Two Arabs make far reaching discoveries about outer space
Regional, Science, 4/10/2000

An interview with Tunisian Dr. Lotfi Ben Jaffel, from the Institute of Astro physics of Paris, following his recent discovery in the field of planetary physics. This interview is a bit technical.

ArabicNews : First of all, congratulations on your discovery, our understanding is that you've studied theoretical physics and afterwards switched to planetary physics. When did that change take place?

Ben Jaffel: Well, after I finished my degree in theoretical physics -- usually a student is looking for thesis subject and you have a feeling for one subject more than others, so you go in that direction. So, after I finished the degree in France -- I was just coming from Tunisia -- I was attracted by the subject, to participate, to analyze the first data from the Hubble space telescope.

ArabicNews: So you got some of the first data that was coming from Hubble. Was that data before Hubble was fixed or after it was fixed? I am assuming it was before.

Ben Jaffel: Yes, it was before. In fact, I have had the chance to participate to analyze data from the telescope -- from the beginning -- from the first year the telescope started working. I was working with the trouble the telescope had because of the aberration in its mirror, and then, the correction. It was in 1993 that they corrected the problem. So I could say that all my work in astrophysics was with the Hubble space telescope, and I still continue to work with the telescope and the data coming from it.

ArabicNews: And since you have been continuously working with the Hubble data, how much improvement was observed after they made the fix to the lens aberration?

BJ: Well, the improvement is huge. It is difficult (to quantify), I will say that it is like when somebody has trouble in his eyes and could not see without glasses .. much like when you observe something behind a haze or foggy atmosphere, something which is not clear and then you wake up and you have the sun from outside, it becomes clearer. It is much like night and day.

ArabicNews: It is that much better? Has there been any quantification saying it is five times or ten time or three times better?

BJ: I will say it is three times better. Almost three times better -- it is difficult to say that from the imaging point of view, you can say three times-- but there is another aspect which is very important in the Hubble, it is called spectroscopy, which means that you look for the signature of a process, physical process -- whatever this process is -- for example the excitation of the atoms in the galaxy or the earth atmosphere or the sunlight or whatever process, (and) if the telescope is not accurate, you will (loose) the information

ArabicNews : So there is even greater improvements in that area (spectroscopy) of the Hubble telescope

BJ: Yes, it is much more accurate. The improvement was great . In fact, our life as researchers is much easier now because (in the past) we have had to face lots of problems seeing the universe, because usually people think about the telescope as -- you observe and you have the information -- when what is coming from the stars is the object (light) that is going through the telescope, so the telescope has an effect on that information (being gathered), which means the information you receive in your computer is a kind of mixture between the light coming from the object you are observing and the effect of the telescope. We need to get out the effect (ie interference) of the telescope in order to get the information we need.

ArabicNews: So It is almost like the Heisenberg Principle (Where the act of observing something effects and interferes with what is being observed) but not quite?

BJ: Yeah, not quite

ArabicNews: The Hubble has been described as a huge leap in terms of the ability to observe outer space, and someone said that since Galileo's time, there has not been a time when there has been ten times improvement -- at one time -- in the ability to see into outer space. Would you agree that the Hubble has been revolutionary in terms of astrophysics and planetary physics?

BJ: Yes, I agree. I think the improvement is huge considering the time before the Hubble started observation, and now, especially after the repair mission, the improvement is huge.

ArabicNews: How far are we in terms of seeing into the depths of space as a result of Hubble? Are we seeing the very end of space, or are we not at that stage yet?

BJ: Well to see far in space, which means far back in time -- the period of the beginning of the universe, at least in the scope of the big bang model (theory) of the birth of the universe -- now with the infrared capabilities of the space telescope -- we can go back in time to just few hours from the creation of the universe.

ArabicNews: Did you say a few hours?

BJ: Yes

ArabicNews: That is quite remarkable in how far you can go back in time, and you can almost say that that is the edge of space?

BJ: I mean --it is difficult when you reach these frontiers, it is no more physics, it is philosophy

ArabicNews: I don't know if you can explain it to someone who is not very familiar with physics-- but how do you know that you are seeing to within one hour from the creation of the universe according to the big bang theory (Which says that the universe exploded outward from a single point in space)?

BJ: In simple terms, you fix a model (a theory), because we need that for our brain as a frame for understanding, if not we're lost, so in that frame, we say that the universe started at some time with some characteristics and properties, and then we have a model that describes the origin of that universe, down to our current time. And then, in the frame of that description, we know right now that we are almost nine billions years or so -- between nine and 15 billion years let us say -- from the beginning of the universe. Then when you measure light from the object that is let's say five billion years age or ten billion years ago, you will see an observed object that is 5 billion years after the beginning of the Big Bang or one year after the Big Bang or one hour after the Big Bang. But that means it is in the frame of the model you described (the Big Bang theory) -- you are using to describe the Big Bang theory

ArabicNews: So you are assuming the Big Bang theory is correct -- that the universe started from a dot, almost, and blew up and like a ball and expanded and based on the amount of expansion, you can tell how far back in time (you are seeing)

BJ: In fact, when you have certain wavelength (electromagnetic waves) which is the first light coming from hydrogen (atoms), it is in the UV (ultraviolet ) light when it is emitted from the object. However, with the expansion evolution of the universe, this wavelength should be observed in the infrared (light). So we can tell the difference between the light you observe in infrared and the light that is emitted in the beginning in the UV (ultraviolet range). You can measure the distance or the time between the two ... ...

ArabicNews: Are you talking about the shift in frequency?

BJ: Yes, that way we can say -- let's say -- we observed an object that is one billion years old

ArabicNews: Your specialty is infrared observation?

BJ: It is UV (ultra violet).

ArabicNews: What is so special about UV when you look out into space? What does it tell you that visible light -- when people look with the naked eye don't see-- what does it reveal?

BJ: The UV, we are lucky not to observe it directly, because it will (damage our eyes), it is very strong rays. UV (light) is shorter wavelength, and that means greater energy, or high frequency. That means you can see at the level of the size of the atom. So you observe indirectly the excitation -- what is going on -- in terms of the atoms and molecules. You are not interested in the large-scale characteristic of the object, for example clouds or the full shape of a planet. You are interested in the constituents of objects at the level of the atoms and molecules.

ArabicNews: So we are moving from looking at large objects the size of planets down to the molecular and atomic levels revealing the composition of planets and (space) clouds and just material in space that is floating around. What does that teach you? What does that tell you ?

BJ: Yes, for example, when you observe Jupiter, for example, I can see using the UV light that the thermal structure ( the temperature) -- the number density -- that means the number of atoms per cubic-centimeter that are in that planet which is five astronomic units (distance) from Earth, which is far from here, but thanks to UV light, I can say I have this abundance of atoms of Hydrogen , Helium etc..

ArabicNews: So you can tell what something is composed of, and you can tell how much it weighs as well. So you can tell us how much Jupiter weighs for example?

BJ: Yes

------------ The discovery:

ArabicNews: You've received acknowledgment for your work and you've had a discovery. Can you describe to us in simple terms what was it that you have discovered?

BJ: The last discovery I made was with regard to the solar system. You know that the Sun is a star, and around it we have planets orbiting, and the whole system is moving in the galaxy. When this solar system is moving in the galaxy, it will meet clouds coming from the galaxy, and the encounter between the solar system and these clouds have never been described in an accurate way, and we never reached the level to describe this interaction, and what is the inference of this interstellar clouds.

ArabicNews: So what did you find out in terms of the interaction and inference? What does it mean?

BJ: What we found is that we defined the outer boundaries -- the outer frontiers -- of the solar system.

ArabicNews : So you found the boundaries around the solar system. What is the significance of that?

BJ: We found that in fact at the edge of the solar system, there is a bow shock

ArabicNews: What is this?

BJ: It is a shock between the edge of the solar system and the interstellar material in the galaxy. It is much like a supersonic jet, and when the jet is moving at supersonic velocity, it will form a bow shock in front of it. We call that the supersonic wall. For somebody who is observing the sky, with the jet moving, you will see first the jet and then you will hear the noise.

ArabicNews: Is it called a bow-shock because it is in the shape of a bow?

BJ: Yes. Much like a wave that you see in the sea in front of a boat moving and you have a bow, which is an arc shape, just in front (of it).

AN: The shock that you are talking about -- and let's use the analogy of the boat going through the water -- so you have the wave in front of it -- the shock -- and that is because the boat is the solar system itself -- the edge of it -- the top of it -- and it is interacting with the material from outer space which you call interstellar material ?

BJ: Yes

ArabicNews: What is the effect of this interaction?

BJ: The effect is that you have atoms, molecules, constituents of the interstellar medium that will enter the solar system and come down to the earth orbit and will interact with the earth atmosphere and could effect the earth climate. And will effect also the connection between the sun and earth. Which means that -- and this has never been measured accurately before for the simple reason that if you don't know what is going on upstream in the interaction region between the solar system and the interstellar medium-- you cannot describe the interference -- the material that enters the solar system. So our discovery was the first to describe accurately what is going on at this frontier.

ArabicNews: That is remarkable. I just want to repeat what you said to make sure I understand. Basically that interaction -- that is how material is absorbed from outer space into the solar system, and that material -- it is like osmosis-- is being sucked in from the interstellar space into the solar system, and from the solar system obviously it effects the whole solar system, and as a result it effects the sun, and effects us as well. So that is very significant, and that is the first time that this has been observed and with an accuracy, in terms of getting the data so that calculations can be made.

BJ: Yes. Now, we can say in the future, we can describe accurately what is going on -- I mean what is the effect of the extra-solar materials on the earth climate.

ArabicNews: So far, have you been able to determine what that effect is?

BJ: We are working on that right on. We have collaborations between my group in Paris, and the group of Mohamad L. Loucif in Algeria, and the group Romana Ratkiewicz in Poland, we are working together to describe the interaction between the solar system -- or if you wish the solar wind -- because the sun is blowing the wind particles and that wind is interacting with the interstellar medium, so we have very complicated modeling to do, and then thanks to the discovery we made now, we can put the equations that describe the interaction very accurately, and we are working to derive the effect of these interstellar medium particles on the earth orbit and the earth climate.

ArabicNews: Do you have any speculation about the possibilities that this discovery would tell us, if under certain circumstances, the earth's temperature may increase, for example causing global warming, or the temperature may decrease causing an ice age because of this whole interaction? What are some of the possibilities? I understand that you are a scientist and are not suppose to speculate and suppose to wait for the data -- but just to understand, what are the possibilities?

BJ: Right now, we could say that we are safe. Safe in the sense that the density of the interstellar clouds we are in right now -- that cloud is called the Local Interstellar Cloud , and this cloud is not dense, and our understanding right now is that the effect is not very important (at least) on a short time scale, but on a long time scale, it could effect the earth climate in terms of magnetic storms. It will play a role of trigger to start (events) but not to sustain them. However, we are moving through one cloud and we can get out of that cloud soon, and could encounter other clouds that are much denser, and in that case, the effect could be very important because we will have much more atoms and material of the interstellar cloud that would screen the light between the sun and earth, and we can predict in fact that if the cloud is dense enough, it could deplete the ozone in the earth atmosphere, which means we will have much more ultraviolet light which is harmful to human beings .

ArabicNews: So your discovery is significant also from a predictive value -- it is like we need to know what the weather is going to be tomorrow and the day after so that we can plan ahead -- it is just the same way the solar wind effects communications and electric equipment, satellites, etc.. So that is a very effective tool that will help us predict what will happen and when, and take counter active measures, just like we do with the weather?

BJ: Yes, but you have to keep in mind that the weather forecast is not easy to make.

ArabicNews: Sure, but it is still a very useful tool . It is better than having nothing?

BJ: It is better to know. Right now, we have the knowledge, and if any galactic cloud of any origin is in front of us in the future -- in terms of centuries (time wise) -- we can describe the effect on us (earth).

ArabicNews: These clouds -- I can imagine they are huge in size -- how long does it take for example for these clouds to move in space? Can you give us a time scale? Is it a year or ten or hundreds or thousands of years?

BJ: It is hundreds of years. So we have plenty of time to decide what to do.

ArabicNews: You are dealing with basic planetary physics and the time scale is very large

BJ: At least in this case. However, we are right now in one cloud. That cloud has effects. The effects are not yet very clear. At least we suspect it is playing the role of 'trigger' just to start events like magnetic storms. Right now, we do not understand how these magnetic storms start. We know that there is some connection with the interplanetary magnetic field, but we are not very convinced of the origin of this process. We suspect that the material coming from the interstellar cloud should have some role in the starting of these magnetic storms.

ArabicNews: So this material comes from the interstellar space into our solar system, it acts -- the speculation is -- as a trigger, and effects the sun, and the sun's solar winds, and that effects us in turn.

BJ: Yes

ArabicNews: can you give us some concrete examples on how it effects us

BJ: Magnetic storms could effect the earth-sun electric circuit, and this could effect satellites in terms of communications. you can have shortcuts and stoppage of communication because of concentration of energetic particles in one region, which makes communication much more difficult. We are not protected very well against that because we do not know exactly the character of these particles is. And that is one of the important results of our discovery in that, now, we will provide soon the energy spectrum of these particles... And then we will see which range of frequency they will effect.

ArabicNews: So if we are talking about frequencies with radios and TVs etc.. so then you can design equipment that use frequencies that are not effected by these solar winds.

BJ: Yes, at least, we will discriminate between particles coming from the sun in origin and those coming from the interstellar medium

ArabicNews: And I am guessing then that this would help you observe outer space better because you can eliminate those particles that now you know where they are coming from, and can see further into outer space. You can discriminate better?

BJ: Yes, in fact, these particles are playing the role of background noise for some data. So if you are studying these particles by themselves, it is OK. But if you are looking for information from the galaxies or a planet etc.., then they are noise making observations more difficult.

ArabicNews: So your discovery allows looking deeper into space because it allows a scientist to eliminate lots of the noise in observations. How much of a factor is that going to help in getting better images. Have you been able to quantify it?

BJ: In terms of imaging, it is difficult to say. But in terms of spectroscopy --which means at selected wave length-- for example -- this is very known -- if you observe the planet Saturn in the ultra violet light, the (light) emission of that planet , near the planet, is -- let us say -- a factor of three. If you observe that same (light) emission from earth, you will see a factor of one. That means there is a loss of a factor of three between the (light) emission observed near the planet and the emission observed near earth.

ArabicNews: Is that 300 percent? the factor of three you are talking about?

BJ: That is 300 percent, and that effect is coming form the absorption by the interstellar particles between Saturn and us. And now, we know exactly how to correct for this absorption.

ArabicNews: That is very dramatic, because part of the reason why Hubble was sent into outer space was to get around that problem of the atmosphere of the earth which distorts light coming into the earth. So using your data and equations, we will be able to illiminate that problem even when making observations from earth for certain frequencies (light waves).

BJ: Exactly. In fact that is why I was visiting the United States just to describe my discovery to my colleagues, and I think the effect was --I would say-- huge, because they understand that we can now interpret our data in a much more accurate way.

ArabicNews: We first contacted you at the University of Arizona. What is it that you were doing there, explaining your discovery?

BJ: I am working with them because I am using data that is obtained by the Voyager spacecraft . The Voyager spacecraft is flying out of the solar system -- is right now almost 70 astronomic units from earth (one astronomic unit is equal to the distance between the sun and earth), and this spacecraft is measuring this sky background in the UV light. We are using this information to describe in a more accurate way the interaction between the solar system and the interstellar cloud.

ArabicNews: What is Voyager providing in terms of data?

BJ: Same as Hubble, but very far from the sun's effect.

ArabicNews: Is that data any better, or about the same or just useful for comparison?

BJ: Useful and better just in the areas where the sun does not have a huge effect.

ArabicNews: So when it is looking away from the sun area, the data is better (than Hubble).

BJ: And that data is unique because we do not have any observatory over there. At least, this helps us to correct our models (theory) and check if they are good or not.

ArabicNews: Anything that we did not cover?

BJ: I would say that thanks to this discovery, when we will send a spacecraft out to the solar system, at least we know what is going on and what are the most interesting regions to visit. I would add that we discovered that outer boundary frontier of the solar system, and one thing that we discovered that the heliosphere, which is the region that contain our solar syste, is tilted.

ArabicNews: It is tilted.

BJ: Yes, it is not straight on the direction.

ArabicNews: How many degrees?

BJ: 12 degrees.

....

ArabicNews: What is the reference? How do you know it is 12 or 13 degrees? Based on what?

BJ: The reference is -- we know were the interstellar cloud is coming from, and we are moving in another direction, and the relative motion between the two (the solar system and the cloud) gives you a reference, and that reference is almost the direction towards the galactic center. So normally, we should be oriented towards the galactic center, but we are discovering is that we are almost shifted 12 degrees from that.

ArabicNews: Does that have any significance?

BJ: Oh yes, because it is a proof of the existence of the interstellar magnetic field. It is the only way to shift plasma -- I mean gas-- that amount of degrees is by having a magnetic field that would push the plasma in some direction. And we are discovering that, thanks to that, that there is magnetic field -- interstellar magnetic field -- and this field is oriented almost 40 degrees from the same direction.

The magnetic field we are discovering is something extra of the solar magnetic field. The solar magnetic field is just inside, but when you go outside -- people where thinking about the interstellar magnetic field for years and years but it was never made in evidence.

ArabicNews: And you discovered this?

Ben Jaffel: Yes. Thanks to the tilt -- to the shift --

ArabicNews: You are able to deduce--

Ben Jaffel: --by deduction, that there is a magnetic field.

Ben Jaffel: We found that there is a bow shock, we found that the heliosphere is tilted, and we found that there is interstellar magnetic field.

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