watch casio australia

capturing the cosmos dr. tanya hill: goodafternoon, everyone. my name is tanya hill. and i'm the astronomer forthe melbourne planetarium. and here at themelbourne planetarium today, it's apretty exciting day as we're launching a brandnew planetarium show. it's called "capturingthe cosmos." and we've createdit in partnership

with the scientificorganization called caastro. and i'm fortunate tohave with me today two members from caastro,ben mckinley and jack line. mr. jack line: hello. dr. tanya hill: they'reboth researchers at the university of melbourne. and so what we'dlike to do today is talk a littlebit about the show, some of the australian sciencethat's happening right now,

the telescopes thatthese guys are using to explore some of thereally big mysteries and the big questionsabout the universe. so guys, do you want tojust say a little bit about your research? maybe ben, what's thething that excites you? dr. ben mckinley: sure. i work using data froma radio telescope that's located in western australiacalled the murchison widefield

array. and it's a new andinnovative radio telescope that uses a lot ofdifferent antennas spread out right across the desert. and it's out there to befar away from any humans so that we don'tget any stray radio signals cominginto our telescope and messing up our images. and i use this data totry and peer back right

to the very beginningof the universe before there was any starsand galaxies to look at. and so i'm just lookingat hydrogen, which sounds really super boring. but there's a biggap in our knowledge. and we don't know muchabout this hydrogen and what it was doing. so it can actuallyteach us a lot about how the universeformed and is evolving.

so it's pretty interesting. dr. tanya hill: yeah,no, it really is. astronomers get really excited. dr. ben mckinley: we getexcited about hydrogen gas. dr. tanya hill: --thisidea about hydrogen and about looking-- becausewhen we look up in space, we're looking backin time, aren't we? dr. ben mckinley: that's right. dr. tanya hill: it'staken light so long

to reach us that we can seethe history of the universe. and i know when i was talkingto a lot of astronomers, they were alllike, we want to go right back to see howthe universe first began, see the first starsand galaxies that lit up, and really excited about this. and one way we used inthe planetarium show to describe thisexcitement is imagine if you had a photo album, aphoto journal of your life,

and you went back fromwhat you did today, and what you did the daybefore, but you get to a point where there's this missinggap where you have no idea. maybe you've lostall your baby photos, or you don't know what happenedin that period of your life. and that's kind of whatthese astronomers are doing, isn't it? we can map so much ofthe life of the universe except for this one little part.

and we'd love to know whatwas happening right there. so jack, what researchare you doing? mr. jack line: so just likeben, i work with the mwa. and like ben says, we'relooking at that period of time where there weren'tactually any stars, and they've just switched on. so that's about 13 billion yearsago, and maybe even further. so just like tanya wassaying, it's a long time ago. we're not really sure whathappened in that time.

and you can't reallyunderstand the entire universe until you've studiedthe whole universe. so that's kind of our idea. dr. tanya hill: yeah, becausecaastro, the organization these astronomers work for, it'sthe arc center of excellence for all-sky astrophysics. so it's about looking in asmuch of the entire southern sky as possible to kind ofpiece things together. it's a little bit--i kind of describe it

like we've been looking at theindividual pieces of a jigsaw puzzle. we've looked at this galaxy thatsits in this part of the sky or this amazing starcluster over here. and what these guysare doing is actually putting the whole jigsawpuzzle together and seeing how it all fits and all works. so that sounds pretty right? excellent, well, if you've gotquestions, send them through.

we'd love to hear from you. so we might start withone of the first questions from keysborough college. and jack, i'll handit over to you. what advances are being madewith the wide field arrays, like the mwa in westernaustralia that you work with? what advances are beingmade with telescopes like that compared to previousgenerations of telescopes? mr. jack line:cool, so wide field

means you can see lots ofthe sky at the same time. previously, we'd havetelescopes that could only see small patches of sky. so as a kind of ascale view, the moon is half a degreeacross in the sky. we call that half a degree. the mwa, our telescope, can seearound 60 widths of the moon. so if you think how bigthe moon is in the sky, we can see all ofthat at the same time.

now to do that, you needspecial kinds of hardware. so i think an image has justpopped up on your screen, maybe, or is about to popup, which is on, awesome. so this is actuallywhat the mwa is made of. it's kind of lots of littlemetal spiders, really. and we work in the radio regime,so triple j, things like that. they're at the samekind of frequencies that we're actuallytrying to study this old fog of the universe.

but due to the waythese things are built, they can see such a largepatch of sky at the same time. it means that wecan look at the sky and map the entiresouthern hemisphere really quite quickly. we can basicallymake up a picture within days of the entire sky. so the mwa has been surveyingthe sky for over a year now, and along with thesame area of the sky

as the skymapper project. but the advancesthat we're making is that we can see lots andlots of things at the same time. if you want to try to understandhow certain galaxies behave, you need to check that theyall behave in the same way, or kind of compare and contrastdifferent types of galaxies. you can't do thatunless you have hundreds upon thousands, sometimesup to millions, of examples. so the real big advances inthese wide field telescopes

is that you can makethem super quick. that's it. dr. tanya hill:yeah, that's amazing. and ben, you weresaying about the kinds of data that is pouringdown from the sky all the time that thesetelescopes are gathering. do you want to-- yeah,you know the numbers. dr. ben mckinley: yeah, sure. so an optical telescopeactually uses a camera.

and you stick it on theend of the telescope. and then you can download animage straight to your laptop. or you could even lookthrough it and see an image. our telescope isa bit different. so it's got all thesedifferent elements. and for each pairof antennas-- so one of those tiles thatyou see in front of you with the 16 spiders onit, that's one tile. so each pair of thosegenerates a number, each

depending on how often wesample it, but like many times a second. and so each time you get one ofthose numbers from each pair-- and across a whole rangeof frequencies as well. so you multiplythe number of pairs of antennas with howmany times you sample it per second with how manyfrequency channels you want it in. you end up withthis big number that

ends up being like a terabyteof data for, what is it, a two minute observation? mr. jack line: no, every hour. dr. ben mckinley: for an hour. so every hour, we're generatingan external hard drive full of data. so we have to pump thatdown a big, fast internet link to a supercomputerand store it. and so all we basicallyhave from our telescope

is a whole bunch of ones andzeros, just ones and zeros sitting there on the computeruntil an astronomer logs on and does some fancy magicwith some software to actually turn it into an image. because what we're tryingto do by spreading out these antennas across thedesert is to sort of mimic having one huge telescope. so what we have isone huge telescope that has a lot of holes in it.

in fact, most of it is hole. there's not that much telescope. and so we have to dosome fancy mathematics to actually turn thoseones and zeros into images. and so that createseven more data. because you have the raw data. and then you havethe calibrated data. and then you have images. and so we need big computers.

dr. tanya hill:yeah, so it really relies on computer power. i often talk aboutradio telescopes that in some ways,as you said, there's a lot of holes in the data. it's kind of like you'relooking through a picket fence, and so what you want to see iswhat's beyond the picket fence. but you only see that betweenthe little holes in the fences. but that's enough to thenpiece it all together

through the computers. and we get a really clearimage of what radio waves are coming down from the sky. actually talking aboutradio waves, in fact, we've got another picture ofthe same telescope, the mwa. but what we've done iswe've changed the sky from being the normal sky tothe radio sky, the signals that this telescope can detect. if anyone has been outand away from the city

and has seen the milky way, thatbeautiful band of stars that crosses our sky,well, that bright line there in the middleof the image, that's how radio telescopessee the milky way. rather than it being nice andbroad-- we're not seeing stars. we're just seeing a verythin band of hot gas, of the gas thatmakes up our galaxy. and you might beable to just notice there's little dotsthat look like stars.

jack, do you want to explainwhat-- they're not really stars at all, are they? mr. jack line: yeah,they're actually sort of big collections. so every single dot thereis actually a galaxy. so a galaxy can haveanywhere between 100 to a trillion stars, or 100billion to a trillion stars. each of those is aradio loud galaxy. so most likely it has ablack hole in the center.

dr. tanya hill: you'vegot to love black holes. mr. jack line: oh, black holes,they're the interesting one. but black holes, they're hungry. if there's gas around them, theysort of slowly eat this gas. as this gas heats,it gets energetic. and combine that withsome magnetic field lines, you can produce lotsand lots of radio waves. and they're super bright. so every single dot thatyou see in that image

is a collection of between 100billion and a trillion stars. so it kind of lookslike our galaxy, which just has stars in it. but they are radio galaxies. and something elsewhich is pretty cool, which is in thegalactic center there, you can almost see sort ofbubbles within that center. that's what we calla supernova remnant. now, when really, reallybig stars get super old,

they get to theend of their life, they actually end inthis violent explosion, which we call a supernova,which you've probably heard of, which also skymapper, whichwe'll talk about later, is good at finding those. but these supernovaeremnants, once you've had this big supernova,you have this big envelope of sort of materialthat gets thrown out, and it's kind of gettingbigger and bigger and bigger

as we go through theage of the galaxy. each one of those bubblesis a supernova remnant. they're easier tosee along the plane, so that's why we cansee so many there. but you can make out 10to 20 just with your eye. and that's an ancientblown up star. they look pretty in optical. but they also look verynice in radio as well. dr. tanya hill: yes,they're amazing,

these rings from the debrisof a star that's exploded. so the supernovae andthe milky way, that's part of our own milky waygalaxy, which, as jack said, a few hundred billion of stars. and then our galaxyis just one galaxy amongst the millions ofgalaxies that are out there. and yeah, we canpeek those galaxies like those little dotsof light in the radio waves, which is pretty amazing.

so the mwa looks at the skyin a completely different way to how our eyes do. but another telescope thatcaastro astronomers work with and that we feature inour planetarium show is a telescope called skymapper. and it's more ofa usual telescope, what people are used toseeing when you think of one. but it's doing something quitedifferent as well, isn't it? it's still in thiswide field space that's

looking at all the sky at once. ben, do you want toexplain a little bit about what makes skymapper adifferent kind of telescope to other ones that we have? dr. ben mckinley:sure, so astronomers have for a long time focusedon tiny little patches of sky, like if you can imagineholding a grain of rice up at arm's lengthand seeing just the bit of sky that'scovered by that grain of rice

and zooming right in on that. and you can seethousands of galaxies and get amazingdetail about that. dr. tanya hill: so that'sthe hubble space telescope. we've seen amazing images fromthe hubble space telescope. often it's only a small-- dr. ben mckinley:yeah, and that's the teeny piece of the sky. so we know a lot aboutthat little bit of the sky.

but we know very littleabout the rest of the sky. is that the same asthe rest of the sky? does the other parts of thesky look wildly different? and what if we want to comparethose galaxies to something like the mwa where we've lookedat this huge patch of sky? we only have opticaltelescope data from that little tiny patch. so what skymapperis doing is it's programmed in to automaticallysearch the sky every night

and map the entire sky. and it can do thisrelatively quickly. because its field ofview is much larger than that grain of rice. so it covers 30 square degrees. dr. tanya hill: so jackcompared the mwa to the moon. dr. ben mckinley: to the moon? i think it's about--how many moons is that? mr. jack line: i thinkit's 10 moons across.

dr. ben mckinley:yeah, 10 moons across. dr. tanya hill: whereasthe hubble can't even picture the moon, can it? it's seeing like a tinylittle crater on the moon. mr. jack line: it's likea quarter of the moon. dr. tanya hill:yeah, yeah right. dr. ben mckinley:yeah, and if you point the hubble atthe moon, it would burn everything and destroy it.

dr. tanya hill:that's true as well. you don't want to do that. dr. ben mckinley: so that's whatskymapper is really good for. it can visit a largepatch in the sky. it looks at it fora minute or so. and then it moves ontothe next patch of sky, and the next one,next one, next one. and what's alsocool about it is it revisits the sameareas again and again

in order to fill upthose patches of sky. and that allowsus also to compare the images to see how they'veactually changed in time. and that's one of theways that we can find these things called supernovae. dr. tanya hill:yeah, so skymapper, because that's theimportant thing, that it takes a view of thenight sky, and then another one again over and over.

and we're used tonot much changing. we don't see much changein the sky with our eyes. but this telescope canpick up these changes too. now, i've just hooked into--there's some great questions that are coming through. and one of them was, howmany stars can we find now, and what's the number? and i don't know. i think all of us wouldhave trouble actually

giving you the number of stars. it's kind of like countingup the number of grains of sand on a beach. and i know i rememberreading something on the internet abouthow they compared it. and it's pretty close. one of the thingsabout astronomy, we're dealing withsuch big numbers. getting things thatprecise is pretty hard.

would you agree, ben? dr. ben mckinley: i guess iwould answer by, it depends. if you look up atthe sky, i think you can only see like a fewthousand with the naked eye. and then if you lookat that little rice grain in the sky withthe hubble telescope, you can see thousandsof galaxies, which each have billions of stars. so you're multiplyingthousands by billions

just for that rice grain. and then you'vegot the entire sky. so to the human brain, there'san infinite number of stars. dr. tanya hill: yeah, it'spretty hard for us to describe. and someone's also asked, pleasetell me the earliest red shift interval at which galaxyand quasars are currently known to exist. so this is the idea,we're looking back. it's about 13 billionyears ago, isn't it?

but they've asked for red shift. do you guys know the-- mr. jack line: so thecurrent record of actually observed is somethinglike 11 i think, or somewhere aroundred shift 11. we think the firstgalaxies and stars formed somewhere around 16, 18. i can't quite remember. we're not exactly sure.

and that's exactlywhy the mwa works. the thing about astronomy,until, well, very recently, is to do astronomy,you need light. that's kind of whatit's actually based on. you need to look and see. before the galaxieswere there, there was nothing producing light. that's why it's sodifficult for us to probe, and why we named thattime the dark ages.

it sounds a bit sinister,and it kind of is. because there wasliterally nothing producing light at that time. so we can't really seeit until they switch on. and there's lotsand lots of stuff in the way withthis hydrogen gas. dr. tanya hill:actually we've got a picture of the fogof the early universe. so the idea is that itwas mostly hydrogen gas.

and it was lightcouldn't escape. light couldn't get throughand travel all the way to get to us until the firststars and galaxies started forming holes. it's kind of like theywere burning away. mr. jack line: it'sa swiss cheese phase, i like to call it. dr. tanya hill:yeah, there you go. and that's something.

the mwa is one ofthe only-- very few-- telescopes in the world where-- mr. jack line: atthe moment, yeah. dr. tanya hill: yeah,the only telescope that can actually potentiallytry and find the swiss cheese effect. it's actually lookingfor the holes in the fog to see how these first stars andgalaxies lit up the universe. mr. jack line: andthat's another reason

we need wide field telescopes. because thesepatches-- obviously, this is almost a wholesky representation. you need to be able to seelarge patches of the sky to be able to pick upthese kind of holes. and they only stillexist on the imprint of the sky because of redshift and the expansion of the universe. so we're lucky thatthere's a snapshot in time,

and we can probe back. but we need reallywide field instruments that also work atthe right red shifts. so red shit andradio frequencies kind of go hand in hand. but yeah, i think 11 isthe best we've seen so far. dr. tanya hill: yeah, no,that's pretty amazing. dr. ben mckinley:and i guess, yeah, relating the mwato that question

as well, the beautyof it is the highest red shift ones havebeen found by looking at individual galaxies. we're not lookingfor the galaxies. we just infer thatthe galaxies are there because of these bubbles. so by looking at thatlarge patch of sky, we can sort of figure outand use some detective work to figure out when thefirst galaxies formed,

even though wecan't even see them. dr. tanya hill:yeah, it's amazing. and this is a greatquestion from penleigh and essendon grammar school. they're asking about howmuch will the data collected from the squarekilometer array, which is the next generationof radio telescopes, differ from the murchisonwidefield array? do you want to talkabout that, jack?

mr. jack line: fundamentally,it is actually the same. so an interferometer just meansa collection of receivers. and you combine theirsignals in a specific way. the big difference is it's goingto have lots and lots more, basically. in the murchisonwidefield array, we have about 128different receivers. in the squarekilometer array, there may be anywhere up to a million.

and the amount of datathat it produces just scales astronomically,unfortunately. one of the figures that gotthrown around a while ago was the data rate transferinside the square kilometer array is going to be more thanthe global internet traffic. dr. tanya hill: soglobal, international, everything that's happening. mr. jack line: as inthe entire internet, the amount of data that'sflying around there--

dr. tanya hill: --willjust be in this telescope. mr. jack line: --will bein this one telescope. then it's an astronomer'sjob to work out how to condense that into a wayof actually getting information from it. so we're in the regime when youcan't store your data anymore. you have to process it. so you have to kind ofdo whatever math you want to do to it on the fly.

at the moment, we'reactually relying on a thing called moore's law. so there's a lawof computing that says as time goes on,computers get better. that's basicallyit in a nutshell. at the moment, the computersthat we need for the ska don't actually exist. we're just assuming thatthey'll get good, good enough to actually run this telescope.

it's a good law. it's a fair assumption. dr. ben mckinley:that's you're job. you're going to be designingand building those computers. mr. jack line:yeah, it's amazing. dr. tanya hill: keeptechnology advancing-- it's pretty incredible. so we've had another questionfrom penleigh and essendon grammar.

and they want to know, whyis it important to know about what's happeningin the universe, and what do youthink the impact is? ben, why is it thatwe should learn this? dr. ben mckinley: well, ithink probably the best answer that i can think offor that is you just don't know what applicationsare going to come out of it. and for example, whatwe've discovered, fairly recently, is wethought that gravity would

be slowing down the universe. so we knew it was expandingand getting bigger and bigger. but because there'smatter in it, and things attract each other,it should be slowing down. dr. tanya hill: because gravityshould be pulling everything back together. dr. ben mckinley: yeah,so they had this idea, we'll use supernovae,and we'll measure how the universe is slowing down.

and they measured it. and they said, hang on,it's getting faster. it's getting bigger faster. why's that? basically theydiscovered anti-gravity. so there is a force,a repulsive force. and so if someone can figureout how to actually make hoverboards out of that, it'sgoing to benefit everybody in the entire universe.

dr. tanya hill: absolutely. so what you're talkingabout, there is dark energy. astronomers have givenit this name mostly-- i think it's dark becausewe don't know what it is. and actually it links us backto skymapper, the telescope that we were talkingabout before. because skymapper can pickup changes in the sky. it can pick up supernovae,these stars that explode. and then it's bylooking at-- supernovae

are fantastic interms of something called standard candles. jack, do you want to explainwhat a standard candle is and why supernovae are so-- mr. jack line: yeah,so one of the issues that we face as astronomersis the sky kind of almost looks like 2-d to us, right? it just looks like abunch of stars painted on to almost like a ceiling.

but in reality, that's not true. we live in a three dimensionaluniverse that we can probe. so we have to try and work ourhow far away things actually are. and it's not as straightforwardas you might think. and we have lots oflittle tools in our bag. dr. tanya hill: because allwe can do is see things, collect the light, isn't it? so we're trying to measuredistance just by the light.

mr. jack line: exactly, exactly. so if you have something thatyou know exactly how bright it is, that's really useful. so imagine youhave a light bulb. you put it right in front ofyour face, looks really bright. put it really far away,it looks pretty dim. you know that it's thesame brightness, though. it's just further away. so if you know exactly howbright your light bulb is,

and you put it on theother side of the room, you can do acalculation comparing how bright it looks to howbright you actually know it is. and then you know exactlyhow far away it is. there's a certaintype of supernovae which we know exactlyhow bright it is. so if you can watchthem going off, and you can associatethem with a galaxy, you know exactly howfar away that galaxy is.

the duality of the awesomething about red shift is it means we can seethings in the past. but it also changes thefrequency that we see them at. so we need to know how faraway something is to know exactly what's happening in it. so the standardrule is essential. and things likeskymapper are able to see them all the way across thesky, which is very, very useful. dr. tanya hill: yeah, so itcan find these supernovae.

they're called typeia supernovae, not the most original of names. but the cool thingabout these supernovae is that it's notjust a star that reaches the end ofits life and explodes. it's a star that is actuallyorbiting around another one, and it's funneling gasoff that second star until it just gets tooheavy, can't cope anymore, and pretty much implodes.

it's an implosion thatcauses the supernovae. so we know how bright thatsupernova event should be. and as you said,that's our standard. the dimmer it appears, then wecan get to measure distance. and that's where things are muchfurther away than we thought. so the universe, ratherthan just getting this kick at the big bang andexpanding, for some reason dark energy switched on andis pushing everything even further apart.

now, i've got agreat question here. i'm not sure whatschool it's from. but what is theuniverse expanding into? ben, do you want totry and help out? it's a bit of amisnomer about it. how do we talk aboutthe universe expanding? dr. ben mckinley: yeah,it's not something that our human brain canreally picture or comprehend. because you'retalking about sort

of an extra dimension of spacethat you're not aware of. so it's not the universeexpanding into anything. there wasn't an empty universewith a little seed that got bigger and bigger and bigger. it's the universe itself. it's the space thatwe're moving through is getting bigger, whichis kind of mind blowing. you don't notice things so much. because there'sother forces that

are holding thingstogether here on earth, like this table and me. but the space aroundus is getting bigger. but it's not aneffect you can really notice until you look atthings that are really, really far away. so the amount of stretchingis proportional to how far two things are apart. so that's why we need tolook at these really, really

bright supernovae thatare really far away to see how the universeis actually expanding. so it's space itself. so it's not expandinginto anything. there is no middle. everything around usis just getting bigger. dr. tanya hill: yeah, andso it's one of these things. the big bang was thestart of the universe. and in some ways, that big bangis all around us, isn't it?

even right now, becauseit happened everywhere in the universe. and so it happened rightwhere we are as well. it's one of thesecrazy, crazy ideas. and so the universeis expanding. dark energy tellsus that expansion is getting faster and faster. jack, what do youthink's going to happen in billions and billionsof years into the future?

mr. jack line: well, if itgoes the way that it is, everything's just kind ofgoing to get a bit cold. and it's all going to turninto a rather boring universe, unfortunately. we're going to kindof have a big freeze. and the temperaturewill just slowly, slowly go towards absolutely zero. lots of interesting stuffwill happen in between. there'll still be lotsof stars blowing up

and radio galaxies switchingon and turning off. but yet at themoment, we think it's going to be pretty boringin the end with everything. dr. tanya hill:yeah, so it'll even get to the point--so at the moment, on sort of smallscales, which even i'm talking aboutthe size of a galaxy, gravity is able to holdthe galaxy together. and so it's not expandingagainst dark energies yet.

it's kind of thedistance between galaxies that's expanding. but eventually wecould get to a point where dark energy can overcomethe forces of a galaxy holding together. we would lose the stars inthe night sky, i'm guessing. would it get to that point, thatthe stars would be moved away, and some would be allalone, and eventually-- mr. jack line: well, we mightrun out of hydrogen eventually.

so there wouldn't be anyfuel left to make stars. dr. tanya hill: nothingmore to make stars? dr. ben mckinley: sogravity is strong enough to hold our littleisland galaxy together. and i think the local galaxiesthat are orbiting around, they're pretty much bound. so i think thestars will probably stay until they allburn out and disappear. but the mwa image that wesaw would completely change.

so that will fade away. and it will be blank. and future mwa astronomers willjust be staring at nothing. it'll make thesurveys a lot easier. [interposing voices] dr. ben mckinley: so yeah,get into astronomy now. because it's all going away. dr. tanya hill: andagain, of course, astronomers talk abouttime in billions of years.

so it's, well, who knowshow humanity and things may have evolved by then. so let's see, what otherquestions do we have there? so one of them soundsquite interesting. if there's so muchmissing mass, why is the expansion of theuniverse still accelerating? mr. jack line: doyou want to tell us? yeah, we're not entirely sure. the reason we callit dark energy

is because we can't see it. and we don't really knowwhere it comes from. and similar with dark matter isthe fact that we can't see it. they're kind of holesin our current theory. it can be slightlyembarrassing as an astronomer to admit that, what is it,about 70% of the universe, of the energy budget of theuniverse, is dark energy. dr. tanya hill:which we don't know. mr. jack line: wejust shrug, right?

you can't knoweverything straight away. we have to put ineffort and work out. but that is one ofthe big questions. i don't know. no one does, i think. dr. tanya hill: yeah, and isuppose actually going back to that earlierquestion about impact as well-- what was it,almost 100 years ago when quantum mechanicswas discovered.

and so this is talkingabout the physics of how things work ona really tiny scale, on the scale of an atom. and well, there's all thesestrange probability effects. and at the time, thescientists were going, look, it's interesting. it tells us somethingabout our universe. but whether it's ever useful--and now every device we use, all our computers, ipads,all the rest, they're built,

they're made, to be so miniaturebecause of quantum mechanics. so i often like to think atthe moment, on the other scale, in terms of the bigscale of the universe, we've got this dark energy, 70%of the universe we don't know. who knows what advancesthat may lead to? mr. jack line:yeah, that is cool. dr. tanya hill: it's areally interesting field. ok, we've got a coupleof questions coming in on my favorite topic,the topic of black holes.

jack, do you wantto explain what would happen if you got a bittoo close to a black hole? mr. jack line:spaghettification. so gravity is basically setup by how much stuff you have. and in a blackhole, you have a lot of stuff in a very,very tiny point. so you get this reallyintense gravitational field. and gravity, you feelthe force of gravity

more the closer you are. but it also has thisvery strange effect of changing the way time works. so at the edge ofa black hole, you have crazy thingshappening where gravity is getting strongerthe closer you get to it. and also time iskind of slowing down. so essentially you can kind ofalmost see your feet going off. because they're kind ofgetting pulled off anyway

and sheered off. but the time the light takesto get to your head changes as well. so you get spaghettification,pretty much. dr. tanya hill: so stretchedout into a long, thin piece. because even over-- gravitychanges on earth, too. gravity at thesurface of the earth is much strongerthan when you go into space 100 kilometers up.

but over the distanceof how tall we are, the gravity changeis pretty minimal. but you get closeto a black hole, and the gravity change betweenyour feet and your head is enormous. and that's whatstretches you out. and i love the wholetime dilation idea, the fact that-- and it is. time for you actually--you feel time the same way.

but it all slows down. so you can lookback and actually kind of see the universespeeding up in a way. because the universe is tickingaway at its normal rate. so time out there seems tomove faster than for you. mr. jack line: and it isn'tactually fully theoretical. we have proven these things. if you put a clockon the surface of the earth-- a very,very accurate clock,

not just your stopwatch. but if you put a veryaccurate clock on the surface and stick it up on a spacestation, just the fact that you're orbitingaround the earth means that the passageof time changes slightly for the clock on the ship. and we've done this. we've seen that thereis a slight difference in the time measured up inspace versus on the earth.

so whenever we throw it around,it sounds like science fiction. but it's just science. it's actually true. dr. tanya hill: and it'sanother thing we use every day. if you've ever usedgps to get somewhere, you're talking to asatellite which relies on a very, very accurate clock. and its clock isticking-- can i remember? it's in the orderof microseconds

different to ourclocks here on earth. but that would translate to--if you didn't take that time difference intoaccount, then you would start to be like a meteraway from where you wanted to go, and then a kilometer,and then it would just get worse all the time. so all the time we're using it. dr. ben mckinley:they calculated what that time difference is.

and then they set theclocks differently on earth. and then they send them up sothey're exactly synchronized. mr. jack line: pretty cool. dr. tanya hill: yeah, so we'reusing relativity and time dilation all the time,which is amazing. dr. ben mckinley: yeah,and einstein never got to see this,unfortunately-- poor fellow. dr. tanya hill:so someone wanted to ask a really good-- i thinkit was from gympie high school,

about if black holes are suckingmaterial in, like we say, turning things tospaghetti, and they're black-- that's why theywere named that way-- how do we see them? we just put up a radio image ofall those little dots and said, you're looking atsort of black holes, at galaxies poweredby black holes. why is it that wecan see a black hole? dr. ben mckinley:ok, well there's

an exciting new waythat we can actually see black holes directly, whichwe can talk about in a sec. dr. tanya hill: let'sdo the normal way first. dr. ben mckinley: butthe normal way first is we're not actuallyseeing the black hole. so we're seeing the stuffaround the black hole. so what happens,because the gravity is so strong around a blackhole, and as jack said, they're really hungry,things are going into them.

but it's actually really hardto fall into a black hole. so if things start goingreally, really fast and getting torn apart--and it's really violent. and you end up withthese big jets of energy that are shooting out eitherside of the black hole. and so that's the bitwe're actually seeing. what we're seeing fromthe radio telescope is the radiation caused bylittle particles, electrons, that are whizzingaround very, very

close to the speed of lightthrough a magnetic field. so they're whizzing andwhizzing and whizzing around out of these jets. and that's what we see. dr. tanya hill: yeah, so theradio telescope sees the jets. they're kind of spewing out. i don't know if anyonedoes it these days. but there's-- is it vitabrits or something or other? they're always the biscuits.

and if you squish them together,all the butter and the vegemite can come out through the holes. it's kind of like that,the jets of the milky way. so that's what aradio telescope sees. and x-ray telescopes,they see all the material as it's spiraling down andgoing around and around slowly trickling into the black hole. it heats up dueto friction, just like rubbing yourhands together.

and it gets so hot,millions of degrees, that the gas actuallyshines at x-ray wavelengths. and so that's anotherway we see them. but very recently,just last month, we found a new way oflooking for black holes and what happens when twoblack holes actually circle around each other andeventually collide from a single black hole. i'm talking aboutthe amazing discovery

of gravitational waves. so jack, you're nodding there. do you want to explain whatis it that's happening? mr. jack line: yeah, so thisis some extreme physics. when you have twoblack holes, and they start kind of doing this oneswan lake dance that they're about to go, they'reabout to collide and die, they kind of do likea whirlpool going down the plughole thing where theyorbit each other very, very

quickly. now because theyhave so much mass, and we said the massaffects gravity, there's hugegravitational effects. well it turns out thegravitational effects actually change the shape of space. so you actuallystretch it and warp it. because you're going in thisregular pattern, the way that these two black holeskind of orbit each other,

they warp space in apattern, in a systematic way. essentially, you can almostthink it as just doing this, really. dr. tanya hill: andthis way as well. mr. jack line: and thisway, exactly right. dr. tanya hill: you'regetting squeezed and pulled, aren't you? mr. jack line: so kind of ifi was at one end of the laser, and ben was at theother end of the laser,

i'd start doing this,and you'd do that, right? you'd go away. i come in, go away. so what we can do with theseinstruments that we set up is you can look atspace stretching. we know how long light shouldtake to go a certain distance. and lasers use light. so if you can shoot a laserfrom one point to the other and watch how timechanges, how long

it takes that laser to getfrom one point to the other, and you watch it changingin a rhythmic pattern, the only thing that couldcause that are things like binary mergers, thingslike black holes going around each other. so you can actually watchspace warp and change shape. and einstein predictedthese things. they're called grav waves,gravitational waves. we've only just gotto the point where

the optics, the lasers andthe mirrors that we use, have got good enough toactually see these changes. but they're minuscule. dr. tanya hill: likethe size of a proton, smaller than a proton? mr. jack line: yeah, i thinkit's smaller than a proton. so things inside the atoms,which are what make us up, you have to be able to lookat space changing-- well, obviously doing this,that's a little bit bigger

than the size of a proton,so ridiculous accuracy. but they've actuallydone it now. dr. tanya hill: whichis pretty amazing. so the way einsteinkind of has taught us to think about theuniverse is this idea that there's this sortof fabric of spacetime. it doesn't really exist,but it's a nice analogy to be able to think about it. and often the way it'smentioned is that spacetime

is like a trampoline. and so gravity is justyou put a big bowling ball on your trampoline. it's going to create abig hole in the center. and that's what gravity is. but then of course if youbounce and pat the trampoline, then it's going to sendripples through as well. and so these are what thegravitational waves are. they're the ripples thattravel through this fabric

of spacetime when thesebig, massive objects are moving around. and it was-- doessomeone remember? the two black holesthat collided, was it 1.3 billionlight years away? so this happened 1.3billion years ago, set off these ripples,just like you'd throw a rock into a pond,set off some ripples. and the ripples aregoing to be dying down.

and yet we've still managed,1.3 billion years later, to be able to detect this kindof dying down of the ripples as it's passed over theearth and made the earth sort of squeeze and stretchby this minuscule amount-- absolutely amazing. so astronomers, scientists,around the world are really excited aboutgravitational waves. what more can they tell us? dr. ben mckinley: well, yeah,the amazing thing about it

is it's a completely newway of doing astronomy. it's not like a differentfrequency of light. it's not light. it's an entirely newscientific field. these gravitationalwaves essentially are so weak and smallyou can only detect them from things that areabsolutely catastrophic, so the most violent things, likethese two black holes merging together and getting so closeand then actually smashing

and do you know how todo the sound of what that sounded like? because what's interestingis there's actually the two black holes smashing together. if you could, it'sin the audio range. if you could actuallyhear this with your ear-- which you can't. but if you could, itwould sound like, voop! it makes a really weird sound.

and that's happening all thetime throughout the universe. so eventually when weget even bigger ones of these interferometersthat are much more sensitive, we'll be able to lookat the entire sky and see voop, voop, voop, voop,all these black holes smashing and i think the holygrail of it is actually looking right backto the big bang itself and trying to measurethe gravity waves from when the actual birthof the universe,

like actuallylooking at and sort of listening to the birthof the universe itself. so who knows whatamazing physics we'll be able to learn from that. dr. tanya hill: yeah,because that's something that light can't probe. it's impossible. dr. tanya hill: we weretalking about the mwa is looking for these holes inthe hydrogen [inaudible].

they're the first starsand galaxies lit up. but we go furtherback, and there's this radiation we call thecosmic microwave, background radiation. it's the remnantof the big bang. and it allows us tosee just 380,000 years after the big bang. so the big bang happened. 380,000 years later, we've gotour first picture of light.

but we can't use light toprobe that first instance. but gravity waveswe can, can't we? so eventually as thetechnology gets better, and we're able to detect moreof these gravitational waves, we can probe right back tothe earliest times, which would be really very exciting. so yeah, gravitationalwaves is a new way of looking at the sky. we talked about light andradio with our telescopes.

[inaudible] has askedus, what other forms of electromagneticradiation are out there? mr. jack line: oh, allkinds of fun stuff. anything under ofthe sun-- so uv, which you're supposed toavoid with your sun lotion. that's out there. infrared we use to look at dust. it doesn't sound interesting,but dust is actually very important in the waythat light signals reach us.

you've got x-rays, astanya talked before. gamma rays-- so thereare these things called gamma ray bursts thatgo off every now and again. again, they're very energetic. so gamma rays are themost energetic light that we can see. and they are prettycataclysmic events. and then microwaves-- sowe use microwaves as well. there's an interesting newdevelopment in radio waves

which are called frbs,which are fast radio bursts. it turns out you can mimicthe signal of these frbs by opening yourmicrowave oven right next to your instrument, whichwe just recently had problems with at the parkes telescope. it's quite a funnyinteresting bit of science. but there's an actual paperon, don't open your microwave next to your radio telescope. dr. tanya hill: so thekey is it's the microwave.

if you're too fastto want your food-- if you use the microwave,and you wait the full minute, and then you getyour food, you're ok. but if you decideafter 50 seconds, oh, i'm hungry now, i wantit, and you open, then there's enough microwaveenergy that sets out. and the telescopethinks that it's one of these fast radiobursts, a different thing than astronomers areseeing in the night sky.

but all the differentkinds of-- and they're all different kinds of light. it's just theirfrequency changes or their wavelengthchanges across. and each of them tells ussomething new and different, doesn't it? so you were saying aboutthe infrared with dust. one of the great thingswith that is firstly, there is a lot of dustout there in the universe.

and so things arehidden behind the dust. and we can use infrared to kindof see some hidden things, can look into star forming regions. ben, do you want totalk about that at all? dr. ben mckinley: i don'tknow a lot about the infrared. i do know that one of thetricky things about infrared is that it can't actuallypenetrate our atmosphere very well. because it hits the watermolecules and basically gets

blocked. so in order to see thisdifferent view of the universe where you can peer and look atthe dust and the warming that's happening, you have to getaway from the atmosphere. so they either stickit on a satellite, one of these telescopes,or a cool thing, they actually mounted atelescope inside a boeing 747. and they fly it up abovemost of the atmosphere. and that's called astratospheric observatory

for infrared astronomy. and it's one of the reasonswhy i called my daughter sofia with an f. dr. tanya hill: oh, ok, yeah,because of the observatory. that's fantastic. that's great. yeah, so we have allthe different types. ultraviolet light thatyou were talking about, that allows us to see someof the really young stars,

when stars firstare born, they're very energetic inultraviolet light. so you can kind of use all thedifferent wavelengths of light. and again, i thinkit's something that caastro does really wellin terms of it's not just looking at all the sky, butthen it's all the wavelengths as well to really piece togetherwhat's going on out there. and now, look, thelast question i think we might have,we're going to bring it

all the way right back tohome, back to our little solar system, our sun, which isjust one of the many millions of stars in our galaxy withall its planets around it. back in the '70s, thevoyager spacecraft was launched offearth and has gone out to probe the solar system. and the question is, hasit left the solar system? jack, have you beenfollowing voyager at all? mr. jack line: it has, yeah.

technically it has. dr. tanya hill:there's different kind of edges to the solarsystem, though, isn't there? so go for it. mr. jack line: so itis still sending us data, which is an absolutetestament to the instrument. that's insane. dr. tanya hill: what would bethe computer power on voyager? wouldn't it be a watch?

mr. jack line: maybe likeless than a casio calculator that you can get these days. i mean, that's what theysent people to the moon with. dr. tanya hill: andthat was amazing. yeah, that wasamazing at the time. mr. jack line: soit can basically sample how many particlesit's surrounded by. so we know thatour solar system is traveling through our galaxy.

and you have what we calla bow shock at the front. so essentially there's abunch of particles and matter associated withour solar system. and then there are thingsthat aren't bound to it. they're sort of outside it. and it's almost likewe're a ship sailing through some water. you can look at theway the water flies off the front of the hull.

so there's a big rise inthe density at that point. and then after that, it'skind of there's nothing. and voyager, it suggestsfrom the data, the way that the density has changed,how much stuff it can see, that it has piercedthrough that. it's gone outside. so it looks like voyager isoutside the solar system, which is the only thing thathas ever done that. universally, tiny scale,but on human scale,

massive, really interesting. dr. tanya hill: yeah,it's pretty amazing that we're able to do that. so look, i want to thank bothben and jack for being here today. they're both researchers atthe university of melbourne and part of caastro, theaic center of excellence and as i said at the startof this, one of the reasons that we were doingthis today, and it's

a big day here at the melbourneplanetarium at scienceworks, is that we're launching a brandnew planetarium show called "capturing the cosmos." it tells you all about the mwathat we've just talked about, which these guys work with, andalso the skymapper telescope as well, and what they'redoing to probe dark energy, to probe the cosmic dark ages,these big mysteries that we're trying to solve. we're trying to understandmore about the universe.

so thank you all foryour fantastic questions. and maybe we'll chatagain soon sometime. thanks. dr. ben mckinley:thanks, everyone.