Astronomy / Space How many Earth-like planets in the galaxy? New Scientist article.

New Scientist is awesome. If it came to a choice between cancelling my subscription to it vs. one to E D (if it existed) I would be really torn.
 
It wasn't so many years ago, that the existence of satellites around other stars was not even accepted.

I'm sure like many other, I well recall the confirmation that the first planet had been identified. It was said to be a super large gas giant. The journalists of course tried to explain it in simple terms that us dumb folk cud un'erstand and as usual, totally missed the point since they didn't understand it either.

It's a remarkable achievement to have refined the process so quickly.

The factors limiting the possibility that any life could have any technology at all remain. But locating extraterrestrial intelligence would be remarkable indeed. Though will probably need a rather different detection method.
 
Rogue hypervelocity stars may have planets in tow, according to this article - if they do exist, I wonder what percentage would be Earth-like planets.
 
Rogue hypervelocity stars may have planets in tow, according to this article - if they do exist, I wonder what percentage would be Earth-like planets.

It's an interesting point. I have wondered how a reasonably advanced culture would perceive us here in the Milky Way?

Might they imagine all the planets in the Milky Way are all in communication with each other and are super advanced? Possibly hostile to them?

Or perhaps they see themselves as being the righteous ones bringing the word from other galaxies and seek to impose their perfections in the name of freedom?

The Milky Way could be ringed by such cultures, each with its own psychotic agenda, each imagining it is bringing its dogma as enlightenment onto us lost souls.

Or, perhaps they imagine we are all destined to certain doom in that huge black hole we're winding toward?
 
They can be just peaceful. If a society can advance to the point it might find other life forms on far planets and be able to communicate with them, the aforementioned society is likely to be truly sentient, so it will have no reasons to start a war. Do not forget, Elite universe is dystopian one, it is purposely made to look like Earth recent history in space, not like an attempt in scientific prediction of space inter-civilization relations.
 
They can be just peaceful. If a society can advance to the point it might find other life forms on far planets and be able to communicate with them, the aforementioned society is likely to be truly sentient, so it will have no reasons to start a war. Do not forget, Elite universe is dystopian one, it is purposely made to look like Earth recent history in space, not like an attempt in scientific prediction of space inter-civilization relations.

That's as likely as anything really.

I recall a discussion by an astronomer back in the early 70s, when discussing the possibility of life elsewhere.

He made the point that the technology we have today which allows us to view the stars and such, is not so very old.

The technology to send radio waves is even more recent.

It is perfectly possible that a civilisation as intelligent as ours, even more intelligent could exist quite near by, but be unaware of even the existence of Earth, let alone anything we have been doing.

Our presumptions that a community of equally intelligent being on another planet would have developed in a similar manner to us and use it in the same way we have done, is not really a good guess f we think about it.

Humans as intelligent as us have existed for thousands of years. Yet only in the past 400 or so years, have any of these advanced technologies been developed.
 
...Our presumptions that a community of equally intelligent being on another planet would have developed in a similar manner to us and use it in the same way we have done, is not really a good guess f we think about it.

Humans as intelligent as us have existed for thousands of years. Yet only in the past 400 or so years, have any of these advanced technologies been developed.

Other life forms can be close to us, because, although in sci-fi we can see many exotic forms of life, in reality there're many reasons why we are what we are and why we search for 'earth-like' planets to find other life. It is highly unlikely that life on earth-like planet will be much different from us. It is even less likely that sentient life form will be radically different from humanoids. If the planet is earth-like, than its environment will be more or less close to ours, and the organisms will be morphologically (in their body shapes) similar to ones we have here on Earth.
And when it comes to wars, that why I said about truly sentient beings. The point is we, humanity as a whole, are not truly sentient species, because even now we live mostly animal lives, that's why we wage wars between ourselves. Technical progress had been quite fast in something like two last centuries, but the social progress is falling behind it horribly. Now we can easily destroy ourselves with nuclear and other types of mass-destruction weapons before we can find other life somewhere else, or that life can find us.
 
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Leaving aside most of those points, you miss the most significant.

Humans have existed for thousands of years. Yet of all the numerous human colonies, only one took that leap, 400 or so years ago.

All of the technologies which have been developed, which have allowed humans to expand their awareness of the universe including telescopes, electricity and radio have been developed by Europeans. Europeans achieved this within the last 400 years. Prior to that, Europeans' technologies were pretty much like the rest of humanity.

We know, for certain, that this was not due to any greater level of nor type of intelligence among Europeans. We do know the progress began about 400 years ago. It happened because of all innovations, in response to a specific set of challenges facing Europeans, 400 years ago. More, the specific mix of social events, the breakdown of of traditional moral supervision, which hasn't occurred elsewhere, even yet!

It is almost obvious that life will exist elsewhere.

It is likely that many of those life forms will develop animal type intelligence, allowing individual organisms to adapt to a changing environment.

Some may even develop intelligence comparable to or even greater than our own. that life may develop most of the tools and processes which humans have, the wheel, metal, complex pulleys.

But there is no reason other intelligent life will be faced with the specific range of challenges or even a compatible range of challenges that Europeans faced 400 years ago and which led them to develop, in a space of 400 years, technology that has taken humans far beyond anything achieved by any other earth community.
 
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Ah, I see what you're talking about. I know this theory, but to me it's not exactly correct. This set of challenges is not something magical, it's just natural. For Europe it was dense population on relatively small territory with good enough transport routes. The same applied to ancient Mediterranean region where the human culture had started, and without that start, western part of Europe would not have a base for development.
Nature laws are similar in every part of the Universe, we do not wonder why distant stars can be similar to our Sun, and sure, why should we wonder about that? Evolution is the same thing. It's not magic, and its laws are similar everywhere just like the laws of physics. So, the laws of social evolution are the same as biological ones. Progress made by Europeans is not exactly unique, regardless of how the western ideology wants it to be so. Various cultures were found on different levels of their social development, from almost Neolithic hunter-gatherers tribes to states and empires similar to ancient Mediterranean ones. They had the progress as well, but they were doing it slowly and thus were destroyed by Europeans.
Again, I see no reason to assume that on some other planet there will be no their analog of our Mediterranean first and western Europe second. It's just environment and adaptation, why cannot it be there? :)
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...All of the technologies which have been developed, which have allowed humans to expand their awareness of the universe including telescopes, electricity and radio have been developed by Europeans. Europeans achieved this within the last 400 years. Prior to that, Europeans' technologies were pretty much like the rest of humanity. We know, for certain, that this was not due to any greater level of nor type of intelligence among Europeans. We do know the progress began about 400 years ago. It happened because of all innovations, in response to a specific set of challenges facing Europeans, 400 years ago. More, the specific mix of social events, the breakdown of of traditional moral supervision, which hasn't occurred elsewhere, even yet!
I put in bolds the point at which you are mistaken. Human cultures always were developing at different rates. Many never actually made it above hunter-gather tribes, because they had no need to go further. Even 400 years ago (I do not know why do you insist on this date, because colonization began earlier and industrial revolution was later than that) humans have quite different technological levels. When europeans discovered American continents, they found here many types of societies, from neolithic tribes to Aztec empire (which had similar level of progress that ancient Mediterranean civilization had). And, speaking of the latter, what did Europe look like in time of ancient Babylon or even in time of Roman republic? Progress is universal thing and it develops according to the laws of social evolution, which are similar to biological ones.
 
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Ah, I see what you're talking about. I know this theory, but to me it's not exactly correct. This set of challenges is not something magical, it's just natural. For Europe it was dense population on relatively small territory with good enough transport routes.
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I put in bolds the point at which you are mistaken. Human cultures always were developing at different rates. Many never actually made it above hunter-gather tribes, because they had no need to go further. Even 400 years ago (I do not know why do you insist on this date, because colonization began earlier and industrial revolution was later than that) humans have quite different technological levels. When europeans discovered American continents, they found here many types of societies, from neolithic tribes to Aztec empire (which had similar level of progress that ancient Mediterranean civilization had). And, speaking of the latter, what did Europe look like in time of ancient Babylon or even in time of Roman republic? Progress is universal thing and it develops according to the laws of social evolution, which are similar to biological ones.

Strangely, I'm also aware of where you are coming from.

Undoubtedly non-Earth life forms will develop by mutation. That is the nature of life.

Undoubtedly some of those forms will develop intellect to a similar or greater level to humans.

Undoubtedly some will become aware of the potential for power and greed in space and build enormous all powerful craft to seek out and take that wealth to their own ends.

But societies that develop along lines similar to humans will be rare to a significant degree.

It has often been suggested that, somewhere out in the universe, there will be another society which speaks English. A variation on the old infinite monkey, infinite typewriter, infinite time, writing complete Shakespeare notion. Statistically, it must happen. In reality, if it does, it will be so outstandingly rare.
 
Undoubtedly some will become aware of the potential for power and greed in space and build enormous all powerful craft to seek out and take that wealth to their own ends.

But societies that develop along lines similar to humans will be rare to a significant degree.
That's where we will disagree with each other. To me it is just obvious that social evolution is but just another case of evolution, and it has its laws. Which, in turn, are not different from the laws of biological evolution, and are universal. They are similar on Earth and everywhere else. They shall be, because it's the nature. Basically, social evolution seems strange only if the humanity is viewed as something different from other animals. There lies the major flaw of any social development theory that does not take biological laws into account.
If you want to understand a person, you need to know person's history. If you want to understand a state, you need to know its history. These are obvious to anyone. But when it comes to understanding the humanity, it is widely supposed that we do not need to know our evolution line at all. How can that be? The answer is no, we cannot understand the social evolution laws and our societies without the full knowledge of our biology and biological history. And, by all means, societies are changing constantly. To ancient romans, they were the pinnacle of advancement, and everyone else were barbarians. Than the barbarians won. Now we, descendants of these barbarians like to think of ourselves as a pinnacle of advancement, forgetting about how we evolved from roman times, forgetting about how we changed. But no, we're the final word! I'm sarcastic, sure.
We are not unique, most of the humans live but animal lives driven by animal motives. That's why we still have wars, we still have greed, jealousy, we still consider that 'homo homini lupus est'. But if we think about that, we will see, that we had changed greatly since the beginning of the written history. And we will change more in the future, or we die out.
Sure, we can project our current general behavior patterns to the future and to the extraterrestrial life forms, because, as we know, sci-fi is not a prophesy, it has purpose here and now, it's a warning mostly. But that does not mean, that advanced civilization able to travel in space will behave like we do now. It does not mean that they will ever consider starting an interstellar war. I do not say that it is impossible (although interstellar conquests are pointless, if a civilization has technical power to attack other habitable planet, it will be much easier just to colonize a planet without life and terraform it, thus not having to sterilize the entire biosphere), but I think that advanced civilization will likely be advanced not only technologically, but socially as well :)
 
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Human development has proceeded for hundreds of thousands of years, possible several million depending upon how you define a human. It has only been in the last 400 years that the sort of technologies needed to create the electronic apparatus needed to have any understanding beyond what can be observed with the naked eye has developed.

If you believe this is some sort of natural inevitability where is your evidence?

Numerous societies have risen and fallen over the millennia, yet none have achieved what has been achieved in the last 400 years. I can't see any evidence of any sort of natural progression. The inhabitants of the Americas, for example, achieved engineering feats that rival anything achieved by any other societies at that time, yet they never developed the wheel. Indeed, until just over 600 years ago, they had never seen one.

If technological development is a natural process then it does call into question how those people missed out on one of the most basic of tools.
 
Yet again these 400 years. I wasn't sure why do you insist on that amount of time, but after giving it some thought, I understand now. 400 years before the current time, it is the beginning of XVII century. And than what exactly had happened in western Europe in the beginning of XVII century? It's the time when the colonization of Americas began to give Europe its central position. It was the time when the balance had shifted from Mediterranean region to western Europe. Until than western Europe was periphery of civilized world. And it is true, that mediterranean countries had similar technological level. That's why the countries of western Europe started their colonization of Americas. They weren't able to colonize Middle East. Colonization began earlier but it was XVII century when it started to pay off. From that time the Mediterranean region became the periphery. Than, as western Europe became the center of activity, it was only natural that it made the technological advancement.

Wheels were sort of easy to invent in Mesopotamian plains, but not in jungles of Mesoamerica. You may as well ask why mammals in Australia remained on early stages and hadn't developed, as they did in the rest of the world. But the answer is simple, they were capable to live in Australia as they were. No pressure from natural selection, than no evolution.

What I talk about, is not who invented what, but that is was possible to anyone living in the environment with pressure of selection. Western Europeans did that not because of some mysterious causes, but because of geography and economy. Colonization, trading and piracy in Atlantic ocean was more profitable these times, so economy grew and technical progress was made. But it wasn't made by miracle, and it wasn't made from zero. Technological progress is known to accelerate from ancient times to modern ones, and it is so because of growing knowledge. Small advancements here and there and everything progresses a bit faster. Few millions years from using fire to using metals, few thousands of years from bronze age to medieval times, few hundred years from medieval to industrial revolution, half of that from industrial revolution to atomic energy. Europe is the last (up-to-date) link in long chain of civilizations started in Mediterranean region, and even that region was able to progress faster than others not magically, but because of its geography. Its environment and adaptation, so I really do not see, why on some different earth-like planet, that has its own continents and oceans, plains and jungles, tropical and polar zones, all the environment we have here on Earth, why its civilization shall develop much differently from our one?
But I see we are going in circles. I probably cannot explain shorter, because actually it needs a book to summarize all the theories from biology and history, to illustrate it with examples from different periods and places. All that info can be found in various scientific works, although I had to read many to see the whole picture.
But than, we all have rights to learn and to judge accordingly to our knowledge and ideals. So, I suggest to end the discussion, because it had already went full offtopic :)
 
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I remember watching several television programmes about scientific progression, and the odd quirks that made it happen. The industrial revolution, they posited, never happened in China because to get from locations rich in iron to major population centres by river (which was the only realistic method for transporting large volumes of such a material) would have required traversing numerous rapids in the wrong direction - While in Great Britain for example, it was a much simpler task. Canals in China were never an option because mountains were in the way. And because they had such advanced pottery technology, they never developed glassmaking techniques, which meant they never produced lenses, which meant they never produced microscopes or telescopes, never began investigating the world beyond what can be seen by the unaided eye, and so on. (They've done some catching up in the meantime, mind you...)

It's funny how much random chance plays into what happens.
 
The figure of 400 years ago, comes out at the 17th century. That was the time the beginning of the scientific revolution.

If you look at Islamic society for example, their academia developed to a level which, in some cases, wasn't surpassed elsewhere until the latter half of the 19th century. But limits were placed upon research by the diktats of their religious scholars, who deemed, among other things, that representations of living things were idolatry. It was that reason alone that caused the fall of the Islamic civilisation in the 13th century, eventually leading to its disintegration in the 19th century.

That led to the Renaissance in Southern Europe, especially Italy when the scholarly focus briefly shifted back to S Europe. However, technological development and especially the introduction of the scientific method, which was the essence of the scientific revolution were held back because the church ran all academic institutions and it was compulsory to take Holy Orders when becoming a scholar. Those Holy Orders meant they swore absolute obedience and fealty to the Pope. Gallaeo for example was forced to recant, not because his claims were heretical, but that he had failed to seek permission to publish. The enormous developments in art were a reflection of what the church could understand and appreciate. Science was considered a matter for God.

The reformation in the 16th century led to a freeing of academic institutions in NW Europe, from where most of the scientific revolution began. The Protestant revolution removed almost all religious restrictions, allowing for the rapid introduction of the scientific method in the 17th century.

The centre if science quickly moved to the Americas mainly because most investment in Europe was retained by aristocrats and those seeking to emulate them. In the Americas, funds were more readily available. This process of transfer was further encouraged by WW2, when many scientists fled the revival of self serving attitudes.

Europe is now in decline. The Americas are peaking and it seems likely that the next shift will be toward SE Asia.

This progression is a consequence of the historical events surrounding them.

And I really don't want to be spending too much time in this forum discussion historical events.
 
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