If the black holes are perhaps the most mysterious objects in the universe, and so much so that the American astronomer Carl Sagan defines them as being "similar to the smile of the cat in Alice in Wonderland, enormous stars which have closed their eyes but are still there", there is a last category of objects which has such amazing characteristics that they border on the incredible. Discovered around the middle of the Seventies, they are very far away and just as heavy as a galaxy but brighter and with a point-like form: astronomers have called them quasars, i.e. quasi-stellar objects. Their nucleus, with a diameter of about 2 light months, appears to be surrounded by a gaseous layer that extends like an irregular and filament-like atmosphere up to at least 3 000 light years from the center. Sometime this shell is also surrounded by a corona of very low density but high energy particles, which emit radio waves: when the corona is absent, the quasar is radio inactive. But what are these objects for which, according to calculations by astronomers, there must be about ten million in the entire universe? Many different theories have been developed, but the most fascinating one is the hypothesis that states that the quasars represent the evolutionary phase immediately prior to the formation of the galaxies. In fact, as we gaze farther and farther away in the universe, we find that the number of galaxies tends to decrease, while the number of quasars tends to increase; however, even farther away, the quasars also finally disappear. Since these variations occur in time and not in space, this means that the farthest quasars, which are about ten billion light years away, are the oldest objects that we can observe. Beyond the quasars or, which is the same, "before" the quasars, is the unknown: as we enter the region where even the quasars disappear we get closer and closer to the origin, when the mixture of hydrogen and helium still did not exist and the universe was completely different from the one we know today. Today, we are on the verge of lifting the last veil: all hope has been placed in the orbiting telescopes which, from an altitude of 500 kilometers from the surface of the Earth, will not be "blurred" by the shield of the atmosphere. In the next few years, these new eyes in the sky perhaps will provide us with that which today is beyond our capabilities: the sphere of primeval fire that represents the last frontier of space and time.
If the black holes are perhaps the most mysterious objects in the universe, and so much so that the American astronomer Carl Sagan defines them as being "similar to the smile of the cat in Alice in Wonderland, enormous stars which have closed their eyes but are still there", there is a last category of objects which has such amazing characteristics that they border on the incredible. Discovered around the middle of the Seventies, they are very far away and just as heavy as a galaxy but brighter and with a point-like form: astronomers have called them quasars, i.e. quasi-stellar objects. Their nucleus, with a diameter of about 2 light months, appears to be surrounded by a gaseous layer that extends like an irregular and filament-like atmosphere up to at least 3 000 light years from the center. Sometime this shell is also surrounded by a corona of very low density but high energy particles, which emit radio waves: when the corona is absent, the quasar is radio inactive. But what are these objects for which, according to calculations by astronomers, there must be about ten million in the entire universe? Many different theories have been developed, but the most fascinating one is the hypothesis that states that the quasars represent the evolutionary phase immediately prior to the formation of the galaxies. In fact, as we gaze farther and farther away in the universe, we find that the number of galaxies tends to decrease, while the number of quasars tends to increase; however, even farther away, the quasars also finally disappear. Since these variations occur in time and not in space, this means that the farthest quasars, which are about ten billion light years away, are the oldest objects that we can observe. Beyond the quasars or, which is the same, "before" the quasars, is the unknown: as we enter the region where even the quasars disappear we get closer and closer to the origin, when the mixture of hydrogen and helium still did not exist and the universe was completely different from the one we know today. Today, we are on the verge of lifting the last veil: all hope has been placed in the orbiting telescopes which, from an altitude of 500 kilometers from the surface of the Earth, will not be "blurred" by the shield of the atmosphere. In the next few years, these new eyes in the sky perhaps will provide us with that which today is beyond our capabilities: the sphere of primeval fire that represents the last frontier of space and time.
