The problem I have with their theory (and don’t get me wrong, I LOVE how they made their argument) is the rapid expansion rate of these grabby aliens. I just don’t think expansion at that significant percentage of the speed of light is realistic. Of course, I could be wrong.
So I tend to look at it as a ‘reductio ad absurdum’ argument meaning there are not many alien civs out there right now.
I do think that the expansion rate would be slower than most of the grabby aliens proponents, but I also don’t know what kind of propulsion technologies we may have in 10,000 years.
But, the idea is that they would be expanding at whatever rate is feasible given the laws of our universe and inherent limits of technology.
I haven’t studied it intently…just read about it and watched a couple vids.
IIRC (and I may not)…they HAVE to be expanding very rapidly at a large % of the speed of light according to the logic used. If it was is slower, like you expect, their theory breaks down as we would see abundant evidence of them and the theory doesn’t work. It is a conclusion of their findings. Which, I think, is possibly/likely makes it reductio ad absurdum.
Well “intelligence is a rare commodity” is always a safe statement to assert!
Agree. “Intelligence” defined as say level of say primates is rare in the history of the one planet that we know has the capacity to develop our sort of technologically capable human sort of intelligence. And the window of time that our level has been here is insignificant … and may snuff itself out before long.
It may be that intelligence is not something selected for under most circumstances, and that technologically advanced intelligence is an evolutionary dead end, destroying itself before being there long. Depressing. Hope we prove me wrong over time, but looking at climate change and blowing past 1.5 as a near given at this point, Putin threatening nukes, it may be kooky to believe otherwise over the next few hundreds of years.
It seems like trying to resolve an unknown by appealing to another unknown. How fast could a hypothetical space-faring civilization go? We don’t know. But we absolutely do know, based on how fast a hypothetical space-faring civilization could go, that (a) there absolutely are not any other space-faring civilizations out there yet because some of them at least should have been here by now if there were. Or that (b) there absolutely could be space-faring civilizations out there and it’s just that we couldn’t possibly have had a chance to meet them yet.
Somehow, everyone is certain that the answer is (a). Unless of course they are certain the answer is (b).
Except no one has a basis on which to claim certainty or knowledge on either because the question of how fast a space-faring civilization might realistically travel is presently unknown by us, reducing it all to speculation and conjecture.
That’s not the argument. The argument is that there are not any within range of having reached us yet, or they would be here by now.
Nah, most people arguing for (a) are pointing to the evidence that makes it seem highly unlikely. It’s not the kind of absolutism that tends to be alleged like in this post.
No one has provided any evidence for extraterrestrial intelligence, and no one has provided any adequate explanation for the lack of evidence. The best anyone has done is an argument of incredulity, in that they cannot imagine a future species expanding into the universe, even though they also cannot imagine any good reason as to why not.
The idea with grabby aliens, and any conjecture when we are talking about that far in the future, the speed that they are going would be the maximum speed feasible given the laws of physics and limits of materials. It’s enough time that propulsion would be optimized and would be as good as it can possibly get.
The grabby aliens proponents seem to think that maximum limit is up close to the speed of light. I’m more skeptical about achieving those speeds, and don’t think that anything remotely close to those speeds is necessary to end up populating the galaxy and observable universe.
Though I used to believe that the possibility, or even probability, of intelligent ET existing or having existed, I just reread Stephen Webb’s If the Universe Is Teeming with Aliens … WHERE IS EVERYBODY?: Seventy-Five Solutions to the Fermi Paradox and the Problem of Extraterrestrial Life https://www.amazon.ca/Universe-Teeming-Aliens-WHERE-EVERYBODY-dp-3319132350/dp/3319132350/ref=dp_ob_title_bk. The description of the construction and workings of DNA has swung my opinion to highly improbable. The inherent complexity, by sheer chance, coming together, just seems like something close to impossible. At the same time I assume that some other version of something functionally the same as DNA may be possible. Disclaimer: IANA chemist, or biologist or anything remotely related.
That’s an abiogenesis argument that leads to it not just being intelligent or spacefaring life being rare, but life itself.
If it really took a chance combination of a bunch of random amino acids to come together to form the first RNA, then we are looking at an extremely unlikely event, one that wouldn’t happen in the observable universe more than 1 time in quintillions.
Given a large enough universe, it’s still going to happen, somewhere. And anywhere it would happen would find itself the only life for further around it than it can conceive.
I’m of mixed minds on that one, but it’s also one that should be getting a lot more evidence for or against in the relatively near future, as we probe Europa and Enceladus for signs of life. I’m in the life is common but intelligent life is rare camp, but we will know more soon.
One interesting factor is that all of the various constituent bases in DNA have now been discovered in meteorites, and that suggests that they form abiotically in deep space with relative ease. The first step on the ladder seems to be one that can occur almost anywhere, at any time.
A lot of these arguments focus on why a future version of humans couldn’t colonize the galaxy. Maybe we wouldn’t want to. Maybe we couldn’t travel fast enough. Maybe we couldn’t retain our culture. Maybe we couldn’t gather enough resources to sustain us on the journey. These are all valid points.
Some arguments even suppose aliens. Maybe they destroy themselves before being able to achieve interstellar travel. Maybe they aren’t expansionist. Maybe only 0.0001 percent of colonies survive. Maybe they grow inward into computer simulations.
These are all valid points. The crazy thing about the Fermi paradox is this:
The Milky Way is 14 billion years old. It contains 200 billion stars. There is no mechanism that we know of or can even imagine that could decolonize a galaxy. If it ever happened once then they would be here to stay.
Galactic colonization doesn’t seem to have ever happened. Not a single time.
You need an explanation that not only explains why WE would fail in this. It must explain why hypothetically billions of attempts, by billions of species attacking the problem from wildly different angles, would all end in failure for 14 billion years straight. It would only need to succeed one time and it seems it never did.
Personally I believe the filter is behind us and life in the galaxy is shockingly, incredibly, rare. I wouldn’t be surprised if we are the only technologically advanced life in the history of the galaxy.
I’m in agreement with this. The explanations offered need to either explain why it is physically impossible for humanity to colonize outside the solar system, or explain why humanity is unique and is the only species that would even try.
Sometimes I do worry that intelligent species are simply doomed to inevitably kill themselves off before they develop robust space infrastructure, which is why I will feel much better about our prospects once we have a self contained off-world settlement.
Yes, that is the horrible thing about it. As I originally mentioned I used to think the opposite. And for the coolness factor I would love it if life was found under the ice on Europa or whatever. But, sadly, I fear that that won’t be the case, which illustrates how horrible it would be if Earth was the only location of life, and we wiped it out.
Apparently a very simple reaction that can be done in a high school chem lab. Put the right chemicals (all of which are found in asteroids) on a slab of basaltic glass (also found in asteroids and common on planets), wait a while, and you get RNA.
RNA at least is therefore likely to be extremely common throughout the universe.
Furthermore, the strands created are long enough to support Darwinian evolution, which might have created a pathway for DNA and complex life.
That’s why we need to go look. Personally, I think the greatest information as to what life is out there in the universe will be largely informed by what we find on those two worlds.
Sure, but does it code for anything? You can slam nucleotides together to make RNA all day, but if it doesn’t code for anything, it’s just random chemical junk.
To return to the basics of this subject - it’s perhaps less about the Fermi Paradox (well where are they?) than the Drake Equation:
N = R × fp × ne × fl × fi × fc × L*
N, the number of civilizations currently transmitting signals, depends on seven factors:
R* is the yearly formation rate of stars hospitable to planets where life could develop
fp is the fraction of those stars with planets
ne is the number of planets per solar system with conditions suitable for life
fl is the fraction of planets suitable for life on which life actually appears
fi is the fraction of planets with life on which intelligent life emerges
fc is the fraction of planets with intelligent life that develops technologies such as radio transmissions that we could detect
L is the average length of time in years that civilizations produce such signs
The Drake equation is more about making our ignorance explicit than anything else.
The op is jumping all over the fact that we now know marginally more about the variable that we’re already the ones that we were least ignorant about. R, fp, and even ne, may be very large numbers. No huge shock.
The numbers that we have no clue about are the ones that follow.
Let’s guess that fl is reasonably large. Life of some sort is wide spread.
Now let’s guess at fi, fc, and L.
Our n of 1 is that life was here just fine for something like 3.6 billion years (give or take a hundred million or so) before anything close to intelligent life developed. That’s a long time even on the scale of the universe as we know it. Clearly life does not necessarily select promptly for intelligent life. It took a long time for the circumstances that did give it rise to happen in the one place we know it did.
And developing civilization, let alone ones capable of technology that could be detected across the stars? Only just happened really. And technology? Not even an eyelid flutter of time of all life on this planet. Life existed mostly without intelligent life. Intelligent life existed mostly without civilization. Civilization existed mostly without detectable technology. And so far we’ve existed without expanding beyond our planet let alone beyond our star.
L for us is less than a century. And indeed may be a short period going forward. We don’t know. It took us this long to get here to start the L clock going. Even if given enough time the path of life to intelligent life to civilization to technologically detectable civilization always happens we have no way of knowing that it doesn’t always happen with at least as much time as it took here and that information still needs hundreds of thousands of years to get here from other early achievers who did not destroy themselves quickly.
It seems to me to be kooky to assume anything about fi, fc, or L. The fact that life has mostly existed without intelligence here, intelligence without civilization mostly, civilization without that level of technology mostly, to me argues against those having big values.
Thank you kindly! Watching now.
IIRC I thought it was noted that even at slow rates, on timescales of millions of years (very short for the lifespan of the universe) it doesn’t matter. Light speed, half light speed, 1/10…it doesn’t really make a difference on these timescales.
That’s for the Fermi Paradox itself. For the grabby aliens scenario, the idea is that they are traveling fast enough that you don’t get much if any warning before they are upon us.
Like I said, I agree with a fair amount of their points, but I’m not so sure on that one.
You make some good points but the inverse square law is missing from that equation. I believe that ended up being one of the least obvious factors of a project like SETI failing.