Relativitätstheorie für Laien

Good evening ladies and gentlemen, I think if we wait until all the numbers come in, we will wait another half hour. It was probably all the time that new participants came. I would like to warmly welcome you to our. long night of science in Konstanz various institutions but also the university and you are here in the audi maximum i.e. in the large lecture hall of the university and despite the early hour, the long night of science is now, at best In all cases, a long afternoon at six-thirty they have already appeared in large numbers. My name is Ganteföhr.

I am a professor of experimental physics at the University of Konstanz and I am now one of those physicists who, at least the organizers of the long night, believe that I am able to talk to lay people without the lay people running away screaming or saying Frustrated, we ran away and the first thing we did this afternoon was because you were still rested, you still had a long night ahead of you. So we choose the most difficult topic, ie. Einstein's theory of

relativit

y, and I'm going to test it for two years without you first. Actually you should have done your basic studies, but still, to bring this highlight of physics to the theory of

relativit

y, maybe let's talk a little about Einstein first.

They always say the picture would be like this, like an older professor, I think at Princeton, unfortunately, it's also this. This dignity and this enormous, deep spirituality radiate that he was once a child, so here is this. photo a little younger and he obtained his diploma at the age of 21 at our neighboring university here in Switzerland at the eth and I have to say yes, that's why our diplomats today The master's degree takes a little longer and then he also worked in the patent office in Beeren and I actually made important publications there. We'll talk about that in a moment, which suggests that that work in the patent office exists today in the European Patent Office and my students also like to go to the European Patent Office, so.

There really is, it's probably not that stressful and maybe also something about the European patent office. You can't pay taxes because you don't know which country you're going to and that's why it's tax-free. So he won well and. Here Einstein also took advantage of his work at Bears to make some important publications. At 26 he got his doctorate, so he got his doctorate in 1905 and today's graduates are very far from that, so they usually need until they are 29 or 30 or even older. , but to ease the burden on the young people of our current generation, we have to say, Mr.

Stein, that we did not have to learn the theory of relativity and that is why the course is longer. You know a little. about this and then you actually only knew normal mechanics, that's the first semester for us in that sense it actually took quite a while, you could say that yes, he didn't get the Nobel Prize for the theory of relativity, for which he later made very famous. Then this deviation of light was demonstrated and it became so well known that today it appeared in a newspaper, so if you want, you can't say anything now, so at least a moment of the day with the one that you can find on every newsstand Cover because made a very important discovery, this deflection of light in the gravitational field.

Yes, today we can only dream about it if we make a discovery like that. There's no way we're doing it. appeared in the daily press, but there was widespread optimism about the discoveries exploring the world. There are still really revolutionary discoveries, but you got used to it a little, then he explained Brownian motion also in this year 1905 and the special theory of relativity. that's why now I have marked it in red the special theory of relativity has that especially because it is suitable for beginners, so if you think it is difficult, the special one, there is also the general theory of relativity and that one is really difficult, okay , but first we will do the special theory of relativity from 1905.

Yes, the professor in his thirties got it at eth zurich and today we have this whole evaluation. I was the students, so I actually have to evaluate the students. That's the other way around, today students evaluate the teacher and if I give a lecture that some students don't understand, then it's not the students' fault, it's my fault. I even got to the point where I had a student. Then the team passed and we didn't understand anything because they can't leave it like that anymore. I never explained it properly, so I should have to get my grades, yeah, so I think okay, there's nothing. can do about it, at least as far as impact goes, his lectures were completely incomprehensible and he had difficulty even getting a professorship because the students really did.

It wasn't that we stayed away, but it was because we were really, really smart. that we then moved to Berlin to the Kaiser Wilhelm Society, the building is still there today, the Fritz Haber Institute, one of the Max Planck Institutes, very worthy and has the best position to get a job that you can still get today director of Max Planck actually then his name wasn't max planck but nowadays it's mainly max planck and that means you don't have any more teaching and it didn't make sense because no one understood you anyway but he didn't have to give a lecture but he could just focus on the research and then in these very good conditions you developed the theory of relativity for advanced people, we will only do it very briefly, okay, yes and then we will go into the dark times in Germany, otherwise 133 emigrated to Princeton and became an American citizen, we'll come back to that again.

So let's start with the theory of special relativity for beginners, regardless of whether someone when buying a car does not want to know about it. how the carburetor works or how many gears are in it Gears you want to know how fast 14 18 proper agreement that means we don't go into the derivation of the theory of relativity and show, we just show what the theory of relativity can do and it says that time is relative because an observer on Earth passes it all at once. A spacecraft passing near the speed of light, time is slower than on Earth.

When you look at a clock on a spaceship you have to go by very quickly. , sometimes the pan and tig the second hand is slower, that's really unusual, some defect in it or something, but no, it's a property of our space-time, that is, our space and our time together, yes , and then there is an associated effect when time goes slower then distances are shorter there is a contraction of space itself in a moving space system a preemptive spacecraft is shorter in the direction of speed yes and so you can believe that I have a computer animation here, although that is of course something so computer animation can be done in many possible ways, but that is what could be done in the experiment, not in cars but in other things.

In fact, I can try it now. I'm trying to get the computer to play this movie so what. What we see here is this car in the foreground behind, it's just a clock as a symbol and this car accelerates the whole numbers and now it accelerates to 50 percent of the speed of light, we move with the camera so that it appears to stop and then , between 80 and 90 percent of the speed of light, shortens in the forward direction, blackens, so it goes straight and in this direction it comes together and this length contraction is also the recession number , they are the answer to the old dream about albert einstein here you can see him he is trying to reach a wave of light that was his question what happens if I move as fast as light then the wave stops but a wave cannot stay, it has than move another way? does not exist.

What really happens when you travel at the speed of light is that the universe in the direction I'm traveling is controlled to a length of 0 and time stops; time itself, yes. Now you can understand it. or say that, okay, that's really hard to understand, but that's how our space behaves at 90 percent of the speed of light, there is a length contraction at 44, that is, about half in the direction in which you are traveling and when traveling. at 100% the speed of light the length reduces to zero and time stops and that actually happens in the universe here where we are at the maximum, let's say now there are many 30 zones, it is not the case, very slowly and On the road In fact, you could travel at the speed of light in Germany, there is no speed limit, which would also be an advantage if driving to Stuttgart at such a high speed.

However, due to the reduction in length, this is no longer the case. 150 kilometers but only 140 Still yes, but I don't know exactly if that's really important, there are no speed limits, you just have to slow down to 60 on the construction site, which can be a bit difficult, well, then let's take a example from everyday life We have a train with a very long flat freight car and there is a driver in it and the train moves at the speed of light, which in physics is always abbreviated as ce, we like to have letters like c. everyone knows it's not speed and the spotter passes in front of the freight car, a cyclist doesn't take it, so do it.

There was no headwind because I had speed, they already had a lot of headwind, so let's say that with no headwind, you as a cyclist are now riding in a forward direction and you would have to add the speeds so that they are not the speed of the train plus the speed of the cyclists of 20 kilometers per hour, they would have the speed faster than light so a thought experiment there is no such thing as a speed faster than light I don't like being faster than light what happens then yes , the question here is that the cyclist is traveling faster than the speed of light as seen by the observer, that is not the case because for the observer at rest, time is frozen on the moving train, the cyclist does not do anything progress, so when you have this long train and now you notice that you yourself are resting and swinging with a lot of weight, now you see this train and this cyclist on it Then it would move very slowly in slow motion and if it really traveled at the speed of light it would even freeze.

The cyclist himself does not notice anything, the servant of these things moves for him, time passes. Normally, only if you look at the outside universe will you see it. Very strange because the length of the outside world contracts to zero, which means he flew across the entire universe in one second because there is this length contraction, so you can't. Actually traveling at the speed of light, that would be a little too fast, but you can. Yes, try to accept that and then these strange things really happen and now you can ask the question: is it really like that if I move at high speed? for a longer period of time and return to earth, so you can't do it now on the track, be singing or Konstanz Stuttgart, which is so short that we have to go light years away, so in a spaceship we are really younger than those left behind. on earth, so of course we have become more experienced and all that, but what about our age and there is this illustration here with this cartoon that is in Spanish and that's why I thought I would tell you about it in case you are not so good ? with Spanish, so the quality is relatively good, but the Germans are good, so we have two less twins here, only if you go to two and one is called Konrad or only one is called Henry and the other Albert well, that is now Albert and Now their paths in life diverge a little because Albert is the theoretician, he's fine with me and he can build something great, invent something great, what do they do from a Rocket and Henry, who also looks a little different, is a little more So? the intern serves the astronauts and now they separate Henry's choice on the rocket.

Now the two say goodbye. Albert stays on the ground and our Henry is on the way in his rocket. At the top left you can see the target area, which is the. planetary system or solar system 10 light years away with the planet in charge. In the lower right you can see the boats and the inhabitants of st. They find these ships that we're supposed to bake here in Europe and money would be made. and henry is on his way and he changes the bread because now they can't use the euro, they have to barter for these delicious cakes it's like that when they can be seen and that's what is shown here when now the one in the movement systemIf you look at the other person, then time moves at different speeds, unfortunately now it's a little hard to see, so this ball dances up and down faster than it is in your movement system, time moves slower, but that's applies to both more symmetrically.

If so, if you are joking with the rocket, time goes slower and when the person in the rocket sees the Earth, then it looks like the Earth is moving towards him, then time would also go slower and that is the paradox, okay, then the Earth. and Earth are ten light years away, which is actually many kilometers and it actually takes at least 20 years to get there and back. What is happening now and what is happening now is that in theAlbert system the one left behind on Earth is. so actually the passage of at least 20 years has traces that now normal is over and Hendry actually needs a total of 20 years until he returns to Earth so if it is exactly at the speed of light , we have 99% of the speed of Earth's light.

He takes a few weeks and into our Henry system. But things look completely different for the astronaut because length contraction is not that far away. In my opinion, depending on how fast you travel, it's a little faster, it's just a few. months away because it is closer and because of the contraction time. Length dilation and contraction go together for the astronaut, so only a few weeks or months have passed and when he returns the two greet each other but are different ages. Ultimately, the two clocks reproduced here indicate that they are moving in sync again before they were synchronized.

One was slower than the other, but the two people are different ages. Our astronaut Henry hasn't aged significantly, so it's only been a few weeks. or months, but our Albert has aged 20 years. The two twins have aged differently and that is indeed the case. So if you travel at high speed then you don't age. Now, of course, you could say yes, great, I fly. a lot with a plane like this and then I don't age. That's really the case. That's a picture from the textbook. We have two atomic clocks here, so we have to look very closely.

Our planes are fast, but only. flying at 1000 kilometers per hour, so a thousand kilometers per second would still be slow because the speed of light is 300 thousand kilometers per second, one second to the moon is fine, so the effect is small because the speed is so Well, we have two atomic clocks here, one is on the plane, here is the plane is still at the airport, next to the clock that is there anyway and that is the time difference between the two clocks, they have to be very precise go because we We are talking about time differences in the nanosecond range and here you can see very well that the clocks on your plane are now working according to the plane, the plane is on the road for about ten hours and all the time this clock is going faster slow until the plane landed again and then they do the same again quickly.

Overall, we have a clock rejuvenation on the plane of 47 nanoseconds. Not so, if you are looking for seconds, it is significantly less than the millisecond, it is even less than on the Migros, so it is really little, but if you fly a lot, then younger. If you want to stay, then it works like this, you gain seconds, but then there are opposite effects because radioactive radiation is cosmic radiation so far. You get more radiation when you fly. flying around for so long, so that's not so good either, so it might complicate things for you. Just nanoseconds are fine, but it's actually been shown here that if I move fast, time passes more slowly for me and that has an interesting effect. field in purely theoretical terms, if we manage to buy a really good rocket, we can't buy it, we can't build it anyway, so we can build it.

We're going to the end of the world, so we're dealing with really big things all the time and physics now is really asking: yeah, where is the end of the world today? In the past, people had the idea of ​​a flat disk and then asked, of course, things. so immediately through the steam at the edge, so the water falls, then someone had these problems at the edges and today we know three-dimensional space, but of course the question can also be asked, what is the end of the world according to today's knowledge and now we are going on a trip.

With the Hubble Space Telescope it is a telescope in a telescope that is in orbit around the Earth and therefore can see very far away and then we will immediately zoom up and then it will look like We are getting further and further away because we are increasing the magnification of ours. Raise the telescope higher and higher, so now we have this. Here is an area of ​​the sky, maybe you should go, this is Orion, this is a constellation in the south, so it is relatively large, so it is already an important part of our starry sky and that is actually the only constellation that I know personally.

I don't actually do any astrophysical research. My wife is always a bit, it was a It's a shame that back then it was always nice to be able to sit on a park bench in the dark and explain some constellations, but you can also find one that you notice. So, in any case, we have all the Orion constellations that can be recognized by these four bright stars that form a square and that diagonal, these three in the middle, well, but what you see here, of course, is not what you see with the naked eye, but with a slightly better telescope, that's a lot. stars We ourselves are sitting on a stellar island with 100 billion stars.

That is our Milky Way. It is an island of stars that rotates on itself once every 200 million years. There's no problem with the big guys saying that's what aid money is all about. The EU is getting bigger, as big as this 100 billion euros, and of course they are in the foreground, so we are sitting in the middle of the forest, so to speak, and now we have all these trees. those are the stars and now if you imagine that you are in the forest and you have to look outside the forest, then you have to find a space between the trees and that's how it is with the stars and that's why the space telescope was installed here. in a place in this sky directed here where it is particularly dull there is nothing in the foreground and it has been exposed for a week from there since the end of the world there is only a very small amount of light that you can see here versus just very far away and That means they have to be long.

Now I have to be careful that it doesn't get erased. For us there are no points but streaks, very difficult thing for a week in the same place and yes, and then you see the one below and I will show you that now with this movie, so it is a zoom, it seems that we are from our night sky, is what you see with the naked eye, like we're just flying out of our galaxy, that's what I have in the field here on the top left So there's a gap, there are still stars here from our Milky Way.

Now we are perhaps 10 or 20 thousand light years from home and we are already at the edge of the Milky Way. intergalactic space and there are only a few stars left and now let's search as far as we can to the end of the world. We can't go any further in groups. That's the end of the day. They are not stars, they are galaxies. You can see them by their strange shape. They are all albums like that. Now I'll show you a still image of us traveling very quickly to the end of the world. here we have again the missing still image, so after a week of exposure to see this, these are extremely distant galaxies, usually ten billion light years away, more than a billion million, you know, and we have these lists here these are these disks that are in a possible orientation if you look at them closely from the side it is a narrow disk they are all star islands like our Milky Way with 100 billion stars so there is an incredible amount of stars, an incredible number of galaxies and the interesting thing is not these very distant galaxies but the black ones in the middle that is the end of the world, what do we see? because there is the end of the world, what we see there is the glow of the big bang, you can analyze the black in between the star and it is not really black, but it has a radiation like a warm opening, but the temperature is only three degrees Kelvin, so it's very cold, but it radiates and the glow from the big bang is this black thing.

There you see it and that. Is it the end of the world. We can see past the age of the universe, so that's not the case. It is traveling at a finite speed and the age of our universe since the Big Bang is 13.6 billion years. There may be something else that hasn't reached further than 13.6 billion light years behind it, but we can't see it because the light didn't have enough time to reach us. That is at least the common belief among us. physics with the big bang theory and that is something like no yes like in the history of creation we have this big bang and since then the universe has been expanding for 13.6 billion years and the theories of the general and special relativity to understand that correctly, okay, the special thing now is with the special theory of relativity in principle.

A journey through the universe with a diameter of just under 14 billion light years within the lifetime of a human being is possible due to length contraction because the diameter of the universe contracts as seen from the rocket time in the spaceship passes very slowly now I would like to finish with the difficult part get into the general theory of relativity, gravity and acceleration are supposed to be linked, which is what keeps us in our seats and there it is where we come up with neutron stars and black holes, really unpleasant things for us, we can't live there, so I have the idea here.

It doesn't illustrate if you now accelerate the car, really give it the accelerator and then it pushes. You sit in the seats, the car just stays upright, again indicated, then you are also pressed against the seat and you are sure that the acceleration is now really enormous. But it's at rest and I see the gravity that brings you back to the seat. , the conclusion of this equivalence and Albert Einstein demanded that it is the same cannot be distinguished in a gravitational field, for example on the surface of a neutron star it is like that very small ball but with enormous gravity time passes more slowly. , that means that when you look at the surface of a neutron star from the outside not everything happens in slow motion, so now you are driving near a neutron star, let's hope there really are some, but physics has found some.

We have not been there yet, we are looking at it and if something moves there, it moves very slowly because it is in a huge gravitational field and the inhabitants of the neutron star, on the contrary, would perceive our outer universe, which is us. These are the questions asked in theoretical physics about neutron stars, which are made up of nuclei that determine matter. Many theories can be formulated or there are indications of its real existence and here we have the Hubble space telescope again. which is an image like that and then the theorist has a file spin it and say that his neutron star actually looks the same as the other white dots, okay, now you have to look a little closer, you can't analyze it and get the temperature of the surface temperature of this white object, which appears white in the photograph, is 1.2 million.

Well, now they are in the millions. They don't even bat an eyelid because they're talking about billions anyway and from billions onwards, now there are 4. million but the surface of our sun is at 6000 degrees 6000 not 6 billion or something, that means This star is incredibly big. Hotter than our sun, there can't actually be stars called that because they would immediately fly around our ears and that's how it only works if there is great gravity to hold this super hot gas together, otherwise it doesn't work. The temperature alone tells us that the thing must have a huge gravitational force and then the diameter is just the constancy of distance. would sing here between songs and it would fit, but then it would flatten the entire earth because it has a very high gravity and is a strong source of X-rays.

From this we can conclude that it likes to be matter, so something completely different is completely foreign to us super dense matter and there are 10 billion now we have millions which is now more than the EU not so many millions it is 1000 billion ten million poets like we have it even worse we have a black hole a black hole has such great gravity that light cannot be transmitted It turns on not like that here when I bring my little laser arc we have to hurry when I follow my little reader here If you point it up then there is no problem making the red dot up there, but it actually works against gravity when I raise it a littleThrow and ball, so you know from experience that it slows down and comes back, that doesn't do that, but it doesn't seem to do that, but it does, it doesn't get tired on the way up, it gets a little redder. from blue up This is the gravitational redshift, which here in our very weak gravitational field is not noticeable.

If we had a gravitational field like that of a neutron star, then they would all have a maximum size of 1 mm. , due to the high gravity, but the light would also have difficulty rising and would move towards the infrared and, if it is a black hole, the gravity is even stronger and the light no longer comes out. The light itself no longer escapes. from the surface of the black hole and of course it was not in the surroundings and there are Do black holes really exist or is it just a game of theory? We have another galaxy here and in our neighborhood, which is the galaxy NGC 44 14. .Astronomers have something like license plates and it looks like our galaxy.

We can use ours. Don't look at your own galaxy, we don't have a mirror and it doesn't take long to get out of it. outside, so we will be around here if our galaxy looks like this and the distance from the center is this distance in 20 thousand light years and now there is the idea that our Milky Way is in the center. Of course, it is difficult to find a black hole now. Look there, there's a lot in the way, there's dark clouds and all that, but astronomers have tried to look there and that's what they've found.

They have a certain wavelength range in the infrared, we can look there and. that with a high magnification that is only ten light days that is the center of our Milky Way and what we see is constantly high the stars are only a few light days away we are in a region where the stars are very far away the stars are farther away nearby are three five or eight no years here is more or less uninhabited you could say that for the stars this is the equivalent of Tokyo or something like that, completely densely populated people are very close to each other and they move here are the numbers of the year 2001/ 2002 the stars move as fast as our planets and are actually fixed stars, they have to stay in the same place, they don't do that, they move violently and you can see that they travel in an elliptical orbit around a heavy center invisible a kind of roller coaster marked in yellow, it is a piece of ellipse and there must be a huge center of gravity that you cannot see, which has like a million solar masses, yes you see yourself as a black hole, of course the proof It's good, there are some more.

There are a few more indications that it is actually a black hole. Our black hole is a very peaceful black hole. There are black holes that become very unpleasant. They are even larger and absorb matter. So now we're getting into the area where there are visions of Star Wars or something like that from our Hollywood filmmakers, science fiction, they're completely harmless, we can't do one of those, physicists, if we get really angry we can have visions about it, so the entire Milky Way is absorbed here we have a Milky Way like that, so you have that This is a Milky Way, a galaxy that is very far away and in there is an active center, a huge black hole that has a much greater mass that says that the Matter is being sucked in all the time and when matter is pulled into a black hole, it eventually gives up a moment before it really damages our known universe.

There is another clamor of X-ray or X-ray flashes, these are extremely intense aggressive black. As I said, our black hole is very peaceful. Otherwise, we will not do well. That was the general theory of relativity. Without it, we cannot get along in the universe. I can assure you that in the world the great Albert Einstein has moved there with his theory of relativity, there are really very, very unusual things. What I personally find fascinating as a physicist is that humans with our minds are able to imagine the really big something that is much, much bigger, not only these 100 billion but also much, much bigger, so very large distances. , long periods of time, we can face it with our mind and it is fascinating but very strange and, therefore, also hostile to life, many things and the same applies to the very small Albert Einstein did it with his third work in 1915 Photographic effect explained This is quantum theory and this is the basis of digitalization and our computing world and this is also It's a very strange world, but today we only review the theory of relativity, so special theory of relativity for beginners I think which is the second semester of physics.

I can only recommend it, so it is not a rate constant and the theory of relativity is derived from these two postulates. contraction so if you move very fast the goal even reaches a friendly time dilation if you move very fast you don't age as fast as your relatives who stayed on earth And then the famous formula is equal to n c squared, I haven't gone into We now know that mass and energy are the same thing, which is also quite interesting for the energy transition. If you could somehow handle mass, you'd need a black hole for general relativity, acceleration, and gravity.

It is the same thing that is deduced from the. The fact that the gravitational field curves space also here on Earth, in a strong gravitational field, time slows down a little by nanoseconds, and this shortens the scale once again to the fate of Albert Einstein, who never again set a foot in Germany. 1933 Goodbye. Stein, from Berlin, says he cannot live in a state where individuals are not granted equal rights under the law and freedom of speech and education. The German government offers a reward of 50,000 Reichsmarks on Einstein's head, whether he is alive or dead in 1933 in the princes.

Americans, we welcome the new Columbus of the natural sciences, who feels alone among strangers. Several worth thinking about, that's just how it is. He was certainly ahead of his time and invented completely new things about space and time that are still not adequately understood today. We are still working on it. Maybe we need to try a little harder to understand everything correctly, what Einstein thought, but also what we continue to discover every day in the large accelerators and with the large telescopes, which they are. Completely amazing things that the outside world has in store for me, so now I'm doing it outside of the earth and that's fascinating, but one stone was actually Columbus who paved the way.

Yes, ladies and gentlemen, that was an introduction to the world. Special and general theory of relativity, thank you and I wish you a good day.