Why We are Alone in the Galaxy | Marc Defant | TEDxUSF

I wrote a book on the history of life and I started noticing when I did my research that there were statistically improbable events that apparently had to happen for us to have life here, intelligent life here on our planet and SETI has been searching now In the search for intelligence alien, they've been looking for life for 54 years and of course they haven't found any intelligent life, so I got to thinking, well, maybe they weren't finding it because it's extremely difficult for evolutionary or whatever to happen tonight. What I would like to do is give you three examples of these statistically improbable events, but keep in mind that there are literally hundreds of these events that must occur for there to be intelligent life on this pants planet. my opinion well, I need to go back to the Big Bang and talk a little bit about the Big Bang theory and I hope that when I said the Big Bang theory the first thing that came to mind was not the television show. because we are all in trouble if that is the case and it could be a long talk at the Big Bang 13.8 billion years ago there was hydrogen and helium and that is all for scientists to recognize that we need another source for all the other elements what we have. found in our universe and now we know that source is a supernova and a supernova is literally the death of a giant star, it collapses on itself, forms all the elements of the periodic table except hydrogen and helium and then explodes and sends that material to your local space.

Well, now I want you to imagine something called a solar nebula. This is a gaseous cloud that once existed there and then collapses to form our solar system and that cloud was originally enriched only in hydrogen and helium. so we have to have all the supernovae erupting out there and enriching that solar nebula in all the elements necessary for intelligent life particularly on our planet and if we don't have that then we can't have intelligent life and then at some point there has to be a supernova near our solar nebula that forces it to collapse. How do I know there was a supernova out there that forced our solar nebula to collapse?

Well, I think it's one of the most interesting scientific discoveries. of all time and doesn't get a lot of press, so I'd like to share it with you tonight. A meteorite is believed to be material that formed from our solar nebula as it collapsed to form our solar system. The reasons we know this is that it has calcium and aluminum inclusions that date back 4.5 6 between seven and 30 billion years ago, so that is the oldest state that we find in our solar system and now we use that date as the beginning or the origin of our In the solar system, in these inclusions of calcium aluminate is something strange, we find an isotope of magnesium called magnesium 26 and we should not have inclusions of magnesium and calcium and aluminum, so the Scientists were puzzled about this and recognized at some point that magnesium 26 is the decay product of aluminum 26.

Aluminum 26 has a relatively short half-life of 717 thousand years, which means that in seven to ten million years all the aluminum 26 will decay into magnesium-26, we don't have any aluminum 26 on the planet today that's because it all decayed billions of years ago when it was first formed from a supernova, so I think you can see here what is happening: we had a supernova near our solar nebula and we injected it with all the necessary elements including aluminum 26. and forced it to collapse and when it collapsed calcium and aluminum inclusions were formed rich in aluminum 26 and that aluminum 26 then broke down the magnesium that points to 6, hence the reason we have magnesium in these calcium and aluminum inclusions, so I don't know, I think it's an incredible scientific discovery.

I'm a little biased, but think about it, we can take things that we see today, we can look at them, we can study them, and then we can extrapolate them to things that happened four and a half billion years ago. I think it's surprising and where does statistical improbability come into play here? Well, think about what has to happen. To begin with, you have to have our solar nebula out there with just hydrogen and helium and then you have to have all your supernovae. exploding it injects all these elements bigger than hydrogen and helium and in just the right amount and none of them can force our solar nebula to collapse and then you have to have this supernova that we know happened close enough to our solar nebula to force it to collapse and when it collapses at just the right time when our solar nebula has the right composition, then it collapses and forms and eventually takes us.

Well, that seems remarkable to me, an unlikely event if ever there was one and we're here, pop, possibly as a result of that. Well, that's the first statistically improbable event I'd like to talk about tonight, but the second has to do with this graph. This is a graph of a brain mass log versus a body mass log. mass and one of the things that I would like to show in this diagram is that I would like to show the relative intelligence of the animals on the planet and to do that you can't just show the brain mass, you also have to show the log. mass or record of body mass and I think you can see what I'm talking about when you see this field, this is the field for fish and phibians x' and reptiles and as you can see for a given body mass, the representation of these The creatures They have a lower brain mass compared to many of the other elements or should I say animals on our planet, well you won't find neurosurgeons in and among the fish, amphibians and reptiles that's for sure, look where the mammals fall. with a much larger brain mass for a given body mass and that's because mammals have a neocortex and that's what evolved into our gray matter, so it's not surprising to see that mammals fall higher than humans. fish, amphibians and reptiles and then the primates that you can see. where they fall they have some of the largest frames in the animal kingdom and I'm going to talk a little bit more about primates and explain why they might have gotten those big brains, but first of all I want to talk about and Focus on this red dot because the dot red falls towards low body mass and very high brain mass and that's where the people who come to TED talks fall, but maybe you'd like to know what we all learn from Jurassic Park that the dinosaurs were geniuses, I mean. think about this they learn to open doors for God to save but I am here to tell you that they were not as smart as we thought in Jurassic Park was lying to us look where the dinosaurs fall towards a very high body mass but relatively low brain minutes were not the most knives sharp on the door that's for sure now that we have the dinosaurs and we see how they fall you know they work this brings me to an important point and it has to do with evolution and that is.

That evolution does not always select the brightest creatures in the case of dinosaurs, they were selected for their large body mass and were immensely successful. They ruled the planet for 135 million years and what did mammals do during that time? Well, mammals first. They appeared in the Triassic about 200 million years ago, they were tiny little creatures that ran around trying not to get stepped on by the dinosaurs and they were like that throughout the Mesozoic and if it weren't for the disappearance of the dinosaurs, I'm going to suggest to you that we would still be tiny little creatures running around and I wouldn't be here talking to you tonight and it's the dinosaurs that lead me to my second improbable event and it has to do with the destruction of the dinosaurs these are the alvarez's standing next to it of what we call the Cretaceous-Tertiary limit is a layer of ash and that layer of ash was deposited by the Alvarez people.

They discovered it 66 million years ago due to the strong impact of a meteorite that hit Mexico. Well, it didn't hit Mexico, but hit 66 million years ago. Mexico wasn't there, but you understand, it hit in that area and sent ash into the atmosphere and those ashes were carried around the planet by atmospheric currents. it caused the planet to go dark for months and it stressed the largest animals on the planet, the dinosaurs, it wiped out everyone and here's something a lot of people don't know: it killed 75% of the species on planet Earth. Horrendous event now, where does this statistical improbability come into play here?

Well, think about this, Álvarez discovered that that meteorite was 10 kilometers in diameter, if those meteorites were a little larger than 10 kilometers, they could wipe out all life on the planet and if it is a little less than 10 kilometers it is possible that we don't kill the dinosaurs and we would still be tiny creatures, so I hope you can see the adjustment that is required here and what a serendipitous event it must have been, think about it, we have to have just the right size of a meteorite impacting the planet Earth for us to get here seems like a statistically improbable event to me and I hope it is to you too.

So what will happen after the dinosaurs are gone? Well, we see mammals radiating across the planet. the niches that dinosaurs previously occupied one of the areas that they radiate into are trees and trees are where we get primates and when you jump from one limb to another, a lot of the things that are required in that process are There are things that need a big brain power, a lot of computing power, so we see big brains, let me give you a couple of examples: primates have three-dimensional vision, they have color vision and they have these digits and it takes a lot of fine movement to move these digits so that it is required immense computing power and, as expected, these things that were selected in primates also come with a large brain, so we see large brains and large primates, as you saw in the graph that I showed you.

I heard before of certain quarters that they gave us digits so we could type on computers and throw soccer balls, but that is not the case, we have digits in three-dimensional color vision because we evolved from creatures that once lived in the trees. I hope it's obvious, well this is where I'm going with this and that is we need all of these, we need this event to happen and we need it to happen, oh that's getting rid of duh, sorry, we, the primates, we need. to pull them out of the trees and throw them to the ground and this is where the third statistically improbable event that I want to talk about tonight takes place and it has to do with the East African Rift Zone, the East African Rift Zone began to tear apart Africa. ten million years ago and has been separating part of Africa since then the faults are in red here the big triangles its big volcanoes the RIT and the blue dots red and blue those are hominid localities now I don't have almonds there, but most of The main ones are there and in these hominin localities is where we find fossils of bipedal creatures that walk upright.

I mean, if someone says to you, well, we're all here, where are all the missing links? Well, we will show in this diagram that is where all the missing links are they are everywhere not only do we have our direct ancestors we have our first cousins ​​our second cousins ​​whatever they are out there you know seven million years ago we found a fossil that walked in East Africa upright and had bipedal movement and had a brain the size of a chimpanzee and it's just when the genetic clocks tell us it should be there so I think it's surprising so what if what has to happen to cause this bipedal walking movement and the The big brains we have today have to do with the East African Rift zone.

The East African Rift Zone caused conditions to become dry and arid in East Africa, destroying rainforests and forcing primates out of the trees and onto the ground. and then we see something amazing happen, we start to see these creatures that walk upright, we start to see them develop brains of incredible sizes and it's like nothing else in the history of life on the planet. I'm not kidding, well, I don't see it. this in any part of the history of life and within I am going to give you an example here Australopithecus about three or four million years ago was a creature that walked upright and had a brain a little larger than a chimpanzee and this type Australopithecus evolves towards stone tool makers, then Homo habilis Homo erectus and then us, Homo sapiens, and it moves to Africa a hundred thousand years ago and populates the planet USA and that happens because of the aridity in East Africa, it is an event surprising in my opinion and where is it? the statistical improbability comes from, let's think about this, if this were an Eastern South American Rift Zone or an Eastern North American Rift Zone, we might not be here.

That rift zone needs to cause aridity where the primates are and not just the primates, the mostbig. great apes, so it has to happen in East Africa, well, that's a chance and unlikely event of theirs. I don't want to speak from an anthropocentric point of view tonight. I am not suggesting that God caused all of these statistically improbable events to occur. That would mean we would be here, that seems a little arrogant to me. What I'm suggesting is that in a nearly infinite universe there might be some localities where all of these statistically improbable events occur at just the right time to get intelligent life like us, but in most places and I'm talking about the rest of our

galaxy

and the Most of the universe, we may have some of these statistically improbable events, but not all of them and not in the right place. order and that's why I think SETI is having trouble finding intelligent life now.

I'm not in any campaign to shut down SETI. I'm not on the warpath to get rid of SETI that's not my point here, in fact it's a relatively negative point of view and that's not the way I want to end it. I want to end on a positive point and my point is and I hope you recognize it. that life is very, very strange, I mean, think about how difficult it was to get our species here and then I want to point out to you that each of you is rare, very rare, I mean, I think about this, I mean each of you. ancestors and I'm talking about your parents, your great-grandparents, your grandparents, from the first cell, each of them had to succeed at at least one thing, and that was passing on their genes to the next generation, and if not you wouldn't be here, that's amazing.

I think about the millions of things that had to happen for you to be here. Well, it's an amazing thing, so what I'd like to leave you with tonight is that life This rare life is precious and we have to take advantage of it and I can't see it. I don't believe in anyone better than John Lennon, so I'll leave you with John Lennon's words tonight and I want to thank you very much. Thank you very much for this opportunity to come speak with you.