This is the best Hubble image ever made!
https://www.youtube.com/watch?v=8EKl9aF4NnM
This is called the Hubble Legacy Field, and
you can find the image here:
http://hubblesite.org/image/4492/news
Quote from: Unbeliever on May 13, 2019, 07:53:47 PM
This is the best Hubble image ever made!
https://www.youtube.com/watch?v=8EKl9aF4NnM
This is called the Hubble Legacy Field, and
you can find the image here:
http://hubblesite.org/image/4492/news
I find it baffling that anyone can see this and then think we are the only life in the universe... and assuming there are multiverses, the only life in all of those as well.
My little brain...oh
Quote from: drunkenshoe on May 14, 2019, 07:34:59 AM
My little brain...oh
https://www.prosperosisle.org/spip.php?article874
Quote from: Shiranu on May 14, 2019, 01:52:13 AM
I find it baffling that anyone can see this and then think we are the only life in the universe... and assuming there are multiverses, the only life in all of those as well.
Max Tegmark, in his book
Our Mathematical Universe, gives an interesting argument for no other life besides ours, based on something called a
uniform logarithmic prior (https://en.wikipedia.org/wiki/Prior_probability). I don't have the book in front of me, so let's see if I can do justice to the argument.
Since we don't know how near is the nearest other intelligent life, then it could be anywhere from 10^21 meters (in our galaxy) 0r 10^100, or 10^1000, or any other order of magnitude, and they are all, a priori, equally likely. Since our observable universe is 10^26 meters, it's unlikely that the correct number is between the 10^21 meters and 10^26 meters, since such a small range is too small to be statistically likely, as any larger order of magnitude is equally likely.
I hope that's clear, if not I can find the book and give it in Tegmark's words.
Quote from: Gawdzilla Sama on May 14, 2019, 07:45:24 AM
https://www.prosperosisle.org/spip.php?article874
Hmmm. OK. I'll check it out.
I'm from the period of "Honey, I Shrunk the Kids."
Quote from: Unbeliever on May 14, 2019, 01:34:36 PM
Max Tegmark, in his book Our Mathematical Universe, gives an interesting argument for no other life besides ours, based on something called a uniform logarithmic prior (https://en.wikipedia.org/wiki/Prior_probability). I don't have the book in front of me, so let's see if I can do justice to the argument.
Since we don't know how near is the nearest other intelligent life, then it could be anywhere from 10^21 meters (in our galaxy) 0r 10^100, or 10^1000, or any other order of magnitude, and they are all, a priori, equally likely. Since our observable universe is 10^26 meters, it's unlikely that the correct number is between the 10^21 meters and 10^26 meters, since such a small range is too small to be statistically likely, as any larger order of magnitude is equally likely.
I hope that's clear, if not I can find the book and give it in Tegmark's words.
I have that book, and I don't care for his reasoning. The implicit assumption here is that intelligent life is exceedingly rare.
Well, it might be. Or, it might
not be.
We don't know because we only have one data point to draw on: ourselves. Trying to make assumptions based off of that is mathematically unwise.
What we
observe is that at least one intelligent life form can arise in an area containing one hundred to four hundred billion stars because a) we are here and b) that's how many stars are around us, in our galaxy. Call it an average of one in a quarter trillion, or 2.5x10
11.
There are something on the order of 10
23 stars in the universe. So if it's an average of one intelligent life form per quarter trillion stars, and there are a hundred billion trillion stars, I come out of that with an average of four trillion intelligent life forms in the universe -- which, because of the vast nature of intergalactic distances, will probably never be in contact with each other.
Tegmark's mistake is assuming we're on the tapering end of the bell curve, when he should be assuming we're in the middle of it.
(https://imgs.xkcd.com/comics/the_drake_equation.png) (https://xkcd.com/384/)
The variables in the Drake equation isn't based on anything tangible, as we have no data points to any of them other than just our own.
I don't have an equation, but I suspect there are none other than us, at least in our galaxy. I await observations, something better than Tabby's star.
Quote from: Unbeliever on July 16, 2019, 07:52:19 PM
I don't have an equation, but I suspect there are none other than us, at least in our galaxy. I await observations, something better than Tabby's star.
You are just as right/wrong as anybody else making a SWAG.
The first radio broadcasts were in the early 20th century. Prior to that how would anyone have known we were here even if they were listening? Even now, the earliest weak radio signals can be no more than 110 light years from earth which means anyone outside that range has no chance of knowing we are here.
Assuming that evolution follows the same basic path ( a rather large assumption!) that means that any society we could hope to contact would have to have reached roughly the same technological level as us at about the same time ( +/- 100 years.) That's asking a lot.
Quote from: Minimalist on July 16, 2019, 10:09:37 PM
The first radio broadcasts were in the early 20th century. Prior to that how would anyone have known we were here even if they were listening? Even now, the earliest weak radio signals can be no more than 110 light years from earth which means anyone outside that range has no chance of knowing we are here.
Assuming that evolution follows the same basic path ( a rather large assumption!) that means that any society we could hope to contact would have to have reached roughly the same technological level as us at about the same time ( +/- 100 years.) That's asking a lot.
Actually, assuming a technology capable of resolving Earth independently of our sun (perfectly plausible, we're very nearly to that point ourselves), the presence of a technological civilization here could be inferred out to a radius of about 200ly, give or take. Spectrographic analysis would reveal pollutants in the atmosphere as the Industrial Revolution got going, and any ETI would be able to observe their growing concentration over time.
Few things in planetary astronomy say "Hey, something hinky's going on over here" as clearly as an unstable atmosphere does. Chemistry is the same here, there and everywhere: there are no (known) plausible processes for maintaining a stable oxygen-rich atmosphere, nor do industrial pollutants resemble volcanic activity.
Of course, a 200ly radius sphere is a spit in the ocean compared to the size of this galaxy, and the odds of finding another intelligence within that radius are even more vanishingly small than the odds of finding another intelligence period. There would need to be about five million ETIs in this galaxy to make that a 50/50 proposition, and I'd be surprised if the number is as high as five.
The 19th C. "industrial pollutants" were wood and coal smoke. Nothing technological about that, both had been around for a good long while.
Quote from: Gawdzilla Sama on July 17, 2019, 03:56:36 PM
The 19th C. "industrial pollutants" were wood and coal smoke. Nothing technological about that, both had been around for a good long while.
Downtown Denver 109 years ago, due to coal burning, was a lot dirtier than today. But now Denver covers a much larger area. The initial objection to coal burning (which came about because of a shortage of wood to burn) was all the soot it produced.
Quote from: trdsf on July 17, 2019, 04:11:18 AM
Actually, assuming a technology capable of resolving Earth independently of our sun (perfectly plausible, we're very nearly to that point ourselves), the presence of a technological civilization here could be inferred out to a radius of about 200ly, give or take. Spectrographic analysis would reveal pollutants in the atmosphere as the Industrial Revolution got going, and any ETI would be able to observe their growing concentration over time.
True, but would they even necessarily know that much about the Earth? Take our fairly recently-assembled catalogue of exoplanets. How much do we know about any given planet? Not a whole lot. We know the star, the size of the planet, the number/size of its moons, maybe some tantalizing glimpses into its composition and habitability, that's pretty much it. Correct me if I'm wrong, but we don't know details like atmospheric carbon ppm.
Hell, one of our catalogued exoplanets could house a technologically advanced civilization and we might not have a clue about that yet. Flip that picture, and that's where our alien observers might be at - looking at the Sol system, not really seeing anything too interesting, and looking elsewhere.
In a quasi catch-22, they're only likely to look closely if they know that there's something important here and they'd only know that if they already looked more closely.
Here's a great resource for exoplanets:
https://exoplanets.nasa.gov/
Quote from: Baruch on July 17, 2019, 04:24:41 PM
Downtown Denver 109 years ago, due to coal burning, was a lot dirtier than today. But now Denver covers a much larger area. The initial objection to coal burning (which came about because of a shortage of wood to burn) was all the soot it produced.
SFW
I don't care if there is intelligent life out there. ANY life whatsoever would be super interesting to find. Back before the game Spore died, I used to make and collect animals for an alien zoo.
Quote from: Gawdzilla Sama on July 17, 2019, 03:56:36 PM
The 19th C. "industrial pollutants" were wood and coal smoke. Nothing technological about that, both had been around for a good long while.
Yes, but not in as high a quantity in the atmosphere. A major forest fire or volcanic eruption would have provided a momentary blip; the Industrial Revolution was an ongoing process, not a random natural event. The steady growth over time would have been the key.
Quote from: Sal1981 on July 16, 2019, 07:45:53 PM
(https://imgs.xkcd.com/comics/the_drake_equation.png) (https://xkcd.com/384/)
The variables in the Drake equation isn't based on anything tangible, as we have no data points to any of them other than just our own.
The only real use in the Drake Equation is for helping frame one's thoughts about the prevalence of intelligent life in the galaxy, and in the universe. Drake himself proposed it in that way, not as a solid mathematical theory of extraterrestrial intelligence. Until we have a galaxy-wide survey of life, intelligence, and the circumstances under which civilizations live and die, that's all it can be.
Quote from: Blackleaf on July 18, 2019, 09:36:12 PM
I don't care if there is intelligent life out there. ANY life whatsoever would be super interesting to find. Back before the game Spore died, I used to make and collect animals for an alien zoo.
Spore died!? I didn't know that. Too bad, I never got to play it. Looked really cool, though.
Quote from: trdsf on July 19, 2019, 04:57:09 AM
The only real use in the Drake Equation is for helping frame one's thoughts about the prevalence of intelligent life in the galaxy, and in the universe. Drake himself proposed it in that way, not as a solid mathematical theory of extraterrestrial intelligence. Until we have a galaxy-wide survey of life, intelligence, and the circumstances under which civilizations live and die, that's all it can be.
Yeah, might as well call it the Dreck equation.
This is interesting:
QuoteWhat is Fermi's Paradox?
Do aliens exist?
Can it be solved. Dr. Duncan Forgan explores that in his new book "Solving Fermi's Paradox", asking if aliens and alien civilizations exist. Where are they? Why aren't they here yet? And what factors can keep a civilization from advancing. What if they are long since dead, how do we look for ancient alien civilizations.
John Michael Godier also spoke to Dr. Forgan on Event Horizon about the protocols for what we should do if we find intelligent life. Especially life that is far more advanced, what do we do if we see a Dyson sphere? How will the world react, and how should that information be shared.
https://www.youtube.com/watch?v=aEmCYv8QII0
My working hypothesis, until further data comes in, is that we are completely alone in the observable universe. I could be wrong, and I'm looking forward to being proven to be.
With regard to the so-called Fermi paradox:
It must be remembered that at the time Fermi asked "Where is everyone?", the Steady State theory of the universe was still an active and reasonable theory. In a temporally infinite universe, yes, we should have been visited by now since in an infinite universe, there's no reason an alien species couldn't have visited every potentially life-bearing star in the galaxy (even universe), even if there's no shortcut around the speed of light as an absolute limit.
In a temporally finite universe, that situation is very different. There are reasons life cannot have existed from the beginning, mainly that the heavier elements required for life need not only enough time to be created, but also time to be concentrated -- and that's just for basic life. The needs for complex life are more stringent still. Personally, I think a certain concentration of slowly radioactive elements like 238U and 40K are necessary to gently elevate mutation rates.
So you can't have life that's arbitrarily old, with an arbitrarily long time to come to sentience and an arbitrarily long time to explore the galaxy, much less the universe. It's possible that it takes on average around ten billion years for enough of the necessary heavy elements to be produced and collect in useful concentrations for planets to form that have all the bits they need, in a typical galaxy. In a larger one, might take less time. In a smaller one, might take more.
Even if you wait out the nine or ten billion years necessary for a suitable habitat to form, there's no guarantee that life will arise. And even if life does arise, it's going to take another several billion years for it to evolve into anything capable of sentience, and it's not guaranteed that it will.
So let's say you've been lucky and your planet developed life and your life evolved into sentience and... hey, 13-some billion years have already passed since the creation of the universe. So where is everyone?
That's a damned good question.
Our instruments cannot take arbitrarily detailed measurements. I doubt much that we'll ever be able to do more than resolve Proxima b (https://en.wikipedia.org/wiki/Proxima_Centauri_b) as more than a dot of light; if and when we can do that, we can at least do spectrographic analysis and determine the contents of its atmosphere (if any). And that's our nearest possible exoplanet; the problems of detection and analysis only get worse the further out we look. Right now, the only thing it has to recommend it as an exploration target is that it's the only exoplanet we can theoretically get a probe to within a human lifetime.
And then there's Einstein. As far as we can tell, lightspeed as a speed limit is a law of nature, not an engineering challenge like the speed of sound. The only way to (partially) circumvent it is with patience and a thundering LOT of fuel.
And lastly, there's the simple fact that half the galaxy is simply beyond observation because of obstructing clouds of matter, and the core.
Furthermore, only the nearest couple thousand starsâ€"out of hundreds of billionsâ€"can even have the chance of having detected our presence, and vice versa. There could be a culture at the equivalent stage of our Renaissance only eight light years away, and we would have no way of knowing anyone was there because that's an insufficiently low technology level to be detected. Likewise, there could be one advanced enough that they have effectively lossless communications, so we can't detect them because there's no leakage, and their shell of open-air radio emissions has long since passed.
These problems exist for any other intelligent species that might in our galaxy or any other galaxy. So the other problem with Fermi's objection is that he assumed the existence of an intelligent species that has both infinite resources and infinite curiosity.
No. There are perfectly sensible reasons that there aren't probes, staffed or robotic, visiting every one of the (average) 250 billion stars in this galaxy, in a universe that's constrained in time.
The answer to Pauli's "Where is everyone?" is "Patience, Wolfie, patience," with just a soupçon of "And why should they look here in the first place?"
Quote from: trdsf on July 19, 2019, 04:57:09 AM
The only real use in the Drake Equation is for helping frame one's thoughts about the prevalence of intelligent life in the galaxy, and in the universe. Drake himself proposed it in that way, not as a solid mathematical theory of extraterrestrial intelligence. Until we have a galaxy-wide survey of life, intelligence, and the circumstances under which civilizations live and die, that's all it can be.
It's not perfect and you could add a lot of variables. Like a large moon, deep AND shallow water, deep smokers, extra large metallic core, etc. But I'll honor the equation as the best first try that looked at it logically.
If there hadn't been a hypernova about 80 million years before the solar system's formation we wouldn't have the heavy elements needed for life in the first place,
https://www.youtube.com/watch?v=kaD32JrWPlI
Quote from: Unbeliever on July 20, 2019, 02:28:21 PM
If there hadn't been a hypernova about 80 million years before the solar system's formation we wouldn't have the heavy elements needed for life in the first place,
Why 80 MYA? Is there a particular one in mind? I know about heavy elements and iron-death...
Yes a particular one, that was close enough to shower the nascent system with heavy elements, such as iodine, gold, platinum, etc.
Quote from: Unbeliever on July 20, 2019, 02:41:28 PM
Yes a particular one, that was close enough to shower the nascent system with heavy elements, such as iodine, gold, platinum, etc.
I meant was there a particular one we know about? Just asking because 80 LY seems rather specific.
Not 80 light years, but 80 million years pre-solar system.
Quote from: Unbeliever on July 20, 2019, 03:02:38 PM
Not 80 light years, but 80 million years pre-solar system.
Meant 80M LY, sorry. Left out the M. Typing is not my forte. Cats all over the keyboard, LOL! I am endlessly editing and miss some.
Wait, why did you say "pre-solar" system? Think about that.
Because the hypernova happened 80 million years before the solar system formed - not 80 million light years away.
Quote from: Unbeliever on July 20, 2019, 03:21:33 PM
Because the hypernova happened 80 million years before the solar system formed - not 80 million light years away.
OK, yes 4.571 billion years (age of solar system) + 80 million. I'm not sure what you are getting at. Why the 80MYA/LY ago?
Not light years, just years. Why? Because that's when it happened.
The video explains it pretty well, and it's less than 10 minutes long.
Quote from: Unbeliever on July 20, 2019, 03:35:32 PM
Not light years, just years. Why? Because that's when it happened.
The video explains it pretty well, and it's less than 10 minutes long.
A Light Year is a year of light travel. What are you saying I'm missing? Do you mean 80M Earth years?
OK, start again. Are the 80MY "light years" or "Earth orbits"? And what does the 80MY represent to you, time or distance?
It's time, not distance.
Quote from: Unbeliever on July 20, 2019, 03:56:05 PM
It's time, not distance.
So you mean Earth orbits then. Why is 80M Earth orbits important?
Well, because that's when the hypernova happened. Of course, at the time there were no "Earth orbits" since there wasn't yet an Earth.
This is starting to sound like "who's on first."
Quote from: Unbeliever on July 20, 2019, 03:02:38 PM
Not 80 light years, but 80 million years pre-solar system.
Pre-solar system, so over 4.5 billion years ago.
Cavebear ... some of my days are like that ;-) Can't quite get it together.
Quote from: Unbeliever on July 20, 2019, 04:16:34 PM
Well, because that's when the hypernova happened. Of course, at the time there were no "Earth orbits" since there wasn't yet an Earth.
This is starting to sound like "who's on first."
My thoughts exactly. I Don't Know - 3rd Base!
I think you are trying to describe a hypernova that occured 80 LY away that caused the solar system to contract the gases from a cloud and formed Sol 4.5 B Earth orbit time ago (not that Earth existed then). Getting that right so far? Then the Earth and many planetoids were formed, some of which joined by gravity to create the current solar system and asteriods under the influence of Jupiter and Saturn, etc, etc, etc.
And I STILL don't know why 80MY means anything unless it was Light Years and you haven't said why THAT means anything and I'm damn well running out of patience...
So you better put some plain facts on the table.
OK! LOL
Eighty million years before the solar system was formed, two neutron stars collided, creating and then spewing large amounts of heavy elements into the surrounding space. Some portion of those heavy elements coasted through space, eventually reaching the vicinity of the then-forming solar system. Those heavy elements became infused with the pre-solar accretion disk, about a tenth the mass of the moon, and became part of the planetary system that then formed. If that hypernova hadn't happened there wouldn't be nearly as much heavy elements in and on the Earth for us to be made from.
This had nothing to do with the collapse of the pre-solar nebula, by the way. That was something different.
The only place light years comes into it is that the neutron star collision happened a thousand light years away from the location of the yet-to-be solar system.
Quote from: Unbeliever on July 20, 2019, 04:49:27 PM
This had nothing to do with the collapse of the pre-solar nebula, by the way. That was something different.
Already denying liability ...;-)
Quote from: Unbeliever on July 20, 2019, 04:57:57 PM
The only place light years comes into it is that the neutron star collision happened a thousand light years away from the location of the yet-to-be solar system.
As I understand it, during solar system formation/star formation ... it gets expelled from the mother nebula. We aren't in the same relative position as back then.
Quote from: Baruch on July 20, 2019, 05:08:44 PM
Already denying liability ...;-)
Of course! Plausible deniability is important!
:-P
Quote from: Unbeliever on July 20, 2019, 04:47:38 PM
OK! LOL
Eighty million years before the solar system was formed, two neutron stars collided, creating and then spewing large amounts of heavy elements into the surrounding space. Some portion of those heavy elements coasted through space, eventually reaching the vicinity of the then-forming solar system. Those heavy elements became infused with the pre-solar accretion disk, about a tenth the mass of the moon, and became part of the planetary system that then formed. If that hypernova hadn't happened there wouldn't be nearly as much heavy elements in and on the Earth for us to be made from.
I'm trying to respect you here, but you are driving me nuts with imprecision.
I understand stellar fusion in the general sense of there being a finite energy offlet. I understand neutron stars conceptually. I understand what happens when they slowly spin together in a general way and the effects that mass has. I understand how elements heavier than iron are formed via gravitational fusion after the iron death.
ITS THE 80MY THAT IS KILLING ME HERE! WHERE DOES THE 80MY COME FROM?
If you know that 2 neutron stars collided 80MYA, then you have to know where they are. Where are they?
2 colliding neutron stars would not eject their heavy elements at the speed of light. What speed did they eject at? That determines how far away they were from Sol-to-be. If you don't know how far away the 2 colliding neutron stars were or the speed of the ejecta how do you come up with "80MYA"?
I'm not trying to be harsh about this. But you are saying 2+2+"something"= 80MY years of our current time (before we existed).
Somewhere, that 80 MYA is quantifiable and I don't mean quantum mechanics.
How do you know the 80MYA?
*I* don't know it, Anton Petrov knows it, and I got it from him, in the video. I don't know who told it to him, though, but some smart astrophysicist apparently figured it out. I'm not an astrophysicist, so I have to rely on what I'm told by those who know (hopefully) what they're talking about.
Quote from: Unbeliever on July 20, 2019, 06:05:47 PM
*I* don't know it, Anton Petrov knows it, and I got it from him, in the video. I don't know who told it to him, though, but some smart astrophysicist apparently figured it out. I'm not an astrophysicist, so I have to rely on what I'm told by those who know (hopefully) what they're talking about.
Well, OK then. Why didn't you just SAY so? I'll always accept a " I read it here" link or source. Or something...
Whew.
Well, that's why I posted a video, so I wouldn't have to explain it myself.
Quote from: Unbeliever on July 20, 2019, 06:18:11 PM
Well, that's why I posted a video, so I wouldn't have to explain it myself.
We both got contra-balanced. Peace, friend...