It was created more than 13 billion years ago as a hot, super-dense expanding point. From that moment, the Universe has been constantly expanding, while the galaxies filling it today are moving away from each other. The Big Bang theory describing this phenomenon has already lived through many dramatic turns. The last time was 13 years ago, when two American research teams reported new facts about the rate of cosmic expansion, who were awarded with the Nobel Prize precisely now. Before their measurements, cosmologists were sure of at least one thing: the Universe is expanding increasingly slowly, because, after all, the objects which are drifting apart from each other are being slowed by gravity which is attracting them to each other.
Saul Perlmutter’s team and the (independent) group managed by Brian P. Schmidt, with Adam G. Riess’ involvement, observed galaxies from which light had been travelling towards us for over 6 billion years. Because of this gigantic distance, they could observe them as they were 6 billion years ago and hence when the Universe was almost half its age today. After analysing the results of the observations, to the huge surprise of the researchers, it transpired that the Universe had been expanding more slowly earlier, wheras now - contrary to previous hypotheses - the expansion is accelerating. But why? Not only do physicists not know the answer to that question, but they simply do not have any idea where it could be found. This is probably the most serious challenge set for basic natural science. The researchers from both groups - today’s Nobel Prize winners - received the Prize not for a great theory and the convincing explanation of the facts, but for a gigantic, fascinating mystery.
More information can be obtained, even today, during the shows at our planetarium.
Comment by Professor Turski – Chairman of the Programme Council of Copernicus Science Centre, on this year’s Nobel Prize in Physics
Physics is the science that attempts to describe our Universe in all dimensions and aspects. Almost one hundred years ago, Albert Einstein gave us a tool for this description, by formulating his General Theory of Relativity. In accordance with this theory, between the geometry of the Universe (a four-dimensional one) and matter in the Universe there is the relation described by one of the most beautiful mathematical physics equations – Einstein’s equations. To put it as simply as possible: in accordance with these equations, the geometry of the Universe (its spacetime) interacts with matter in the Universe, in such way that this spacetime is being curved by matter. While climbing the stairs, everybody “experiences” this curvature, while overcoming the phenomenon, referred to as gravitation by Newton – a crucial forerunner of Einstein. Predictions resulting from these equations have been confirmed by many great experiments and they are employed to the benefit of users of even the simplest GPS device in a car, on a boat or when picking mushroom in the fall. The beauty of Einstein’s equations and the General Theory of Relativity stems also from the fact that some limitations are imposed on the relation between matter and geometry, allowing presenting this relation in the most general form. Einstein himself presented such relation, but after some time he considered one of its elements, referred to as cosmological constant, as inconsistent with physics (although consistent with geometry). He even referred to it as the “biggest blunder” of his life.
The expansion of the Universe is the consequence of the General Theory of Relativity. We are aware of this expansion since 1925, as a result of observations by Edwin Hubble, later confirmed with high precision by several experiments, including the experiments conducting using the space telescope named after Hubble. The universe has been continuously expanding since the Big Bang – a mysterious phenomenon that created spacetime and matter.
This expansion started to pose some problems, when a dozen or so years ago, research teams of Saul Perlmutter, Brian Schmidt and Adam Riess, based on specific features of explosions resulting in formation of type Ia supernova, discovered that the expansion of the Universe is faster than predictions resulting from Einstein’s equations WITHOUT cosmological constant. In order to explain this phenomenon, physicians introduced the concept of “dark energy”, making up as much as 75% of the mass of the Universe; we know almost nothing of this force, but it influences the whole Universe.
When commenting the Nobel Prize, Brian Schmidt emphasised that Einstain’s cosmological constant is what describes the impact of “dark energy" in his and his colleagues’ experiments. The General Theory of Relativity prevailed again, but we still do not know what is the “thing” which makes Einstein’s constant different from zero. Certainly it was not Albert’s biggest blunder.
This year’s Nobel Prize for Perlmutter, Riess and Schmidt has proved that big things are happening in the science. Our eyes replaced by telescopes and our hands replaced by space probes robots are reaching more and more distant regions of the Universe. By these experiments we uncover the first veil covering its secrets. Further veils will follow. Talent, perseverance in work, courage in thinking, unintended mistake acceptance, modesty in the face of the secret referred to as the Universe – are the features of the life and work of laureates. In those days of the celebration of the rationally thinking world (we already had an opportunity to admire successes of laureates of Nobel Prize in medicine and chemistry, and are awarding the announcements in literature, economic sciences and, ultimately, peace), it is worthwhile to give some thought to what the great phenomenon science is and what the world would be if we were eager to discuss problems of the Earth, the scale of which is really small compared to “dark energy”, as seriously as today’s laureates discuss the “biggest blunder” of Albert Einstein’s life.