into a drain on the home planet. That isn't sustainable.

Drain on the home planet? I think your model of how this would occur needs updating. Let me give you a hint: Earth represents a minuscule, tiny, not even worth counting fraction of the resources readily available in the solar system.

Re: The Fermi Paradox

#106

Post by maaku »

darkmighty wrote: post #84
quotemstr wrote: post #78

Earlier quoted context omitted.

The OP's post rests on the Anthropic Principle. Essentially, we don't see evidence of a Type III civilization because anyone who dies is very quickly thereafter consumed by that civilization as it expands across the observable universe. It's a terrifying idea.

Note those are two distinct explanations. OP's point about the speed of light explains only why we're not observing any civilization from the last 50,000 years, while the anthropic principle and the "quick, devouring species" assumption explain why no alien life exists at all in our past light cone.

Yes, and those were both my points :)

Re: The Fermi Paradox

#107

Post by danieltillett »

maaku wrote: post #102
danieltillett wrote: post #56

Earlier quoted context omitted.

I actually posted about this very topic a few days ago here. Once you have von Neumann machines spreading they will take over each new star system pretty much as soon as they reach it. Assuming the von Neumann machines are small and are being powered by an energy source (i.e lasers) from their origin star system they will spread through the galaxy at close to the speed of light. This spread method creates an interest…

Another testable variation of this is the gravitational effect of voids. Voids[1]are regions of the universe devoid of visible matter (stars), as far as we can tell. These are predicted by the inflationary model as regions of low energy distribution in the early universe. But if we find a void that appears to have gravitational effects on its neighbors, what an astronomer might call "a concentration of dark matter",…

Another testable variation of this is the gravitational effect of voids.

Yes, the only problem might be that we don't yet have a good explanation for dark matter so it would be hard to know if a void with mass is due to a Type III civilisation or just a local concentration of dark matter. A spiral galaxy with a perfectly spherical void would be pretty hard to explain as anything other than the result of intelligence.

Re: The Fermi Paradox

#108

Post by MrBra »

Think of something like the "Human Brain Project" [1] scaled to what it could become after evolving/improving/growing for 3.2 billion years..

[1] humanbrainproject.eu

Re: The Fermi Paradox

#109

Post by maaku »

joe_the_user wrote: post #22
maaku wrote: post #10

The "we are the first" argument seemed less convincing than it could have been. A better argument from that perspective is the observation that Type III civilizations expand at an alarming rate. Whatever the motivation for expansion[1], basic simulations and back of the envelope calculations show that even with technology we could imagine building in the not so distant future, humans could expand into the cosmos at >…

I feel there's a language used here to conceal some questionable reasoning; "Why don't we see a civilizations spanning a galaxy? How would that work? No idea but why don't we see it?" We could ask why we don't see Lovecraftian gods or giant life forms that each stars. We don't know how that works either.

We have plenty of ideas for how that would work. Are you familiar with a Dyson sphere? A Type III civilization is just a Dyson sphere around every star in the galaxy.

Re: The Fermi Paradox

#110

Post by maaku »

sampo wrote: post #20
maaku wrote: post #11

Earlier quoted context omitted.

A very short distance. IIRC something like 20 or so light years, but I'm having trouble finding the citation. That's for radio waves (and the number is getting smaller as the technology is getting better -- EM radiation blasted into the universe is considered waste by hardware engineers). For direct detection of life, that's still an open question. I remember a poster done by a grad student who looked at whether life…

The chemical composition of Earth's atmosphere (21% O2) is so far away from a long term chemical equilibrium, that any current astrobiologist would interpret it as a sign of planetary scale life. (And correctly so: the oxygen was produced by life.) So life on Earth is pretty visible from the other planets in our solar system. And spectroscopy to observe the composition of atmospheres of planets orbiting the nearest s…

Meh, it's a long way from saying that "we don't know how the O2 could have been produced except by life" to "the O2 was produced by life." Just look at the current debate about methane on Mars.
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