The current crisis in Cosmology - it just got a lot worse | Night Sky News November 2019

[Music] all right I promised you last week I would tell you all about the current crisis in cosmology and I'm not kidding when i use the word crisis crisis in this respect it's totally justified but before we get to that let's have a look at what's gonna be in the night sky to look out for this month so on November 22nd to 25th the moon is gonna be getting progressively smaller so going from a very large president to a very thin Crescent it gets towards new the thing is every night it will look lower and lower in the sky at the same time so if you go out and look at 7 o'clock on the 22nd and the next night at 7 o'clock it will be slightly lower and also slightly smaller and as it gets lower and smaller on each night from the 22nd for 25th it's gonna actually get closer to a different object in the sky the three brightest things that are in the eastern sky at the moment it's on their 23rd it will be close to Spiker which is the brightest star in the constellation of Virgo and then by the 24th it will be closest to Mars then on the 25th it's gonna be close to mercury very very low on the horizon just before it becomes a new moon so it's a very very thin Crescent so it'll be a good way to find mercury if you want to try and spot it it's a little bit difficult because it's so close to the horizon into the Sun on November 24th as well we have a Venus and Jupiter conjunction this time in the evening sky so about an hour so after sunset look out for Venus which will be incredibly bright and then Jupiter probably the next brightest thing in the sky in the southwest Venus is gonna be about a degree and a half below Jupiter so about three sort of thumb widths down from Jupiter Saturn is also gonna be above them sort of along the ecliptic as well and then when the moon comes out of its new moon phase moon is actually going to swing past Venus Jupiter and Saturn on the 28th 29th and 30th of November so look out for that as well we had a Venus and Jupiter conjunction earlier in a year back in January but it's also quite close to the moon but the next one isn't actually gonna be until February 2021 we don't have one next year at all so get you fill of this conjunction while you can sit gonna be a really pretty sight in this guy then by December 10th Venus is actually gonna be much closer to Saturn in the sky this time about 1.8 degrees south of Saturn so maybe almost 4 thumb widths away but it's a really good way of finding satin because satin is nowhere near as bright as Venus or Jupiter it can be very easily confused for a star so again an hour or so after sunset look for Venus and you should be able to find Saturn as well then on December 13 14 15 this is the peak of the Geminids meteor shower and I see on this channel a lot you know be wearing that the media will report on a meteor shower and say that one is coming and you should go look out but in reality you know there's not gonna be that many meteors probably hard to spot not true of this or if you get chance you need to get outside to try and spot some meteors because the Geminids is one of the highlights of the year you can get up to a hundred meteors an hour or so that's more than one a minute and of course a lot of those all be quite faint and so you won't always spot all of those but so you have a very very good chance of spotting them the Geminids meteor shower means the radiant eye the point where all the meteors look to be coming from is in Gemini which is quite close to a Ryan in the sky so the best thing to do is to look for Orion and then turn away from Orion prints on the back of your head to it and then look at the rest of the sky because then the rest of the meteors should then shoot out and over your head and that'll be the best way of spotting them remember though December at least in the northern hemisphere here it's no record so please wrap up warm if you are going outside because standing around or lying down in the cold obviously get much colder than if you're moving around so please take precautions when you're trying to spot these things but remember if you get pictures please send them to me on social media because maybe eat your shower pictures are my favourites alright so with that out of the way let's turn to Astro news that we need to catch up with from the past month including that crisis in cosmology okay before we get to that crisis you know me I love black holes so the first piece of news that I want to talk about is that the smallest black hole we've ever found has been discovered now I guess the question that everyone always asks is what's the biggest black hole you know because we're always bothered about the biggest and most energetic things and we never really stop to think about necessarily what the smallest black hole is and why that actually might tell us a lot about how black holes are formed so when massive stars run out of fuel to fuse together in nuclear fusion and I mean you know run out of hydrogen and they start burning helium and all the way up to carbon oxygen nitrogen all the way to iron weapons in a supernova when all of that fuel runs out is that essentially there's no energy pushing outwards to counteract the pull of gravity inwards and so in a normal supernova what happens is that everything collapses inwards but eventually it reaches the point where the core of the star is held up by atomic forces and so a supernova is essentially the point at which the outer layers of the star rebound off that core due to the atomic forces and then that's why we get these these huge big nebulae forming where the outer layers have been thrown out and you've been left with something like a white dwarf which has held up by the pressure between electrons or a neutron star which is held up by the pressure between neutrons if you have a star that's incredibly massive then the force between the atomic particles in that central core sometimes are large enough to counteract that push of gravity inwards and what happens in that case is the whole thing collapses down to a black hole ie the mass is all concentrated at a single point a singularity and the speed at which you would need to escape that gravitational potential well is greater than the speed of light but we don't really know the point at which for a star it becomes so massive that it will become a black hole at the end of its life we don't know what that sort of cut off mass is so by searching for the smallest mass black holes and also the biggest neutron stars we can try and pinpoint that so some of you might remember two months ago in a previous night's going to news I talked about the fact that they had found the largest neutron star ever at something like two point zero four times the mass of the Sun and the theorized limit from LIGO the gravitational wave detector was two point one seven times the mass of the Sun so within error it was actually a pretty good fit to that best estimate at best model that LIGO came up with now this black hole they found is 3.3 times the mass of the Sun which means it's still in agreement with that best model that we currently have a LIGO of saying that threshold is about sort of two point one seven times the mass of the Sun this black hole though is only twelve miles across the event horizon of the black hole is only twelve miles across having three point three times the mass the Sun it which is kind of incredible nothing to panic about because it's ten thousand light years or so away at the edge of the Milky Way and the reason they've been able to find it is because it's been in a binary system with a white dwarf star one of these stars that has been left over from a supernova and it's held up by the pressure between electrons and the thing is with that white dwarf because it's orbiting a black hole and the black hole is orbiting it it obviously has a very weird pattern of movement on the sky it sort of wobbles a lot and so by studying that white dwarfs wobble they've been able to infer the presence of a black hole by sort of you know using just orbital mechanics math to determine how big the thing it's orbiting is and of course they couldn't see another star there so when the math popped out this huge mass and they can't see anything it's clearly very obvious that the thing it's orbiting is a black hole so this result is really exciting not just to be able to find a black hole in that way but also to keep thinking about this threshold at which stars can collapse down and become a neutron star or become a black hole instead because it could be that all supermassive black holes in the universe there are millions to billions of times the mass of the Sun all started from this initial collapse of a star down to three ish times the mass of the Sun black hole and have grown from there so to understand the biggest things we also need to understand the smallest things speaking of the end of a star's life so the first stage of the end of a star's life is it running out of hydrogen to burn in the region that it's hot enough in its core when that happens the star contracts ever so slightly because the energies all of a sudden run out and gravity starts to take hold but when that happens it then becomes hot enough in a very small shell around the outside of the core just kickstart hydrogen burning again into helium when that starts there's a sort of big kick out of energy and it causes the outer layers of the star to expand to absorb the huge amounts of energy and heat given off by the burning of hydrogen and helium in that shell around the core and these layers when I say they expand outwards they expand outwards so this process is probably going to happen to our Sun in about four-and-a-half billion years or so so now it's panic and it could engulf all the way past Earth and all the way to the orbit of Mars so the size of the star really does just go up by over an order of magnitude and the question is when that happens to a star what happens to those planets around it that are engulfed in those outer layers of the star which essentially is like a plasma you know which is kind of gasp where all the electrons are free to roam around so it's like a charged gas it behaves in slightly different ways to a gas but it's essentially what you can think of it as is an incredibly energetic hot not exactly very dense gas that these planets are going to be completely engulfed in so what will happen to you know the structure of the planet will it maintain its like what like structure or will it be completely broken down like melted like what will actually happen because the temperatures in these red giant star envelopes as we call them are in the thousands of Kelvin so this question was highlighted again this month when a paper was published by Ken Ponte and collaborators using data from test the transiting exoplanets satellite test has to be very very good at detecting small changes in brightness of stars because that's how it detects planets it detects when a planet passes in front of a star and causes the dip in the star's brightness as it blocks out some of the light so it is very very precise and detecting those changes in brightness that means that what it can also do is something called Astro seismology which is essentially looking at the pulsations over stars brightness as it goes through these different phases of hydrogen and helium burning as gravity makes it contract and then pulse back outwards as it gets an extra kick from fusion starting in some little shell around the inner core so by using tests can Ponte and collaborators manage to study a red giant star that had already been discovered but the very specific pulsations of it allowing them to pinpoint at what stage in its lifetime was it a red giant star and therefore how massive should it be so this star was called HD two zero three nine four nine and so they managed to measure a mass of it of 1.2 3 plus or minus like 0.15 solar masses so 1.2 3 times the mass of the Sun the thing is when this red giant star was first discovered and it sort of announced in a discovery paper to say we found another red giant star the mass that they quoted then a couple of years ago was 2 times the mass of the Sun plus or minus 0.1 ish masses of the Sun so that's a drop in about 30% of the star's mass which could suggest that maybe it sheds some of its outer layers somewhat in those intervening years and may be reduced in mass that would mean it would have reduced in size as well the interesting thing they found in this paper though with Tess is that this red giant star also has an exoplanet that if you believe the hypothesis that this star has sort of shrunk since it was first characterized that exoplanet should have been in these outer envelope of the red giant star when it first swelled up so it should have been engulfed this planet and now it no longer is and has clearly survived that engulfment and so the question is how in the universe did that planet survive being engulfed in thousands of kelvins worth of energetic plasma now of course there could be nothing left on the surface of the planet if it had any liquid on its water it's probably been completely boiled off but obviously the rock or the core of the planet has survived what if it was something like a gas giant like Jupiter or Saturn or something and it's been completely stripped of that outer gas layer but you've been left behind with the core and now that's what we're detecting essentially we don't know we can speculate all day about what's happened to this planet and so the authors of this paper have said more study on this system this red giant star and this planet is going to be needed in order to understand whether it was engulfed or whether perhaps our model of the star is not quite right about what's going on and what happened in its lifetime and we need to figure that out so future work needed so yes we found the smallest black hole and yes we don't understand this strange acts upon it but there is a crisis in cosmology and this was the subtitle of a paper that came out this month by D Valentino melchiorri and silk they essentially said Planck evidence for a closed universe and a possible crisis for cosmology okay so maybe they clarified with possible because they were hedging their bets in a you know proper scientific publication but after reading it and after me explaining what's going on here you probably agree that this is a crisis so we've talked a lot on this channel before about how there is a massive debate currently raging on the age of the universe and I will link that video in a card above so you can go back and watch it if you like but come back here afterwards essentially to summarize there are a couple of different ways that we can measure the age of the universe one of the ways is sort of the original way that Hubble did it back in the 1920s is we can use what's called a standard candle something that's the same brightness wherever it is in the universe no matter the distance so that if you measure its apparent brightness to you you can work out the distance to that object once you know the distance to an object if you have the speed that it's moving away from you from its redshift how much it's light is red and by as it comes to us from the expansion of the universe you can rewind time and essentially end up with an age from distance and speed you know speed equals distance over time the other big way that we do this is by looking at the radiation echo from the Big Bang something we call the Cosmic Microwave Background and that's been measured by satellites such as Kobe W map and most recently Planck and the way we get an age out the Cosmic Microwave Background is to say okay if that's what the Big Bang gave us then given our best model of the universe of its structure and its expansion and its contents then what age of the universe does that model spit back out at us and the thing is the ages of those two different methods have not agreed for quite a while so the supernovae and more local measurements done in different ways give you sort of 14 and a half a billion years whereas the echo from the Big Bang gives you more something like 13.7 billion years and for awhile the errors on those measurements did overlap so we were saying okay so it's probably somewhere in the middle that's why everyone sort of kind of quotes like 14 billion years for the age of the universe and given that error they'll all sort of come out in the wash and everything will be fine the thing is we've got better and better at measuring the ages our telescopes have got better our software our instruments I said sure it has all got more precise and so the errors on those measurements have build drill down and drill down until all of a sudden the errors don't overlap anymore and now there is actual contention between the ages being measured locally yes you know with galaxies quite close to us and universally with the Cosmic Microwave Background which is permeating every direction of the sky that we look in and is an echo from the Big Bang and as men lots of different ways that have been suggested that could reconcile this problem one of which was that maybe the expansion universe is different locally to at great distances but there's not a lot of evidence so instead this month these three cosmologists have reanalyzed this cosmic microwave background data and allow different parameters in their model to vary so one of the things that was always kept said in the models was the geometry of the universe this is whether it's flat open or closed now this has nothing to do with the end of the universe being sort of like you know expansion forever open closed is in a Big Crunch or flat as in we'll just sort of regional equilibrium and sort of stopped expanding this is to do with the actual geometry of space is space flat is spaced curves and again I'm not talking about curvature of space because of like mass like in Einstein's theory of general relativity this is like the physical shape from space in the universe so when I say that it's flat what that means is that if I set two parallel lines going or like two parallel beams of light they will never ever converge meet because the space they're traveling on is flat if something is closed then that means that the two parallel lines will eventually meet which sounds strange but that happens on the surface of a sphere so at the equator on earth longitude lines are parallel to each other but they all meet at the poles so that is an example of a closed space it doesn't necessarily mean that the universe is hysterical as such but that was what a closed space would mean the opposite of that is an open space which is where like two parallel lines you would completely diverge and would never ever meet so the sort of shape that people quote a lot of times it's like a Pringle shape for an open universe like a saddle maybe I guess as well but maybe I'm just got food on the brain today and so allowing that parameter to vary from the universe having to be flat and two parallel lines never actually converging or diverging there is evidence that the universe should actually be closed ie there are two parallel lines will eventually meet like on the surface of a sphere and it's like okay fine we could probably accept that our universe has this intrinsic shape to it but what does allowing that parameter to vary due to all of the other parameters in your model of the universe and first as I was reading this I sort of got hopeful that it might fix all of this contention with the age problem but alas it made it worse so they show a plot for all the parameters they derive and one thing it did fix was the fact that if you look at on large scales in the Cosmic Microwave Background and try and derive these properties and you look at very small scales and derive these properties you get very different answers she was again a weird thing that they were finding but if you allow the universe to be closed then those problems go away which is great right the problem is that when that problem goes away the values that you then derive for for example the age of the universe are even worse than before so they found an age of the universe that's about 18 billion years old which is even more in tension with the results of supernovae the other thing that they find is that the fraction of matter in the universe which is you know this thing that we always quote weathers like 75% dark energy 25% matter of which you know 80 odd percent of that is dark matter they find that the fraction of matter in the universe is closer to 50% than it is to 25% they don't know whether they are precise or not or accurate or not any more because of the discrepancy with so many other local measurements of the age of the universe and other properties of the universe so it really is a crisis there's two possible explanations for this crisis the first is that there is new physics here that we have never thought of that needs to be explained and hypothesized and obviously people would like it to be that because then there's more to do and there's more to find out and I'm pretty sure there's people up and down the country even around the world right now writing proposals for a new job or a new fellowship that's like we need to solve this problem and come up with all this new physics the second option though is that there is something wrong with the data or with the analysis of the data for the Cosmic Microwave Background it's something we call a systemic something that's there in the system that's affecting our results with this data and there are people that have been searching for these systematics in this data for a while now they've just not been able to find one because obviously the pipeline to the station is just so much to do with it and there's so many places there could be an issue either from the actual observations or from taking the data from ours in the data or compiling the data whatever it might be and so obviously Noah wants it to be that because then everything we've done with it for the past decade or so will have something wrong with it that's obviously the less glamorous side of the science but if there is something in there then we need to know because anything that's done now in the future with this data will have some doubt cast on it because people will be wondering whether is that just because of a systematic or something wrong with the data so I have to say I'm quite glad I'm not a cosmologists I'm not someone who studies the the Big Bang and the evolution of the universe as a whole I'm someone who actually focuses on a specific thing in the universe I focus on supermassive black holes inside galaxies and the effect they're having now of course my work is affected a little bit by cosmology because everything sort of feeds into each other saysay though this problem needs sorting out and if it does get sorted out then you can bet that I will be reporting on it right here for you okay that's the end of this month night sky news I hope you enjoyed it despite me negative that we ended on there I have a very exciting video coming for you next week which I am really looking forward to posting I always get asked you're a scientist you're an astrophysicist what do you actually do all day so I'm gonna leave it at that and I will see you in that video next week I'm filming on a Monday rather than a Sunday as well so anything Becky won't be happy because she does not have as much time to edit this as normal oops who wrote this paper Tiago come Monday Monday accompany please don't um and so using tests come Ponte and collaborators managed to study the asteroseismology Oh doubt hit Richard is now following me hello I keep catching myself technique where's my songs it's not quite as Europe

Channel: Dr. Becky

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Keywords: astronomy, dr becky, night sky news, astrophysics, physics, space, science, jupiter, venus, mars, mercury, spica, moon, geminids, meteor shower, geminids2019, black holes, neutron stars, supernova, red giants, stars, exoplanets, planets, star death, cosmology, age of the universe, crisis, dark energy, dark matter, shape of the universe, cosmic microwave background, planck

Id: cnn_5YMpo3Q

Length: 25min 28sec (1528 seconds)

Published: Wed Nov 20 2019