*** VD 13 Commentary Thread ***

[johnnya24]

Watched this Live on Sunday night ... funniest thing I've seen in ages. "You son of a gun!"

https://www.youtube.com/watch?v=nJBDXXGAY8c

[heyelander]

Simmons was my pick. I'm out right now but will try to get back to make a pick in an Irish bit

[billbuckner]

You guys are stilll doing these? Keep banging, gentlemen.

[johnnya24]

You guys are stilll doing these? Keep banging, gentlemen.

Bucky > Bill

[Bene Futuis]

I had to save my cosmology rant because it's getting long and I have to run for a couple hours. Suffice to say that it will be underwhelming and unconvincing, but what the hey(e)....

OK, here's where I'm at with the "are we alone out in this big ol' universe?" discussion:

There are things that we know to be certain.

We know that the probability of the existence of intelligent life in the universe is more than zero. We know this, arguments about this reality being a simulation aside, because we are living proof. We also know that rudimentary life can form in a relatively short period of time. We know this because life first originated about a billion years after Earth came into existence. We also know that a couple billion years later, we evolved from that primitive life. We know what the building blocks for the emergence of life as we know it are --- things like hydrogen, carbon, and oxygen --- and we also know they are incredibly prevalent throughout our galaxy. Hydrogen is the most common element in the universe, oxygen is third, etc.

The most common way scientists estimate the number of communicating civilizations in our galaxy is the Drake Equation, in which N = R* • fp • ne • fl • fi • fc • L where

N = The number of civilizations in the Milky Way galaxy whose electromagnetic emissions are detectable.

R* = The rate of formation of stars suitable for the development of intelligent life.

fp = The fraction of those stars with planetary systems.

ne = The number of planets, per solar system, with an environment suitable for life.

fl = The fraction of suitable planets on which life actually appears.

fi = The fraction of life bearing planets on which intelligent life emerges.

fc = The fraction of civilizations that develop a technology that releases detectable signs of their existence into space.

L = The length of time such civilizations release detectable signals into space.


Of course, any zeroes in this equation mean we're alone, at least in our galaxy (one of hundreds of billions, remember).

But we do know some of these variables. R is somewhere between 1.5-3. F(sub)p is something approaching 1 --- stars with planets are the rule, rather than the exception. Fp minus Ne is somewhere around .4 --- there are more than 40 billion Earth-esque planets in habitable zones orbiting stars in the Milky Way alone. But now we start getting into the sticky stuff. For brevity's sake, of the remaining variables really only Fl is worth discussing here --- "is there any life at all out there?" The rest just speak to whether we (or they) would ever know of the other's existence. Of course, the enormous distances between planets makes all of this even more difficult --- if a civilization 65 million light years away, that is, not even outside our own galaxy, was somehow looking directly at Earth, they would see dinosaurs and not people. The time factor complicates everything enormously because even if there is other life out there, it would take a very, very specific window or some sort of prescience to be able to communicate. Humans have only been able to transmit radio waves beyond our atmosphere for 100 years.

But scientists often employ the Central Limit Theorem when trying to muscle through the Drake Equation. That is, given variables with finite mean and variance, the variables will be normally distributed on a plot. And when the theorem is applied to the Drake Equation, the probability of each of the seven variables of the Equation become positive.

There's an easy way to look at it, too. It's called the "pessimism line". Let's assume that ours is the only life ever to have existed in the universe. Given what we know right now and our ever-increasing knowledge about the other quantifiable variables, human civilization must be the only civilization in the universe if the odds of a civilization developing on a habitable planet are less than one in 10 billion trillion (one part in 10 to the 22nd power). This, of course, is an unbelievably small number and generally falls well below nearly all of even the most pessimistic projections.

It seems to me that it's likely that some life, at least some rudimentary form of life, has formed somewhere in the trillions of solar systems in the universe over the course of its 14+ billion year existence. Obviously the probability of life, in general, exceeds zero. But the vast distances and long time scales complicate things so much that even if there were billions of intelligent, spacefaring civilizations to have emerged, it is still likely we would never know. The best answer is that, for all practical purposes, we are alone in the universe even if there are millions or billions of other lifeforms out there.

[heyelander]

The Fermi Paradox thread threatening to suck me in. I freakin' LOVE cosmological discussions! Suffice to say I think that Seitzer and Ken are way off base in their evaluations. 1J is, too, but that much can be assumed every time he speaks.

Dude... you really should stay out of the sports bar...

[heyelander]

sorry, got a friend in town from Philly and was showing her the placer county sites... which are limited when it's actually raining here. She came out here to escape the east coast winter and this is the one week it is going to rain here for the next 3 years.

[Kevin Seitzer]

But we do know some of these variables. R is somewhere between 1.5-3. F(sub)p is something approaching 1 --- stars with planets are the rule, rather than the exception. Fp minus Ne is somewhere around .4 --- there are more than 40 billion Earth-esque planets in habitable zones orbiting stars in the Milky Way alone. But now we start getting into the sticky stuff. For brevity's sake, of the remaining variables really only Fl is worth discussing here --- "is there any life at all out there?" The rest just speak to whether we (or they) would ever know of the other's existence. Of course, the enormous distances between planets makes all of this even more difficult --- if a civilization 65 million light years away, that is, not even outside our own galaxy, was somehow looking directly at Earth, they would see dinosaurs and not people. The time factor complicates everything enormously because even if there is other life out there, it would take a very, very specific window or some sort of prescience to be able to communicate. Humans have only been able to transmit radio waves beyond our atmosphere for 100 years.

But scientists often employ the Central Limit Theorem when trying to muscle through the Drake Equation. That is, given variables with finite mean and variance, the variables will be normally distributed on a plot. And when the theorem is applied to the Drake Equation, the probability of each of the seven variables of the Equation become positive.

There's an easy way to look at it, too. It's called the "pessimism line". Let's assume that ours is the only life ever to have existed in the universe. Given what we know right now and our ever-increasing knowledge about the other quantifiable variables, human civilization must be the only civilization in the universe if the odds of a civilization developing on a habitable planet are less than one in 10 billion trillion (one part in 10 to the 22nd power). This, of course, is an unbelievably small number and generally falls well below nearly all of even the most pessimistic projections.

I get that N, R, and Fp are really big numbers. I just don't know how we have any clue how to estimate the proper order of magnitude for Fl (or Fi or Fc, but leaving those aside for the moment). How do we know Fl > 1*10^-22? I just don't see any evidence one way or the other. Saying it feels pretty pessimistic to think it's lower than that...okay. But that's not proof one way or another. It's not even evidence short of proof.

It seems to me that it's likely that some life, at least some rudimentary form of life, has formed somewhere in the trillions of solar systems in the universe over the course of its 14+ billion year existence. Obviously the probability of life, in general, exceeds zero. But the vast distances and long time scales complicate things so much that even if there were billions of intelligent, spacefaring civilizations to have emerged, it is still likely we would never know. The best answer is that, for all practical purposes, we are alone in the universe even if there are millions or billions of other lifeforms out there.

I don't necessarily disagree with you. If you asked me which way I think things are, I'd guess Fl > 1*10^-22. But that's just based on a "there's one of us, so there's probably more of us" line of thinking rather than any real mathematical proof, which is what Fresno Bob was claiming to have.

[johnnya24]

I'm not sure how much the Drake Equation has been updated since the 1960's, but science has moved on a lot since then.

It seems to me that it's likely that some life, at least some rudimentary form of life, has formed somewhere in the trillions of solar systems in the universe over the course of its 14+ billion year existence. Obviously the probability of life, in general, exceeds zero. But the vast distances and long time scales complicate things so much that even if there were billions of intelligent, spacefaring civilizations to have emerged, it is still likely we would never know. The best answer is that, for all practical purposes, we are alone in the universe even if there are millions or billions of other lifeforms out there.

This is the crucial point IMO, because it's something we have within our grasp. We could of course eventually invent telescopes that reveal telltale signs of life on goldilocks worlds, such as high methane content. But the more we learn about the evolution of life on our planet, the more we can estimate the likelihood of life elsewhere. The field of biochemistry is moving so fast, it's almost impossible to keep up:

Number 5 (Rare Earth) is a theory that has been deepened with recent biochemical research into the origins of life on Earth. It suggests, that if the conditions for simplistic life (single cellular) can exist, they probably will. Therefore we will probably find simple bacterial life everywhere in the galaxy (possibly even our own solar system!). Life is probably abundant in the universe. Good, right? Well no. However, it also suggests that complex life (multi cellular) is far far far rarer than previous imagined. There is no necessary evolutionary connection between single and multi cellular life forms, as I think most of us imagined. The jump from abundant single cellular life (bacteria etc) to complex multi cellular life occurred only ONE TIME in the 4 billion year history of earth. ONE TIME! All non-single cell life on earth is related to a single freak occurrence of successful endosymbiosis - that is, to put in simply, a bunch of these single cell lifeforms got trapped inside each other, and survived to form unique roles within the cell, which lead to the explosion of multi cellular life. All non-bacterial / archaea (that is, all plant and animal life) on earth are related back to this one freak occurrence.

Add this parameter to number 5, it will seem almost impossible that we will discover intelligent life in the universe. It will be far rarer than even number 5 suggests. But we will probably find bacteria and archaea everywhere.

It's not often you read a book and have a mind-blowing insight like "oh shit, we may as well be alone in the universe". But that was my reaction when I read Nick Lane's book, The Vital Question (Good Reads link) about 2 years ago. It's not about the possibility of alien life at all, but about the biochemical origins of life in general. The 2 are indelibly related.

Nick Lane, The Vital Question (amazon link)

To lazy to retype.

[johnnya24]

sorry, got a friend in town from Philly and was showing her the placer county sites... which are limited when it's actually raining here. She came out here to escape the east coast winter and this is the one week it is going to rain here for the next 3 years.

Make sure you aldi stunt care when you take her to placer county sites

[Kevin Seitzer]

I think it's a real place that Heye might plausibly be:

[Kevin Seitzer]

According to Wikipedia

Placer County took its name from the Spanish word for sand or gravel deposits containing gold. Miners washed away the gravel, leaving the heavier gold, in a process known as "placer mining".

[heyelander]

I think it's a real place that Heye might plausibly be:

yep, I'm in rocklin, down at the bottom... Folsom Lake there is next to Folsom State Prison... There's a decent Italian restaurant up on Newcastle... Truckee is where the Donner party got snowed in... I know nothing about foresthill.

[Bene Futuis]

I get that N, R, and Fp are really big numbers. I just don't know how we have any clue how to estimate the proper order of magnitude for Fl (or Fi or Fc, but leaving those aside for the moment). How do we know Fl > 1*10^-22? I just don't see any evidence one way or the other. Saying it feels pretty pessimistic to think it's lower than that...okay. But that's not proof one way or another. It's not even evidence short of proof.



I don't necessarily disagree with you. If you asked me which way I think things are, I'd guess Fl > 1*10^-22. But that's just based on a "there's one of us, so there's probably more of us" line of thinking rather than any real mathematical proof, which is what Fresno Bob was claiming to have.

We know that the probability of intelligent life in the Milky Way galaxy is at least one in a billion trillion. It cannot be lower than that, unless I am missing something obvious. And yes, if certainty is the standard by which we're discussing, this will be a very short discussion. There is no certainty or proof, only probability. I mean, that just goes without saying. Since we know the probability of life forming is more than zero, we can only make educated guesses based off of the information we possess. The pessimism line, however, is the absolute lowest probability of the existence of life in this galaxy, one of hundreds of billions of its kind. It cannot be lower and it cannot be zero.

[Kevin Seitzer]

We know that the probability of intelligent life in the Milky Way galaxy is at least one in a billion trillion. It cannot be lower than that, unless I am missing something obvious. And yes, if certainty is the standard by which we're discussing, this will be a very short discussion. There is no certainty or proof, only probability. I mean, that just goes without saying. Since we know the probability of life forming is more than zero, we can only make educated guesses based off of the information we possess. The pessimism line, however, is the absolute lowest probability of the existence of life in this galaxy, one of hundreds of billions of its kind. It cannot be lower and it cannot be zero.

So, Fresno Bob was claiming Gregg was proved wrong by math. I just don't see that.

But beyond that, I don't see what evidence we have around the bounds for Fl other than what you say, which is that because we know of the existence of one (us), it must be greater than zero. Okay, but...we already know we exist, so that doesn't tell us anything helpful. Since we don't have a two (somewhere else), we really don't have any idea whether it's 1*10^-10 or 1*10^-20 or 1*10^-30, or something else.

I don't understand why you're claiming it can't be lower than the pessimism line? On what basis? Applying the Milky Way rate to the rest of the galaxies in the universe?