Are They Really There?
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Life is Easy to Make:

Since 1953, with the Stanley Miller experiment, we have, or
should have discarded the theory that we are unique in the
universe. Production of organic life and even DNA and RNA
have been shown to occur in simple mixtures of hydrogen,
ammonia, methane and water when exposed to an electrical
discharge. The existence of most of these components has been
frequently verified by spectral analysis in distant stars
but, of course, we can't see the star's planets. Based on
the most accepted star and planet formation theories, most
star systems would have a significant number of planets with
these elements and conditions.


Quantifying the SETI

A radio astronomer, Frank Drake developed some equations that
were the first serious attempt to quantify the number of
technical civilizations in our galaxy. Unfortunately, his
factors were very ambiguous and various scientists have
produced numbers ranging from 1 to 10 billion technical
civilizations in just our galaxy. This condition of a
formula is referred to as unstable or ill-conditioned
systems. There are mathematical techniques to reduce the
instability of such equations. I attempted to do so to
quantify the probability of the existence of intelligent
life.

I approached the process a little different. Rather than
come up with a single number for the whole galaxy, I decided
to relate the probability to distance from Earth. Later I
added directionality.

Using the basic formulas Drake used to start, I added a
finite stochastic process using conditional probability.
This produces a tree of event outcomes for each computed
conditional probability. (The conditions being quantified
were those in his basic formula: rate of star formation;
number of planets in each system with conditions favorable to
life; fraction of planets on which life develops;
fraction of planets that develop intelligent life;
fraction of planets that develop intelligent life that evolve
technical civilizations capable of interstellar
communications and the lifetime of such a civilization).

I then layered one more parameter onto this by increasing the
probability of a particular tree path in relation to one over
the square of the distance. This added a conservative
estimate for the increasing probability of intelligent life
as the distance from Earth increases and more stars and
planets are included in the sample size.


I Love Simulation Models

I used standard values used by Gamow and Hawking in their
computations, however, I ignored Riemannian geometry and
assumed a purely Euclidean universe. Initially, I assumed
the standard cosmological principles of homogeneity and
isotropic distributions. (I changed that later) Of course
this produced 1000's of probable outcomes but by using a
monte carlo simulation of the probability distribution and
the initial computation factors of Drake's formula (within
reasonable limits), I was able to derive a graph of
probability of technical civilizations as a function of
distance.

100% | *
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0% |_____________________________________

Distance -->



But I Knew That

As was predictable before I started, the graph is a rising,
non-linear curve, converging on 100%. Even though the
outcome was intuitive, what I gained was a range of distances
with a range of corresponding probabilities of technical
civilizations. Obviously, the graph converges to 100% at
infinite distances but surprisingly, it is above 99% before
leaving the Milky Way Galaxy. We don't even have to go to
Andromeda to have a very good chance of there being
intelligent life in space. Of course, that is not so unusual
since our galaxy may have about 200 billion stars and some
unknown multiple of planets.


Then I made It Directional

I toyed with one other computation. The homogeneous and
isotropic universe used by Einstein and Hawking is a
mathematical convenience to allow them to relate the
structure of the universe to their theories of space-time.
These mathematical fudge-factors are not consistent with
observation in small orders of magnitude in distance from
earth - out to the limits of what we can observe - about 15
billion light years. We know that there is inhomogeneous or
lumps in the stellar density at these relatively close
distances. The closest lump is called the Local Group with
22 galaxies but it is on the edge of a supercluster of 2500
galaxies. There is an even larger group called the Great
Attractor that may contain tens of thousands of galaxies.

By altering my formula so that I took into account the
equatorial system direction (ascension & declination) of the
inhomogeneous clustering. Predictably, this just gave me a
probability of intelligent life based on a vector rather than
a scalar measure. It did however, move the distance for any
given probability much closer - in the direction of clusters
and superclusters. So much so that at about 351 million
light years, the probability is virtually 100%. At only
about 3 million light years, the probability is over 99%.
That is well within the Local Group of galaxies.

When you consider that there are tens of billions of stars
within detection range by Earth and some unknown quantity
beyond detection, the formula to quantify the number of
technical civilizations in space results in virtually 100% no
matter how conservative you make the input values. It can do
no less than prove that life is out there.

so?
we are kinda like an ant-hill in a remote part of the amazonas.
there are many humans not that far away yet no1 steps on us.

statistics are just what they are.
every this or that male is gay(while people around me are not gay
{not that there is anything wrong about being gay}

while if i went to a gay bar all present besides me are gay.

maybe earth is in the wrong side of the cosmos?


while all the others are crammed in a tiny portion having chats all day long?

Moses
You can estimate with figures till your heart is content. But garbage in makes garbage out. There are factors not taken into consideration. In the Drake equation, how many stars do you estimate contain life? Are you certain that this figure is accurate? How many stars that contain life harbor intellegent life? Once again, are you certain? You see no matter how you answer this question you can not know the answer. If you did you would not be trying to say how many are there, you would know. So what you come up with is a guess, no better nor worse than the next ones guess. All are unproven.

Hello Moses, welcome to sciforums. Have you heard of a statistian who drowned trying to cross a river...an old story...If the very assumption of sample distribution is wrong, then all results are unreliable. We do not have enough data to extend our part of the world to the universe.

So, it is neither here not there....until we get the data....

It is a common complaint that statistics or any estimation of what "might be" has little value since it is only as good as the imagination of the analyst. I have a slightly better view of the process.

When we cannot see something but we can imagine what it might be like, it gives us a starting place to look for hard evidence. The list of discoveries that have been mad with this approach is long and includes a good deal of work that has been done in the areas of astromony and cosmology.

After all, a "theory" is, in fact, our guess at what might be true and then we go seek proof. Like the "Theory of Evolution".

I would rather speculate with numbers and my imagination on what "might be" rather than not seen anything except that which can be "proved".

OBTW, Drakes formula does take into account things like how many worlds might have developed life, how many of those might have developed intelligent life and how many of those might have developed the ability to communicate and/or travel across the cosmos. His formula was based on a lot of data collected from our own planet history, science, chemistry, biology and observations of the cosmos. It is still conjecture but it happens to represent the best we can do for now until we can actually see or meet the "others".

Moses

Thank you, Moses. That was preciously the point.

As you see I disagree with your assumptions on this one. The next may find me in total agreement. Don't think you were picked on for your post. Rather it is the posts that drives the forums. The next one may find everyone against my thoughts. Such is life.

On this subject Carl Sagan addressed many of the questions. Astronomers point to the major factors of life that will probably never contact us. First we are dealing with imense distances. The nearest star is 4.2 Light years away. I don't have the conversion, but I know this is a distance of high magnitude. Second we have the issue of the relatively short human existance. We have not been here very long.

It is unlikely that we are alone, considering the apparent uniformity of our galaxy. Other observable solar systems have been shown to follow a similar beginning. It would only be human arrogance to think that we are the only life existing.

The problem with radio signals is that they are limited in the same way as all light. Like a bunch of random darts we send them out, but they have only traveled as far as the amount of years they have existed. We are also relying heavily on the fact that other sentient beings have radio technology.

From what I understand of how people theorise of time travel I have realised that if there was another race on another planet somewhere in another galaxy, they would probably be related to us.

Imagine, Our descendants manage to create a drive that can propell them across great distances, but inturn the jumps of those distances effect the time they arrived there at.

Rather than arriving there a week later after travelling a week, they arrive hundreds of years past (Before they left)

This would mean that we could have our very descendants living on a planet across the universe in some corner somewhere.
It would mean that what ever method we send out information they would surely have an understanding of how to communicate with our "ancient" selves.

Of course since we haven't seemed to have made contact with our descendants it either proves that the barrier can't be broken or can't be broken that far or they managed to transverse a greater distance than our signals can reach.

Of course you could turn that around and say our planet started with that catalystic jump, and that there are others far more ancient than ourselves.

The other reality is that if life existed on a planet an it was frozen and then destroyed, lots of frozen pieces of life could ride across the universe for a countless number of years. It is known that worms can be revived from frozen, so a bunch of frozen worms could thaw at different intervals across a vast number of hospitable planets.

As for aliens that people mention of at present, I would say that people test things and cover there tests in a multitude of mysterious ways.
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Stryderunknown

Moses, I find your theory and equation very interestng. I think you may have left out one factor. In a universe estimated at over 15 billion years old and space travel between other star systems only theory at this time, other civilizations may be missed in time. They may be already done and gone [natural disasters, germ and nuclear warfare, stellar evolution of their stars] or we will be gone [same reasons] before they have evolved to the point of looking for us. Maybe an equation about the length of time a species has the ability to look and survive would have to be taken into account in the search. More probabilites.... just what we need, O WELL.

Here is another probability:

How about a generational starship arrived from a dying planet 3 million years ago and landed on the Nile river valley. The descendants did not have enough knowledge to repair the machine except a few tools, and over the years of natural disasters and everything, all the hard evidence is perhaps disintegrated by now....the hall of the ship may be buried under the sea...

Since the universe evolves with symmetry, our earth counterpart, at the otherside of the galaxy is probably at our stage of evolution. That means, no communication for another 500 years.

I would say if that was the case, then the evidence would be completely destroyed by the people themselves.

Imagine a particular country or governement having to maintain control over people finding out the truth and always having to live up to Expectations.
The possibility that even then you might make some alterations and create some parallel from the original timeline would mean that the continued secrecy of any occurance like that would have to continue.

So perhaps the only way to destroy the evidence was to throw things into Volcanoes... oh look that's where human sacrifices came from... I wonder what worldly god they were appeasing (Namely who asked for them to sacrifice there stuff :D)

Also the interaction with historical figures would also occur if I hazard a guess, especially that of religion or a major discovery nature, take for instance Pythagorus or Archimedes, oh and who other than the Australian invented the wheel?
Perhaps a certain Star light was actually some form of satellite node that had been set up to watch how events unfold, which is now long dead from it's fiery death of re-entry before we had a chance to start exploring space.

Of course this does take us away from the original thread of "Other life must exist within the universe Statistically." I meniton that as I wonld want this thread having to be moved by its loss of topic.