How many aliens are in the Milky Way?

[Eldorado]

"In the 12th episode of Cosmos, which aired on December 14, 1980, the program’s co-creator and host Carl Sagan introduced television viewers to astronomer Frank Drake’s eponymous equation. Using it, he calculated the potential number of advanced civilizations in the Milky Way that could contact us using the extraterrestrial equivalent of our modern radio-communications technology. Sagan’s estimate ranged from “a pitiful few” to millions. “If civilizations do not always destroy themselves shortly after discovering radio astronomy, then the sky may be softly humming with messages from the stars,” Sagan intoned in his inimitable way.

"Sagan was pessimistic about civilizations being able to survive their own technological “adolescence”—the transitional period when a culture’s development of, say, nuclear power, bioengineering or a myriad of other powerful capabilities could easily lead to self-annihilation. In essentially all other ways, he was an optimist about the prospects for pangalactic life and intelligence.

"But the scientific basis for his beliefs was shaky at best."

Full article at Scientific American: https://www.scientificamerican.com/article/how-many-aliens-are-in-the-milky-way-astronomers-turn-to-statistics-for-answers/

[micahc]

i remember a Cosmos show where Sagan did a calculation of sorts about the likelihood of intelligent life in the universe. Seems i remember he concluded that there could be many intelligent civilizations but they are separated by time and distance, they are very unlikely to ever meet each other.  there could have been an advanced civilization that  is a millions years ahead of us, yet disappeared several million years ago.  maybe the episode is out there somewhere.  I really liked that show.  

[Piney]

45 minutes ago, Eldorado said:

"But the scientific basis for his beliefs was shaky at best."

Too broad of a brush.

The "Rare Earth Hypothesis" of the Fermi Paradox nails it. 

[XenoFish]

If humans make it a 1000 more years I'd be surprised, I won't be around then, but it would be a surprise. 

Edited July 17, 2020 by XenoFish

[astrobeing]

It depends on what random numbers you put into Drake's equation. So if you want the Milky Way to have a million advanced civilizations then just put numbers in that result in a million. Your values are just as valid as anyone else's guesses.

[+Hammerclaw]

What are the odds convergent evolution would lead to something enough like us to have a civilization and be detectable? They would have to be an intelligent communicating species, not only technologically adept, but would have evolved to be enough like us for us to, at least, recognize communication is taking place. Even with mammalian species here on Earth, whom we suspect communicate with one another, we have yet to establish a common frame of reference for communication to take place. What we find out there, on the other hand, may be very different, indeed. 

[SHaYap]

Five dozen, eight if you count butterscotch... 

~

[jethrofloyd]

About as much as there is a bigfoots on the Earth. Zero (0).

Edited July 17, 2020 by jethrofloyd

[Hawken]

[Hazzard]

The Drake equation is nothing more than an educated guess.

Could be one hundred million neighbours, could be that we are alone in the entire galaxy?

Edited July 17, 2020 by Hazzard

[astrobeing]

6 hours ago, seanjo said:

I believe there are other intelligent beings out there, but, because of the vast distances and the plodding speed of light limit, we are effectively alone.

Why would you believe there are other intelligent beings? There's no evidence.

[astrobeing]

58 minutes ago, seanjo said:

We are the evidence. The Universe is vast, probability dictates there must be other life elsewhere. By the way belief does not require proof.

One data point is not enough data to extrapolate from. Our existence may have gone against probability -- yes it's possible that it's more likely that intelligent life would never appear in the universe anywhere and we beat the odds. When you go down the long long series of extremely unlikely events that lead to life on Earth, it's not hard to come up with odds that are more stars in the Milky Way.

Belief does require evidence, otherwise you'll believe in any ridiculous thing you can imagine.

[Robotic Jew]

All of them.

[Essan]

We know there are a great many planets in the universe, it's not unreasonable to suggest millions in our galaxy alone.

We only know of one on which life exists, though it is not unreasonable to suppose it exists elsewhere.

We do not know of any planets that have the unique circumstances that have allowed life to flourish on Earth.   The Moon being the major factor here.   It may  be that life is more likely on Moons of gas planets like Jupiter.

We do not know of any planet on which intelligent life exists.   

[astrobeing]

1 hour ago, seanjo said:

One data point in a vast universe filled with billions of galaxies that are filled with billions of stars and billions of planets is enough to believe we are not the only intelligent life.

No, statistically you need more than one data point. For all we know, the odds of life appearing anywhere in the universe was a trillion to one and Earth is the single planet in the universe to beat those terrible odds.

Also by your logic, since I exist (one data point) that means somewhere in the universe there is someone else who looks exactly like me and has the same name as me. Hell, there could be several people!

1 hour ago, seanjo said:

Belief does NOT require any evidence as can be seen with flat earthers and people that kill in the name of any god.

Wrong. Flat Earthers and religious nuts will gladly show you the flawed evidence they base their beliefs on.

[Dejarma]

i'd say around 76

[+Noteverythingisaconspiracy]

Obviously the number is 42. 

[Dejarma]

1 hour ago, Noteverythingisaconspiracy said:

Obviously the number is 42. 

yep, silly me- of course

[Hanslune]

On 7/17/2020 at 5:02 PM, Noteverythingisaconspiracy said:

Obviously the number is 42. 

117 or so says Rupert

[jethrofloyd]

36 Alien Civilizations In The Milky Way?

36 Alien Civilizations In The Milky Way? The Science Behind A Ridiculous Headline

https://www.forbes.com/sites/startswithabang/2020/06/16/36-alien-civilizations-in-the-milky-way-the-science-behind-a-ridiculous-headline/