Really?

Oct 2007 poll shows 30% of people believe in UFOs

Last time I checked my math books, "1/2" did not equal "34%".



So you want explanations without evidence? Good luck...



Don't mistake "possible" with "probable".

Are Aliens possible? Absolutely.
Are Aliens probable? With no evidence, your guess is as good as Drakes!

Is Alien visitation possible? Absolutely.
Is Alien visitation probable? With no evidence to guide us, your guess is as good as Macks!

Yes, but later he claimed to have seen the object from up close and so on. He literally changed his whole witness report.



I am open to the possibility as well, but I don't think it's likely.In fact, there's really not enough evidence to be able to claim that aliens or UFOs (as in alien spacecraft) exist.



I totally agree. But on the other hand it's also too easy to say that the lack of evidence doesn't mean it proves that aliens do not exist. For a lot of theories, like the belief in Gods and so on, people tend to lean on this idea of how things unproven can be valid or something. Following that line of thought is a bit crazy in my opinion.



I don't quite get why it should be terrifying in either case. For mankind it's probably better to be alone, considering how many wars we fight, but alien civilizations might be a huge source of new knowledge.

Let's consider the following scenario
A super advanced civilization decided, some time ago, to send a fleet to explore the galaxie

Some figures

Alien fleet : 10.000 stars ships
Cruise speed : 10 % of the speed of light
crew : 100 members
average life span : 1.000 years

Mission : To explore 1 % of our galaxi
Expected time to complete the mission : 40.000.000 years
Human resources : 4.000.000.000 people, living 100 % of their life on board

You can make more sophisticated simulations, including for example the foundation of colonies but you will alwayes obtain non realistic scenarios

No seriuos scientits beleive that aliens visited our earth because of the size of our galaxie and the speed limit of light
The average distance between a star system and the next one , in our galaxi, is about 10 light years
A star ship would take 100 years to jump from one star to an other one
The number of stars is supposed to be about 400.000.000.000

An other matter is the existence of aliens

There are 400 bilion galaxies in the universe
Very likely aliens do exist

Either way it's based upon assumptions for which there's no evidence at all. One scientists thinks it's an educated guess to think the galaxy must be crawling with life, another thinks we probably are the only planet on which there's life.

I tend to agree with the first group of scientists, but until we've found some actual proof, it's as good as either guess.

Also, don't forget those chance figures are incredibly arbitrary and no scientist thinks of exactly the same figure... there's no simple rule to determine the real chance of life, especially since we don't really know much about the earliest phase or at least what or how it started.



That's an assumption on your side as there are definitely also serious scientists that believe it's very possible that other civilizations have already overcome such obstacles. Problem with such theories is that we don't really know how they have managed to overcome those problems... But just because we don't understand how doesn't mean it's not possible at all or even unlikely for that matter.

It's the big issue when there's a lack of evidence... we can fantasize all day long, but it would still get us nowhere unless we actually solve those problems ourselves or capture and reverse-engineer one of their space craft.



Assuming there's at least more than just one planet on which life started / or spread to, it's still incredibly questionable whether there's advanced and intelligent life comparable or better than here. (Mind you a lot of this talk is based on our rules of statistics that could be far off anyways.)

Obviously a few cells on a distant planet won't be able to visit us and we won't be able to visit them either as they are likely way too far away.

Perhaps there are or have been conditions elsewhere in our universe good enough to support life, but until we find such a place it's still a huge step to assume there might be life comparable to us.

It is not an assumption, it is a matter of fact and more important it is not of my side,
these kind of simulations have been made by many scientists, including Enrico Fermi, and the conclusion was alwayes the same, impossible...

The number of star systems of our galaxi is huge but the density is estremely low
Some serious scientists believe that some other civilizations has already overcome such obstacles ?
Really ? which ones ?

I took into account a speed 10 % of the speed of light
From earth to moon in 12 seconds
I suppose a life span 1000 years
I was happy to explore just 1 star out of 100 of our galaxi , assuming that our earth was one of them
Nevertheless I got 40 milions year to accomplish the mission

Facts about stellar populations do not translate to facts about alien life. And as there are no facts about alien life, any conclusion on this topic is assumptive and not factual.



I am unaware of Fermi doing any simulation on this topic.

And the poster child for exobiology, Drake's Equation, shows far from "impossible" results.

I did not make any strange assumption about the aliens
I said :

Suppose that they exist and their level of technology is very high ( of course it must be) , even so it is unlikely that they reached us because of the size of the galaxi , the distances and the speed limit
The only assumptions I made is that the physical laws are valid also for them , thus it make no sense to claim " the may have already overcome such obstacles "


Are you not unaware of Fermi's simulation ?

He took into consideration the foundations of colonies and he came to the conclusion that our galaxies should be crowded with alien colonies and the ether full of radio frequencies
Even nowadays SETI radio telescopes have not yet detected even one signal

Obviuosly it was not his main area of interest

The result of the Drake's equation depend on the value assigned to the parameters which are mere speculations
I have never taken this equation that seriously
However evolutionism is a deterministic theory

if the enviromental conditions are suitable life must evolve

There are 400 bilion galaxies with 400 bilions stars with , may be, 10 planets each
The number of planets can be estimated in :

n = 160.000.000.000.000.000.000.000

It is hard to think that none of them is suitable for life except the earth
Obviously nobody really knows

Deterministic or not there's nothing really inevitable about the evolution of life. The natural selection is inevitable, the coming into existence of life might not at all be as inevitable.

Besides, God or no God, you can't rule out the possibility of life being a unique event caused by unique conditions, regardless of whether there are millions or billions of planets elsewhere that might have been suitable too.



It may look like a huge number but considering the countless amount of stars it might not really be a huge number, besides what if the chance for life is only 0.000000000000000000000016??

So the their existence and level of technology is not an assumption?



I am aware of a back of the envelope "sound bite" about Fermi's Paradox. I'm unaware that he quantified his thoughts as an equation (like Drake) or that people work at proving the assumptions (again, like Drake).



Right. An Opinion based on an Assumption with no quantifiable evidence and no resultant equation to examine.... not a simulation, not much more than one scientist's opinion at that.



Correct. But unlike other models or Fermi's opinion, this one has an equation with variables that can be tested. On the objective side, as we learn more about the number of "earth class" planets, Drake's will be modified.

So there are a number of facts (number of objects in the heavens), a number of educated guesses in there (number of habitable planets), and a number of pure guesses (number of civilizations per galaxy).... but each one is put in a way that they can be tested somehow, sometime. That is why Drake's equation is not science, but it can be and is setup so it can become science.



And if we apply the Vogt-Russel theorem of Steller evolution, the same conditions must lead to the same life. Again, purely subjective arguements, but that is the way science looks into the unknown: by looking to the past for answers to the future; taking what we do know and applying it to the unknown; letting the data guide us and not our preconceptions.

We can put it this way: If there is no other life out there, it's a damn huge waste of space.

Now, what always bothered me, is that scientists try to look for planets with similar conditions like earth. But it's very subjective to estimate that for life to be possible, life conditions have to be exact or similar to earth.

Maybe im just totally wrong, but: Why does noone take into account that maybe life could evolve on a different type of planet? Maybe a planet that makes life impossible for US, but maybe enables other lifeforms to life and evolve.

Well just my two amateur cents.