2. The horizon problem. Our universe was extremely homogeneous, and the temperature of the background radiation is the same everywhere you look. The fact that the temperature is uniform would not be surprising were it not that between the two ends of the universe is a distance of nearly 2,800 million light years, while the age of Universe is 'only' about 1,400 million years. Given that nothing can travel faster than the speed of light and the hypothesis that there was an initial time or big bang, the question is: ycomo regions may physically disconnected from the "beginning" of the universe were in physical states so similar? This is what is known as the 'horizon problem', one of the biggest headaches of cosmologists, who are unable to find the solution. 3. Ultra-energetic cosmic rays Cosmic rays are particles that arrive from space and constantly bombard Earth from all directions. Most of these particles are nuclei of atoms or electrons.

Some are more energetic than any other particle observed in nature. The mystery is in its high energy. The special theory of relativity Einstein said that any cosmic rays reaching the Earth from outside our galaxy will have suffered many collisions that maximum possible energy that can have is 5 to-1019 eV. Rays detected from a decade ago by the Akeno observatory Japanese are well above this threshold, thereby or data-taken at different times and bad, are always similar, or Einstein was wrong. 4. The results of homeopathy in Belfast in 1810 the German physician Christian Friedrich Samuel Hahnemann published the "Organon, the art of healing", the cornerstone of homeopathy.