Where Are All The Aliens? | Tim O'Brien | TEDxOldham

so much I would also saw an interesting question I think which is were all the aliens which might I am a scientist I'm not crazy but I actually think maybe there are aliens are out now want to sort of convince you that this is a worthwhile scientific question to ask but I think first of all we need to appreciate how big space is I think the best answer that I ever heard was in the Hitchhiker's Guide to the galaxy Douglas Adams that space was was big very big extremely big we really don't know don't know how big it is but let's give guts could get a little chance to understand that this is the Sun even occasionally spotted from here in Manchester but the Sun is about 150 million kilometres away which is a bit hard to imagine the earth is about twelve thousand kilometres across so 150 million kilometres is a large distance one of the things we tend to do is we think about how long would it take to get somewhere if we traveled at a certain speed so in this case the fastest we can travel is the speed of light so that's about 300,000 kilometres every second and at that speed you would get to the Sun in about eight minutes so in fact when you look at the Sun that light has taken eight minutes to reach you which is you know the sort of length of time you're in here listening to a part of all of these talks or not too long but space is obviously bigger than that if we go out into our Milky Way galaxy our Milky Way galaxy has many Suns many stars hundreds of billions of stars so you know if we shared all the stars out in the Milky Way between all the people on the earth we'd all get about 50 H base plates that sort of number of stars in our Milky Way galaxy and the nearest other star to the Sun that light that took eight minutes to reach us from the Sun it's on its way now when I started talking some lights set off from the Sun and then it'll get there about half way get here about halfway through this talk if that lights are passed by the earth and we've waited for that light to get to the nearest other star we'd be sitting here listening to my talk for about four years so probably not the best thing to to be doing so huge distances between the stars and across the whole of our Milky Way galaxy that that light would take a hundred thousand years to cross it with those hundreds of millions of stars within it actually that picture there is is a galaxy it's not our galaxy it's the nearest big spiral galaxy to our own it's called the Andromeda galaxy so it's the nearest other big large galaxy like the Milky Way and the light from those stars that you see in that picture you can actually see this if you know where to look you can look at you see the center of this galaxy just with an unaided eye you don't even need a telescope a little fuzzy blob that light that you can see from the center of that galaxy takes two and a half million years to reach us so you see back in time two and a half million years when you look at a galaxy like this so space is big and this is just the nearest other galaxy what about if we're talking about life and we're asking the question about where were the aliens we need to probably ask were the planets we know we only know of one example of life so far life here on this planet so we know there are many stars we can see them shining in the night sky but it's very hard to see the planets so do these stars do these hundreds of millions of stars have planets orbiting them they do and we're living in a very special time at the moment actually were twenty years or so ago we found the first planet orbiting another star like the Sun I looked up what the number was yesterday and the number now is 1642 confirmed planets all between all the stars so that's just the ones we found by extrapolating that to all the stars in our Milky where we know there are billions and billions of planets in our Milky where virtually every star you see in the night sky night sky will be orbited by by planets of course you can ask the question do those planets have life on them and one of the key things there is whether they're too close to their star would to be too hot so for example liquid water is something we think is key to life here on earth the only example of like we have so if you were too close to your son it'd be too hot that water would would would evaporate if you were too far from your star from your Sun then then you would actually find that that water would freeze and so you wouldn't have the liquid water which we think would be essential for all the salt biochemistry to go on that keeps us that allows us to be alive to allow the lowest out of life on earth again looking at what we found in our Milky Way along with these you know 1000 confirmed planets so far we know there must be billions of so-called habitable planets just in our Milky Way galaxy not in the Andromeda galaxy they want to just showed you this other galaxy and not in the not in the 100 billion other galaxies that we can see in the observable universe just in our own there must be billions of habitable planets potentially habitable planets in other words ones that are not too close to the star not too hot not too far away not so cold so they've got liquid water now have aliens visited earth who thinks aliens have visited the earth or nobody's daring to put their hands up okay there's quite a lot of people around the planet who do believe aliens visit the earth and visit the earth all the time and indeed claimed to have met them but I don't think there's actually much good evidence for that but it's sort of an interesting question you know might they have done we've only you know we've only been around for well you know modern humans have not been around for that long at all in terms of the history of the planet just a few hundred thousand years so my aliens have visited the earth at some point well here's an interesting sort of thing to think about and it's something we might we might do in the future which is to send out a fleet of what are called von Neumann probes their space probes that you send off and they go out to search around other stars to see what they can find around other stars we just discussed the fact that these stars are very far away even light takes four years to reach just the nearest other star and we can't make things travel the speed of light the fastest spacecraft travel at something like 60,000 kilometres an hour all that sort of that sort of speed a small fraction in the speed of light so imagine sending out one of these space probes is travel in a that's a fraction of the speed of light that's the salt speed we can we can say things out at the Mormon it would take it you know maybe 50,000 100,000 years to reach the nearest of the star but when it gets there what it does is it self replicates so he gets there and maybe along the way it gathers material it gathers material from the stuff between the stars maybe when it gets to the planet around one of those stars and gathers more material and it builds a copy of itself and then actually those spacecrafts set off again and they head off in different directions and they go to the next of the stars and when they get there each of those self replicates and sends off again this is not sounds a bit like science fiction but in fact it's possible to imagine that we would be able to do this in the not-too-distant future and again if you work out how long this ticks you can calculate how long this process would take you could actually explore the whole galaxy in less than 100 million years now to an astronomer that sounds quite quick because the earth is about five billion years old four and a half billion years old for in half thousand million years this was less than 100 million years you can speed it up by making multiple copies or making them travel a bit faster so this is actually short on the lifetime of a planet like the earth or in the lifetime of the stars that are in the galaxy so if you imagine that there might be life under these other planets that might be doing this one interesting question is were the aliens if there had been a civilization before us that were able to do this might they have done this might we have actually been visited by these fleets of probably robot spacecraft self-replicating and spreading through the galaxy we don't see we haven't seen any evidence for that but it's an interesting question we've not been here for very long in the history of the earth is it something we should be looking for it's called the Fermi paradox if aliens exist where are they because really this this is actually not too long too popular in the galaxy so how are we going to look for life on other planets well one of the ways to look for intelligent life and I'm only going to talk about intelligent life here and that's because we know that on the history of life on Earth most of that time life was bacterial life so it's basically microbes for billions of years before it evolved into anything complicated like plants or animals or even intelligent life like us so it may well be the bacterial life is common but if we were interested in intelligent life you've wanted a conversation with some of these aliens one of the ways we might do is by using a radio telescope this is the one at Georgia Bank where I work the Louisville telescope and this is just a recording of the solar signal we pick up with that telescope obviously the Rebbe a problem arises looking for the cells there but maybe you might get a little bit bored it just sounds like hiss it's just noise that's actually read your way in that case it was read your ways that came from a star that exploded in about the year 1670 as it happened but you know you can't really hear much it just sounds like noise if you were expecting to pick up a signal from aliens you probably expect something a bit more complicated in that signal than just art than just that noise and here's an example of something that was picked up not long after we started to think about using radio telescopes big ones like the the Louisville telescope there at Jodrell was built in 1957 so in the 1960s we started to use these telescopes to look out for messages maybe Morse code type messages buried in that in that noise and just a few years after that in 1967 one of these signals was picked up and here again is a recording made with our telescope pointed at a particular direction in the sky this is a bit of a surprise I've been used to hearing the noise the hiss a hear the seen you regular regular flashing of an object in the invisible sky would require surprise actually that first object was discovered by Jocelyn Bell at Cambridge University in 1967 that first thing was called a little green man one lgm1 they called it because they thought you know this is this is possibly an alien signal we actually now know though the remnants of exploded stars the things called pulsars very exotic objects that we use to test our understanding of physics and Einstein's theories of theories of gravity so not aliens perhaps sadly but exciting for physics although there what do we do with other telescopes well we use telescopes like this one this is the Arecibo telescope this is a massive radio telescope the world's biggest radio telescope it's in a valley in Puerto Rico it's 300 meters in diameter that makes it four times the size in diameter of the of the level telescope of Jodrell Bank a huge telescope that's used for lots of different things but one of the things it does is a project called Serendip which you might some of you might know a SETI at home you can download a screensaver for your computer and it will basically process data looking for these sorts of extraterrestrial signals being picked up with a with a radio telescope like that one another radio telescope around the world has been has done and is doing this sort of work is the Green Bank telescope this is in West Virginia this telescope is about 100 meters in diameter these large telescopes collect lots of radio waves they say you're they if you like they hear very faint things coming from the distant universe and so these are the sorts of things we might be interested in using to pick up extraterrestrial signals and this one's been used to search out those look in the direction of those planets that we that we know of the Parkes telescope here is in Australia again this telescope and the greenback telescope were involved in a new project looking for these extraterrestrial signals called the breakthrough listen project our own telescopes you're in the UK we started a project with these telescopes a network of telescopes spread across the country between here and between Jodrell Bank and all the way up to Cambridge seven radio telescopes all connected by optical fibres linked together to act as one giant telescope when again amongst all the other things we're doing we're starting to look through those signals looking for potential extraterrestrial signals and what's coming in the future is an amazing telescope we design at the moment it's called the Square Kilometre Array it's going to be built in southern Africa and Australia it's going to be made up of hundreds of dishes connected together and other types of aerials connected together that will make a giant telescope whose whose size is equivalent to 220 times the size of the level telescope of Jodrell Bank it will see incredibly faint things in the universe pick up incredibly weak signals and in terms of looking for aliens in just one minute that telescope will be able to look for look at every star in the direction it's pointing out to about 300 light years away from us so the nearest of the star was four light-years it will be able to get 300 light-years away searching every star in just a minute for the sorts of strong signals that come from those the radar systems that we use on our big telescopes so if there are aliens out there with this sort of technology and if there's messages the signals coming out where this telescope is going to be an amazing facility for us to be able to detect those signals so I'm afraid I can't what I can't do is give you the answer to my question the beginning which is where all the aliens we don't know we haven't detected aliens anywhere we do believe we do know there are potentially habitable planets that's that's a fact that wasn't we didn't know that 20 years ago we know that now we have got the technology we will have the technology that is allowing us to search ever greater bits of our galaxy searching for the sorts of signals from technology from the technology we produce the the radar systems that we use in airports and saw looking out for these signals that might be coming from aliens and I hope I do hope that at some point in the not-too-distant future we will be able to answer question of how we alone in the universe thanks very much

Channel: TEDx Talks

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Keywords: TEDxTalks, English, United Kingdom, Science (hard), Science

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Length: 15min 19sec (919 seconds)

Published: Mon Apr 25 2016