Deep in our solar system, a new era of space exploration is unfolding.
Beneath the thick ice of Europa, in the vapor plumes on Enceladus, and within the methane lakes of Titan, astrobiologists are on the hunt for extraterrestrial life.
We’ve honed in on these three moons because each is an ‘ocean world,’ an environment that contains a liquid ocean– and liquid can support the formation of life.
Living organisms have to be able to grow, reproduce, and feed themselves, among other things.
All of those functions require the formation of complex molecules from more basic components.
Liquids such as water allow chemical compounds to remain in suspension instead of sinking under the force of gravity.
This enables them to interact frequently in a 3-dimensional space and, in the right conditions, go through chemical reactions that lead to the formation of living matter.
That alone isn’t enough; the small but complex biomolecules that we’re familiar with are sensitive to temperature— too hot or cold, and they won’t mix.
Liquid water has an additional advantage in that it’s relatively temperature-stable, meaning it can insulate molecules against large shifts in heat.
On Earth, these and other conditions in aquatic environments may have supported the emergence of life billions of years ago.
Tantalizingly, the same could be true in other parts of our solar system, like these three icy moons.
Europa, which is a moon of Jupiter, is probably the most intriguing ocean world.
Beneath a surface layer of ice thicker than Mount Everest, there exists a liquid ocean as much as 100 kilometers deep.
Astrobiologists think this hidden ocean could harbor life.
Thanks to the Galileo probe, we can deduce that its potential salt content is similar to that of some lakes on Earth.
But most of its characteristics will be a mystery until we can explore it further.
Like Jupiter, Saturn also has moons that might have the right conditions for life.
For instance– Enceladus is a tiny ball of ice that’s small enough to nestle within the surface area of the Gulf of Mexico.
Similarly to Europa, it likely contains an ocean deep under the ice.
But Enceladus also has geysers that frequently vent water vapor and tiny ice grains into space.
Astrobiologists are curious about whether these geysers are connected to the ocean below.
They hope to send a probe to test whether the geysers’ plumes of vapor contain life-enabling material from that hidden sea.
Although it’s the best known substance for nurturing life, water isn’t necessarily the only medium that can support living things.
Take Titan, Saturn’s largest moon, which has a thick nitrogen atmosphere containing methane and many other organic molecules.
Its clouds condense and rain onto Titan’s surface, sustaining lakes and seas full of liquid methane.
This compound’s particular chemistry means it’s not as supportive a medium as water.
But, paired with the high quantities of organic material that also rain down from the sky, these bodies of liquid methane could possibly support unfamiliar life forms.
So what might indicate that life exists on these or other worlds?
If it is out there, astrobiologists speculate that it would be microscopic, comparable to the bacteria we have on earth.
This would make it difficult to directly observe from a great distance, so astrobiologists seek clues called biosignatures.
Those may be cells, fossils, or mineral traces left behind by living things.
And finding any biosignatures will be challenging for many reasons.
One of the biggest concerns is to make sure we sterilize our probes extremely thoroughly.
Otherwise we could accidentally contaminate ocean worlds with Earth’s own bacteria, which could destroy alien life.
Titan, Enceladus, and Europa are just three of possibly many ocean worlds that we could explore.
We already know of several other candidates in our solar system, including Jupiter’s moons Callisto and Ganymede, Neptune’s Triton, and even Pluto.
If there’s this much potential for life to exist in our own tiny solar system, what unimagined secrets might the rest of the universe contain?
I worked as a war reporter for 15 years before I realized that I really had a problem.
There was something really wrong with me.
This was about a year before 9/11, and America wasn't at war yet.
We weren't talking about PTSD.
We were not yet talking about the effect of trauma and war on the human psyche.
I'd been in Afghanistan for a couple of months with the Northern Alliance as they were fighting the Taliban.
And at that point the Taliban had an air force, they had fighter planes, they had tanks, they had artillery, and we really got hammered pretty badly a couple of times.
We saw some very ugly things.
But I didn't really think it affected me.
I didn't think much about it.
I came home to New York, where I live.
Then one day I went down into the subway, and for the first time in my life, I knew real fear.
I had a massive panic attack.
I was way more scared than I had ever been in Afghanistan.
Everything I was looking at seemed like it was going to kill me, but I couldn't explain why.
The trains were going too fast.
There were too many people.
The lights were too bright.
Everything was too loud, everything was moving too quickly.
I backed up against a support column and just waited for it.
When I couldn't take it any longer, I ran out of the subway station and walked wherever I was going.
Later, I found out that what I had was short-term PTSD: post-traumatic stress disorder.
We evolved as animals, as primates, to survive periods of danger, and if your life has been in danger, you want to react to unfamiliar noises.
You want to sleep lightly, wake up easily.
You want to have nightmares and flashbacks of the thing that could kill you.
You want to be angry because it makes you predisposed to fight, or depressed, because it keeps you out of circulation a little bit.
Keeps you safe.
It's not very pleasant, but it's better than getting eaten.
Most people recover from that pretty quickly.
It takes a few weeks, a few months.
I kept having panic attacks, but they eventually went away.
I had no idea it was connected to the war that I'd seen.
I just thought I was going crazy, and then I thought, well, now I'm not going crazy anymore.
About 20 percent of people, however, wind up with chronic, long-term PTSD.
They are not adapted to temporary danger.
They are maladapted for everyday life, unless they get help.
We know that the people who are vulnerable to long-term PTSD are people who were abused as children, who suffered trauma as children, people who have low education levels, people who have psychiatric disorders in their family.
If you served in Vietnam and your brother is schizophrenic, you're way more likely to get long-term PTSD from Vietnam.
So I started to study this as a journalist, and I realized that there was something really strange going on.
The numbers seemed to be going in the wrong direction.
Every war that we have fought as a country, starting with the Civil War, the intensity of the combat has gone down.
As a result, the casualty rates have gone down.
But disability rates have gone up.
They should be going in the same direction, but they're going in different directions.
The recent wars in Iraq and Afghanistan have produced, thank God, a casualty rate about one third of what it was in Vietnam.
But they've also created -- they've also produced three times the disability rates.
Around 10 percent of the US military is actively engaged in combat, 10 percent or under.
They're shooting at people, killing people, getting shot at, seeing their friends get killed.
It's incredibly traumatic.
But it's only about 10 percent of our military.
But about half of our military has filed for some kind of PTSD compensation from the government.
And suicide doesn't even fit into this in a very logical way.
We've all heard the tragic statistic of 22 vets a day, on average, in this country, killing themselves.
Most people don't realize that the majority of those suicides are veterans of the Vietnam War, that generation, and their decision to take their own lives actually might not be related to the war they fought 50 years earlier.
In fact, there's no statistical connection between combat and suicide.
If you're in the military and you're in a lot of combat, you're no more likely to kill yourself than if you weren't.
In fact, one study found that if you deploy to Iraq or Afghanistan, you're actually slightly less likely to commit suicide later.
I studied anthropology in college.
I did my fieldwork on the Navajo reservation.
I wrote a thesis on Navajo long-distance runners.
And recently, while I was researching PTSD, I had this thought.
I thought back to the work I did when I was young, and I thought, I bet the Navajo, the Apache, the Comanche -- I mean, these are very warlike nations -- I bet they weren't getting PTSD like we do.
When their warriors came back from fighting the US military or fighting each other, I bet they pretty much just slipped right back into tribal life.
And maybe what determines the rate of long-term PTSD isn't what happened out there, but the kind of society you come back to.
And maybe if you come back to a close, cohesive, tribal society, you can get over trauma pretty quickly.
And if you come back to an alienating, modern society, you might remain traumatized your entire life.
In other words, maybe the problem isn't them, the vets; maybe the problem is us.
Certainly, modern society is hard on the human psyche by every metric that we have.
As wealth goes up in a society, the suicide rate goes up instead of down.
If you live in modern society, you're up to eight times more likely to suffer from depression in your lifetime than if you live in a poor, agrarian society.
Modern society has probably produced the highest rates of suicide and depression and anxiety and loneliness and child abuse ever in human history.
I saw one study that compared women in Nigeria, one of the most chaotic and violent and corrupt and poorest countries in Africa, to women in North America.
And the highest rates of depression were urban women in North America.
That was also the wealthiest group.
So let's go back to the US military.
Ten percent are in combat.
Around 50 percent have filed for PTSD compensation.
So about 40 percent of veterans really were not traumatized overseas but have come home to discover they are dangerously alienated and depressed.
So what is happening with them?
What's going on with those people, the phantom 40 percent that are troubled but don't understand why?
Maybe it's this: maybe they had an experience of sort of tribal closeness in their unit when they were overseas.
They were eating together, sleeping together, doing tasks and missions together.
They were trusting each other with their lives.
And then they come home and they have to give all that up and they're coming back to a society, a modern society, which is hard on people who weren't even in the military.
It's just hard on everybody.
And we keep focusing on trauma, PTSD.
But for a lot of these people, maybe it's not trauma.
I mean, certainly, soldiers are traumatized and the ones who are have to be treated for that.
But a lot of them -- maybe what's bothering them is actually a kind of alienation.
I mean, maybe we just have the wrong word for some of it, and just changing our language, our understanding, would help a little bit.
"Post-deployment alienation disorder."
Maybe even just calling it that for some of these people would allow them to stop imagining trying to imagine a trauma that didn't really happen in order to explain a feeling that really is happening.
And in fact, it's an extremely dangerous feeling.
That alienation and depression can lead to suicide.
These people are in danger.
It's very important to understand why.
The Israeli military has a PTSD rate of around one percent.
The theory is that everyone in Israel is supposed to serve in the military.
When soldiers come back from the front line, they're not going from a military environment to a civilian environment.
They're coming back to a community where everyone understands about the military.
Everyone's been in it or is going to be in it.
Everyone understands the situation they're all in.
It's as if they're all in one big tribe.
We know that if you take a lab rat and traumatize it and put it in a cage by itself, you can maintain its trauma symptoms almost indefinitely.
And if you take that same lab rat and put it in a cage with other rats, after a couple of weeks, it's pretty much OK.
After 9/11, the murder rate in New York City went down by 40 percent.
The suicide rate went down.
The violent crime rate in New York went down after 9/11.
Even combat veterans of previous wars who suffered from PTSD said that their symptoms went down after 9/11 happened.
The reason is that if you traumatize an entire society, we don't fall apart and turn on one another.
We come together.
We unify.
Basically, we tribalize, and that process of unifying feels so good and is so good for us, that it even helps people who are struggling with mental health issues.
During the blitz in London, admissions to psychiatric wards went down during the bombings.
For a while, that was the kind of country that American soldiers came back to -- a unified country.
We were sticking together.
We were trying to understand the threat against us.
We were trying to help ourselves and the world.
But that's changed.
Now, American soldiers, American veterans are coming back to a country that is so bitterly divided that the two political parties are literally accusing each other of treason, of being an enemy of the state, of trying to undermine the security and the welfare of their own country.
The gap between rich and poor is the biggest it's ever been.
It's just getting worse.
Race relations are terrible.
There are demonstrations and even riots in the streets because of racial injustice.
And veterans know that any tribe that treated itself that way -- in fact, any platoon that treated itself that way -- would never survive.
We've gotten used to it.
Veterans have gone away and are coming back and seeing their own country with fresh eyes.
And they see what's going on.
This is the country they fought for.
No wonder they're depressed.
No wonder they're scared.
Sometimes, we ask ourselves if we can save the vets.
I think the real question is if we can save ourselves.
If we can, I think the vets are going to be fine.
It's time for this country to unite, if only to help the men and women who fought to protect us.
Thank you very much.
(Applause)