us is involved with roots recent discoveries that may lead to an explanation dr munoz is a post doctoral fellow in physics at harvard university where he's collaborating with leading scientist rather unique investigation that has attracted a good deal of attention how dark matter might interact with ordinary matter along with that discussion he'll talk about some of his other cosmological interests including gravitational waves we're delighted to welcome dr julian one euros welcome thank you for having me and if you will start us out just with some background about people sort of looking at the motions of stars galaxies and they realized that the stars moved faster than they should just given the regular matter that we have around us and this indicated that there's all the matter there is pulling gravitationally the stars so there's no question there's something else out there that's right and this is true in the scale for galaxy but it's also true a much larger scale so for example we look at the cosmic microwave background which is the light that was made in the st instance of the universe when the universe st became spare and we can see the gravitational potential due to the regular matter but also due to the dark matter so we can infer that it's actually about five times more dark matter than regular matter so not only  mysterious dark it's also money in some way makes it easier to detect that's where we're fairly sure that there's dark matter ok but it makes it that much more that we kind of know what it right so it's been frustrating for quite a while so there's no question that there is such a holes so you don't have to have new particles you just have to have a way to back a regular particles in a non emitting way yes just real quickly and i thought that the dark matter had been detected around like galaxies and so forth and that is by observing show this this is the bullet cluster so it's a cluster of galaxies ok so this you know every one of those little circles is a galaxy roughly like our own and the red and blue are maps of one of the  guess right right so you see dark matter is in a different place than so not only you know we have that matter and only we know that we have five times more than regular matter yeah we also know that it's an independent thing you cannot just of experimental effort to reproduce the direct attention constraints that we have for very heavy wind mines underground you might have heard they have like this seen on experiment dark side they will have some noble gases so you have some you have some noble gases candidate that you would expect now we are looking for things that might be a little less obvious a little less canonical your mind there is a way to find it right you expect one of these days they're going to come up with the right something we were really very sure here you know but in terms of the things that would actually catch it for you and again to fire it for you that is still out of reach that's the thing that's really out of  net now ok so what would you need to find out at this point is that i think there's there are possibilities that you could you know that are already happening within maybe a decade you'll have a very clear picture whether it is some of them the axiom searches for business are moving very fast ok things like i said low mass wimps there are some other candidates where  what presumably could happen that would lead to promote coals is that some parts of the universe are very dense so you can think that you know there's there's different parts of the universe and we know that cities are not connected to each other they don't talk to each other so some of these patches are very dense yes and then just from their own gravity the collapse into a black hole ok all right so let's go ok let's go sort of the way in the left ok big bang ok where we don't really know what happened what we know is the size of the universe this hard and then it's maybe part of the universe collapsed into a black holes maybe not but we know that at some point the universe expanded yes he became cold enough that protons and electrons were able to combine the for don't talk about wave thing with our frequencies that are comparable to the f m ok c so here in the bottom axis you see they have frequencies in megahertz yes for each of these frequencies corresponds to a particular instant in the  this right one of the few ways to reconcile it with astrophysics and east to have dark matter is still energy from the regular matter yeah so the lying can go lower ok all right would there be other alternatives because the edges things still i'm sure has to be disputed people have to it takes time to determine these things once you get a good theory out there so here's a here's a hypothesis for milky way ok they made synchrotron radiation when they travel in by kinetic fields yeah and that is an overwhelming signal and the way they go about this problem is they marginalize or foreground some people might have concerns about how do you do that exactly six people yeah right that is amazing that is amazing but yet seems like well like discovering the final confirming that this after a long while or gravitational waves after a long while this might be right in there that sort of thing because this is a big issue the dark matter getting so we we realized is that we st heard of the signal before getting you maybe it's something weird but in some ways natural that he would interact through one of the forces that we know yeah so we know that interacts the gravity yeah that is how we look at it we are fairly certain that he cannot interact with a strong force because that is a very force the electromagnetic force yeah which we understand really well and in that case we can say is it dark matter doesn't have you need charge like the electron does have the same charge as the electron is much less charged yes in fluctuations of about one part in a one thousand and one dollars part in a one million yeah but still tiny fluctuations in the sky right and that is the frontier that is what we want to get yes those fluctuations would not only tell us what is the average of the signal but was a small it just so he gave me some problem and i worked on it for a while and i realized i really this is right this is it i was hooked yeah it's easy to understand really is it is it is there's a lot of technical parts to it but at the end we shoulder studying the universe yeah it's by definition in writing and you have other things that you are interested in you were interested in gravitational waves and the of the sun ok and that is what our models were also predicted ok people run models for what the black holes do and that is the number and thirty is a very large number ok we none of the models at the time  excitement another reason for being in this work at this time when so many things are happening what do you predict in terms of like the next twenty years in developments so i think my for the and perhaps where the properties are and this should lead to us understanding where they come from but also what can we learn about the universe and about dark matter from them so you think that is there is a possible connection something we that about one in a one hundred different piece should be echoed so we only have thirty or forty of them for now so we cannot say anything but within a year or two of operation of china yeah which is being built or hierarchs we will be able to definitively calls can be dark matter this is really neat isn't it i think you have a lot to do if you're right i think it'll keep you busy but i really appreciate very much you giving us this fabulous information and i wish you the very best in your career and you have to come back another time talks about these things thank you again very much