Birth, Age and the Future of the Universe

INTERNATIONAL SPACE SCIENCE INSTITUTE No 3, May 1999 SPATIUM Published by the Association Pro ISSI

Birth,AgeBirth,Age andand thethe FutureFuture ofof thethe UniverseUniverse

Recent results of space research tell us a story of unlikely events. Life emanating from the vaste of exploded stars is but one of them. Editorial

We are here. There is no doubt Impressum about it.–

Research, however, has shown that life, our solar system and all the SPATIUM galaxies interrupting locally the Published by the voidness of space have been caused Association Pro ISSI by tiny unbalances, which seem once or twice a year very unlikely a priori. Recent results of space research tell us a

story of unlikely events. INTERNATIONAL SPACE SCIENCE This fascinating history of our INSTITUTE universe was the subject of the key Association Pro ISSI note address by Professor Gustav Hallerstrasse 6,CH-3012 Berne Andreas Tammann,Director of the Phone ++41 31 631 48 96 Institute for Astronomy of the Fax ++41 31 631 48 97 University of Basle on the occa- sion of the third anniversary of President the International Space Science Prof.Hermann Debrunner, Institute on the 27th of November University of Berne 1998. Publisher Dr.Hansjörg Schlaepfer, It is with greatest pleasure that we Contraves Space,Zurich devote this issue to Professor Layout Tammann, who has actively con- Gian-Reto Roth, tributed to the understanding of Contraves Space,Zurich our universe over the past 40 years. Printing Drucklade AG,CH-8008 Zurich

Hansjörg Schlaepfer Berne,May 1999

Front cover Rings of glowing gas encircling the supernova 1987A. (Hubble Space Telescope, NASA/ ESA,February 2,1994)

SPATIUM 3 2 Birth,Age and the Future of the Universe

G.A.Tammann, Director, Institute for Astronomy, University of Basle Key note address at the third anniversary of the International Space Science Institute, November 27,1998

The sciences have fundamentally For thousands of years the human is gained, a new paradigm is born. changed the views of our world life has been an interval of 40 years These are the great discoveries during this Century. They have of suffering of hunger and freez- which influence our understand- brought a cultural revolution by ing. Science has doubled its length ing, thinking, and culture. affecting technology,medicine,civil- and it is now expected to be pain- isation and, perhaps most impor- less, comfortable and pleasurable. A few examples will be given in tantly, the thinking of men. At the end of this century man the following from the realm of finds himself in a world which has astronomy. They are to illustrate Man has explained the origin of all been fundamentally changed by how the scientist works on a life, i.e. the energy source of the the sciences from what it was gigantic mosaic that suddenly Sun which had remained a total at the beginning of the Century, reveals a face or contour. mystery up to 1930. He has estab- – and not only the world has lished a worldwide net of commu- changed but also man himself, nication and transportation such – and were it just in physical size. that he partakes almost instantly in occurrences all over the world. It may seem surprising that this Humans have left the Earth’s grav- radical change has been brought ity field and have seen that the about by the sciences which are Earth is round. The Moon has believed to progress step by step by been occupied – so far temporarily a painstaking method dominated – by men and the planets have by mathematical logic and bare of been visited by spacecraft. The fantasy.While it is true that all sci- triumph of rational thinking has ences proceed in minute steps, it even brought an unprecedented happens once in a while that the 50-year period of peace in Western understanding jumps suddenly on Europe. a higher level. A broader insight

Lines from galaxies Lines from Earth atmosphere

Figure 1. The spectra of 16 galaxies.They are perfectly aligned as seen from the lines originating in the Earth’s atmosphere. However, the galaxy lines (originating from different chemical elements) are progressively shifted toward the red.This redshift effect is caused by the expansion of space stretching the light to longer wavelength. The different redshifts correspond here to recession velocities of 3000–16,000 km s –1. (From P.Stein, Basle).

SPATIUM 3 3 The expanding Universe

In 1912 Vesto M. Slipher took the first spectra of what was then called spiral “nebulae” (now known to be galaxies). It was a tedious process with small telescopes and slow emulsions. He found the spectral lines shifted toward the red (Figure 1) and he Figure 3. A yeast cake as a model for the expanding Universe. As the cake increases in concluded correctly that the size the distances between the raisins become larger. Close raisins get separated by small objects were hence receding from (absolute) amounts, distant raisins by large amounts.The aspect is the same for all raisins. us, – yet faster than any known star (Neglect the rim).The model has the disadvantage that one can oversee it instantaneously while the concept of simultaneity fails in the Universe (see page 5). in our Galaxy.The large recession velocities became a puzzle which many astronomers tried to solve. Finally Edwin Hubble, after hav- also that their velocities were pro- cluded that the whole Universe ing proved in 1925 that the “nebu- portional to their distances! (Figure was expanding like a yeast cake lae” are distant galaxies, consisting 2) The picture was like that any and that there must have been a of hundredthousand million stars raisin has in a growing yeast cake: time where the Universe was arbi- like our Milky Way, realised in all other raisins are moving away trarily small. The Universe had a 1929 that not only (almost) all and the faster the further away beginning, now known as the Big galaxies move away from us but they are (Figure 3). Hubble con- Bang!

In the last seventy years the Big ]

1 Bang has become a physical fact. – The most distant galaxies have Distance 100.000 redshifts corresponding to almost the speed of light. Several inde- pendent experiments prove beyond 30.000 doubt that the young Universe Recession velocity [km s must have been tiny, extremely dense, and excessively hot. 10.000

The expansion of the Universe gives us a simple tool to determine bright Apparent Magnitude faint bright Apparent Magnitude faint its age. At a very early epoch all Figure 2.The demonstration of the linear expansion of the Universe. Left: Standard can- galaxies (or the matter or energy dles (e.g. 60 W light bulbs) get fainter as the distance increases. Right: The brightest they were later made of ) were galaxies in clusters of galaxies are good standard candles (note the relatively small scat- compressed in one place. When ter!). As they get fainter they must be more distant, but at the same time their recession velocities increase. (Linear expansion requires in this logarithmic plot a slope of 0.2, the expansion began some were which is shown). slowly carried away; they are today

SPATIUM 3 4 our neighbors. Others were car- travelling through space cannot by our yeast cake: not the raisins ried away with high speed; they be correct. In reality space expands move apart, but the dough ex- populate now our horizon.All had and carries the galaxies along. pands and increases the distances the same travel time, i.e. the age This is perfectly reasonable with between the raisins. of the Universe. Therefore one Einstein and is again exemplified must determine “only” the distance to one galaxy – or much better to many galaxies, which is technically not easy (Figure 4) – and divide this distance by the recession velocity.The result is nothing else but the expansion age of the Universe.

Measured redshifts and the corresponding recession velocities plus the best distance determinations give an expansion age of 14 (±2) Gigayears (1 Gigayear = 1000 million years). This time may appear long, but when one realizes that life began 3 Gigayears ago,that the oldest rocks on Earth have an age of almost 4 Gigayears, and that the oldest stars in our Galaxy were formed 12 Gigayears ago,one cannot but be impressed by the youth of the Universe. Imagine you take a very old rock in Greenland into your hand and it has almost one third of the Universe’s age!

The expanding Universe revises in several ways our thinking. For instance, the fact that all galaxies are receding from us makes us falsely believe that the Big Bang has taken place here. In reality any galaxy, like any raisin in the yeast cake, sees all other galaxies (raisins) in recession. There is no preferred, absolute point in the Universe. Our thinking is unjusti- Figure 4.The Hubble Space Telescope has a mirror of “only” 2.5 m diameter, but since it fiably egocentric.After some more orbits the Earth above the atmosphere it provides exceptionally sharp images. It has thought (concerning the “edge” greatly helped to determine galaxy distances and hence to determine the expansion age of the Universe.The telescope was built and is operated by NASA with a 15% share of the problem of the Universe) one European Space Agency (ESA).The telescope is here docked to the Space Shuttle during realizes that the picture of galaxies a repair mission involving the Swiss astronaute Claude Nicollier.

SPATIUM 3 5 Evolution stituents annihilate each other to form energy again. It therefore in the Universe seems that the Universe cannot ever create lasting matter. How- ever, there is a very slight unbalance favoring matter over antimatter. The excess of newly created Still hundred years ago there was matter is only one part in 2000 an embittered debate between million.The bulk of all matter has creationists and evolutionists. Did actually been annihilated. Only God create the world as we see the tiny excess matter has survived it today? Were the large erratic and is nowadays what we see as blocks placed by him into the matter. The unbalance between midst of green meadows,or where matter and antimatter is called the they transported there by the ice? symmetry breaking; it is still not Do the fossils give clues to the fully understood. And yet it is evolution of life, or did God make decisive for our existence. the rocks including the fossils? But as correct as the evolutionists Hundred seconds after the Big were, they could not answer the Bang the temperature had dropped question where evolution began. to 1000 million degrees and for the first time protons and neutrons The starting point of evolution could stick together to form the became clear only with the discov- most simple elements, deuterium ery of the Big Bang.At the begin- and helium and traces of lithium. ning,an unthinkably small fraction Theory predicts that 24 percent of of a second after the Big Bang, all matter was transformed into the Universe was unmeasurably helium, and it is a triumph for Big hot and it contained nothing but Bang theory that one has never immensely condensed energy.As it found a gas cloud in our Galaxy expanded and cooled the energy or other galaxies with less than transformed into matter, first this amount of helium. Also the into exotic, short-lived particles, observed abundances of deuteri- 1 then at an age of /10,000 seconds um and lithium agree well with into protons and neutrons, i.e. the theory.The chemical composition matter we know today. At that time the temperature had fallen to a few times 1012 degrees and Figure 5. A part of the large “Lagoon Nebula” in our Galaxy (here about 1 the density had decreased to 1000 lightyear x 1 lightyear).The bright hot star million tons per thimbleful. in the lower right ionizes and excetes atoms of sulphur, oxygen, and hydrogen which radiate at different wavelengths The creation of matter is no trivial (here in false colors red, blue, and green, thing. When one produces matter respectively). The heated gas is in torna- from energy in the great particle do-like turbulence and triggers star for- accelerators, e.g. at CERN, equal mation in the surrounding cold, dark cloud of molecular gas and dust.This is a amounts of matter and antimatter typical cradle of newly born stars. (Space are produced. But the two con- Telescope Science Institute).

SPATIUM 3 6

dark and life would have become impossible. The reason that most hydrogen (protons) has survived is that the neutron is more massive than the proton by 0.14 percent. Hence more energy is required to create a neutron and there are fewer of them. When all neutrons were used up the helium production stopped. Again we realize that life hangs on a thin thread, i.e. on the tiny mass difference between the neutron and the proton.

In its early phases the Universe was very simple; one says that it was in thermodynamical equilibri- um.That means it was everywhere the same. The whole Universe could be fully described by a few numbers. One might now expect that the expanding Uni- verse would just cool and thin out. Nothing interesting would ever happen.

The opposite is the case. That is, the Universe formed structures. There were regions where by chance more matter was than at others. In these dense regions gravity had its way to locally slow Figure 6. Structure formation has produced galaxies like this beautiful spiral (NGC down the expansion and even 1232).The Milky Way seen from outside would offer a similar view.(Picture taken by the to reverse it into a contraction. European Southern Observatory, ESO). Gigantic, contracting clouds of hydrogen (and helium) were of these gas clouds is telling The “primordial nucleosynthesis” formed, which fractionated into because they have yet experienced of the lightest elements raises a smaller, still contracting clouds. little chemical mixing and they fundamental question. Why was The latter evolved into what we reflect still today the primordial not all matter transformed into see today as galaxies (Figure 6).The composition.The relevance of the helium? In that case all “fuel” for galaxies had spun up during their abundances of the lightest ele- later stars (which shine because contraction, and their rotation ments for cosmology was first they convert hydrogen [protons] protected them from further col- recognized at the University of into helium in their interior) lapse. But individual cloudlets, still Berne, and it is still an important would have been exhausted early with thousands of solar masses, research topic at ISSI. on. The sky would have remained could continue to contract and

SPATIUM 3 8 form stars. The formation of stars is an ongoing process in galaxies (Figure 5). New stars are born and old stars die continuously until all gas is used up. Some galaxies have already exhausted their gas supply; our Galaxy can still go on for a long time.

A contracting star heats up until its interior has reached a temperature of a few million degrees. At this moment a hydrogen bomb is ignit- ed and hydrogen is fused into helium, a process which releases enormous amounts of energy.The energy protects the star against further contraction and lets the Figure 7. The Planetary Nebula in the constellation Lyra.The faint central star has lost star shine. In the case of the Sun its envelope which is enriched by the chemical elements formed during the lifetime of this energy is also the basis of all the star. The central star is only the left-over nucleus with a surface temperature of 120,000 degrees. It is going to become a White Dwarf. life.

Low-mass stars die as so-called Figure 8. The remnant of the supernova 1987A in the Large Magellanic Cloud, taken seven years after explosion with the Hubble Space Telescope. Large amounts of freshly White Dwarfs (Figure 7) when they formed heavy elements are expelled into the interstellar gas of the galaxy. Pre-ejected have converted all their hydrogen matter echoes the flash of the explosion. into helium. More massive stars can then take regress to “burning” helium to carbon, oxygen and other more complex elements up to iron. The production of still more heavy elements does not release energy but costs energy. This energy can only be provided by the most massive stars when they die in the gigantic explosion of a supernova (Figure 8). It is an unfamiliar thought that the gold on our finger was once produced in a supernova explosion.

Yes, all chemical elements in the Universe and on Earth have once been produced in stars.When stars die they eject part of their mass, either peacefully as a Planetary Nebula or explosively in a supernova. In this way some of the chemically processed material The conclusion is that the chemi- Bang. Computer models fail to comes back into the interstellar cal variety on Earth is possible form structures in so short an gas. Newly forming stars are in this only because previous generations interval, unless one assumes that way “contaminated” with carbon, of stars have produced all elements, more than one half of all matter is oxygen, iron etc. When our Solar except the primordial hydrogen not in form of protons and neu- System formed 4.6 Gigayears ago and helium.We are made of stellar trons,but is “exotic”.This so-called all 92 elements were already pres- material. Dark Matter consists of unknown ent (Figure 9). This was possible particles with unknown proper- only because the most massive, The most puzzling point of this ties, but it seems unavoidable to chemically most productive stars story is that the formation of explain structure formation. Great are paradoxically quite short-lived, structures (galaxies and stars) went efforts are presently undertaken to and most elements were actually so fast. The oldest stars in our detect this elusive form of matter. built up long before the Solar Galaxy have ages of 12 Giga- There are still things in the System isolated itself from the years,i.e. they were formed within Universe we only can dream of. interstellar gas. the first 2 Gigayears after the Big

Stars born on the Milky Way Stars bornper year on the Milky Way Epoch of galaxy formation Formation of the Sun Plants on Earth Dinosaures First Men per year 50

0 today Big Bang 10 Gigayears 3.3 Gigayears 6.6 Gigayears

Figure 9. The star formation rate in the Milky Way in function of time. Most stars were formed about 3 Gigayears after the Big Bang. When the Solar System, including the Earth, was formed about 5.4 Gigayears later, all 92 chemical elements had already been formed in stars and expelled into the interstellar gas.This explains why the Earth is relatively rich in processed material. (From M.Samland, Basle).

SPATIUM 3 10 The Astronomer hoped to find in this way a perfect We know today that the speed clock which would have been of of light is c = 300,000 km s–1 and, as Perfect upmost practical importance for according to Einstein, that this is navigation.Yet he noticed irregu- the largest velocity possible be- Historian larities: the predicted occurrences cause the light particles (photons) happened sometimes too early or have zero rest mass. Any particle too late by several tens of minutes. with mass can travel only slower. The puzzle was solved by Olaus In particular this means also that Römer in 1677 who realized that no signal can be transmitted faster In the 1660’s G.D.Cassini observed the occultations occurred early than with the speed of light. in Paris night for night the four when Jupiter was relatively close (So-called phase velocities,e.g. the Galilean moons of Jupiter as they to the Earth and late when the movement of a shadow,can exceed revolved around the planet and planet was distant.This led him to c, but they involve neither mass disappeared and reappeared be- one of the most fundamental dis- motion nor signal transmission). hind or in front of the planet’s coveries of the millennium, i.e. the disk. As Galilei before him he speed of light is finite.

Figure 10.The Very Large Telescope of the European Southern Observatory (ESO) in the Atacama Desert in Chile where the observing conditions are optimal.With four 8 m-telescopes it will be the largest telescope in the world.The first 8 m-telescope is already success- fully working.A major goal is to study the most distant (i.e. youngest) galaxies during the formation process.

SPATIUM 3 11 Within human dimensions light as they are today. Here theory radiation’s wavelength must have travels almost infinitely fast. But jumps in. One assumes as a first been stretched by the same factor over cosmic distances light is a step that one has observed a time such that – as predicted by G. slow messenger. It takes 8 min- series and then checks with more Gamow in 1946 – it must now lie utes from the Sun to the Earth, and more sophisticated computer in the mm wavelength region.The 4 hours from Pluto, 10,000 years models, always maintaining the actual observation of the so-called from a distant star in our Galaxy, universality of the laws of physics, “Cosmic Microwave Background” and one million years from our whether the information from (CMB) with a radio telescope by nearest large neighbor galaxy, the the young Universe does indeed A. Penzias and R.Wilson in 1965 Andromeda nebula. The light of lead to the present (nearby) is considered as the definite proof the most distant known galaxies Universe.With gigantic computers for a once very hot and tiny takes more than 10,000 million this process can be carried now Universe, and the discoverers were years! to such detail that there is no accordingly awarded the Nobel doubt that the observed differ- Prize. This implies immediately that we ences between “out there” and can never have an instantaneous “here” are simply due to evolution. The CMB radiation not only sup- picture of the World.The informa- ports the Big Bang Universe, but tion we receive here and now is If one looks into extremely large also shows minute temperature staggered in time according to dis- distances one will see no more variations from one place in the tance. Any object in the Universe galaxies because the look-back sky to another. These fluctuations gives us information about the time brings the observer back into are the very early seeds of the appearance it had when it emitted an epoch before structure forma- subsequent structure formation. the light we receive today. The tion when the stars had not yet The smallness of the fluctuations is time interval between light emis- lit up and the Universe was still the most dramatic demonstration sion at the object and reception dark. The observational proof of of evolution in the Universe, be- on Earth is obviously just the this distant cutoff of galaxies seems cause they reveal that the Universe (distance-dependent) light travel presently at hand. at an age of 500,000 years was time. Looking at (very) distant almost structureless and has since galaxies means therefore to in- There is, however, one still earlier mysteriously evolved to ever high- vestigate (very) young galaxies.The source of radiation which can be er complexity. evolution of galaxies can therefore observed today. It comes from a directly be observed. time, barely 500,000 years after Although electromagnetic radia- the Big Bang, when the entire tion cannot bring us information The enormous progress in the Universe was a single “primordial from still earlier epochs, there construction of modern telescopes fireball” with a temperature of are other ways to investigate the in space and on the ground (Figures 3000 degrees. At this temperature young Universe. The primordial 4 and 10) is therefore driven not the Universe became transparent nucleo-synthesis 100 seconds after only by the aim to use them as for the first time, because the the Big Bang has already been “space ships”, bringing distant free electrons, which had made it mentioned. Theory supported by objects closer to the observer, but opaque, could now take their direct experiments at CERN, can also as “time ships”, bringing past places around the protons. Once describe the Universe back to events into the present. the Universe was transparent, the an age of 10–10 seconds. Then one glow of the primordial fireball depends on certain observed The unique ability of the could not vanish and it must still boundary conditions and our astronomer to observe the past is fill the present Universe. Yet the knowledge becomes more and not a free ride. The prize is that Universe has expanded since by more speculative with every factor he cannot observe distant objects a factor of about 1000 and the of 10 one goes back in time. At

SPATIUM 3 12 an age of 10–42 seconds our under- Figure 11. The so-called Einstein Cross. standing of physics breaks down, It shows in the center a galaxy which acts as a gravitational lens.The four surround- because General Relativity and ing images come from one quasar in the Quantum Physics have to be background.As the quasar varies in lumi- applied simultaneously, which is nosity the four images react at different still impossible. Even if this barrier times (!) because the light paths differ by some light-days (i.e. several 25,000 mil- will eventually be overcome there lion km). is no hope to ever describe the time zero. The Big Bang itself will always remain hypothetical.

SPATIUM 3 13 The Concept of In addition time is uniform only are impressive demonstrations of for an observer who travels with Einstein’s prediction that light rays Time constant speed through space. Any are deflected by gravity.Therefore acceleration will change his clock light propagates through space rate.Consequently there are hardly along curved lines. But since noth- any two observers in the Cosmos ing is more straight than a light ray, In daily life one has a rather unre- who have the same clock rate. In our believe in the existence of alistic concept of time. Time is our technical age this relativistic straight lines is also a misconcept. considered as connecting the past effect has already practical conse- eternity with the future eternity quences. Clocks on satellites orbit- In principle the entire space could in uniform steps. In reality time ing the Earth run slightly differ- be positively curved, flat, or nega- began at zero in the Big Bang. ently than on the ground. If this tively curved. Even if space is flat, There was no time before the Big difference was not accounted for as presently believed,the existence Bang, and the question what was communication with these satel- of structures and the accompany- before the Big Bang has for the lites would soon be lost.This leads ing variations of the gravity field, physicist no meaning. Whether, also to the famous “twin paradox- force every light ray on a curved on the other hand, time will lead on” which requires that a twin path. into a future eternity depends on travelling fast through space will whether the cosmic expansion will return younger than his brother eventually be halted, in which case left on the ground. the Universe will collapse under its own gravity into the “Big The variability of the clock rates Crunch” and this would also be implies immediately that the idea the end of time, or whether it will of simultaneity is a misconcept. expand forever. Astronomers be- A stunning example is the Einstein lieve there is not enough matter Cross (Figure 11), where the grav- in the Universe (including the ity field of a foreground galaxy Figure 12. All the blue images in the picture come from the same galaxy or from above-mentioned Dark Matter) bends the light rays of a distant parts of it. In about half the galaxy’s dis- to ever halt the expansion. This quasar (i.e. a particularly luminous tance is a large cluster of galaxies whose believe was strengthened in 1998 galaxy) such that the same quasar tremendous gravitational field bends the light and causes the multiple, distorted when rather strong evidence was is seen four times! Quasars have images of the background galaxy. (Picture found for a fifth force in the variable luminosities and the four taken with the Hubble Space Telescope). Universe (Einstein’s so-called images vary accordingly in bright- “Cosmological Constant”) which ness. However, the four light paths drives the Universe into an accel- differ somewhat in length, and as erated expansion. It would corre- a consequence a given luminosity spond in the yeast cake to an outbreak of the quasar is observed increasing power of the yeast. in the four images at different Therefore the view is favored that times! If the Einstein Cross was a the Universe will expand forever prominent object in the sky this and time will never come to an would have been noticed long ago end. It is, however, imprudent to and the concept of simultaneity extrapolate our limited knowledge would never have been born. into eternity, and one should say more carefully that the Universe is In addition to the Einstein Cross likely to expand into a very distant many other gravitational lenses are future. known today (Figure 12). They all

SPATIUM 3 14 Epilogue to do with reality. Apparent facts assume that the present World and like the absoluteness of time or the present man are the end product existence of straight lines are erro- of evolution. In reality evolution neous. On the other hand specula- must continue.In 100,000 years we tions about a single creation event will not recognise our descen- The few examples from the field and subsequent evolution are fac- dants, and in say 50 Gigayears the of astronomy show that our think- tual. last star will extinguish and thus ing is fundamentally influenced by terminate all possibility for life. science. Nature is infinitely more It is here the place still to counter Organic life, which we value so complex than conceived in daily another misconcept. We have highly,is nothing but an intermez- life. The human mind tends to today not much difficulty to zo in the evolution of the extrapolate daily experiences into accept the fact of evolution. But Universe. natural laws which have nothing we make easily the mistake to

SPATIUM 3 15 SPATIUM

The author

Gustav Andreas Tammann,born in became Director of the Astro- Göttingen on the 13th of June in nomical Institute. In these years, 1932,spent his early years in Basle, G. A. Tammann began with fur- where he attended the schools and thering scientific activities in then registered at the University Switzerland. Among many other of Basle in astronomy.Indeed, this honours, he was elected scientific proved to be a wise decision. On representative in the European one hand, the old humanist tradi- Space Agency’s Science Pro- tion of this University provided gramme Committee and Chair- G.A.Tammann with essential cul- man of the Swiss Committee of tural ingredients. On the other, it Space Research. In both functions, was the key to a field of science he followed Professor Johannes which was due to bring forth Geiss. When it came to decide many spectacular discoveries in on the Swiss membership to the the years to come. Further study European Southern Observatory, years saw him in Freiburg i. Br., it was up to J. Geiss and G. A. Göttingen and Basle again, where, Tammann to develop the neces- in 1961, he acquired the Dr. phil sary lobbying activities. degree. G.A.Tammann is not only a won- In 1963,the great American astro- derful teacher, but also an out- nomer Professor Allan Sundage standing communicator to the offered G.A.Tammann the oppor- public at large. In countless inter- tunity to join his research team views on radio and television but in the frame of a post-doctoral also in many articles, he reported employment in Pasadena (USA) on the findings of modern astron- introducing him into the research omy. of the extragalactic Universe.The focus of research was on the de- A curriculum of G. A. Tammann termination of extragalactic dis- would not be complete if one tances and the expansion of the would not brieﬂy mention his Universe. This subject, and the interests outside the boundaries of still lasting friendship with Allan natural sciences: music,history and Sandage, are among the most art. Classical humanistic tradition important cornerstones of his stay and the paradigms of modern in Pasadena. In 1972, he returned scientific research have been the to Europe and was appointed Pro- grounds allowing G. A. Tammann fessor of Astronomy in Hamburg to grow to one of this country’s and in 1977 in Basle, where he best-known scientists.