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Technology Sounds 

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Technology Sounds 

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Technology Sounds 

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//applause//

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//applause//

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Dr. John Holdren: Life is the most complex thing in the known universe.

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Just ask anybody in the White House. Abundant on Earth,

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hugely successful in colonizing every available

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niche. It seems that once started, life is

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unstoppable. But does that mean there's life on other planets,

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elsewhere in the universe? So far we have not seen signs

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of life elsewhere, and not for lack of trying.

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Is there other life or traces of former life out there?

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Is there now or has there ever been intelligent life

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anywhere but on our Earth? With a hundred billion

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galaxies, the order of a hundred billion galaxies,

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each containing the order of a hundred billion stars, most of which we 

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now know have their own planets,

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the probability of life having evolved elsewhere 

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seems very, very high. Indeed, on the numbers,

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it seems highly likely that intelligent life has 

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evolved in the universe at some other time, at some other

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place, and maybe is out there now.

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How will we find out for sure? Tonight, we're going to take you on a 

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journey from Earth, through the solar system, to planets around 

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other stars in the search for life.

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Let's start with the Earth, and I note that some have asked whether there's intelligent 

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life on Earth I believe there is, but let me turn

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it over now to Gavin Schmidt. Gavin?

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//applause//

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Dr. Gavin Schmidt: Earth is the only example we have 

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so far of a planet with a biosphere. As we get 

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further away, Earth shrinks from a recognizably inhabited

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place, to a blue dot and then to just a tiny point

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in orbit around the sun. The further out we go,

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the harder it is to tell that there is life on Earth.

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But there has been life on Earth for more than three billion years.

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The universe has existed for 13.8 billion years

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since the Big Bang, and our solar system has been around for the last

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4.6 billion years of those. But 

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remarkably quickly after the solar system formed and rocky planets

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condensed and cooled, there was liquid water on the surface of our

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planet. For a planet 4.5 billion years old,

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we have evidence of water from only .2 billion years later.

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But it took life perhaps another

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500 million years to appear. Early life 

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forms weren't much to look at, but life itself has been here 

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a long time. We don't yet know how life got started,

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there are many theories, but we do know that it got going

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under some very challenging conditions.

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The sun was 30 percent dimmer than today, but with more 

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solar flares. There was no oxygen, and therefore 

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no ozone layer to protect the surface from harsh ultraviolet

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rays. But Earth did have the ingredients necessary

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to support life. A solvent like water, an energy 

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source, and abundant nutrients.

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For 1.5 billion years, this primitive life survived

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in the oceans, protected by the water's opacity.

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But around 2.5 billion years ago,

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bacteria started to use sunlight directly to fuse 

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water and carbon dioxide to make sugars, which were then used as food.

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But for every molecule of carbon dioxide they used,

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and there was a lot of carbon dioxide in the atmosphere,

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they released a molecule of oxygen. Those bacteria were followed

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by photosynthesizing algae, mosses, and plants.

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And eventually, after a number of false starts,

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the oxygen built up in the atmosphere until around 500 million years ago,

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it got close to present day concentrations, giving a start

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to the huge variety of land animals, insects, and

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plants we see today. Meanwhile, the 

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climate was not static. The planet went through cycles of snowballs

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and hot houses, driven by plate tectonics, volcanism, greenhouse

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gases and impacts. Indeed, it was only

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after the last snowball Earth event that set the stage--

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that the stage was set for the evolution of multicellular life in the

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Edicarian 600 million years ago. The new

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species that were rapidly born, evolved and died

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changed the planet forever. The surface became completely covered,

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you could say infected, infested, with life.

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And that life affected the climate, changing the

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composition of the atmosphere, the reflectivity of the surface, and the cycling

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of water, radically transforming the view from space.

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Life co-created the broad

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array of special, unique ecosystems and microclimates that

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characterize the Earth today, visible even from a million miles away.

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But remember, for most of the time 

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that life existed on Earth, it did not have a land fingerprint,

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and the oxygen that we now rely on wasn't detectable

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for perhaps half that time. Under those conditions,

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or any others in Earth's history, how can we know what would have been

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seen from further away? This is where our 

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understanding of current climates, and of processes that control

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composition, clouds and dynamics come into play.

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We can simulate the impacts of climate on life, and the impacts of

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life on climate at each stage of our planet's history.

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Simulations which include the physics of clouds,

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oceans, ice, and of atmospheric particles like dust.

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We can take those results and then project how those 

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climates would look from space, from beyond even the solar system.

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But we can go further, we can even 

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simulate the climates of Venus and Mars three billion years ago,

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when they were both very different places. Places that 

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perhaps also had the seeds of life. And Jen can discuss that.

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//applause//

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//applause//

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Dr. Jen Eigenbrode: If life ever existed in our solar system

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then it found a way to adapt to extreme conditions.

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Conditions that may be more extreme than what we have on Earth.

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I am constantly amazed to find that life has adapted

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to every niche, no matter how harsh the environment.

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Take for example, the extraordinary springs of Dallol in the

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Danakil Desert of Ethiopia. These springs are hot,

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salty, rich in heavy metals, and they're 

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acidic. Microorganisms thrive in these pools,

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even the pools of pH less than one. That's more acidic than battery acid.

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Life adapted.

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Another example, the Atacama Desert in the rain shadow of the Andes

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Mountains. It is the driest land desert on Earth. This 

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Martian-like landscape has been shaped by the wind and salty aerosols 

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for millions of years. It has been one of the most

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challenging places to find evidence of life.

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And yet it's there, a few cells here and there. Life adapted. 

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One last example, and this one really 

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me, Chernobyl. This diverse life 

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in this agricultural region is punctuated by the presence of 

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fungi that live off the radiation from the 1986

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meltdown of reactor four. These fungi 

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use the radiation, the gamma radiation, in the same way

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plants use sunlight to grow. Life adapted on Earth.

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Could life have arisen and adapted to the extreme

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conditions of other places in the solar system? 

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We're going to find out. We will search for biomolecules,

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the organic compounds that make up life, its food and waste products.

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We may need to extend that search to other types of signatures,

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to build confidence in that detection. We might search for active

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cells, and catch extraterrestrial life in action.

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We might search for fossilized cells 

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in ancient rocks and ice. Gavin explained that

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Earth is the only known biosphere. However, Mars is a 

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close neighbor. Although it looks like a rusty,

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barren planet today, its history was very similar to Earth's in the beginning.

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Did life arise on Mars around the same time that life

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arose on Earth? Why are these 

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two planets so vastly different today?

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Both Earth and Mars had a liquid core when they

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formed. Movement of this molten iron 

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generate a magnetic field that shield the atmosphere and surface from being

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blasted by ionizing radiation. Earth maintains its

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magnetic field, but not so for Mars. Convection of the 

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Martian core slowed or stopped four billion years ago.

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Without the protection of the magnetic field, the powerful solar 

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wind streaming continuously from the young sun crashed into the 

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red planet, piling up in front of it like a bow wave of a ship, except in this case, 

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the wave is charged particles that electrically strip away the

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Martian atmosphere. This process continued 

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for eons regulated by the sun's activity, and slowly stripped

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away gases from the volcanoes and the rocks.

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With the magnetic field and atmosphere mostly gone, the rocky 

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surface of Mars was bombarded by ionizing radiation from the 

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galaxy and the sun. This radiation 

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comes in the form of photons, such as UV, x-ray,

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and gamma rays, as well as charged particles. However, unlike what we experience

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here on Earth, all of these forms have an enormous amount of energy.

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When ionizing radiation encounters

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molecules, it changes them. Radiation damage 

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to molecules means damage to life and the 

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signatures that we seek. We know that life 

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adapts. If life ever existed on Mars,

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did it adapt to the harsh radiation environment at or near its  

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surface? Life has surprised us on Earth and perhaps 

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life will surprise us on Mars too.

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I have spent the last four years exploring Mars through the imagers and the

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instruments of the Curiosity rover. We have discovered that Mars is not

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really red, it's grey with a rusty skin. 

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Mars is not really dry, either. Liquid

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water on Mars formed rivers, deltas, lakes, 

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maybe seas. It has been cold and warm, acidic and 

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alkaline. Its surface and atmospheric chemistry evolved.

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It has organic matter and the key nutrients needed

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for life. We have only scratched the

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surface of Mars and begun to decipher its story. 

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Did life ever live there? Is there life 

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on Mars now? And could life live here

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in the future? Beyond Mars, we will

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search for life in the ocean worlds of the moons of Jupiter and Saturn.

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Jupiter has a magnetic field 

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20,000 times stronger than Earth's. The field 

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produces a donut-shaped belt around the planet in which charged particles get trapped.

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Europa is a water ice-covered ocean

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world, and one of great interest as a possible abode for life.

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It sits right smack in the middle of Jupiter's magnetic belt, 

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which means that it is being bombarded by intense amounts of radiation.

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Although the Europan surface 

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is inhospitable, it may offer a glimpse of 

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the chemistry of what lies beneath. Europa's thick crust 

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is sufficient for protecting the underlying 

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global ocean from radiation. And it is hypothesized

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that Europa may have hydrothermal vents stemming from its rocky 

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interior. And if so, these are ideal sites for life,

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and they support the potential of life in the ocean.

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Now let's go to Saturn, where the moons are embedded in 

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the rings, where we think life may exist on some of these moons.

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Like Europa, Enceladus is an icy 

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ocean world. And in 2005, the Cassini spacecraft witnessed 

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geysers of gas arising from the surface. These

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plumes are direct conduits to a deep ocean. We might search 

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for signs of life by flying through these plumes.

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And then there's Titan. A rocky moon 

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with seas of liquid methane and an atmosphere of organic smog.

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Titan is drenched in hydrocarbons, and it's cold enough

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to freeze most of them. Life as we know it is largely 

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made of hydrocarbons. Although it may be a stretch of our imagination 

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to think that life might live here, it is considered 

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potentially habitable. Did life arise on

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Titan? There are 

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possibilities for extraterrestrial life in our solar system. However, as 

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Aki will explain, there even more possibilities of life outside of it.

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//applause//

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//applause//

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Dr. Aki Roberge: If we're going to look for life that's really Earth-like, we need to look for planets 

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around other stars. Exoplanets, for short. When I started 

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undergrad, we only knew of nine planets in the solar system. Actually, eight 

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now. //audience laughter// And in grad school we thought exoplanets

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would be rare. Twenty years ago we discovered the first planet around another

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star. Since that time, we've gone from a few planets in the solar system 

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to literally thousands of exoplanets orbiting other stars.

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And we have only searched a tiny portion of the galaxy with the Kepler

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'space mission. We think there's at least one exoplanet 

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for every star in the galaxy, which would mean over 100 billion planets in the

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Milky Way alone. So that's at least 14 planets for every human

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on Earth. And the Milky Way is only one of a myriad

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of galaxies in the universe. We've found that the planet formation process

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is more robust and easy than we thought, and exoplanets 

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are common. They can form around all different 

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kinds of stars, even ones not like the sun. There are even planets around binary

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stars, just like Tatooine in Star Wars. To our delighted

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surprise, exoplanets are not only common, but diverse.

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The first planets discovered are unlike anything we have in the solar system.

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They are hot Jupiters, massive, gassy planets orbiting closer

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to their stars than Mercury orbits our sun.

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So in the solar system we have two basic classes of planets. We have 

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massive gas giants like Jupiter, and small rocky planets like Earth.

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But there's all sizes of planets out there. From super Jupiters

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to Neptunes, to rocky planets several times more massive 

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than Earth, all the way down to true Earth-size planets.

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So with all this richness of planetary real estate,

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it encourages us to start thinking more ambitiously. To search for 

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those rocky planets that are actually like Earth. We may have 

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already found some, but we can't actually tell right now what their surfaces are really

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like. So as Gavin mentioned, Earth's abundant

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surface life makes it unique in the solar system. And this is probably 

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the only kind of life that we can detect from really far away.

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There might be other kinds of life on other kinds of worlds out there, but we

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probably won't be able to recognize it. So astronomers are really 

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focused on finding the true Earth twins out there, and we will look for them 

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in the habitable zones of nearby stars. So,

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the habitable zone is the region around a star where an Earth-like planet 

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is just the right temperature to have liquid water on its surface, the key ingredient 

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for Earth life. So for the sun, the habitable zone stretches from

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just outside Venus' orbit to Mars. For bigger, brighter stars, 

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the habitable zone moves out, to cool off, like moving away from a campfire.

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And then for smaller, dimmer stars, the habitable zone moves in

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to keep the planet warm. Now this spectrum

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is how astronomers want to look for life on other worlds. It's the light from the 

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Earth as if it were really far away, separated by color. Don't panic, we'll go through it.

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So this rise in brightness on the 

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far left is literally our blue sky.  And this narrow dip

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comes from oxygen, which is produced by plants. These several deep

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dips come from water vapor. And then over here is a methane

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feature. So methane in our atmosphere 

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largely comes from bacteria in the guts of our livestock, and in swamps.

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So the Earth's atmosphere is full of bio signatures, gases 

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that wouldn't be present in our atmosphere without life.

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Now, the technical challenge of ever seeing something like this is one of the hardest things

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scientists have ever thought of trying, and here's why. The Earth is 

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10 billion times fainter than the sun. So, if the

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Luxor Sky Beam, the brightest man-made light in the world, is the sun,

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the Earth is four candles on your dinner table. But 

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astronomers actually observe things that faint all the time. The real problem

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is those four candles are sitting right next to the bright lights. If we're

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looking at the solar system from 33 light years away, which is not that far,

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it's pretty nearby, the separation between the Earth and the sun 

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.1 arc seconds, or the width of a human hair from the distance of two

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football fields. So imagine trying to see those candles if they were right on top of

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the Luxor Sky Beam. We have to suppress the light

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from the star before we can see the faint blue dot next to it.

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There are a couple of different technologies people have come up with to do this. One of 

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them is a star shade, a gigantic deployed screen that would fly tens of thousands of

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kilometers in front of a telescope. You'd be aligned with a star 

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to block its bright light. But this telescope is a relatively 

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small one. If we really want to get a spectrum like the Earth 

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one I showed, we need a bigger telescope. So, NASA has 

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begun a concept study for a super-duper Hubble called LUVOIR,

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which will search for dozens of Earth-like planets and probe their atmospheres.

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In addition, it would enable a wide range of general astronomy,

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just like Hubble did. With powerful future missions,

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we could see the pale blue dot of Carl Sagan's imagining, and have a fighting 

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chance of finding life out there among the stars. So to 

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put this grand endeavor into perspective, we turn to Piers.

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//applause//

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//applause//

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Dr. Piers Sellers: The universe is really big and really old.

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Life has been on Earth for about four 

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billion years. Now we know that in the universe, physics and chemistry 

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are the same everywhere. A Hydrogen atom here 

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is just the same as a Hydrogen atom on the other end of the universe.

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The laws of physics and chemistry work the same everywhere.

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Now we strongly suspect, based on an example of one,

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our Earth, that the laws of biology work the same everywhere too.

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And by that I mean the laws that Charles Darwin discovered for us.

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We think that based on these laws, that

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evolution can drive life. To greater complexity,

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and ultimately to intelligence. It's the smart thing to do.

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Now look at this tree of life. We can see intelligent 

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animals that we're familiar with. Humans,

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elephants, dolphins. These creatures are very 

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closely related to us. But look over here on the far right.

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There's one other intelligence, an invertebrate 

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intelligence, that evolved completely separately from the rest of us.

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They split off from us before brains were even thought of,

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when all creatures had were just a few nerve cells.

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Octopuses have an intelligence that's comparable to quite a lot of 

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mammals, and it evolved completely separately.

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These guys are like little aliens 

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living with us on our own planet. If you look at an 

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octopus, you can see that its brains are actually distributed all over 

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its body. Most of its brains are in its feet, or in its legs,

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and they're connected to the nerve center in its head by a neural

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network. It's a distributed intelligence.

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But it turns out that they think pretty much the same way that mammals do.

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They have a short-term memory and a long-term memory,

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they learn, and they get mad. They basically tackle the

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business of living in a complex environment the same way that we mammals do.

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We think that we understand

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how an octopus thinks. So the secret of intelligence 

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is in the software, it's not in the hardware.

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It's very likely that an alien intelligence would be 

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comprehensible to us in the same way that an octopus'

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thoughts are more or less comprehensible to us too.

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We should be able to communicate with them if we met them.

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So, you'd think there'd be plenty of opportunities for life to evolve 

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somewhere else, and maybe swing by the Earth, or at least call on the radio.

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But we haven't found any alien monoliths,

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or beer cans, or cigarette ends,

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and we have not heard them tweeting on the radio either.

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So, where are they? That's what Johnny von Neumann asked.

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Where are they? There are lots of theories about that,

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but I'm going to concentrate on the more plausible ones.

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First of all, there's the water trap. Maybe the worlds 

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that have water on them are all ocean, for the most part.

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And if that's the case you can't discover combustion, you can't 

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make metals, so you can't make a radio or a spaceship.

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If our dolphin friends lived on an ocean planet, they would be stuck where

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they are, in the Stone Age, forever.

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We might discover intelligent life here, but they could be incredibly

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boring. Talking endlessly about the flavors of different kinds of plankton,

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and that sort of thing. Or maybe on a

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planet that has dry land but no metals,

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same problem. You can't develop a technology.

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And how about the difficulty of interstellar travel?

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Maybe it's just too hard. It looks like a real challenge for us,

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it could be a couple of hundred years before we try that. Maybe it's just too hard.

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And then there's the great sci-fi standbys, hostile 

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races evolve, they wipe out everyone else, that's sort of an ugly end. 

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I think we should move on quickly, this is meant to be a fun evening. 

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And then there's another theory, which is that we could be the first. 

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We could be the first intelligence to evolve

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in this part of the galaxy. Someone has to be. We could be 

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the elder race. So here's a time history of Earth.

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When you look at all the time that life has been here. Nearly four

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billion years, humans have only been around for a couple of 

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hundred thousand years, civilization for about 6,000 years, 

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depending how you count it, and our technical era 

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only for 200 years. When you look at this picture,

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it is obvious that the most likely first alien life forms

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that we discover will not be intelligent. They will be somewhere back

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here, equivalent to life on Earth during the first three billion years 

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of evolution. Similarly,

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nearby life on an exoplanet is probably plodding its way 

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up the evolutionary ladder. Remember how long

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it took us to get where we are. Where we could even think about life 

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elsewhere. So, what are the chances 

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of us finding anything, or anybody, soon?

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Here's a timeline of missions for exploring the solar system

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with some notional ideas of what we'll be doing in the next

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50 years. I think that over the next 30 to 50 

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years, we will have thoroughly explored every nook and cranny of the solar system,

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and seen or determined where there is life here, or past life, 

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or not. I think there's a good chance we'll nail that one flat.

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And then there's a chance of looking for bio signatures

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in the atmospheres of exoplanets.

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Here's the missions, again, pretty notional, and it's all the 30

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to 50-year timeframe, in the future that we could see looking at exoplanets 

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where we'd be looking for traces of life in their 

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atmospheres. It turns out 

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that we Earthlings have the prime real estate in our solar system,

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as far as having a habitable environment is concerned.

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Most of the rest of the solar system looks like a really tough place to live.

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But, you never know. We need to

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thoroughly check out our own backyard as well as the planets around other stars.

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We'd look like idiots if we failed to check for life

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close to home, and failed for lack of trying.

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Now back to the beginning. John Holdren's question.

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Why do we even care about this stuff? We think it goes 

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beyond just intellectual curiosity. It's in our nature

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because we humans grew up as part of nature, and need to pay attention to it.

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I want you to imagine what humans could do in a couple of

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hundred years or so. Imagine a probe

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from Earth entering the solar system of another star

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after a journey of decades, maybe a century.

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Note the MSBR logo.    

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What would it find? My advice to you is eat 

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healthy, don't smoke, don't jaywalk,

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and you might find out. It'd be good to find out we're not alone.

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Thank you for your attention.

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//applause//

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//applause//