dna-based . so watch out if you meet and ambien. you could be infected with the disease against which you have no resistance. -- an alien. you could be infected with the disease against which you have no resistance. feasibility on the probability of life appearing is that we have energy the earth was formed 4.6 alien years ago and was probably too hot for the first half a billion years. so life appeared on or within half a billion years of it being possible, which is short compared to the lifetime of an earthlike planet. this would suggest either transfer mia or that the probability of life appearing independently is reasonably high.

if it was very low, one would have expected to take most of the 10 billion years available. if it is transfer mia, life in the solar system or nearby stellar systems will also be dna-based. while there may be from its of life in our region of the galaxy, there don't seem to to be any advanced intelligent beings. we don't appear to have been visited by aliens. i'm discounting reports of ufos. why would they appear only to cranks and weirdos? [laughter] if there is a conspiracy to

suppress the reports and keep for itself the scientific knowledge the aliens bring, it seems to have been an ineffective policy so far. for it is quite an extensive search and we have not heard any alien television quiz shows. this probably indicates there are no alien civilizations at our stage of development within a radius of a few hundred light years. issuing an insurance policy against abduction by aliens seems a pretty safe bet.

why haven't we heard from anyone out there? one view is expressed in this the caption reads "i think the insurance sign -- the surest sign intelligent life exists intelligent life exists in the universe is that none of it has tried to contact us. more seriously, there could be three possible explanations why we have not heard from aliens. first, it may be that the probability of primitive life appearing on a suitable planet is very low.

second, the probability of permit of life appearing may be reasonably high, but the probability of that life developing intelligence may be very low. just because evolution led to intelligence in our case, we should not assume intelligence is an inevitable consequence of darwinian natural selection. it is not clear that intelligence confers a long-term survival advantage. bacteria and insects will survive quite happily if intelligence leads us to destroy ourselves. this is the third possibility --

life appears and then in some cases, develops to intelligent beings. but when it releases -- reaches the stage of sending radio signals, it will have the technologies to make nuclear bombs and other weapons of mass destruction. it would therefore be in danger of distro eight of destroying itself before long. let's hope this is not the reason we haven't heard from anyone. personally, i favor the second possibility, that primitive life is relatively common but intelligent life is very rare. some would say it has yet to occur on earth.

can we exist for a long time away from the earth? our experience with the iss, the international space station shows is possible for human beings to survive for many months away from plan to that -- away from planet earth however zero gravity of orbit causes a number of undesirable physiological changes, weakening of the bones, as well as creating practical problems. one would therefore want any long-term base for human beings to be on the planet. by digging into the surface, one would get thermal insulation and protection from cosmic rays. the planet or moon could serve

as a source of materials that would be needed if the extra terrestrial community were to be self sustaining independent of earth. what are the possible sites of a human colony in the solar system? the most obvious is the moon. it is relatively easy to reach. we have already landed on it and driven across it in a buggy. on the other hand, the moon is

small and without atmosphere or magnetic field to deflect solar radiation particles like on earth. there is no list would water but there may be ice in the craters at the north and south poles. a colony on the moon could use a source of oxygen with power provided by nuclear energy or solar candles. the moon could be a base for the rest of the solar system. mars is the art of -- is the obvious next target. it is half as far from the earth as the sun and so receives half

the earth -- half the warmth. it once had a magnetic field but indicate 4 billion years ago, leaving mars without attention from solar radiation. most of its atmosphere has been stripped, leaving it with only 1% of the pressure of the earth atmosphere. however, the pressure must have been higher in the past, because we see what appear to be runoff channels and dried up lakes. liquid water cannot exist. it would vaporize in the near vacuum. this suggests mars had a warm wet time during which life might

have appeared either spontaneously or through transfer mia. there is no sign of life on mars now, but if we found evidence life had once existed, it would indicate the probability of life developing on a suitable planet was fairly high. nasa has sent a large number of spacecraft from earth starting with mariner four in 1964. it has surveyed the planet with a number of orbiters, the latest being the mars reconnaissance orbiter. these orbiters have revealed deep gullies and the highest mountains in the solar system. nasa has landed a number of probes on the surface of mars

most recently, the two mars rovers. these have sent back to cures of the dry desert landscape. however, there's a large quantity of water in the polar reason that polar regions. a colony on mars could use this as a source of oxygen. there has been volcanic activity on mars. this would have brought minerals and metals to the surface which a colony could use the moon and mars are the most suitable sites

for space colonies in the solar system. mercury and venus are too hot while jupiter and saturn are aghast giants with no solid surface. the moons of mars are very small and has no advantages over mars itself. some of the moons of jupiter and saturn might be possible. in particular, titan, the moon of saturn, is larger and more massive than our moon and has a dense atmosphere. the cassini mission of nasa has landed a poker -- landed a probe on titan which has sent back pictures of the surface.

however, is very cold, being so far from the sun, and i wouldn't fancy living next to a lake of liquid methane. what about be on the solar system? our observations indicate a significant fraction of stars have planets around them. so far, we can detect only giant planets like jupiter and saturn, but it's reasonable to assume they will be accompanied by smaller, earthlike planets. some of these will be in the goldilocks zone where the the distance between the stars and liquid water to exist on their surface.

there are rounded thousand stars within 30 light-years of earth. if 1% of each of them had earth sized planets, we have 10 candidate new worlds. we can not envision reaching them with current technology but we should make it a long-term goal. i mean over the next 200 to 500 years. the human race has existed as a separate species for about 2 million years. civilization began about 10,000 years ago and the rate of development has been steadily increasing.

if the human race is to continue for another million years, we will have to hold the go where no one has gone before. thank you for listening. [applause]

>> thank you, professor hawking for that series of insights and a challenge to us all. i believe now, for those of you who wanted to do flash photography, it would be ok for a few moments. i have a you all to head upstairs for a very nice reception for our sponsor, lockheed martin. thank you all. >> our look at academy award nominated films continues later today with author george dyson. his book is a reference to alan turing who is portrayed in the film "the imitation game. >> in about 15 minutes, our live coverage of the national governors association winter meeting continues with the epa

administrator, gina mccarthy. she will be part of a session on energy and water security. until then, we bring you part of this morning's "washington journal." we want to welcome adam green the cofounder of the progressive change campaign committee which is what? guest: it is a million member national grass roots organization, we do about half electoral work and our main focus is economic populism issues and democracy issues. in fact we coined the phrase, elizabeth warren wing of politics. our members chipped in over $1 million in small dollar donations. and we have been a champion of some of her issues. host: we love political paraphernalia. she insist that is she is not running.

do you think she might? guest: never say never. and she said that herself. right now i don't think she is but our organization's focus is trying to incentivize all presidential candidates including hillary clinton to have a race to the top and basically campaign on elizabeth warren style issues. our basic theory is the only way the democrats can lose is by not running an economic populous elizabeth warren style campaign. and when you hear income inequality, i think it's happening in america. there's a rising tide and therefore her message is a smart one. host: secretary clinton and senator warren had a meeting back in december at white haven not far from where the vice president's residence is, the two talking about issues politics and policies. if you were a fly on the wall what do you think transpired?

guest: i would be breaking some heavy news in various sites. i think it was a huge step forward that she does not see elizabeth warren as oppositional but is seeking her guidance. there is going to be a degree of skepticism among some progressives who want more than just rhetoric and meetings. they want progressive economists in her inner circle. they want real policy positions backed up, the actual actions on things like wall street reform where you talk to your guest. a lot of their funding came from wall street. there were red flags raised around secretary clinton $200,000 speeches. so the burden is on her to show that she is not jist going to talk the talk but walk the walk. the more she seeks the counsel of progressives, the more competitive she will be in the

general election. host: on these issues that are so important to you and to those who support the progressive caucus by way of the democratic party, where would you place the president? guest: he's somewhere in the middle. that's where he wants to be. but he campaigned as more of a progressive than he has actually governed. imagine who you surround yourself by. and rahm emanuel as the chief of staff brought an old ethose to the white house. one that learned certain lessons in the 920's before the internet and before the current populous tide. i think he has been a little more timid than he needs to be. that said there's been a dramatic difference in the last several months. and his being out there pushing the issues of net neutrality, immigration, asking the rich to pay their fair share in order to fund things like free

community college and universal pre-k. i wish this was the obama we saw in e89 but it is better than never. it is constructive for him to be putting oxygen in the room for some of these big bold progressive ideas. host: when you say big bold progressive ideas, some will look at that and say bigger government. how can you expand the government and also bring down the debt? guest: you don't have to expand government. you can cut military waste and cut hundreds of billions in corporate welfare that goes to wall street or the big oil companies or big pharmaceutical companies. the question is where and who does the government prioritize? does it stand with the big industries or with middle class families? our sister organization recently did two things.

one a bottom up process where basically for a month from december to january asked people across the nation to submit big ideas that they want progressives to focus on. and thousands of ideas were submitted. from regular people and from folks like the policy director. thinks thanks around town. and after 1 million votes ideas that rose to the top including things like expand social security benefits. let's have a national goal of debt free college. and things on campaign finance reform. and the next thing that the change is a national poll. and surprise, it wasn't even close. when it comes to a government that actually helps people's lives, even a republican mother wouldn't you like to send your kid to college without saddling her to debt?

these are overwhelming benefits. hopefully democrats learned over the last couple of years. my prediction is if hillary clinton decides to work on debt free college reforming wall street. she won't just win the primary. she will be very, very successful. >> one of our viewers has this. why would you not want hillary since it's very unlikely that it is liz warren? >> i said we're trying to create a race to the top. we want hillary clinton and everyone else who gets in the field to compete with each other to adopt messages that are super popular in red purple and blue states. there's a reason that she was the most popular campaign even in places like georgia, west virginia, and kentucky. when it comes to holding big guys accountable, that is a message that sells. and i hope hillary clinton

understands that lesson. host: adam green, cofounder of the progressive change campaign committee. our lines are open and we divide our lines between democrats republicans and independents. you can also send us a tweet. rick from massachusetts. independent line. good morning. caller: good morning. i have a question for you. where do you stand on the tax issue? how can somebody pay 25% of their income not be paying their fair share? yet the people paying no federal income tax are? guest: that's a great question. first my sympathies for the snow that you're probably digging out from up there in massachusetts. we saw this in the institute polling as well. there are corporations that pay zero% taxes. wall street banks basically admit to doing crimes and have

to pay huge pements can deduct those from their taxes. helps their debt. and meeble regular people are paying 25-30%. mitt romney pays less of a tax rate than you or i do. the real question is who is paying their fair share? how >> thank you for taking my call. i do believe democrats should

run and elizabeth warren, the way she looks at the middle class, saying that, i just think it is ironic to me to see hillary clinton and jeb bush are running for president when the country is in a crisis that these two parties are drunk on power. they don't look at the country anymore and i think people have to open their eyes and we need somebody like elizabeth moore and that ease the country, the education, wall street, all of the problems sending us to help so that we can have our country back. >> you are certainly not alone in feeling that way. the number of voters who stayed at home on election day in 2014,

democrats really failed to have a unified message around populist ideas that stick up for everyday families. a mother who did not vote on election day in 2014 did not wake up thinking at stake is whether i can send my kid to college at an affordable rate. it was a question of fragmentation run democrats in our small ideas put out there and it was just a lot of us saying i'm not a republican. the same arguments people have made for decades. that's not what is necessary in this government. really speaking to the passions of middle-class families, being willing to take on power, fisa little guy, that's what people need to hear. elizabeth moran has been a model for that. we hope hillary clinton steps in the right direction comes to full fruition, surrounding herself with people like elizabeth moran, dean baker

sheila bair, and really embrace these policies. >> i know you have probably seen these -- you have a poll from moveon.org showing if the primary were held today among those voters, elizabeth ward would get 30%. bernie sanders would get 6%. look at the difference in iowa where senator warren is ahead of hillary clinton in that state where hillary clinton did not win the iowa caucuses. elizabeth warren, 31% and hillary clinton at 24% stop and this story -- once more, a new brand for clinton, focusing on how the clinton the visors are trying to rebrand the former secretary of state. they are introducing themselves and clinton is almost universally recognized, love her or lowther, potential voters

know who she is after more than two decades in public life or, they think they know. your reaction? >> of the great point and most people won't be deciding to do i know hillary clinton, do i know what she's about? they will be saying am i inspired enough i the message to come to the polls and vote which mark about the new hampshire and iowa stuff, i think it is really positive so maybe people are out there visibly in the streets doing various other actions talking about how supportive they are of elizabeth moran's message. whether you support drafting her or not, it speaks to a passion out there in the country, like our caller from message but in places like south carolina kentucky, west virginia, people who really want someone to stand up to the little guy. that increases the pressure on hillary clinton to adopt that message. our strategy is concurrent with

that but a little different. we had an organizer in iowa. we had an organizer in new hampshire. they are meeting with local party officials and elected leaders, asking them to keep their powder dry. >> i'm pleased to have this opportunity. i enjoyed by governor dan malloy of connecticut. the chair was not able to make it, but governor malloy, we appreciate it. the national resource committee legislative director, we appreciate all your work will stop as -- all of your work. the briefing materials were sent out in advance of the meeting and i hope you have all had a chance to get through them. so let's begin. i will start with some opening comments. they will be brief because we're so