Life as we do not know it: What would aliens really look like?

[Megatron]

I've been reading a book called "Life As We Do Not Know It" by Peter Ward and he talks about the possibility of alien life forms on other worlds, including on bodies of our own solar system. Of course, not necessarily intelligent ones, but other life forms native to other planets.

Some points I found interesting was that he tries to address the possibility that life on Earth might have originated in the atmosphere (or in space), that life on other worlds may not be DNA based, and panspermia (the idea that the materials necessary for life struck several planets at once in the solar system).

I've barely scratched the surface of the book, but I'm finding it an interesting read. Another thing that it addresses is that maybe the reason we haven't found any life beyond Earth yet is because we are looking for the wrong things (he uses SETI as an example).

[freeztar]

It seems like an interesting book, although purely speculative.

The formation of life here on Earth is yet unknown. Was it God? Or was it a chance occurrence of radiation and elemental bindings? Or was it both? It could have been from a starseed or even seeded from an alien culture. Very interesting to think about...

I'm particularly interested in the last sentence you posted. What alternative search methods does he suggest?

[Megatron]

Well, anything regarding aliens, future tech/societies, etc is purely speculative. But I find that his arguments hold water so far.

The formation of life is as of yet unknown but there are some good theories talked about in the book, and many scientists doubt that "Darwin's Pool" was the way it was started. (Darwin's Pool is basically a pool of organic goop from which the one common ancestor of all life forms was born, it cannot exist at environments extreme for modern day life forms).

The most talked theory are the ones that hypothesize that life (or the essentials of life) might have come from space during the early days of Earth, as it was being bombarded by comets and asteriods. Extremophiltes are believed to be dominant in that era because of the high temperatures that were common in early Earth. He talks about the possibility that they probably existed on early Mars and maybe even Venus.

They also talk about the artificial synthesis of life and related experiments and how it may help explain how our own life came to be. The Miller-Urey Experiment is discussed and analyzed in detail in particular.

The reason all of this is important is because life on other planets might start in a completely different way than the way it was started on Earth, and may involve different chemicals. Also, it may help us to be able to identify life on another planet.

The reason he said that SETI is headed in the wrong direction because we are making way too many assumptions about the nature of intelligent life that could very well be wrong, and it doesn't really help us figure out what really is out there.

For one, I read somewhere (not in this book) that our own radio signature would not be detected even from the Alpha Centauri simply because the energies involved are much too low to be noticable under the glare of our own sun. Also, there are a whole bunch of civilizations out there that probably employ different ways of telecommunications, civilizations that may not be at our level of technology (What would aliens find if they tried to detect a signature from Earth during 1700?), civilizations advanced enough to hide themselves, etc. The list goes on and on, but given the vast possibilities this makes it very, very unlikely to find life on other worlds using current methods, never mind intelligent life.

Pretty much, SETI is trying find a needle in a haystack, and since that haystack is the size of the Universe, what chance do you have at finding anything at all? It's more productive to use those radio telescopes to study natural phenomena. Of course, I might be wrong, but I agree with this guy on the issue.

One suggestion he talks about is redefing how we define life, that life on other worlds may not have a chemistry that is anything like our own. He cites the deep sea lifeforms (the ones around ocean vents) as an example.

After all, it would be a shame if, sometime in the future, an astronaut exploring Titan steps on a puddle and it ends up eating him/her simply because we didn't know that it was alive.

[InfiniteNow]

Originally Posted by Megatron

Well, anything regarding aliens, future tech/societies, etc is purely speculative. But I find that his arguments hold water so far.

No news is good news, eh?

Originally Posted by Megatron

The formation of life is as of yet unknown but there are some good theories talked about in the book, and many scientists doubt that "Darwin's Pool" was the way it was started. (Darwin's Pool is basically a pool of organic goop from which the one common ancestor of all life forms was born, it cannot exist at environments extreme for modern day life forms).

Can you support this "many scientists" comment? It sounds a bit off to me, but I'm willing to keep an open mind in light of supporting evidence.

Originally Posted by Megatron

The most talked theory are the ones that hypothesize that life (or the essentials of life) might have come from space during the early days of Earth, as it was being bombarded by comets and asteriods.

Okay, so then... uhh... where did that life begin? Panspermia is great an all, but that too came from somewhere and via some explainable mechanism. Where are details on that?

Originally Posted by Megatron

Extremophiltes are believed to be dominant in that era because of the high temperatures that were common in early Earth. He talks about the possibility that they probably existed on early Mars and maybe even Venus.

We still have extremophiles. What I'm curious about is whether these are the same organisms from the same source (that you reference on Mars and Venus), or if they are organisms which arose locally, but had some overlapping and parellel traits and characteristics.

Originally Posted by Megatron

The reason all of this is important is because life on other planets might start in a completely different way than the way it was started on Earth, and may involve different chemicals.

Of this I have no doubt. However, I do suspect that, while the consituents and groupings of life are very different, the mechanism is much the same. Darwin's idea is pretty robust, and it works across contexts.

Originally Posted by Megatron

The reason he said that SETI is headed in the wrong direction because we are making way too many assumptions about the nature of intelligent life that could very well be wrong, and it doesn't really help us figure out what really is out there.

There are definitely limits to the current SETI approach, however, we have to start somewhere. Does the author provide any alternative approaches which would be better? Again, I'm open to new ideas.

Originally Posted by Megatron

For one, I read somewhere (not in this book) that our own radio signature would not be detected even from the Alpha Centauri simply because the energies involved are much too low to be noticable under the glare of our own sun.

A claim such as this assumes way too much for a technology about which we know nothing. Maybe using our own current technology this would not be detectable, but who the heck knows what other life in other areas of the universe (themselves still speculative) would have in terms of technology and sensing ability?

Originally Posted by Megatron

Pretty much, SETI is trying find a needle in a haystack, and since that haystack is the size of the Universe, what chance do you have at finding anything at all?

That the search is difficult is no reason to stop searching, is it?

Originally Posted by Megatron

After all, it would be a shame if, sometime in the future, an astronaut exploring Titan steps on a puddle and it ends up eating him/her simply because we didn't know that it was alive.

Now, I'd watch that movie!


Cheers Megatron. Keep your mind open and imaginative, but your feet grounded in the real.

[JamesBrown]

In the development of my own SETI station I gave a lot of thought to what ET might look like. This is what I came to:
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After looking at the software and hardware requirements for my Project Argus station, and mulling over such technical questions as integration time constant and Doppler shift correction, I have come to the following epiphany:

I must look for the most obvious signal - and that is the signal that I would choose to send myself, if I had the money to do so. What that means (and it seems obvious once put on paper) is that:

I must look for myself

Any ETI that I might hope to detect must be more like myself than unlike me, in most basic ways. Not to put too fine a point on it, but, for example, I think this ET would think in the same time frame as we do. Not at the speed of a glacier or at the speed of bullet, but somewhere near our 'thinking speed'. This is necessary to make the signal recognizable to us when finally detected.

ET's physical makeup would have to be about the same as ours. Not as small as a bacterium or as large as one of the rolling hills I can see from my window, but somewhere in-between. This would give him the same type of control over his environment, and the same capability as I have to construct the needed transmitter, which could produce a signal which I can recognize. Not all ETI need be like me; only those who I have a realistic chance of detecting.

ETI's transmitter must be an RF signal generator. Some other, more exotic form of communication may well be in use, but since I can't construct a receiver to detect exotica, it's not worth considering. This leaves open optical SETI - but not for me. I know nothing about the optics required on that scale. As a microwaver, I'll stick to the area where I have a shot at SETI success.

The signal must be a deliberate beacon. That's the only type I and most other Argus stations would have a ghost of a chance of hearing. Leakage detection seems less likely, if only because of the transmit power requirements needed to show up on my system. Detecting planetary Radar also seems unlikely, because it seems that it would only be sent for short periods. Once a radar echo was recovered, the transmitter would most likely be turned off or pointed somewhere else. The modulation scheme needed for an effective Planetary Radar might also make it difficult to recognize on this end.

I would set my beacon up in the waterhole to maximize its chances of discovery. I would want to be heard, and that is the most obvious place to start. The hydrogen line is at 1420 MHz and the hydroxyl line at 1662 MHZ. I would transmit at exactly 1/2 way between the two at 1541 MHz. (One could also make a case for the geometric mean of the hydrogen and hydroxyl lines, which is 1536 MHz. But we're splitting hairs here.) I would expect ETI to similarly transmit somewhere near the middle of the waterhole, if he wants me to detect him. Unfortunately, my Project Argus system (receiver and filter) can't tune this frequency, but if I were to make changes to my system, that is where I would choose to monitor.

An ideal interstellar beacon should be narrow band to concentrate the transmit power, and to make it distinguishable from natural sources. It must be directed at our star. This is necessary to conserve power, and to make possible reception over huge distances. So a directed beacon is what I am looking for. I can see ETI pointing such a beacon at each candidate star, one at a time, sending the beacon for some length of time, and then moving to the next star.

The above targeted beacon strategy implies that earth rotation Doppler compensation is a minimum requirement of our Project Argus receiving stations, if only to exclude local signals. Correcting for the Doppler shift due to our travel around the sun is also a requirement. I have the earth rotation Doppler chirp running now - the other compensation is an unknown quantity to me at this point, but something which Project Argus participants should be working on.

My hypothetical interstellar beacon would be locked onto each star for about a year at a time. We may have missed ETI's signal already, and may have to wait another 300 million years for it to show up again. Or, it may be starting tomorrow. Since we just don't know, we may as well assume that it starts tomorrow.

If I were sending a beacon, its transmitter frequency would be Doppler-adjusted to the Galactic center of rest. Since the purpose of a beacon is to be seen against a background of other signals, this would make it clear to anyone receiving it that it was an intentional signal. Again, I have no idea how to design this correction into my receiver chirp. If it's small (less than about 0.01 Hz/sec), no matter where I point my antenna I can't use it anyway, because my 10Hz/Bin resolution and planned 30-minute integration time constant make such small Doppler rates moot. If the compensation for the Galactic center of rest is a sizeable fraction of a Hz per second, I'd better figure out how to implement it!

My beacon would be a CW signal on/off modulated in a regular way. I might send morse code in a repetitive pattern, and I would send it at a speed slow enough to allow integration of each character, but not so slow as to allow the signal to drift across many bins during a given key-down period.

If I concentrate on looking for myself, I may well miss signals sent by those not like me. But I know that creatures who think like me exist (if only by Earth's own example.) Designing our search around those not like us involves pure speculation, and may reduce our chances for SETI success
---------------------------------

[mynah]

It has been suggested that RNA preceded DNA as the principal genetic material of life on earth, although that is no longer true for anything except some viruses. If so, such life forms were probably very simple, given the shortcomings of RNA. Could anyone suggest a plausible alternative to DNA, or even a significantly modified form of it, as a principal source of genetic coding on another world?

[UncleAl]

1) Put the first third of the Periodic Table into a sealed glass flask with elements in their relative planetary abundances.
2) Add any form of energy at any equilbiirum temp and pressure where liquid water exists,
3) Patience
4) You get out Terran biochemistry in about a week. Cook as long and hard as as you like.

You can diddle with composition, energy input, temperature and pressure. You will not change the end result chemistry in any major fashion. One could argue that chance and evolution can select for outcomes far outside Terrestrial observation. Chemistry is chemistry. The necessary complexity and information persistence of life brackets what is obtainable and sustainable under any conditions.

Inhabitants of the Mariana Trench, geothermal smokers, the Sahara desert, and Pacoima, CA vastly differ. Ditto a billion years ago versus today. For all that, Archaea to gangbangers, there is nothing astounding to be found in any of the biochemistry or genetics. Cell organization differs, cell membrane chemistry differs, enzymes differ... but nobody is going to say "this doesn't belong here." One of the most destructive seaweeds, Caulerpa taxifolia, is a single cell. It is aggressive, invasive, survivable... and big,

Caulerpa taxifolia - Invasive Aquatic Plants of the United States
Facts about Caulerpa taxifolia - February 2003

Just another day at the office.

[mynah]

It is likely, though, that all life we know on earth today originated from a single source. That is not to say that there has never been any other life - just that this organism and its descendants were more successful, and prevailed over whatever else was around. On another planet, one of those other life forms may have made it to the top, especially if Daddy DNA happened to turn up late or never.

BTW, I'm not saying you're wrong - some of those green algae are amazing - but I find it hard to believe that Caulerpa taxifoliais a unicellular organism. You have any links to info about that?

[UncleAl]

Google
Caulerpa "single cell" 1660 hits

Caulerpa is a multinucleated single cell organism, a big one! Fragments are totipotent - they seal, heal, and start growing.

[mynah]

Thanks - here's a reference - it just seemed so unlikely. Goes to show again, you don't need to leave earth to find the stuff of science fiction!