I envisage this thread as a place for commentaryless posting of videos on subjects I find interesting on YouTube (or elsewhere) but which I am not inclined to bloviate hereupon. (If you want to discuss a video just create your own thread and invite comments.) Sharing the good stuff. That’s what I intend to do anyway. I have of late restricted my visual media exposure** but there are some interesting things amongst all the crapola. These three videos are from sources I still enjoy and visit. So if you find something you feel like sharing please do!
**Why? When I read a book I feel as if a doorway opens into a larger, more expansive world. When I watch TV I feel as if a doorway is shut tight and my face is being smashed up against it. But that’s just me.
Both great videos.
Interesting subject!
I’ll likely comment more but for now let me just say I do like Sagan’s definition of faith: belief in the absence of evidence. Also, the idea to withhold belief until there is compelling evidence.
Whenever I think of Sagan, I can’t help but remember my dad, a civil engineer by profession but an astronomer at heart, sitting in his armchair in the living room poring over books on astronomy. For the longest time, he was working on reformulating the mathematical formula for the Titus-Bode law so as to include Neptune, if I understand correctly. Once he thought he’d come up with it, he had it copyrighted, and sent it off to Sagan. He received a long letter, a truly gracious response; I wish I still had it.
Anyone who looks an inch beyond their nose must consider our place in the universe. For most of our history people have considered the earth as a privileged garden, an oasis, the center of and the reason for all things. Only in the modern age have we begun to have these illusions shattered.
It was only in the 1920s that Edwin Hubble was finally able to determine that there were other galaxies beyond the Milky Way. Before that it was imagined that the Milky Way was all there was. Overnight the size of the universe was expanded almost beyond our ability to conceive. And the revelations have kept coming ever since. There are hundreds of billions of galaxies in a universe that is a bit shy of 14 billion years old. Can a human being really internalize that? We have made a myriad of amazing discoveries but to me the most profound concepts presented to us by science are Deep Space and Deep Time.
Some sort of existential vertigo is unavoidable. In all we see, and whatever lies beyond even that, can we really be alone? It does seem arrogant to suppose that we are the only ones who stare outward, and ponder.
I think that whether sentient life exists elsewhere or not, on a purely functional, existential level, we are alone. Even if the universe is teeming with intelligence, because of it’s size and age, we may never know. Look at it this way. Let’s say that on average, in every galaxy, there is at least one sentient species. That means there will be hundreds of billions of intelligent races in the universe. You would have to say that intelligent life is common. But what are the chances that we will ever be able to contact another galaxy?
Whether or not there are others, I think we must act as if there are not. In the speculations of even the most rationalistic scientists you can detect the idea that aliens will provide a source of timeless wisdom that might heal us and correct us of our limitations. (Carl Sagan himself occasionally had this attitude.) We have to realize that nothing will save us from ourselves. As hopeless as it sounds when we look at a news report, we have to build a sustainable, long-term ,mature civilization. The idea that we can leave behind an exhausted, ruined earth and go in search of a New Jerusalem amongst the stars is a hopeless delusion. Space will crush our pretensions.
Sorry, reading this back over it sounds like a sermon. Watching those videos put me in a mood. Here is a book I’ve found very useful to consider. ** you do not have permission to see this link ** considers how earth is actually unusual and indeed privileged in the universe.
Stephen, how prominent is the Drake equation in discussions of the likelihood of intelligent life elsewhere in the universe?
The Drake Equation is extremely useful as a tool to focus our analysis. But, as everyone agrees, the values for several of its factors are highly speculative and can only be estimated. The conclusions we draw are based on the assumptions we make and so we can’t really come up with anything approaching firm conclusions.
The problem is that we can’t extrapolate from a single example. Even the discovery of life (or more likely the fossils of life) on Mars won’t be probative because there was so much planetary interaction in the formation of the early solar system. What’s most likely is that life originated on either Earth or Mars and spread to the other. This is what’s important about those hypothetical subterranean oceans on moons in the outer solar system. Their icy environment would have served as a seal to isolate any life that might have developed. If we can demonstrate that life originated independently twice in a single solar system then you could reasonably extrapolate that life must be common in the universe. Once can always be a fluke.
The ** you do not have permission to see this link **, based on the book I mentioned above, does not claim that there will be no life elsewhere whatsoever, but that as you move up levels of complexity, life will become rarer and rarer. So it is at least potentially testable. Lots of microbes. Very few intelligent civilizations.
Thanks, Stephen.
The Rare Earth hypothesis, based on the book I mentioned above, does not claim that there will be no life elsewhere whatsoever, but that as you move up levels of complexity, life will become rarer and rarer. So it is at least potentially testable. Lots of microbes. Very few intelligent civilizations.
I think that makes sense.
What do you make of the objections to it? I only just glanced at them on that Wikipedia link you provided but hopefully will have a chance to go through them slowly in the next few days.
There was some pretty astounding news recently about the possible detection of life on planets orbiting other stars. Because we cannot go and look we must use our instruments to search for what are called “biosignatures”, readings that would seem to indicate the presence of active biological processes elsewhere.
The James Webb Space Telescope detected traces of two gases, dimethyl sulfide and dimethyl disulfide, on a planet named K2-18b, orbiting a star, K2-18, 124 light years away. On Earth these gases are produced by living organisms, primarily marine algae. The gases are present in concentrations 20 times higher than on Earth. Since these molecules are short-lived the implication is that some mechanism (life?) must be present to replenish them. Previously water vapor, carbon dioxide and methane had been detected leading astronomers to speculate that K2-18b might be a water ocean planet with a hydrogen-rich atmosphere.
K2-18 is a Red Dwarf type star. These stars are very old and and very common. In that sense good candidates for life. The down side is that they tend to flare up regularly and eject deadly solar radiation. Also, planets in these star type’s habitable zones (the distance from the star where water would be found in liquid form) are close enough to the star they would almost certainly be tidally locked, meaning that one side of the planet would always face the star, just as we only see one side of our moon. The temperature difference between the day and night sides of such worlds would be extreme.
Results are difficult to interpret. Questions abound. Nothing is conclusive. But the data is provocative.
What I find interesting is the response to this discovery. In almost every case the conversation in the media moved immediately to the prospect of intelligent life, of “inhabited” planets. The likely reality, that we should expect to find many (most?) planets with what we would consider “primitive” biological processes only, is glided over without a thought. I think a lot of people have the “Star Trek” view of aliens, lots of intelligent races at more or less the same level of technological development spread throughout the Milky Way. (And never mind the UFO silliness which imagines the earth as the crossroads of the universe – everybody comes here for some reason.) In fact “Star Trek” is the least likely scenario. What we are most likely to find are either microbes or ruins a million times older than Göbekli Tepe. No one to talk to.
What I find interesting is the response to this discovery. In almost every case the conversation in the media moved immediately to the prospect of intelligent life, of “inhabited” planets. The likely reality, that we should expect to find many (most?) planets with what we would consider “primitive” biological processes only, is glided over without a thought.
It’s much flashier for them to talk about intelligent life than primitive biological processes, which is probably what we should expect find.
I do think glided over without a thought describes much reporting in the media pretty well.
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