are we alone in the universe?

[KenWittlief]

Originally Posted by Marc P.

...Also, the assumption that all life is based on DNA is a bit presumptuous. They key words are "life as we know it." Like Ken, I don't want this to become a religious debate, but let's say for the sake of argument that life on earth did start from a spontaneous chemical reaction, producing bacteria which then evolved into higher life as conditions became more favorable. Given that if all life rose from simple amino acids and then bacteria, it only makes sense that all life here would share the same structure in DNA. However, the theoretical existence of silicon based life-forms means there may be life in places carbon-based life couldn't possibly survive. In any case, my feeling is there's really not enough data either way to draw any sure conclusions.

it may seem presumtuous at first, but DNA based life is the only form of life in existance on the earth, the moon, on Mars - everywhere we have been able to investigate so far

and its incredibly complex. If simpler life forms could exists then probability says they would have spontaiously been created long before DNA life would, and there would be billions and billions of different life forms - all based on different molecular arrangements

but we find none, nothing here, only DNA life

now if lifeforms other than DNA based can exist, but they are more complex than DNA, then the probability equations hold true for them. They would be even more unlikely to spring into existance spontainously than we were

so (according to statisics) they are not out there either.

[mechanicalbrain]

Originally Posted by KenWittlief

it may seem presumtuous at first, but DNA based life is the only form of life in existance on the earth, the moon, on Mars - everywhere we have been able to investigate so far

and its incredibly complex. If simpler life forms could exists then probability says they would have spontaiously been created long before DNA life would, and there would be billions and billions of different life forms - all based on different molecular arrangements

but we find none, nothing here, only DNA life

now if lifeforms other than DNA based can exist, but they are more complex than DNA, then the probability equations hold true for them. They would be even more unlikely to spring into existance spontainously than we were

so (according to statisics) they are not out there either.

However.... i think certian material made today merit attention. there are materials with a "memory" for their shape. i know it may not merit much at first glance but neither would amino acids to an alien. also if their is life like us than they probably wont be the ambasidors for their kind. look at our robotic research is the human race that far a way from giving birth to a mechanical life. and if so will they have a glowing red light that goes back and forth accross their faces. yes deep questions are these. and in responce to the last post the statment was that we didnt know how amino acids were created not DNA.

[KenWittlief]

Originally Posted by mechanicalbrain

...in response to the last post the statment was that we didnt know how amino acids were created not DNA.

it becomes a chicken/egg problem. DNA based single cell organisms can take oxygen, carbon, hydrogen... and build its own amino acids, its own protien strands, and create a complete perfect copy of itself

but anything less than that one cell organism cant - cant build any of the molecules needed

so that puts you back down to random chance - back to the 1E350 probability of it happening at random

it only has to happen at random once, in the right place, and the spark of life is ignited. All life on the planet can be the result of that one spark

but it has to happen spontainiously at least once.

[mechanicalbrain]

first of all viruses can be considered to do those things and what i ment was i was responding to the statement that we didnt know how amino acids were created.

[KenWittlief]

If I understand it correctly, viruses dont reproduce themselves, they infect a DNA based lifeform and cause it to reporduce the virus (RNA strands) instead of reproducing DNA - so a virus could not be first, without DNA cells to reproduce them

most likely a virus is a mutation of a DNA cell that causes DNA cells to become corrupted.

I have to take off and dont know if I will be back online this weekend.

Its not really my intention to convince everyone that my ideas on the webpage are absolutely correct. The main thing is the idea that life is rare, and that possibly the earth contains all the life there is

I know that is a big leap for most people who want to believe in star wars and star trek like galaxies, but science is cold and un-emotional. The facts are what they are.

I did some surfing on the web and found a few other sites that explore the same idea from different angles. As I have time I will update us-spark.com and include links to those sites.

Like the name implies, the concept is a spark, a hope of starting a new way of thinking - a new level of responsibility for humanity.

If it doenst sit well with you for one reason or another, thats ok. Im not thinking in terms of individuals, or of today or tomorrow. The idea of humanity spreading life throughout the galaxy pushes you out into the realm of the universe, into a task that will take millions of people to engage, and might take a million years to accomplish.

[Alan Anderson]

Originally Posted by KenWittlief

it becomes a chicken/egg problem. DNA based single cell organisms can take oxygen, carbon, hydrogen... and build its own amino acids, its own protien strands, and create a complete perfect copy of itself

but anything less than that one cell organism cant - cant build any of the molecules needed

Viruses reproduce just fine with only a fraction of the complexity of a full-blown cell. They can't do it without the proper conditions, but given the appropriate environment they manage. Mitochondria are an interesting example as well, as they appear to be genetically distinct from the cells they inhabit.

Amino acids are easily created in the laboratory using chemicals and processes intended to mimic the young Earth's environment. Some of them combine on their own to form peptides, and given enough time there's a nonzero probability that relatively complex molecules will arise just from random mixing. Hundreds of thousands of years of such mixing is going to yield a lot of potential precursors to life as we know it using non-living processes. It's not much of a stretch to imagine a short chain of RNA that spontaneously duplicates in the presence of the right mix of amino acids.

Why don't we see this happening in the laboratory, or the wild, now? In the lab, there arguably hasn't been enough time for it to occur at random. In the wild, the environment is no longer amenable to such processes.

[KenWittlief]

Originally Posted by Alan Anderson

Viruses reproduce just fine with only a fraction of the complexity of a full-blown cell. They can't do it without the proper conditions, but given the appropriate environment they manage.

maybe Im not understanding this correctly, but from the way I read it, a virus on its own cannot reproduce, there has to be a full (DNA) based cell for it to infect or take over. A virus is like a parasite, it cannot exists (spread) by itself - it needs the higher lifeform (the DNA cell) to propagate

or am I missing something?

http://biology.about.com/library/weekly/aa110900a.htm

[MrToast]

I'm jumping into this thread a bit late, but I have to ask....

What would it matter if we find other signs of life? If we do find any other signs, they'll almost positively be in some form of non-natural radiation (ie decodable radio signals, etc). However, if we do find anything like that, it will have come from so mind-bogglingly far away, that our 1E350th children probably wouldn't even meet them.

Yeah it'd be cool to know we're not alone, but in the end, you end up knowing no more than when you started. Just that someone up there has got a big radio.

Dave

[KenWittlief]

from the perspective that I tried to convey on the us-spark.com site, if we know for certain that we are not alone, then one major issue is different

look at it this way. If my wife and I are one of 6 billion people on the planet, then what we do as individuals is not really that important in the larger scheme of things. We could have a family or not, do what is most important to us as individuals.

But if we know we are the last two humans on earth, then we would have a very strong direction to re-establish the species, to have as many children as possible

same with our planet as a whole. If everything we are able to measure and observe tells us we are alone in the galaxy, or the universe, then we have a responsibility to ensure the survival of life, because we have control over all life.

thats why its important to know.

[Francis-134]

Personally, I believe that there is life outside of Earth that we have not found. We probably haven't heard from them because they can't "see" us, or they are activly trying to not contact us. For the relativaly short period of time that we have been transmitting radio signals (50 years) its no wonder no one has found us. It is really possible that the first, relativly weak radio signals have remained at a reasonable strength for ET's to recieve it and understand it? And even if they did get it, why would they want to visit us?

[sciguy125]

Let's consider this for a minute:

Assume that the universe has a finite lifespan, but time is infinte. Every something-billion years, someone hits the reset button and everything starts over. Let's also assume that it has different inital conditions each time. We now have a random universe generator with infinite trials (not necessairly infinite initial conditions though).

We know for a fact that AT LEAST one of these universes supports life. Any universes that don't support life would go unnoticed. Those that do support life will probably contain beings having the same discussion we are right now. This means, however, that life isn't that improbable. If the universe doesn't support life, there's nobody around to care. The only universes that have beings to define the improbablity of life are those that support life anyway.

I know it doesn't address the original topic, but it's something to think about...

[KenWittlief]

Im hoping to get some free time to add more to the us-spark web site. I think the idea that some aspect of the universe is god-like permeates human thinking

and I think infinity is one of those aspects - if we can somehow involk infinity into the equation, making the universe infinitely large or infinitely repeating, then we are saved in a way, because we have this unlimited amount of time or matter or energy

so whether you apply these god-characteristics to a conscious being and call it God, or you apply them to the universe, and say the universe is unlimited in some way, isnt that really like throwing your hands up and saying "I dont have to worry about this because God or the universe will take care of it for me".

?

The laws of physics as we have been able to observe them require that space and even time itself did not exist before the big bang - so there was a discontinuity there. The universe cannot collaspe back in on itself and start over, because time and space are already in existance now, they did not exist before the big bang. We can never get back to those initial conditions.

Besides, the universe expansion has been measured, and it is expanding too fast to fall back in on itself.

[mechanicalbrain]

i know Ive pointed this out before (looks back yep definitely said it) but due to the vast amount of undiscovered molecules and forms of planar existence (I'm talking about general things that exist out their) that we know nothing about and due to the fact that if life is like us it means the life form would have to develop in very similar conditions as us I'm willing to bet all my worldly possessions that any "being" (the quotes are their for a reason) we discover will be very different than us and almost guaranteed to be overlooked as intelligent maybe it wont even have any form of "thought'. our ideas of aliens are limited to the examples of life found around us and are thus almost guaranteed to be wrong. anything a terrestrial animal has is in no way needed for an alien. an alien might lack a circulatory or nerves system it might not even have a body. a great example to their potential abstractness is the virus. scientists are debating if a virus is a living organism. it pushes the bounds of what we consider life but what if somethings not even in those bounds (cold you have for example life that has no body or maybe lack a recognizable brain). and finally I'm curious to what constitutes intelligence. the only thing that truly makes us a thinking being as apposed to lets say a chimpanzee is a more developed prefrontal cortex (the tool using and adaptation part of our brain) the main difference that sets us apart from other primates.

[KenWittlief]

so, from what you have said, it sounds like we really need to define the words "life" and "intelligent" before we can determine if those things exists outside our planet.

Id be hesitant to delve into matter and molecules or forms of energy that do not exist here on earth. We can fill in the periodic table of elements with all the reasonable combinations, from one proton and electron up.

but if forms or states of matter and energy exist outside our solar system, which we cannot observe or interact with, then I dont see the rational behind that

why would basic laws of physics or types of matter exist in one part of the galaxy, but not be present here?