Is there life in the universe, and if so has it visited Earth?

[VooDooX]

Again i dotn think you guys realized last time what i was saying ... LIFE CAN SURVIVE IN SPACE WITHOUT A SPACE SUIT OR ANYTHING AND THRIVE...http://www.esa.int/esaCP/SEM72XRJR4G_index_0.html So all you people earlier who were dismissing the comet seed theory of life may want to think again since these microbes could EASILY live on a comet with absolutely no problem

 

[CEL]

Again i dotn think you guys realized last time what i was saying ... LIFE CAN SURVIVE IN SPACE WITHOUT A SPACE SUIT OR ANYTHING AND THRIVE...http://www.esa.int/esaCP/SEM72XRJR4G_index_0.html So all you people earlier who were dismissing the comet seed theory of life may want to think again since these microbes could EASILY live on a comet with absolutely no problem

That microorganisms, specially is the form of spores, can survive in space is a known fact. Nobody is contesting it.
But postulating that life on Earth came from space, merely transfers the origin of life somewhere else.
We are only using Occam's razor. Why should we add another hypothesis to the origin of life?

 

[dacruick]

I think that it would be extremely ignorant to assume that life off of Earth doesn't exist. But I also think that the probable distance between Earth and any other planet with life is far to great to ever cause an encounter.

 

[DaveC426913]

But postulating that life on Earth came from space, merely transfers the origin of life somewhere else.
We are only using Occam's razor. Why should we add another hypothesis to the origin of life?

I wondered this myself. But it does accomplish one thing: it gives life a lot longer to spring from non-life - at least 10 times longer.

 

[Bartleby50]

Vegetable life and the green algae in the ocean provide us with oxygen from the carbon dioxide responsible by the major part of the greenhouse effect. The growing temperature is in the origin of phenomena like El Niño, that cause droughts and inundations all over the world.

Higher Temperatures means MORE vegetable life and MORE green algae.

 

[dacruick]

I watched a documentary on the weekend on the discovery channel. They had a professor from the University of Toronto visit Australia. He talked about these things( I can't remember their name and it is upsetting me because its on the tip of my tongue), and they are basically accumulations of bacteria that lined the bottom of the ocean which spawned all life. They start with an 'S' I believe. And he also went even further back to when the Earth was purely molten lava on the surface. He said that it is speculated that all of the water on the surface of our planet came from the core. I was only able to watch about 15 minutes of it so I can't tell you guys what the title is. But it was concluded in the documentary that life is from earth, and the fact that there are mammals(oxygen breathers) is simply evolutions part in making use of the by products of photosynthesis. When you think about the balance that our planet has, and how everything works perfectly together it really makes you wonder. Then you keep wondering and realize that everything that doesn't "work perfectly" is dead for that exact reason. Or the things that don't work perfectly got too smart and decided to d expand enough as to strain the Earth's resources. Just a thought.

 

[DaveC426913]

He talked about these things( I can't remember their name and it is upsetting me because its on the tip of my tongue), and they are basically accumulations of bacteria that lined the bottom of the ocean which spawned all life. They start with an 'S' I believe.

Cyanobacteria? It comprised the vast bulk of life on Earth 3.5Gy ago.

It also poisoned itself virtually out of existence. Its very success lead to an accumulation of its own waste product: oxygen, leading to its near extinction.

It is this poisonous waste product that allowed oxygen-breathing animals to arise.

...it was concluded in the documentary that life is from earth,

This seems to be a misunderstanding. Not sure if it's on your part of theirs. It's not like anyone's suggesting complex life forms have an extraterrestrial origin. But it is possible that the precursors to that earliest cyanobacteria were seeded from elsewhere. They'd have been little more than self-replicating organic molecules.

When you think about the balance that our planet has, and how everything works perfectly together it really makes you wonder.

Balance is not the mechanism of nature; competition and extinction is the mechanism of nature. New species are wiping out old species all the time. And I don't mean long-term. Every invasive species of plant in fallow fields, every place where crows are filling the niche of mammalian carrion-eaters on the US NE, every place where elms and birches are dying from disease.

The only reason it seems in balance is because you're taking a static slice of time on the order of the human attention span.

 

[dacruick]

The only reason it seems in balance is because you're taking a static slice of time on the order of the human attention span.

your definition of balance is different than mine. It seems in balance because it is. Everything is constantly balancing out. too many rabbits in the forrest? well i guess the amount of rabbits are going to go down as the amount of wolves go up. you seem to want to attack the things i say before you give me the benefit of the doubt. And the "s" thing that i speak of was not called cynobacteria. Although I've searched google and still can't find this name.

 

[Jake Eddowes]

Interstellar travel is not possible. Look at the mathematics.

 

[DaveC426913]

Interstellar travel is not possible. Look at the mathematics.

It's hard to know where to start in refuting this. I'll sum up.

1] Only a Sith speaks in absolutes. Of course it's possible. It's just highly impractical.
2] Any particular mathematics you think is sufficient to categorically make IST impossible?


I'll give you a head start. Colony ships.

 

[jreelawg]

The impracticality of interstellar travel leaves me to think that it is most likely they, or we would send drones.

 

[imiyakawa]

Interstellar travel is not possible. Look at the mathematics.

Please don't speak.

 

[DanP]

1] Only a Sith speaks in absolutes.

 

[Anticitizen]

Interstellar travel is not possible. Look at the mathematics.

'Impossible' is the nuclear bomb of words, but I'll agree that it's very improbable for life as we know it. Unless one has near incalculable amounts of time, energy, and physical resilience. It's even highly impractical to send humans to Mars due to all that pesky solar radiation that would kill you dead unless you have ten feet (or whatever) deep water tanks surrounding the 'payload'. That's a lot of kilograms of mass to push across the solar system, and every kilogram is expensive (in fuel/energy terms)...

I agree with the above poster who mentioned that drones could make it, though you could replace the idea of a simple drone with an engineered artificial life form or AI. I imagine that 'first contact' for Earth will be between some exploratory Earth AI and whatever Race X of the Planet Unpronounceable spawned. Prior art? Drones have scoured Mars, we monkeys haven't.

Whatever artificial consciousness we eventually create will probably outlast us anyway.

 

[wavering]

Is there life in the universe?

Well, the latest estimates I have read suggest that there are between 10^22 and 10^24 stars in the universe. That is such a staggeringly big number that even if only one star in a billion had life on one of its planets then there would be trillions of planets with life.

A more interesting question may be: "Is there intelligent life in the universe?" To answer that it would be useful to know if anybody has updated the Drake Equation? If there is intelligent life then it is likely to have put together considerable artificial intelligence giving it potentially enormous intelligence and machines which could be used for serious space exploration. The beauty of intelligent machines is that you can just send them off into space at zero cost - they will look after themselves in terms of resources. It also gives them something useful to do and a sense of mission to stop them causing trouble on your own planet.

It is hard to see how they could travel at much faster than say 20% of the speed of light using known limits of science (but if they have super intelligent machines - ie IQ of thousands - maybe they can overcome such limits). And maybe an expedition could travel for say 2,000 years with embryos on board. meaning they could reach out about 200 light years compared with a radius of our galaxy of about 100,000 light years. So, in a million years or so (a blink of an eyelid in universe time scales) they and their descendants could cover the whole galaxy and then think of going on to the next and so on.

This would fit in nicely with religious myths - maybe Eden was some sort of "start up" - they took the somewhat dumb natives and smartened them up using genetic engineering then came back a few thousand years later did stage two (the Jesus stuff to try and introduce a durable and relatively harmless religion). So maybe we are due for a re-visit about now ... must be touch or go whether the aliens get us or Yellowstone blows first

 

[DaveC426913]

This would fit in nicely with religious myths - maybe Eden was some sort of "start up" - they took the somewhat dumb natives and smartened them up using genetic engineering then came back a few thousand years later did stage two (the Jesus stuff to try and introduce a durable and relatively harmless religion). So maybe we are due for a re-visit about now ... must be touch or go whether the aliens get us or Yellowstone blows first

Ok, you sortta crossed the line here. You might want to carefully step back over that line.

 

[Ivan Seeking]

Yes, no wild speculation please.

 

[wavering]

Yes, no wild speculation please.

Well, the guy did ask the question " ... has it visited Earth?". So I think that is a question to which the only answers must be speculative. As far as I am aware, there is no scientific evidence either way.

Accordingly, you could look back through events recorded by historical commentators of which the Bible is one. The events it describes are presumably based on something and if aliens had been taking an active role in the proceedings then presumably they would have been viewed as gods. Their ungodlike behaviour, "the sons of God saw that the daughters of men were fair; and they took to wife such of them as they chose" (Genesis 6) tends to suggest they were flesh and blood and of similar design. It also has the "ring of truth" to it - an event which a starry eyed writer is unlikely to just invent as it hardly does much for his story - they were writing a religious book not Heat Magazine

Certainly, if we had intelligent machines, an event which, like nuclear fusion, is always due in about 30 years time, there would be the question of their role and sending them off into space seems a reasonable thing to do. Once there, they may well see a sensible role would be to speed up evolution and correct unreasonable tendencies on planets they visited. Their human passengers (carried as genetic material to be hatched out on arrival) getting their leg(s) over would just the sort of irresponsible behaviour a bunch of layabouts would indulge in and with their parents 200 light years away, who was going to tell them off? They saw it as one of the perks of the job ...

As Niels Bohr said "Your theory is crazy, but it's not crazy enough to be true". So, there is precedent for wild speculation
.

 

[Ivan Seeking]

Well, the guy did ask the question " ... has it visited Earth?". So I think that is a question to which the only answers must be speculative. As far as I am aware, there is no scientific evidence either way.

Accordingly, you could look back through events recorded by historical commentators of which the Bible is one. The events it describes are presumably based on something and if aliens had been taking an active role in the proceedings then presumably they would have been viewed as gods. Their ungodlike behaviour, "the sons of God saw that the daughters of men were fair; and they took to wife such of them as they chose" (Genesis 6) tends to suggest they were flesh and blood and of similar design. It also has the "ring of truth" to it - an event which a starry eyed writer is unlikely to just invent as it hardly does much for his story - they were writing a religious book not Heat Magazine

Certainly, if we had intelligent machines, an event which, like nuclear fusion, is always due in about 30 years time, there would be the question of their role and sending them off into space seems a reasonable thing to do. Once there, they may well see a sensible role would be to speed up evolution and correct unreasonable tendencies on planets they visited. Their human passengers (carried as genetic material to be hatched out on arrival) getting their leg(s) over would just the sort of irresponsible behaviour a bunch of layabouts would indulge in and with their parents 200 light years away, who was going to tell them off? They saw it as one of the perks of the job ...

As Niels Bohr said "Your theory is crazy, but it's not crazy enough to be true". So, there is precedent for wild speculation
.

The purpose of the poll is to allow people to vote their opinion. The occasional reference to historical claims are fine, but delving into specific speculation about such accounts or the possibilites goes beyond the scope of the forum.

This is not subject to debate: Discussion must remain within the bounds of known science.

 

[Max Faust]

The beauty of intelligent machines is that you can just send them off into space at zero cost - they will look after themselves in terms of resources.

Wasn't this the basic premise of Star Trek (the book)?

As for the question itself, I am of the mind that "life" is something inbuilt and fundamental (like gravity) in the universe; something which will happen whenever the conditions are favourable for whatever complexity.

 

[wavering]

This is not subject to debate: Discussion must remain within the bounds of known science.

Point taken. I will confine myself to analysis.

There would seem to me to be two classes of Alien visitors - those who like us are restricted by the speed of light and those who have found a way round it

Class 1 Aliens - Restricted by speed of light
I have seen analyses that suggest there are theoretical limits as to the extent to which you can accelerate a ship or asteroid or whatever but let's be very optimistic and assume that they can get up to a measurable percentage of the speed of light - say 20% for discussion purposes. Allowing for acceleration and deceleration this gives an average speed of 10% of light speed. So how long could they reasonably travel for? Even allowing for hibernation and reconstituting from genetic information (the polio virus has been famously put together from bits ordered by mail order) it is hard to imagine a trip of much more than a few hundred years but let's be very optimistic and say 1,000 years.

So, how many stars are there within 100 light years of earth? Well, as it happens this has been asked before:

http://wiki.answers.com/Q/How_many_star_systems_within_100_light_years_of_earth

and the answer is evidently about 170,000. So, maybe one of them has intelligent, successful life on one of its planets? What are the odds of that? Well, if 1 in 200,000 (lets be pessimistic and say 1 in 1 million) stars has intelligent well organized life then given that there are 10^22 to 10^24 stars in the universe that would imply that there are at least 10^16 stars with intelligent life capable of making voyages through space of 1,000 years

So, let's spell that out:

10,000,000,000,000,000 planets with extremely advanced civilizations. What are the odds of that? Zero, I would have thought

Class 2 Aliens - NOT Restricted by speed of light
So, they can visit any planet in the universe at the drop of a hat. What are the chances they would consider coming here? Well, presumably, about 1 in 10^22 (the number of stars). What does that mean? Well, as it happens, I could visit any spot on earth. The surface of the Earth (including the sea) covers about 10^19 square inches [Edit: it is even worse - the surface of the globe covers 10^20 sq mm]

So, the odds of these aliens visiting us are the same as me deciding to visit an area of the Earth covering one tenth of a square inch. Not very likely. So if there are a million such civilisations the odds are slightly better - they are the odds of me deciding to visit a piece of the world about ten feet square. Zero, in other words

Other factors
If they have been here what are the chances of them leaving a record? Well, the Earth has been around for about 4 billion years or so. Nothing historical is likely to last more than a million years so if they did come there would be at most a 1 in 4,000 chance we would know about it. Unless they left a marker in our DNA - so that is the place to look ...

Super Optimistic View
Self replicating, super intelligent space probes ... but that is wild speculation outside the bounds of normal science so we won't go there.
.

 

[DaveC426913]

So, they can visit any planet in the universe at the drop of a hat. What are the chances they would consider coming here? Well, presumably, about 1 in 10^22 (the number of stars). What does that mean? Well, as it happens, I could visit any spot on earth. The surface of the Earth (including the sea) covers about 10^19 square inches [Edit: it is even worse - the surface of the globe covers 10^20 sq mm]

So, the odds of these aliens visiting us are the same as me deciding to visit an area of the Earth covering one tenth of a square inch. Not very likely. So if there are a million such civilisations the odds are slightly better - they are the odds of me deciding to visit a piece of the world about ten feet square. Zero, in other words

This analogy assumes all areas to visit have equal weight.

If you were going to visit a ten foot square area of the Earth, and Earth was all desert except for one ten foot square area that was a lush oasis, where are you going to visit?

 

[wavering]

This analogy assumes all areas to visit have equal weight.

If you were going to visit a ten foot square area of the Earth, and Earth was all desert except for one ten foot square area that was a lush oasis, where are you going to visit?

That assumes the Aliens who are not bound by the speed of light can somehow view every planet remotely. I would have assumed this would be very difficult and must have a cost associated with it. Let us suppose they could do this for .000001c ie one millionth of a US cent per planet considered. Then the cost of looking at 10^24 planets would be $10^16 which is about one thousand times the GDP of the USA. Even for really loaded aliens this is a lot.

There may also be time constraints. Let us assume they can examine one million stars per second. Then it will take them 10^ 18 seconds, which is about thirty billion years ie a very long time.

What I am really saying is that the numbers are just so mind boggling that the odds of them even considering coming here must be minute. Also for one lot of Aliens the odds are actually the same as me deciding to look at one hundredth of a square millimeter on earth. The ten foot square is if there are a million planets containing aliens who have overcome the limits of the speed of light.
Bob
.

 

[DaveC426913]

That assumes the Aliens who are not bound by the speed of light can somehow view every planet remotely. I would have assumed this would be very difficult and must have a cost associated with it..

You think that observing would be so expensive that they would simply send their ships out blind?

Kind of putting the cart before the horse isn't it? Especially when the cart is going to be far, far more resource-intensive and costly than the horse.

I think it is much more plausible that they would not send expiditions out until they had a destination in mind. And I think they would probably do a lot of observing until they found a destination of interest.



Also, your numbers still don't make sense. You're calculating it like any alien civilization anywhere in the universe isgoing to have to stumble upon us even if we're a billion light years distant. You're not judiciously paring your numbers down. We don't need to calculate the chances of any of them finding us, just one. And I think it far more plausible that a civilization near us will find us. Try limiting your volume to just our galaxy, or even just our spiral arm, and I think you'll find the numbers far more palatable.

The upshot: calculating these odds is much more complex than simply figuring the volume of stars in a given expanse of the universe.

 

[wavering]

I think it is much more plausible that they would not send expiditions out until they had a destination in mind. And I think they would probably do a lot of observing until they found a destination of interest.

That is precisely my point. They would examine the universe to assess where to go but even that is a herculean task and could take millions or billions of years and use huge resources

Try limiting your volume to just our galaxy, or even just our spiral arm, and I think you'll find the numbers far more palatable.

That is exactly what I did earlier but in fact the numbers look worse. In a nutshell if there are super intelligent aliens in our galaxy then this implies that there are 100 Billion advanced alien civilizations in our universe. To me, this seems unlikely - many observers have difficulty even believing there could be one, never mind a hundred billion
.

 

[DaveC426913]

That is exactly what I did earlier but in fact the numbers look worse. In a nutshell if there are super intelligent aliens in our galaxy then this implies that there are 100 Billion advanced alien civilizations in our universe. To me, this seems unlikely - many observers have difficulty even believing there could be one, never mind a hundred billion
.

Why is one hundred billion less likely than one? If every galaxy on average is like ours, and ours sprouted one, why is any other virtually identical galaxy not going to do the same?

So the numbers don't get worse.

That being, said, it should be noted that no one seriously discusses alien civilizations outide our galaxy for the very reason that they could never reach us.

 

[Max Faust]

if there are super intelligent aliens in our galaxy

Perhaps there is. But how could we tell? Humans aren't very intelligent.

 

[Count Iblis]

That being, said, it should be noted that no one seriously discusses alien civilizations outide our galaxy for the very reason that they could never reach us.

Why not? They could transmit extremely powerful radio signals that we can pick up. While this will be a one way communication (we'll be listening to what they've transmitted millions of years ago), the civilization could have simply repeatedly transmittted the same message over and over again. If the civilization is a machine civilization, then they can travel to here if their message contains the information telling us how to build them from scratch.

 

[Max Faust]

They could transmit extremely powerful radio signals that we can pick up.

They could also produce mathematical symbols in wheat crops by processes we don't understand.

Why would they do this? And why would you even suspect that this was happening? We need to realize that there is a lot of gray area (and even more BLACK area) when it comes to the idea of communicating with aliens. We lack a proper methodology for the investigation.

 

[Dembadon]

... Humans aren't very intelligent.

To whom are you comparing human intelligence? How is intelligence measured/defined in this context?

 

[DaveC426913]

To whom are you comparing human intelligence? How is intelligence measured/defined in this context?

Ah leave it be; it's a throw away cliche. No need to breathe life into it.

 

[Count Iblis]

They could also produce mathematical symbols in wheat crops by processes we don't understand.

Why would they do this? And why would you even suspect that this was happening? We need to realize that there is a lot of gray area (and even more BLACK area) when it comes to the idea of communicating with aliens. We lack a proper methodology for the investigation.

They could do that in order to live on elsewhere in the universe. Suppose you are a machine and you transmit the information in your digital brain and the information on how to manufacture the hardware that is running you from scratch. If this signal is picked up billions of years later by a civilization on the other side of the observable universe, then you will find yourself there in what seems to you to be just an instant.

 

[Bored Wombat]

Class 2 Aliens - NOT Restricted by speed of light

I don't believe in class 2 aliens. They violate causality, and interfere with the arrow of time. (Notice that FTL travel is backwards time-travel for some observers.)

Super Optimistic View
Self replicating, super intelligent space probes ... but that is wild speculation outside the bounds of normal science so we won't go there.
.

Self-replicating nano-probes isn't that super optimistic, given that they only have to be built by one civilisation (Or whatever ... single entity ... non-sentient genetic factory), and they're off, and will be here.

In fact, I think that that is so likely that "Where are they?" is a pertinent question.

But perhaps we need to check bacteria DNA for signs of them.

 

[baywax]

I don't believe in class 2 aliens. They violate causality, and interfere with the arrow of time. (Notice that FTL travel is backwards time-travel for some observers.)



Self-replicating nano-probes isn't that super optimistic, given that they only have to be built by one civilisation (Or whatever ... single entity ... non-sentient genetic factory), and they're off, and will be here.

In fact, I think that that is so likely that "Where are they?" is a pertinent question.

But perhaps we need to check bacteria DNA for signs of them.

What did you think viruses were?

 

[Frame Dragger]

What did you think viruses were?

Now that is an extremely good point, with many implicitions.

As for the OP... I bit my tongue. When it comes to life in the universe I'm "who knows?"... when it comes to visiting US... vanishingly unlikely.

I also note the OP was banned... I hope he takes comfort that his thread has outlived him!