What Is Dark Energy? | Full Debate | Erik Verlinde, Sabine Hossenfelder, Catherine Heymans

our our notions of dark matter and mistaken and and do they have to be radically reformed we still don't know what dark matter is dark energy is I pointed out it's a very different thing it has a name dark in the name it is true but it's a very different thing has a very different effect it pushes the universe apart while dark matter seems such much more structure and during your lera t and seems to associate yourself with matter in some ways catherine you measured the existence of dark matter one might assume that she believes it exists she does that with very new and advanced ground-based telescopes that allow her to map very large areas of the sky and what you get out of this filaments structure of dark matter that you might have seen somewhere then we have next to her as a being a awesome Vader who is from the frankfurt institute of advanced studies she the theoretical physicists it's also interested in dark matter and alternative explanations for the phenomena that we see when we think they are made by dark matter and Eric Valentin is the theoretical physicists and he has recently built a theory that does away with dark matter which is a tricky business because the theory of gravity has worked very well so far so modifying it has to be done with great care I start with Eric and then go this way all right so I mean I'm not sure whether you're all familiar of course what dark energy and dark matter are really about to mean dark energy is related to observations of the fact that the universe is expanding even accelerated and we need in some substance that spread over the universe that explains this and it actually was already part of Einstein's theory along about a century ago that he could add this possibility of adding a constant that made the universe expand dark matter is a totally different phenomenon it has to do what happens in galaxies and the fact there is more gravity there that keeps galaxies together but also the formation of galaxies in the universe needs dark matter but that's an hypothesis and it's true that most theoretical physicists and even cosmologists and as offices think there is a dis particle out there that explains this additional gravity because then you can do it with the existing theory why would you change the theory at work so well as Einstein's theory if well you can add this additional component and explain these phenomena for me the reason to doubt this is that there's a theoretical reason why maybe Einstein's theory doesn't work the way it does and this has to do with our insights that we have been gaining about gravity over the last century after Einstein we learned about quantum mechanics we've learned more about how the cosmos works I mean at the time of Einstein people didn't understand even the size of the cosmos was in fact there were galaxies so we were dealing with an old theory and there are reasons to believe that it needed has to be changed that comes from thinking about black holes and even insights that come from string theory which is a field I've been working on tells you that simply representing dark energy with this constant of einstein's theory and thinking about dark matter as a particle is well may not be the right way actually our reasons to believe that we should modify gravity when we are dealing with the very large distances I mean like Einstein's gravity works very well when gravity is very strong but in galaxies when we are going further out the gravity becomes very weak and this is where the theory may be different and what I'd like to explain in my way of thinking about it is the connection between these two objects that do phenomena the dark energy and the dark matter so dark energy is something that I believe is really there in the sense that there is a energy in our universe that is required to explain its behavior but the dark matter is not really a particle it should be of an effect of the dark the interactions between ordinary matter and the dark energy so I have sort of a mixed point of view on dark energy in dark matter that I think dark energy is really there but the dark matter should not be a particle but it's some way that gravity indeed works differently in our galaxy in our unit when we look at the interactions between matter and and the dark energy thank you very much maybe we go to Catherine you measured the existence of dark matter so do you think it is not there it's not there it's tricky tricky I know I measured something and we've called it dark matter but III don't know what it is I mean let me tell you what Who I am I'm a professor of cosmology at the University of Edinburgh and that means it's it's my job to try and understand the universe that's what a cosmologists does now if we had a bunch of professors of cosmology in this room we could broadly split them up into two camps now we'll call our first camp of cosmologists we'll call them the the smug cosmologists and they are rightly so now these are the cosmologists who have looked back to the universe as it was right after the Big Bang and they have made exquisite observations and use that data to tell us exactly what makes up our universe today less than 5% of the universe is made up of the stuff that we are made up of the stuff the earth and the moon and the Sun and everything you can see that accounts for less than 5% of our universe then we have 25% made up of dark matter the strong gravitational force in our universe that binds everything together and the rest the other 70% something that we've called dark energy that appears to be causing the expansion of our universe to get faster and faster each and every day now this is a beautiful theory it's a beautiful model of our universe and it explains the observations that our smug cosmologists have made incredibly well there is no better theory that we have to explain these observations and so it's an amazing testament to how far science has come in terms of technology instrumentation data analysis statistics and theory that we've come to this point of this beautiful match between observations and theory so those are our smart cosmologists and we happen on the back because they've done an amazing job now we have our other group of cosmologists that we will call the embarrassed cosmologists and I fit certainly into this camp and the reason why we're embarrassed is because if you try to explain this model to anyone who's not a professor of cosmology they look at you nagar watts hey hang on hang on hang on less than 5% of the universe is made up of the stuff we are made up of and hang on you've invented two things that you've called doc and one of them you've called dark matter because it acts kind of like extra matter but you don't know what it is you've never seen it you've never touched it you just think it's there you've invented it and hang on a minute you're sourcing energy out of nowhere to make an infinite universe expand even faster this just doesn't make sense and it is quite embarrassing to to share share that theory with someone so on the one hand you know as cosmologists we're feeling very pleased because we do have this beautiful model of the universe now but the flipside of that is it relies on these two dark entities that to be very honest with you we don't understand and so to be frank we don't understand 95% of the universe and you might be thinking at this point Wow you scientists totally failed that is an epic fail you don't understand 95% of the universe but I think everyone on this panel will agree that you should be looking at that in another way because you should be seeing that as an amazing opportunity when you don't understand something is gargantuan there's 95% of them universe it means you're missing a key piece of the puzzle maybe the framework that we're working in isn't quite right and so yes you're right I have mapped out the dark matter in our universe I we have some beautiful maps charting out where all of this invisible stuff would be in a framework where Einstein's theory of gravity is right and we and it matches what our theory predicts and another great example of observations matching the theory but we still haven't found that thought of matter particle and until that day comes I I remain the the observer in here and it's my job to test the theories that people like Eric ins been come up with and try and disprove them so mean dark matter dark energy he believes dark energy exists certainly okay so I'm a theoretical physicist and my task is to come up with explanations for what the astrophysicist find preferably some simple explanations because if you have a lot of parameters you can fit pretty much everything so first I would like to object on this idea that it that it is embarrassing that we can't explain 95% of the universe because this 95% is a totally meaningless number the point is that these 95% are really really simple at least on cosmological scales we can describe them with one parameter for each there's the cosmological constant and there's the average density of this dark matter stuff and that's pretty much it so I would agree that this is a nice and simple theory the problem is that if you look at galaxies and Eric already said that our best observations about dark matter and so on come apparently from the galaxies then it's not quite as simple you actually have to do some work to get these galaxies to work out properly the thing is that you can do it with dark matter because this is stuff that is distributed somewhere in the universe and you can put it in the right amounts wherever you need it so if I give you any galaxy and you have to explain what you see there you just put the dark matter where it has to be in the right amount and then you call this an explanation so now from the perspective of theoretical physicists that's a little bit unappealing in particular because if you look at the structures of galaxies they have a lot of regularities that are really really hard to explain with this hypothesis of dark matter one of which is for example that the amount of dark matter in a galaxy and not only the amount but also the distribution seems to very closely track the amount of vis matter and you can make that work with particle dark matter you can't calculate it on a paper but you have to do fairly complicated computer simulations and after they've been twiddling with these simulations for 20 years and added a lot of parameters they've managed to produce some galaxies that look like what we actually observe now on the other hand there are various theories that modify gravity from which Eric Eric theory is one and they manage to get these regularities out basically in a two line calculation and I find it very hard to believe that there is not something to it so now I want to answer specifically the question that you had here are our notions of dark matter and dark energy radically mistaken so I've taken offense with a question of course it's not our notions that our mistake it's everyone else no it's actually a mixture of dark matter and modified gravity in the sense that it is some kind of particle that sometimes behaves in a way that looks like it modifies gravity so it is a particle which gives me as a particle physicists hope that maybe I can still build detectors that find it but let us let us go back to Eric you have basically removed the need for for dark matter and and another said that in her view of dark matter there's not a simple element it has and distributed however you want to make the theory fit you have many parameters after all so is it so them that we don't need any dark matter and extend this question what about the other mysterious darkness and there the dark energy can we get rid of either get rid of that or incorporate it into a knife theory where emerges in a sensible way so as I mentioned already in my first opening remarks is that I think there's a fundamental difference between adding dark energy or dark matter dark matter is assumed to be poor very much like the particles we are made of dark energies as other mysterious stuff that we don't know what it is I believe that we have to first of all explain all of these things and not just one without the other and and I for me the dark energy is something that I think means that we have a some mysterious component of energy in our universe so that our universe is not really in its lowest energy state we have sort of added from there and we have to explain this and so I see our current theories are clearly not enough to describe what dark energy is that but I think when we understand that we can also explain those phenomena that we now attribute to dark matter and then we don't need it but that doesn't mean that I have already deceived completely ready there I mean we I made some calculations that could explain what happens in galaxies those regularities that Sabina talked about those regularities come out of this idea but there's another role for dark matter which has to do with this early universe explaining what happens in well the observations of what was called the Cosmic Microwave Background or the way that structure forms and so these cosmologists that are using dark matter to explain all these phenomena very precisely they indeed use very specific ratios of these things to explain this I have to do still the same thing I mean this is some work for me to be done but then I have to do it without adding this dark matter and so this is a challenge still I mean the theories are not complete yet but this is where I think indeed the fact that we have this mystery out there is for a theorist an ideal opportunity to solve these problems and it doesn't always mean that those solutions already the first one that people thought about like adding dark matter maybe a different way and for me it's indeed trying to understand gravity better and then explaining all those phenomena but dark energy for me would be an element actually that should be added and maybe I should mention this I mean I have many colleagues in string theory that are working on a universe that does not contain dark energy or even if the opposite sign of what we call the dark energy enemy a negative cost motive constant that's a mathematical universe that doesn't look like ours but they can understand gravity very well there so I have to take those people and motivate them to also work on this universe that does have dark energy in it in the positive contribution and I think that is a very important component of our universe we have to take that seriously so will we be able to make a mathematical universe that matches the real one but means that it has a positive dark energy and an expanding universe with you or a model where you take dark energy it's there that's how I understand it and you have essentially gravity itself emerge from something I don't understand but we just didn't talk to us first maybe I go back to Kathryn he can explain how galaxies move in his model it seems can he explain how you're when you're measuring dark matter by measuring how slight deviations of light going all the way through an even universe how light slightly deflected by the mass by the gravitational pull of dark matter which is not quite the same as of thinking of of galaxies moving around each other's or stars moving in galaxies which is the most famous evidence I'm talking about yeah does it work so Eric and I actually have published a paper together we were one of the it was one of the first papers that tested your theory and let's take a little step back so what we how do we actually see this invisible dark matter so I said I've mapped out this dark matter you're probably thinking well if it's invisible how the hell is she mapped it well what we do is we look at very distant galaxies light travels through the universe for about seven billion years and as that light travels through the universe it doesn't travel in a straight line its path gets twisted and pulled by the gravitational pull of all of these invisible dark structures around it and so what we do is we spend a lot of time on remote mountaintops far away from all of the light pollution in cities and we take very very deep images of the universe collecting all this light from these distant galaxies and then we interrogate that light to tell us about its journey it's seven billion year journey from that galaxy to our telescope what we can do is we can work out how its lights been bent and distorted by all of this invisible stuff that's out there now I said that you said you know does Dark Matter exists I know that something's there I know that there's something that's curving space and time that's distorting these images of the very distant universe that I map out but I don't know what it is but I know it's there and what we did when we when we tested Eric's model was we said okay what would it predict for the gravitational pull around galaxies and when we started working on it I was like this is never gonna work this is gonna be great we're gonna disprove this theory in a week unfortunately not Margo who is leading this analysis she's a fantastic PhD student in Leiden at the time came up with these results and she compared our best model of what dark matter should be with with Eric's theory and found that it fitted our data equally well so both theories fitted our observations equally well and but what was important this is what Sabine was saying was that this new theory requires we say no free parameter so a parameter is it is something in your theory that you can use to tweak tweak and turn the knobs to boost the theory or lower it and there's no free parameter in this theory and that was very motivating and supportive of this theory but I think you know Eric does and team and collaborators and indeed you've written a paper extending this analysis this theory as well and I think that's where we need to be going because yeah I would love the particle physics experiments to actually catch a Dark Matter particle or I'd love someone in CERN to create a Dark Matter particle because then that piece of the puzzle would be done and you know maybe that's just around the corner stones going up going through an upgrade it's going to be colliding particles together much faster with much higher energies than it's ever done before maybe they'll be enough to create a Dark Matter particle the simplest theory that we think is out there and we've got that bit solved but until that happens I think we've got to investigate new theories something you investigate yourself new theories going taking some of Eric's ideas I understand and your own and as we mentioned earlier in Europe your favorite model they're still a particle in there yes at least you could interpret it this way so I have not written a paper with Eric but I read a paper or I tried to read it and while I was reading the paper I was reminded of a passage from Stephen Weinberg spoke dreams of a final theory where he describes that there are two types of theoretical physicists there are the CEOs and the Mystics and the CEOs are the ones who make an argument straightforwardly go from A to B to C and everything one follows after the other and you can very easily follow their argumentation and the Mystics they assemble a cloud of facts which they lay out and then a miracle happens and out comes the result and I think that Eric's is definitely of the second kind and I had a hard time making sense of the paper so I said I would try to put this into a more digestible form and I found interestingly two things one is that he says he needs to start with dark energy and then dark matter is a consequence from this so I find that if you try to write it down in a rigorous mathematical way you actually get both together so you do not you do not need to start with assuming that dark energy is there but they're both parts of the same story Eric did you not write it down in the rigorous mathematical way and you need to fix there is a starting point I mean I mentioned this that if you want to really make things mathematically rigorous we we haven't found the model yet for our actual universe at positive dark energy the people that are working my fieldwork have to work in this fictitious universe with a negative cosmological to be mathematically rigorous but mathematical rigor or very medical medical precise things can sometimes be Ethan tube constraining so I laid out a number of ideas and assumptions and from there on I started reasoning I think mathematically precise in the sense that the steps are mathematically precise but I have to make also some hypotheses in there which I'm motivated from a certain intuition so physics cannot be started from no assumptions at all and then just reasoning you have to make some hypotheses and then continue and then that's that's what I wrote down is mathematically precise but it's based on certain assumptions now one could be forgiven for thinking okay twenty years ago we could have had a very similar debate quite the same we didn't have Eric's theory for example twenty years ago but nonetheless there was evidence for dark matter cosmological evidence evidence based on the fact on that how light bends in under greater influence and also already somewhat we didn't really touch on that very much on dark matter evidence and cosmic microwave background and early structure of formation of the universe which also touches on to the dark energy side a little bit so why haven't we moved on libido yes I'm happy to say something about it but I feel like I should add something here because I think that some of you might be missing a piece of the story because up to now you might have gotten away with the impression that Eric's model actually explains it all so why are we even discussing this the point is of course that it does not there are some observations that at least it presently cannot explain for example the structure that we see in a cosmic microwave background this is just something where for which particle dark matter works very very well but that at least presently cannot be explained with modified gravity and there are also some problems with other observations so this is why there is still a debate in the community right so just one is ought to be on the same table now the issue about why we haven't made progress one of the reasons why this hypothesis of proteger Dark Matter became so widely adapted was that thirty years ago or so theoretical physicists had a lot of other reasons to believe in the existence of additional particles that conveniently enough also could make up dark matter for example there there is an extension of our current theories that is called supersymmetry in which you get a lot of additional particles some of which just have the right properties to make up dark matter and this certainly land a lot of credibility to this hypothesis now people have looked for these particles since the mid 80s with increasingly higher precision you know a bill are larger detectors and better apparatuses and they haven't found any and now the most recent round of experiment just concluded and I think there's now you know some sense in the community where people are asking yourself how far do we really want to push this like do we want to continue building larger and larger detectors forever trying to hope to find this particle which may not even be there now the particle physicists we would probably not say we have concluded quite yet I mean the next generation of Dark Matter experiments should increase sensitivity by a factor of 100 so there's my toe quite a distance to go but Katherine has a fellow experimentalists yes do you think we have made no progress I saw why it's always an interesting interplay in science between theory experimentation and instrumentation and it's what drives what so normally the way it works is kind of a looper a theorist will come up with a really awesome theory and an observer on experimentalists will design an experiment to go out and test that theory and that may take require innovation new technology that will eventually feedback into a wider wider realm but they'll they'll test the theory and they'll find something new which will stimulate another theory which will stimulate another experiment more instrumentation and and so on and so forth and I think you know you say we haven't moved on but actually this is a really short amount of time if you want that loop to work so what we're very excited about at the moment is next year we are going to be opening a brand new telescope in Chile again on top of a beautiful mountain top high above the clouds and very very dry region it's called the large survey synoptic telescope and we're going to be imaging the entire night sky every three nights we're gonna be building it for 10 years so absolutely massive telescopes one of the largest telescopes that's going to be working on the ground and we're going to be building up the deepest image of the universe yet which allows us to confront a whole range of different theories and in doing so it will stimulate theorists to come up with even more theories I mean it was only very recently that it was when I was at universities in 1998 was when the first evidence came about for dark energy now that's very recently and it's only now well next year that will have the instrumentation and ready to really robustly test and these different theories being a yachtie in your blog and your publications hint that you think maybe the way we do science scientific or academic process might be holding us back in finding new and unconventional theories can you comment on that yes I will just latch on to something that you just said that if you get new results quite possibly null results then this will stimulate theories to come up with new theories which is undoubtedly true because the theories that they now have they can always be adapted to accommodate a null result and actually we have a huge amount of theories for particle Dark Matter already that can eternally be adapted and that's very convenient if you are a theorist because these are basically theories that cannot be ruled out now you were talking about this virtuous cycle in which experiment go out and they find some evidence and that guides the development of new theories but the problem is that null results are very bad guides you know they tell you very very little about the new theory that you hope to develop and that risks that we end up in a vicious cycle in which the null results do not lead to better theory so we get stuck with the theories that were not good to begin with we stimulate further of the more experiments will lead further null results and so on and so on and personally I think we've been stuck in a cycle for some while already and one of the reason is that theorists i think a lot are actually quite comfortable with theories that cannot be ruled out and now the great thing i want to emphasize this again is that eric's model at least in the way that's in the paper doesn't have any free parameters so it is a principle very easy to rule out and that's quite a daring thing to do yes please yes beautiful difference between astronomy and particle physics though when you design the experiment for particle physics it's to answer one question how much money do we spend on certain fabulous CERN is fabulous I love it it discovered the Higgs boson fantastic haven't found anything else yet they so this wonderful telescope that I'm talking about not only are we going to be able to test theories about dark matter and dark energy we're also going to be mapping out all of the killer asteroids that might one day obliterate look after you reassuring I would argue that we found things that sound actually interesting ones but not yet a new particle new composite particles but they're not new fundamental ones yet and certainly nothing that really contradicts the standard model and allows us to distinguish a standard model from possible new physics models with new particles in them some of them could or could not be dark matter does your model allow us to make such a test can I go somewhere I about Katherine or to CERN and say your model contains an element allows me distinguish it from the standard mainstream theory that dark matter has a particle well there's certainly the idea is that when he developed a theory and you understand better that you don't have all the three parameters that allow you to explain every observation so eventually one other theory which has the particular predictions for well things that you can observe and I think those observations will not be here on earth they're mostly the kind of things that Katherine is doing where you look at how dark matter is distributed around the universe and how it is behaving at least effectively I mean this extra gravity that we see how that's behaving you want to make predictions for that and then you can test these these ideas and so I feel the reason why we didn't make a lot of progress is that those observations were not precise enough and we had these crude models that could be adjusted by so many parameters that they seem to be be consistent with everything having more precise observations and more situations where we see dark matter really directly what is doing then a theory becomes also about testable and you can exclude a theory if it's not a youie that has all these adjustable parameters you won't have a theory that has a logical framework without being just well too flexible yes but to to push it a little bit further what we really like as experimental is our theories that I make predictions so before the data from the NS STR there that's right then make predictions that then can be tested after the data arrive have you got any of those no I bet but I think that that this may be a very beautiful time where theory and experiment are working together I think in understanding nature it's not like the theorists have to be locked up in one room and the experimental is in the other one where the theories come out and now they say we have something and then the experimentalists say let's look at this and then test it no there can be exchanged and it doesn't mean that the theories are developed to explain exactly only the data but they can give hints of what direction to go into so I think the reason why we didn't make a lot of progress may also because we had not enough data to even guide us in the right direction the complicated the problems that we are having may be so complicated is by sitting in a room you may not just find the solutions you have to also be able to see what your look trying to explain this is a notion that warms and experimentalists heart very much because I also believe that data is of course the the crucial element to make progress so the last theme your let's look again at your theory of an example it's a very radically new theory in many ways I mean as I mentioned at touching gravity something many people have tried and usually burned their fingers because it is a very successful theory already will the development of such a radically new theory also give us insights beyond dark matter will be will change our view of the universe maybe also in a way that one day I can find new particles at CERN which would either I understand that that's one of your motivation but I think the the thing issue was already raged Dark Matters also needed to explain what's happening in the early universe we want to understand where all the structure comes from and if we start understanding gravity in a different way we may have a different explanation of those same phenomena and even have a different story to tell about how many of these things are rose I mean I'm not very happy with the current way and we have done this if we think about how we extrapolated the current theory I mean using Einstein's equations all the way back they've made many assumptions and I think that story may change but I think it's it's a general fact that certain theories eventually we were replaced by the next one where we can explain more phenomena and sometimes it's not even easy to predict which phenomena can be explained in advance I mean you have to first go through the steps of developing with the full theory and actually I'm not doing this by myself in that sense and maybe I would even put it well make clear that I'm not only bending a new theory or many theories thinking now about changing the way that we think about gravity in trying to define derive it think about it as an emergent force where we start from a different language microscopically what my colleagues are not seeing yet is the connection with the phenomena associated with dark matter but the fact that we have to think about gravity in a different way it's being done by many other theorists at the same time so I think it's just a matter of time before that theory is developed and hopefully not by myself only but by a group of theorists working on this problem science is a collaborative process that's why and not not one by a single hero's rule I'd very much like to hear that and it was collaborative amongst theorists most extra mentalists and clearly between theory and experiment I mean it what do we need to do to get a better theory of everything let's let's not help still care for small things everything the universe our universe my universe everybody's well I do think that dark matter is a good place to start with because in this case at least we know there is something there I mean we do have some observations which cannot be said about other problems that people have tried to solve in the foundations of physics where they worry that their equations are not beautiful enough you know like this search for unified force that unifies the interactions that we have and that may exist or it may not exist so I think that dark matter is a good place to start with but you were asking about what what else can we learn from it so there's an interesting thing about Eric's approach which is that it tries to make contact contact to a possibly underlying structure of space-time so the way that we currently deal with space-time in our theories is that its primary its fundamental it's just there but there are some approaches that try to give quantum properties also to space-time which are generally collected on the determine gravity of which a string theory is one example that posit that maybe there's something more to it and one manifestation of such an underlying theory could be something that looks like dark matter so indeed finding a dark matter finding out that it is maybe best described by a theory of modified gravity could also tell us something about this underlying structure of space-time which would really be very very exciting and for me it's also one of the motivations to work on that thank you yes really what do we need to do what do we need steam big telescopes big basically up in space yeah my ultimate dream if if some really rich person is out there I really really really like a liquid mirror telescope on the Dark Side of the Moon please I think that would be really awesome good like carve out one of those craters have on the dark side the room the bigger the telescope you get the more information more light you collect the further back in the universe that you can see and with more data more information we can really test all these theories and really find out the answers I always think of sort of our job as astronomers and looking back in the past if we wanted our civilizations wanted to explore the earth and I think what we need to do now is explore the universe and to do that really big telescope so the way you want to go big got a wonderful I have my part of it I want big detectors not I would be on the moon but down there underground it was disturbed by all these cosmic radiations all these things to see the dark matter particles that might or might not be there and anecdotally rich person the the next big thing of this kind of detector will be built in the Stanford underground Research Laboratory and Sanford would need a very rich man who made his money with credit cards so I don't know how many families he ruined in the presence of that but then but this love is actually partly funded by by somebody like my family I think my own lab and safety I think the earth of moving towards what's slowly toward the end of this the audience should start thinking about their questions while I'm making my microphone somewhere go where okay um and what we need to make progress is more data elaboration more theories more theories well maybe maybe I should add something there I mean many of my colleagues are indeed thinking about a universe that's not like our own and they are more motivated by the mathematical consistency or the beauty of their theory and I think we should also motivate em to get out of their room and contact and talk to these nomads for us to do with reality reality and then if a larger community works on this I think this is the way to make progress I think that's a very important element otherwise it will not happen indeed there has been a little bit and I think that's one of your concerns have been a motion towards theories that are little disconnected from reality which are very beautiful and very nice but mainly mathematical and not so much Rico well I agree with that point of view so something to agree on many things to agree on I mostly agreed broadly it's time to wrap up now so thank you very much to the audience and thanks to all our panel members for a very interesting debate and for answering all these questions thank you very much [Applause]

Channel: The Institute of Art and Ideas

Views: 103,956

Keywords: erik verlinde, dark energy, dark matter, the universe, physics, sabine hossenfelder, particle physics, quantum, quantum physics, CERN, what is the universe made of, debate, education, science, hawking radiation, dark gravity, black holes, string theory

Id: Zte2qrqLNfc

Length: 40min 38sec (2438 seconds)

Published: Fri Jan 25 2019