Do you think we are alone.

[astro mick]

If you think about it Radio has been around in some form or other since about 1875,so in theory all these waves have been travelling out into space for well over one-hundred years.

So any planet within this distance would be continually bombarded by these waves.

On the other hand here on Earth we have heard nothing.

Now I know this distance is just a drop in the ocean,but can we deduce the following.

(a)There is no one there to receive them.)

(b)They have not attained the Tecnology to receive and transmit this kind of wave.

©They use a totally different type of communicating.

I suppose planets we have reached so far could be classed as Batch Sampling,and on Earth we use this method to determine if a product has passed muster,but we don't check all,we just assume the rest is ok.

Could this be applied here?

I for one cant believe we are alone,but most of the alien worlds discovered so far seem like Hell on Earth.

So again are we alone?

Mick.

[Alien 13]

Hi Mick

The problem with these signals is that 100 years (70ish years for any real power) doesnt get you all that far out if you also consider the round trip.

The signal strength would also be minute and probably not detectable unless transmitted as a narrow beam so its not suprising that nothings come back.

Any adavanced civilisation would be capable of detecting earth and would probably know we had liquid water but again we might not even detect any signal from them against the background noise YET.

Alan

[jnb]

If you think about it Radio has been around in some form or other since about 1875,so in theory all these waves have been travelling out into space for well over one-hundred years.

So any planet within this distance would be continually bombarded by these waves.

On the other hand here on Earth we have heard nothing.

Now I know this distance is just a drop in the ocean,but can we deduce the following.

(a)There is no one there to receive them.)

(b)They have not attained the Tecnology to receive and transmit this kind of wave.

©They use a totally different type of communicating.

I suppose planets we have reached so far could be classed as Batch Sampling,and on Earth we use this method to determine if a product has passed muster,but we don't check all,we just assume the rest is ok.

Could this be applied here?

I for one cant believe we are alone,but most of the alien worlds discovered so far seem like Hell on Earth.

So again are we alone?

Mick.

With those figures that means that we have been sending radio signals into space for 1/50000000 of the suns life so far. How many stars within 100 light years?

[Tinker1947]

Finding aliens is one thing, its whole new ball game getting there....

[Moonshane]

really it's a question of how many stars within 50 light years as presumably they have to receive and then reply.

[leelee970]

There could be many factors why we’ve not detected “intelligent” life so far but my take on it is this -

Universe is about 14+ billion years old

Sun/Earth 4.6 billion

Life on earth appeared 3.6 billion years ago (simple cells)

Multi cell life 1 billion years ago

Mammal’s 200 million years ago

Humans on earth appeared 200,000 years ago

“Intelligent” humans capable of transmitting/receiving signals about 100years

Life expectancy of “intelligent” humans on earth before extinction ???????

It may be we are here at the wrong time in the life of the universe, there always has to be a first and last and some in the middle, which are we?

Lee

[Myopicus]

Are we alone? No, probably not.  But, because of the ridiculous distances, yes.

I'm not sure that Small Greens or Tall Greys are popping by to doodle crop circles. But hey, I could be wrong!

[michaelmorris]

I suspect unicellular life is quite common in the universe

I suspect instances of unicellular life that persists long enough to evolve into mulit-cellular organisms is pretty rare

I suspect instances of multi-cellular life that persists long enough to evolve into intelleigent, technological organisms is unbelieveably rare.

So either we are alone (incredible), or there are intelliegent aliens out there somewhere (equally incredible)

[Sandancer10]

I first saw this equation demonstrated by Carl Sagan.  To be honest I thought it was his work, but it turns out to be 'The Drake Equation'. 

Here's the link: http://science.howstuffworks.com/space/aliens-ufos/extraterrestrial-life-odds1.htm

[LukeSkywatcher]

Maybe if there is life out there somewhere, it could be a simple case of them not wanting to talk to their neighbours from hell. I mean,look at all the man made pollution etc we have created. It could be a case of us bringing down the tone of the neighbourhood.

[rory]

No , I don't .

[wxsatuser]

I would think somewhere out there could be intelligent life, but we won't find them in my life time.

[SnakeyJ]

I for one cant believe we are alone,but most of the alien worlds discovered so far seem like Hell on Earth.

So again are we alone?

Mick.

It's fair to note that the majority of planets detected thus far are big planets orbiting close to their stars (Hot Jupiters), these are what's most easily detected with current techniques.     As techniques become more sensitive and new space based detectors get launched, we will undoubtedly start discovering a lot more of the smaller rocky planets within the CHZ (Circumstellar Habitable Zone) around our closest neighbouring stars.

Given the size of the universe, I suspect we will find life is quite a wide spread phenomena - though stable conditions that favour evolution of more advanced 'intelligent' life  may be rather more rare. 

[ronin]

I suspect unicellular life is quite common in the universe

I suspect instances of unicellular life that persists long enough to evolve into mulit-cellular organisms is pretty rare

I suspect instances of multi-cellular life that persists long enough to evolve into intelleigent, technological organisms is unbelieveably rare.

So either we are alone (incredible), or there are intelliegent aliens out there somewhere (equally incredible)

I think along the same lines.

The Drake Equation is overly simplistic.

We are finding out that our solar system is getiing to be less and less "normal".

Do you need a large tidal creating moon to evolve significantly, the Earth is somewhat odd in this aspect and the creation of our moon appears to be low probability. Our evolution appers to have taken leaps after extreme ice age events, that is a factor of our orbit and the tilt - a tilt slightly different and no ice age or a continuous one, both meaning no meaningful evolution.

The cloud our sun formed in had to have the right composition of elements, meaning there had to be the correct supernove to create to cloud mix before there was even a sun.

We may be a lot more of an improbility then we simply assume.

[starman1969]

It's a favourite question, but one which may be impossible to answer. I think with what we have learnt with our new technology & planet hunting satellites that it is almost certain there is some other form of life somewhere else. I beleive so anyway.

On the subject of radio waves. Despite radio transmissions existing as long as they have, they've barely made a dent even within our spur off the spiral arm. I looked at a diagram of how far they will have travelled in about 200 years, and it is a drop in the ocean.

[jnb]

I think along the same lines.

The Drake Equation is overly simplistic.

We are finding out that our solar system is getiing to be less and less "normal".

Do you need a large tidal creating moon to evolve significantly, the Earth is somewhat odd in this aspect and the creation of our moon appears to be low probability. Our evolution appers to have taken leaps after extreme ice age events, that is a factor of our orbit and the tilt - a tilt slightly different and no ice age or a continuous one, both meaning no meaningful evolution.

The cloud our sun formed in had to have the right composition of elements, meaning there had to be the correct supernove to create to cloud mix before there was even a sun.

We may be a lot more of an improbility then we simply assume.

Which are reasonable objections to human like life appearing. But those objections are all based on the question "what did it take for us to appear?" not "What would it take for life to appear?" Ask the first question and it is not surprising that the answer is that in order for us to appear the conditions that exist where we appeared are what was necessary.

Do we need a large tidal moon? probably not, it stabilises the earth's rotation but so does the sun. Do you need ice ages? Probably not, any perturbation that will create evolutionary niches would do the same. Do you need the same composition of elements? probably not, the planets vary in the compositions even when formed from the same cloud. Did we need those for us to appear in the form we have? probably yes.

[ArcticCircle]

" Sometimes I think we're alone in the universe, and sometimes I think we're not.  In either case the idea is quite staggering."

     -Arthur C Clarke

[Nakedgun]

As far as THIS dimension is concerned, I have seen no reason, thus far, to think life exists anywhere but on the ball we occupy.

[nucleardwarf]

Perhaps they are Aquaphobics.

[starnut]

I'm alone as no one else is here and if they are their not paying me any rent

[Knight of Clear Skies]

" Sometimes I think we're alone in the universe, and sometimes I think we're not.  In either case the idea is quite staggering."

     -Arthur C Clarke

I like the quote. I'm quite agnostic on the issue really: chemically speaking, there is no reason why life couldn't be exist in many different environments, but on the other hand we have no idea how improbable abiogenesis actually is. Both ideas - that life might be rare or that life might be common - are well worth thinking about. But the distance between the stars is so vast that even if life is relatively abundant we might never receive a signal from another civilization.

There is a chance that we might make some progress of answering this question in my lifetime. Mars, Europa and Enceladus - they are are just waiting out there to be explored (probably by probes and robots), if we can find a way of doing it.

[astro mick]

"Thanks everyonr for some great replies,and if I may say so some "Deep Thinking".

If you look at the Earth,there is an awrful lot of coincidences to allow life to develop.

(The Earth is in the so called Goldilocks zone.

(It has a Moon far larger incomparison to its parent body than any other body in the Solar System.This Moon is fairly important to Earth,as it stabilizes our Planets rotation,thereby allowing the seasons to to occur without too much chao,s(Although at the moment you might disagree.It controls the Tides,and so on.

(The Earth has a molten iron core that generates strong magnetic currents,which of course protect us form Solar Radiation.

(In its upper atmosphere,it has the all important Ozone Layer.

(Not forgetting the Van Allen Belts.

So for us to exist,an awrful lot has to be in place,and I bet that's NOT common.

One last question.

Photon,s do not degrade over Distance,but I guess Radio Waves do?

Mick.

[Welrod50]

I reckon there are many forms of life out there, some intelligent, some less so and some beyond our comprehension of what lies beyond a cogniitive existence, and perhaps not only in our own galaxy, but many many others besides.  That life I will suggest is likely in a different form to ourselves and with different abilities.  There may well be living things in the cosmos more ancient than ourselves and others in their infancy (which we are if you consider the age of our race, in comparison to the age of our planet, to our star, to our galaxy and so on).

For how long we have had the capacity to send and receive radio, it is unsurprising we have not received an answer.  Perhaps, if there is a life form out there capable of discovering and building a radio transmitter, and assuming they receive our message, decode it into an understandable dialect and then send a reply, we may all be long gone before this response ever gets here.  Lets face it in astronomical terms, we have been around for about 10 seconds and have had technology to send radio for about 1/1000th sec. 

There are perhaps advanced races out there, flying about in their star ships, teleporting between ships and throwing a dice to decide which galaxy to head for next - and then flashing light signals to their neighbouring ship, because they haven't yet invented a 'radio'.

Who knows !! 

[Luke]

Can we be sure that they would have replied, even if they had received the signals?

My hunch is that perhaps worlds are left to develop on their own until we are ready to fly to the stars, perhaps we are just not ready yet to meet ET

I would love to know in my lifetime whether ET definitely is out there, that big question is part of why I love stargazing

[rory]

Thing is , and I've always thought along these lines, the set if coincidences needed for live , particularly intelligent life might be rare as some put it . But with the billions if galaxies each with billions upon billions of suns , to me the maths put the odds that there must be life elsewhere .