[Lanny_McDonald]

This is gong to be an interesting discussion.

Originally Posted by GGG

Go play with the Drake Equation. Find sets of variables that allow for more than one intelligent species in temporal space/time contact which don’t suggest millions of species.

Happily, except the equation has many flaws in it and has long been subject to criticism, especially with the advances in cosmology and physics since the equation was first proposed in 1961. For those who may not want to chase down the Drake equation, here is a quick outline of it.

R*, is the average rate at which stars are formed in our galaxy; fp, is the fraction of those stars that host planetary systems; ne, is the average number of planets around the star that can support life; fl, is the fraction of planets that could support life that actually do support life; fi, is the fraction of planets that develop life that go on to develop intelligent life; fc, is the fraction of planets with intelligent life that develop civilization and technology that we can detect; and L, is the length of time each civilization emits radio waves.

The problem with this equation is that it makes a number of assumptions, that we already know the answer to all the variables, which we do NOT. It also makes a major assumption that all "intelligent" civilizations will rely on technology that emits radio waves. This is problematic with the equation and makes the results open to much conjecture. It is a very interesting exercise, but nothing more than that, especially on the heels of the advances in detection since the equation was presented in 1961.

In an interesting twist, back in 1961, Drake and his colleagues estimated the number of civilizations in the Milky Way galaxy to be in the 20 to 50 range. That is just the Milky Way Galaxy. Now consider that there are estimated to be 2,000,000,000,000 galaxies in the universe.

An interesting development is in a recent article, the estimate of potentially habitable worlds in the Milky Way sits in the 300,000 range, thanks to information from Kepler research.

https://www.nationalgeographic.com/s...vey-holds-clue

https://iopscience.iop.org/article/1...881/abc418/pdf

I am suggesting the following

1) There is no requirement that intelligent life or life of any kind exist outside of earth because life exists here

There is no "requirement" as you state. This is all noise. Who cares if life exists here? Life could cease to exist on this planet and have zero impact on life on other planets. This condition is irrelevant. Only the arrogance of humans think that our condition or knowledge means anything in the universal context.

2) It’s difficult to create scenarios where life exists and FLT exists and Aliens have visited us where their wouldn’t be abundant life in the universe that we could easily detect.

You're conflating four very different issues here and making them all conditional for alien visitation. First being the existence of life in the universe. The second being Faster Than Light (FLT) travel. The third being visitation to our solar system and planet. The fourth being detection. I get that you are saying that the first three must exist together to explain alien visitation, but I think the fourth condition (detection) is another red herring. How would we detect that which we don't know what we are trying to detect? We are attempting to detect life based on our context and technology (emissions of radio waves), what if the intelligence in question uses different technology we are not aware of? What if the technology emits a byproduct that we would not consider evidence of an intelligence, or emits something we don't yet understand ourselves?

3) if there is life elsewhere in the universe but do to technology, time, space prevents their photons from reaching us then as far as the aliens visiting us here it’s meaningless. It’s important to our understanding of the universe but doesn’t really add evidence to Aliens having visited us.

Emphasis added. OUR understanding of the universe. You're making an assumption that we have complete understanding of the universe, which we clearly do not. I contend we are toddlers in the universal context, and there are many civilizations that have reached maturity and have advanced degrees in comparison. We have but read the first paragraph to the book of universal knowledge, which is the size of War and Peace. We aren't even 90 years from first splitting the atom and just 60 years from putting the first man in space. How could we possibly claim to know what civilizations thousands or hundreds of thousand years more advanced know?

Number one in any rational discussion of aliens is what is the speed limit of the universe because it sets the parameters of how many planets are relevant to the discussion.

You're basing this on our understanding and a belief in linear travel. This may not be how advanced civilizations travel. Advanced civilizations my bend or warp the fabric of space to close the gap and time required. This is something cosmologists have suggested possible, and supported by Einstein's theory of relativity. Where we run into problems coming to grips with this is we are basing all possibilities of this on our limited understanding of the universe and what is evident here on earth. What exists in other solar systems or galaxies may greatly differ and not yet be discovered by our science. An example would heavier elements, unstable here on earth, but stable elsewhere.

On Earth we didn’t evolve independent intelligent species. We came from one evolutionary tree at one location on the planet and then spread out. So that would be the Star Trek scenario where aliens seeded life and not simultaneous evolutions.

We are one species, but we developed multiple "intelligent" civilizations. And of those civilizations we know very little about them and the technologies THEY possessed. We have just scratched the surface about our own planet, and the human race, but we're supposed to know everything about the universe beyond our own world?

Most of your posts on aliens is what could be. And I agree the Aliens could have visited here. It’s just exceedingly unlikely given the size of the universe and our current observed frequency of life.

Again, OUR observations. We have JUST started exploring our own solar system. The first probe to successfully reach Mars arrived there only 56 years ago. The first lander arrived 45 years ago. We've had a rudimentary probe leave our solar system. Our understanding is greatly limited. It's like asking a baby in diapers to solve the Erdos-Strauss Conjecture. Maybe some day, but the baby doesn't even have the language skills to understand the question. That to me is what we are facing. We need more understanding to answer some of these questions.

This idea of 100,000 years of additional time to develop leading to advanced tech we don’t understand requires some weird assumptions.

Really? Considering that it took decades of research before Marconi was able to make his first trans-Atlantic wireless transmission (1901), and then another half decade before the transmission of a voice (1906). I think time is a big player in the development of technology. We have been trying for decades to make fusion reactors a reality. Time and technological development matters.

They need to have developed such that all of the species that did develop have left no evidence in terms of radiation that reached us throughout their hundred thousand years of development. They need to be few enough of them that all of these species have been consistent in that approach. They need to be far enough away to avoid recreation but close enough to have found us. Unless the universe is filled with these technologically advanced super beings it’s unlikely they found us.

Or the very technology they use emits the same radiation we are see from other sources? Again, we are working very hard at harnessing fusion, the very same power generator that drives our sun. What byproduct do you think that reactor would emit? Would that byproduct not look like any other background source of radiation in the noise of the universe?

You've kind of lost me in the second part of this section. They need to be few enough but far enough... ??? I don't get what you're trying to get at here.

I do agree that somewhere in the History of Universe it is likely there has/dors/will exist another intelligent species. The likelihood of them visiting us is near zero.

We'll have to disagree on that. I think that our behaviors would make us of interest, especially based on the past couple hundred years. I mean, WE are monitoring the universe for certain signals of "intelligence" why would other intelligences not be doing the same, and then "take a look" if something caught their eye/ear? If suddenly a planet is emitting new radio waves, it may be a calling card and worthy of exploration, no? I mean, that's what SETI is looking for. That could be our calling card as an emerging intelligence. If all of a sudden there are massive bursts of radiation from a planet (nuclear explosions for example), that may be a calling card to other intelligences of our emergence as an intelligence and make us that much more interesting.

What I see in all of these discussions is we are way too focused on what we understand and putting things in a context that we can rationalize. As the past 100 years should show, there are many things we thought we had come to an understanding of, but turned out there was a lot more to the subject than meets the eye. Remember when neutrons and protons were fundamental? Yeah, good times. Also a good reminder we don't have half the insight into the universe we think we do.

BTW... great points and challenges to bring out important perspective. Discussions like this are fun and they really generate some mental gymnastics and deeper thought. Great stuff!