- [Jim Lattis] Good evening and welcome to UW Space Place.  Tonight is another one of our guest lecture series on the second Tuesdays of the month.  And tonight I'm very pleased to introduce Professor Alex Lazarian of the UW astronomy department.  Alex is a worldwide known expert on astrophysical magnetic fields, and has been honored, among other things, with a Humboldt Prize, from the Humboldt Foundation in Germany, and he's here to talk to us tonight about interesting aspects of interstellar and intergalactic, and I don't know what else, magnetic fields.  So join me in welcoming Professor Lazarian.  (applause)  - Thank you very much.   I will be talking about  magnetic fields in the universe.  And here we see magnetic fields  of the galaxy, and this is magnetic fields of a Bohr magnet.  I will start my lecture showing you an experiment which  clarifies the importance of magnetic fields.  For example, this is a magnet, this is a metallic tube. 

 So, look.  Listen.  Normal magnet.   Again.   Why is that? Because magnetic field of this magnet induces currents in this tube, and the interaction of these currents and magnet makes the motion of,  slows down the motion of the magnet.  I'll give this tube and you may play while I'm giving the lecture.  (audience laughing) Just return it to me later.  Yes, it's copper.   Right.   This is also a citation:  Those whose restless minds study the world's structure, search for the beginning of things should inquire into the origin of murmur magnet. 

 And this is the citation from an ancient Roman writer.   So, in the University we have particular installations which use magnetic fields to confine plasma.  And I would claim that this is the future of  energy industry, because  this is the  unlimited source of energy, and if we think about what humanity was always  limited by, it was energy.  And this development would be as remarkable and as important, and more important than the  use of fire by human beings.   But let's talk about history of magnets.   Okay.  Lodestone was the first natural magnet, and it is presumably produced naturally during lightning, when we have  more iron ores in the earth, and there is lightning.   Why it is called magnet?  It is from the place which  called Magnesia.  And there are two theories where this Magnesia was situated.  One is that it was situated in the  northern Turkey, and another is it was not probably far from Athens in Greece. 

 But there the first magnets were found and described by people.  What were the first practical use of magnets?  We have actually two uses.  One was by Chinese fortune tellers, and another is by Vikings.  What were Chinese fortune tellers doing? They were putting  a boat, or in a bucket of water, and would say this is your destiny.  And then they move this bucket of water, but the boat would still point in the same direction.  This would be very convincing way to persuade people that they have some magic powers, and for some limited sum of money,  you can know what's your future.  You can play with this and predict future this way, by taking  cork and having magnetized needle put into it and you will see the same effect.   What about the Vikings? Vikings were using them for seafaring.   They were actually a pest of Europe.   They would, for example, plunder Britain, and to get the quickest way to Britain they needed some navigation, and they were using  different navigation tools. 

 Magnet was one of them.  What do we know about strength of magnetic fields? We have really  a big variety of magnetic field strengths.  For example, Earth magnetic field,  you can say that it's ballpark value is one gauss.  It's in fact 0.5 gauss.  But the magnetic fields in between the stars, in the interstellar media, is a million times less.   Some spot on the magnetic field, on the contrary, is a thousand times more, but this is not the limit.  In the laboratory, you can in some explosion devices, reach magnetic fields which are  10 million times stronger than the Earth magnetic field.  But this is essentially nothing compared to the magnetic fields of magnetars, which can be 10 to 15 gauss.  And the scales, scales are really  of wide range.  They can be a million, or 10 million light years. 

 So such scale of magnetic fields.  And I mentioned to you already  the applications were fortune tellers in China in 200 BC, and  the navigation by Vikings.   The first description, detailed description, of magnet and its properties is in the manuscript by  a monk in 1269.  And the first theory of magnetism was suggested by Rene Descartes.   Descartes was a really remarkable man, and his Latin name is  related to this Cartesian system of reference, because it was he who really introduced it.   At the same time,  a particular discovery of his is not associated with his name.  I can now ask you what is the  measure of  atmospheric pressure.  And you answer to me, Pascal's.  Because it was, it is associated with Blaise Pascal.   However, it was Rene Descartes who devised this experiment. 

  The experiment was that you put mercury in a tube, go to the  mountain and see the change of the level of the mercury, and this is the pressure of the atmosphere.  It was devised by  Descartes, but he did not have a small thing, well actually, a big thing, a mountain.  He was living in Holland.   It's pretty flat.  He could not make such an experiment.   He could surely travel somewhere, but he thought why I not write to my friend Pascal,  and to describe he's living exactly near the mountain. He did it.  Well, Pascal performed all that Descartes was writing to him.  Then he wrote  his scientific paper, which had one small deficiency.  He forgot to mention whose idea it was.  (laughter) Well, in any case,  this is again the citation,  and this is the portrait of Descartes. 

 Well, Descartes actually was  chosen to be a tutor of  Swedish queen,  Christina, who comes to the throne at 19, was very active.  And actually, this is the tragedy of Descartes  because here they become lovers.   Well, you would say it's not a tragedy,  but, you know, Christina was 19 and he was a middle-aged man,  and Christina was very active.   She would dance  'till two with Descartes,  and in the morning at six o'clock she would wake him up to have  some, for example, horse riding,  and the guy got sick,  and he dies of pneumonia.  Christina becomes very  desperate.  She abdicated very soon.   She actually kept his head with her.  So only the body of Descartes was  buried, and head was kept  and preserved with Christina.   (audience laughing) Well, he still  surely was pretty naive.  The actual theory of magnetism was suggested by James Clark Maxwell. 

  And these are the creations of Maxwell.  Well, then it became some business.  You have them on the mugs.   And some students have them on  tattoos and T shirts, and this lady has it on the back, probably it will help her fellows on the exam.  (audience laughing) What we have in astrophysics, in astrophysics we have not only magnetic fields but also we have ionized gas, or plasma.  And plasma and magnetic fields  are inseparate in  the case of  astrophysical phenomena.  Plasma follows magnetic fields, and magnetic fields follow gas.  So they...   I mean plasma and magnetic fields behave  like this cord.  If you move plasma, magnetic field is moving. 

 With this device, we can explain many properties of  magnetic fields.  For example, we can explain how to increase the strength of magnetic fields.  Magnetic field strength, is, in this case, may be represented by the thickness of this cord.  But what I'm doing now, I'm doing an experiment which is called Zeldovich dynamo.  So I am  twist,  this band, then I fold, and I stretch.  What do I have? I have twice the magnetic field.  I can do this again and again,  and increase the strength of magnetic field.   This is the way plasma, moving  plasma can enhance magnetic field, and create magnetic fields.  Magnetic fields that we see in the universe are not primordial.  They are generated. 

 The sun is generating magnetic fields, and magnetic fields are related to plasma.   The plasma activity is really a magnetic activity related to, for example, this solar spot.  The solar spots are particular places, for example, this is a solar spot, this is also the solar spot, and these are places where magnetic fields are enhanced.  And I will be telling a bit later that the number of the solar spots may be related to the temperatures that we experience on the Earth, and to the Earth's climate.   Solar spots were discovered by  Galileo, and they contain very intense magnetic field lines.  These are actually spots that we see as dark, but if you bring the material of the solar spot in this room, it will be shining.  It's just relative temperature of the solar spot is less than the temperature of the ambient plasma.  Their size can be much larger than the size of our planet, and  they actually contain very intensive magnetic fields which are measured by Zeeman splitting.  Solar spots present one example of magnetic activity.  There are other examples. 

 For example, these are arches, plasma arches, that we see.   And they are formed also by magnetic field.  Plasma is moving along magnetic fields.   These arches can be stable for some time,  but then they can destabilize and eject  high-energy particles.  And for example, here we see this  arch, prominence, and this is Earth for comparison.  These are really huge events, and this is, they're comparable to the size of  the Sun.  These are examples of magnetic phenomena.   These magnetic phenomena are related to ejection of energetic particles, and these energetic particles can create a lot of effects  for us.  Aurora is one of these effects, and this is an example of aurora.   We can see different  examples here, some of them are called Aurora Australis, in the Southern Hemisphere, and Aurora Borealis in the Northern Hemisphere. 

  This is our planet, and this is the  aurora around the Pole.   I can also show you  some of the pictures  from the Space Station, from the International Space Station, as it,  you see, flies.  And you see the spectacular event.   What is the cause of them? You have  energetic particles which interact with atmosphere.  For example, red and green light are related to  oxygen, atomic oxygen.  And there can be  also blue light related to molecules.   We see, for example here, mostly green light.   Interestingly enough, this aurora can happen not only for our planet.  The planets which have magnetic fields, also experience similar  events, and this is Aurora Jupiter.   You see, even at Uranus you have aurora. 

  Well, the boundaries of aurora in the Northern Hemisphere are shown  here.   These are...   They depend on the intensity of aurora.  So, for example, this red light, red line corresponds to most intensive aurora.  Well, these are interesting, spectacular phenomena, and sometimes aurora can be so bright that you can read a newspaper at night, but  it also can be pretty pernicious.  And it's important to understand  this event  to, for example, save  equipment on satellites.  This is the subject of space weather.  So, the idea is very simple.  You have the  generation of energetic particles by Sun, and these particles then propagate towards the Earth.  They're diffusing or moving together with the solar wind. 

 And it gives us hours, around 18 hours, to for example, switch off  equipment on our satellites to prevent short-circuiting.   Well, but we should not switch our equipment all the time.   The satellites-- they are not for fun.  They should work.  We should switch them off only when it is necessary.  And to predict when it is necessary, we need to know how intensive is this event that is coming.  And this is space weather idea.   This is an illustration of  these particles, and their interaction with Earth's magnetosphere.  Magnetic field of the Earth protects the planet, does not allow these energetic particles to come directly to the planet.  And this is good, but at the same time. 

  the perturbances in magnetic field  can create a lot of problems, because, for example, you can have short-circuiting  of electric equipment; you can have induction of currents in these cables; you can have disruption of communications between satellites and airplanes.   And this is a very, very serious issue.  It is estimated that the  effect of  such events could be,  could cost, usually, several billions of dollars per year.   And as we have more sensitive equipment in space, the price may go up.   Well, sometimes we have  flares, which are unusually  bright.   For example, a typical solar flare  releases one hundred million times  of the world's consumption of energy.  But there can be  solar flares much more powerful.  One of these, or actually, the most powerful recorded solar flare, is the so called Carrington Event.  And this, when this solar flare happened, it was,  aurora was seen near Equator.  And to such an event, if it happens nowadays, can probably destroy most of the equipment in the orbit, even if it's switched off. 

 But these are not probably the most dramatic solar flares associated with our Sun.  For example, the studies of  a particular isotope, Carbon 14, in cedar, Japanese cedar, revealed that  at that time, probably between  774, 775, there was an event  which was a thousand times more energetic than Carrington Event.  This such event actually is dangerous not only for  electronic equipment, but it's also dangerous for biosphere.   And such solar superflares are observed,  in fact, for other stars similar to our sun.  If you have a substantial sample of stars, and you observe them, from time to time you see such events.   Well, let me touch upon a rather sensitive topic, which is relation of solar activity and climate.   Well, solar activity.  Formerly, during  the solar cycle as we have change of  the number of the sun spots, we have a substantial change of the solar flux.  But because of magnetic activity, we can have a substantial influence on what's happening on the Earth.   For example, if we are talking about extreme UV, in this case, the change of the flux of the UV radiation is not 0.1%  as in just visible light, but in extreme UV, it can be substantially larger factor, factor 10 or more. 

 And this can have an appreciable effect on ozone layer.  And it's very difficult, actually, to understand the consequences of all these changes, but we know that  during these  flares you have this change of the concentration of ozone, and it can  have different consequences.  I will mention one of the consequences, and it's related to La Nina  event in the Pacific.  It was found that  you change substantially precipitation  and temperatures in the Pacific region during these solar flares, and this is a result of a complex processes change.  It's triggered by changes in the ozone concentration, or the ozone column densities.  Another important event that we know  took place in history is the change in the number of solar spots.  As I told you, Galileo was the first  who discovered these solar spots.   Earlier on, they were also observed in ancient Greece and also in China, but then  no one was looking at Sun, somehow.   But Galileo found them.   Actually, he was using his telescope but not his eye. 

 There is a joke that you can  watch your sun with your eye, but only twice.  Once with your left eye, then with your right eye.  (audience laughing) So, he was not as stupid as that.  He was projecting this on a screen and was experimenting.  And after that, the number of the sun spots was studied.  And we know that there was a period  which is called Maunder Minimum, during which there were essentially no sun spots,  and interestingly enough, this period coincides with the so-called Small Ice Age.   This is  a picture of Holland.  You see, everything is frozen.  You travel to Holland and you'll see it's not, nowadays.   Well, there was some other period of  low solar activity. 

  And this is Napoleon  in Russia.  The particular winter of 1812,  was extremely, extremely cold.   We know that Napoleon  lost his great army,  but it's less known that Russian army lost nearly all its cavalry and guns, because it was so cold.   Well, there are scientists who believe that there is quite a relation between the changes of climate and the solar activity.   And this is related, actually, not with the energetic particles of  the Sun, Sun also emits energetic particles, but it's related to the energetic particles related to the galaxy.   What would you say relation of the solar activity and galactic flux? The relation is through the solar wind.  There is a wind coming from the Sun and its intensity depends on the solar activity.  If you have strong wind, you have a plarion around the solar system, and less cosmic rays are coming from  the outside, and less cosmic rays interact with the Earth's atmosphere.   People believe that this creates,  this is the key to the relation of climate and solar magnetic activity.  What's happening? If you have more galactic cosmic rays coming into our atmosphere, these cosmic rays passing through the atmosphere ionize atmosphere, and this  creates the seeds for  drops of water. 

 Creates clouds.  And these clouds, when they are at lower atmosphere,  reflect solar light.  If they're in the upper atmosphere, the effect is opposite, interestingly.  They act more like  a blanket, not allowing the Earth to lose its heat.  But in the lower atmosphere, they create clouds, and decrease the flux of solar radiation towards  the Earth.  And this is what they show.  They show that there is variation of  galactic flux  detected, galactic cosmic ray flux detected in the Earth and the cloud, amount of clouds in the atmosphere.   They also claim, and this is controversial, I will show some  data by other researchers, that you can  essentially explain most of the changes of climate by this effect.   In terms of the  variations of climate, it's also interesting that sometimes these variations of climate are pretty rapid.  For example, they can happen in,  as here explained, in dozens of years, which somehow acts against a competing theory which tries to explain the variations of climate by the changes of  the procession of the Earth, or some variations in the Earth's orbit. 

 Interestingly enough, this research is also related to the Ice Ages,  to the motion of the solar system within our galaxy.   As you know, our galaxy is a spiral galaxy, and as the solar system moves, it goes through this  spiral, and then space between the spirals.  And the intensity of cosmic rays is known to be different in spirals and outside spirals.  It's stronger in the spirals.  And so, this graph shows the intensity of  this epochs of glaciation,  the periods of  Ice Age on the Earth.  Incidentally, we are still living in the ice age, because ice age is defined by the part of Earth history where we have either  South Pole or North Pole, or both, covered with ice.  And this relates to the  times of this glaciation,  and the flux of the cosmic rays  which was detected by a particular procedure of studying meteorites.  So these people believe that we can explain, essentially, all the changes of the climate by  the flux of cosmic rays, both in the during previous history,  through millions of years,  these are millions of years, and on the time scale of  dozens of years and years.  So, in fact, in their papers they say at least two-thirds of the variations of the climate of our planet can be explained.  Well, this is not an accepted point of view. 

 For example, there are some studies  which show that, indeed, if we look at the  records of  solar activity, this is solar activity averaged over an 11-year period, which is the cycle, and this is the temperatures,  also averaged over 11 years.  And they say okay, this is  probably not bad correlation between these activities up to, maybe, 1960,  even maybe further, but later, we see a decorrelation  between this.  So the present warming is not due to the cosmic rays, and it's probably we humans are responsible.   Well, accepting this,  the authors of the theory that I  showed you  do not agree.  They have different data, and I will not go into all those details.  But what I believe, still, is not controversial,  is that there is still correlation  for earlier.  Maybe now, it's not correlated.  We are emitting too much of  these greenhouse gases  in the atmosphere, but we could not, probably, deny the fact that there is correlation between these activities.  And also, I showed you these  plots of the  clouds and cosmic rays, and these are also plots from people who argue against this  present correlation.  They say no, there is no correlation right now. 

 But nevertheless, for a substantial period, you see this correlation.  So I think this is difficult to deny that this is an important fact, and it's an important process to study, and this is related to magnetic activity.  Well, if we think about climate variations, it's really interesting.  We see really big changes of the climate.  And irrespectively, what is happening now,  it's a big scientific problem to understand why we had these big variations of climate through the history.  Well, let me change the gear and discuss something different, but still magnetic.  And this is related to pulsars.   Our Sun is  magnetic star, but there are stars  which are much more magnetic.  In some sense, pulsars cannot be called stars, they should be called corpses of stars.  Because these are the objects which  are created during the death of the stars, when the star dies, producing a supernova. 

  Interestingly enough, these  objects show very strong magnetism, and they are observed because it's magnetism.  So we have  neutron star.   This is probably 10-kilometer object,  with a mass higher than the solar mass.   And all the matter is compressed into neutrons.  So, electrons are squeezed into the nucleus, and everything forms neutrons.   And there are currents in such a system which creates magnetic field, and there is beam radiation along the magnetic axis of such a star.  And as this neutron star rotates, from time to time this beam will be pointing towards our planet and we'll see these pulsars.   There are, in fact, more magnetized objects than pulsars, and they are called magnetars.  In this object, their magnetic forces are comparable with the gravitational forces which actually squeeze electrons into nucleus.   So, these are really remarkable objects,  and we have some evidence of their existence. 

 Interestingly enough, I showed you the solar activities  in terms of the solar flares.   Now we believe that similar to solar flares, we can have flares on magnetars.  And it is also believed that the processes  similar to solar flares, may be the source of  gamma-ray bursts.  These are the most energetic events in the present universe.   In fact, if  a similar gamma-ray burst happens somewhere in the vicinity of the star, our Sun, meaning in the vicinity,  the galactic vicinity,  we would be completely exterminated.   There is no way to be saved.   I talked about the corpses of the stars, but what about young stars? Young stars also show a lot of magnetic activity.   In particular, young stars show jets, and jets are ubiquitous phenomena  for different objects.  It's somehow related to the processes of accretion, and accretion is also a magnetized process, and when you accrete material, part of this material will be ejected along these jets.  And these jets can be collimated, And they can be collimated for example, for galactic jets  over the distance of many dozens, and sometimes hundreds, of light-years, they're collimated, they're directed, and magnetic fields are responsible for this. 

  So, we have many  magnetic processes also happening on the scale of the galaxies.  And even our galaxy is  something that we still need to understand.   Interestingly enough, the particular  event, or particular phenomenon,  of really gigantic proportions, was discovered quite recently, and it's called Fermi Bubble, because it was discovered with a Fermi satellite.  This is a picture representation of our galaxy.  And this is the cloud of magnetized plasma, this was discovered.  And you see this cloud  is comparable to our galaxy.   So, I touched upon, in my lecture, different phenomena, on different scales.  And we are discovering more and more  magnetic phenomena in astrophysics.  Let me just, in the last couple of minutes, mention, for example, what I am doing in relation to this big picture.   What I am doing is  related to  the process of annihilation of magnetic fields. 

 So, we may have magnetic fields of different direction, and when they are frozen in plasma, they have their own life.  And if these magnetic fields of different direction come together, they reconnect.   This is the source of energy for solar flares, for all these magnetic processes that I was describing.   Interestingly enough, the process of reconnection is still mysterious.   We don't have good,  well, it's not agreed upon, I would put it this way, what is the process which makes the connection fast.  Interestingly enough, to explain solar flares, it's not enough to have a connection fast.  It also should be slow.  So, look how mysterious is it.  Sometimes it's fast, sometimes it's slow.  Why it should be slow? Because we know that accumulation of the magnetic flux for the solar flares happening for weeks, and magnetic fields, in this case, are in contact, and they are reconnecting probably very slowly. 

 And then suddenly they start reconnecting fast.   So, with my collaborator we suggested a particular model which  develops the classical textbook model of the process.  There this upper panel shows  this classical model of reconnection.  It's called Sweet-Parker reconnection after the researchers who introduced this model.  This is the model in which you have magnetic fluxes in the opposite direction.  And the plasma, which is coming in the vertical direction, is being ejected from this slot of the size delta, in the horizontal direction.  And you have the annihilation of magnetic field  in this region.   What's the problem with this model? It can explain slow reconnection, but it cannot explain fast reconnection.  Why? Because if you think about this, what is this scale? This is the scale of your magnetic flux tubes, and this is astrophysical scale.   Big scale. 

 And what is the other scale? The other scale is microphysical.  It is determined by your plasma properties.   And this disparity of the scale makes, through the conservation of your  matter, a connection velocity slow, it's the velocity of the ejection of the material, times a very small factor.   Well, what we suggested, we suggested to add  a natural phenomenon, which we know exists in nature,  which is turbulence.  The real plasma is not calm.  When we observe solar flares, we see turbulent motions, turbulent plasma.  Actually, air in this room is also turbulent.   Blood in your big vessels is also turbulent.  Turbulence is everywhere.  And the larger the scale, the more  turbulent phenomena we see. 

 We added this, and because of that, we managed to explain  the processes of fast reconnection.   Because when you have turbulence you can have much larger outflow velocity.   And in some sense, this is very natural process.  Turbulence is known to accelerate processes of,  for example, mixing.   If you rely on simple process of molecular diffusion, you would need four months for your coffee to become sweet.   You don't wait four months!  You just mix the coffee, you create turbulence, and that's it.   Okay.  I can show you  also, as the final note, some simulations of  this turbulent reconnection.   And this shows turbulence naturally develops  when we bring magnetic fluxes,  but use very big boxes.  So this was testing of our idea. 

 And do you see this development of turbulence, and enhancement of  reconnection, which is related to it.   What we see actually, and this is interesting,  such patterns sometimes you see  in the sky with clouds.  This is Kelvin-Helmholtz instability.   We also see this instability in these turbulent layers.  I don't have time to describe you the consequences of this fast reconnection.  And we suggested a new theory of star formation related to  this fast reconnection, and also provided an explanation of anomalous cosmic rays, which were detected by voyagers.  But this is probably the subject of more specialized lectures I can answer your questions if you have, but for the time being, thank you for your attention, and I will be happy to answer your questions.  Thank you.  (applause)   - [Jim Lattis] Good evening and welcome to UW Space Place.