I'm curious what an advanced alien species would think if they saw a wooden satellite. Would they be able to extract the DNA and think that it's something humans created, same as the code on the CPU? Or would they just think the wood is some type of synthetic like fiberglass?
Maybe worth remembering that "trees" have evolved many times on earth. i.e. trees do not all share a common tree-like ancestor. The woody-trunk-and-branches pattern was just useful enough that it evolved many times. Which makes me suspect that aliens would likely have something tree-like on their home world, and would have also learned to build using it.
IMO it's likely that alien life would mirror the life we have here in a lot of ways. It's likely that aliens would have DNA or RNA, and would be made out of cells (unless they've become machines). So I think they would be pretty likely to understand what they are looking at given a bit of time for analysis.
The reason aliens are likely to be made out of DNA and have cells is simply that those things tend to naturally come to exist in our universe. We don't really have any evidence that any other chemistry (e.g. silicon-based) can produce life in this universe. If DNA-based life comes about elsewhere in the universe, it won't look exactly like us, but that life is also likely to have both plants and animals, just because life tends to try to fill every available evolutionary niche.
> The reason aliens are likely to be made out of DNA and have cells is simply that those things tend to naturally come to exist in our universe.
I think you are confusing carbon-based life with DNA-based life, for which N=1, the Earth. There is absolutely no evidence that DNA exists anywhere else. I'm prepared to accept the argument that carbon+water is a good basis for life, but this does not inevitably lead to DNA-based replicators.
Ha, interesting proposition. What do you think would be the alternative to DNA? I'm curious as I'm a complete layman. Intuitively, I'd think that a self replicating life form will need something to carry it's program, and this is what DNA is. Alien life might use different molecules to carry that program, but conceptually it would be the same, no?
I'd even go as far as to say that DNA arose out of the fact that carbon based chemistry is good for life (we see N=1 case at least), and once we accept carbon based chemistry, amino-acids are the next optimal step, followed by something like the DNA to program the construction of proteins for amino acids.
Again, I'm just a layman so it'd be nice to know the views of experts in this area.
> I'd think that a self replicating life form will need something to carry it's program,
Well yes, for sure, a replicator needs some sort of 'program', and if you go for carbon+water, amino acids are a good bet.
> and this is what DNA is
Yes, on Earth. But the actual horrendously weird and complex molecule Deoxyribonucleic acid is not the only way of implementing such a program. Check out a text such as 'How Life Works: A User’s Guide to the New Biology', by Philip Ball to see why I'm being picky here.
I think that the only thing that is inevitable is complexity changing over time. My first thought was maybe there could be a more distributed sort of "program", but maybe we already have that - either evolution itself, or if evolution somehow isn't inevitable, something that bootstraps or otherwise facilitates it.
Imagine yourself existing on a microscopic scale, with your current consciousness intact. You'd look into the 'sky' and see an organelle membrane or nuclear envelope... what would your concept of the "program of life" be, while existing adjacent to DNA itself? Would this activity look a bit like some of the natural processes we witness and take part in on Earth?
> IMO it's likely that alien life would mirror the life we have here in a lot of ways. It's likely that aliens would have DNA or RNA, and would be made out of cells (unless they've become machines).
This is very, very, very much "in your opinion". It's not impossible that you're right, but there is no plausible basis for saying "it is likely".
Wooden boxes in space seems to me to have the potential of the Flinstone's car. It's techy thing in the lowest tech possible to the point of being comedic. So when aliens find our wooden satellites, they'll think what kind of redneck uses wood? Have they not found metal yet?
Maybe I've consumed too much Douglas Adams type of humor
Define « too much ».
I don’t disagree with you that we are currently only looking for life like our own, but « too much » makes it sound like this is some form of short sightedness, whereas it’s just that trying to find something we can’t define is basically impossible.
We can define life as it is on earth, and we have proof it’s possible.
It might be an outlier form but it’s the only one we can effectively look for.
Why not? The only thing you need to prove is that this is the most energy advantageous process for the common components of life that produces a reliable and durable self replication. The amino acids might be different but even there it’s only physics there are only so many likely permutations.
And as far as intelligent (technological intelligence) biological life it’s more likely than not to be far more similar to us than completely alien.
It would have to develop on land or at least be able to transition to land at some point. Can’t have complex chemistry under water, can’t have fire can’t have metallurgy.
Vision in a spectrum similar to us or higher is pretty much a must, both as a requirement for higher brain development as well as to actually be exposed to all that information. A star fairing civilization that can’t see stars isn’t likely to develop and as far as odd spectrums go RF and Xray might be able to see stars but not predators so it unlikely to develop in the first place.
Appendages that allow fine tool development is pretty much a must for incremental technological development also.
Gravity at least at the upper bounds would need at minimum to obey the rocket equation any world with heavier gravity than that would allow that wouldn’t likely to produce a space fairing civilization.
Lower limits might be imposed on powered flight and missile weapons that may be a required developmental phase also.
And as far as planetary makeup goes then again should be rather similar including likely evolutionary phases that would produce large fossil fuel deposits.
Atmospheric oxygen is also a must no oxygen no fire.
As for as other elements enough metals to support a technological civilization as well as possibly enough fissile material for at least a partial nuclear phase tho lack of fissile material might put developmental pressure on the fusion part of the tech tree so there is some wiggle room.
Your argument makes interesting observations, but relies on Earth-centric assumptions. For instance, the requirement for land-based development of complex chemistry and metallurgy assumes there couldn't be alternative pathways in different environments. We already see complex chemistry happening in deep-sea hydrothermal vents that challenges our assumptions about where complex processes can occur.
Similarly, the needs for human-like vision or specific tool manipulation may be limiting our analysis. Consider how bats and dolphins build sophisticated mental models of their world through echolocation, or how octopodes demonstrate problem-solving abilities with fundamentally different appendages than ours.
Given we only have one example of technological civilization, we should be cautious about declaring which features are truly universal requirements versus those that just happened to work for us. There might be paths to advanced technology that we haven't yet conceived.
