Imagine yourself in a boat on a large ocean, the water extending to the far horizon, with the weakest features of land just beyond that. In the morning, before the dawn, and a thick fog settled along the coast. As the cool looks at you at your early clock, you take off the corner of your eye a light, slowly tangible through the fog.
And – yes – there! Another light, closer, its light a little stronger. While you shake the horizon, more lighters sign the dangers of the far off shore.
You know this coast, returning to the same port year after year. You know that the lights are all the same brightnesses, made of the same manufacture and kept in good work during the years.
And thus spend the time when you play a bit. By consulting your letters, you know the distance to each lighthouse, and how long their light has traveled to reach your salient eyes. But their light, shining and shining on clear evening, is diminished and shaded by the constant fog. You know how they are shining should Be it, and you can compare that brightness to what you see, looking through the layers and fog layers, to assess how foggy is inhibiting the coast.
Do not like that you have something better to do.
This is exactly the procedure astronomers have just used to measure the total amount of star in the universe – less, of course, the fog and lighthouses and salt sailors.
Our cosmic lights are the active galaxies, the most powerful motors in the universe, where it flows into huge black holes is compressed and heated, turning on radiation radiation before the event of the horizon. In these deaths these swinging, chaos crackers emit more energy than millions of galaxies, and are able to pump their light throughout the universe.
When they turn on the young cosmos, they seem like lights, glittering but far away.
Among these lights and our telescopes are all things in the universe. Most of the universe is empty, but to fill these vacuum is the accumulated light of all star generations that have lived and died because of these distant times, illuminating the cosmos in a thin and thin fog of photons.
The radiation of the distant active galaxies is extremely high energy – no surprise, given the powerful nature of its origin. And because this light of high energy is exploding through the universe, it meets that thin fog. A possible interaction of random interaction, accidental collision by accidental collision, high energy radiation loses energy and scatters.
When examining the light of more than 700 active galaxies, the team of astronomers could evaluate the whole starlight produced throughout the universe and throughout the cosmic time, after only the time of the first stars only 500 million years after the great blow up to this day. The crude calculus? 4 × 10 ^ 84 photons, what's it … a lot.
This rating coincides with other calculations of this so-called extra-galaxy background light, but buried in this last observation and others are anxious finding: our universe dies.
When compared the light of different active galaxies that we have set at different distances from us, astronomers have not been able to calculate the total amount of stellum ever produced, but also to track the plane and currents of this star for millions of years of cosmic history.
And the awful news is that the lights come out, one by one. As best as we can say, through various observations and estimations, it is that our universe has peaked in a star that formed 9 billion years ago, when the space was only a quarter of its present time.
The precise reason still leaves us. Of course, our expanding universe has something to do with it – galaxies decrease one of the others at the average, resulting in fewer fusion and less supplies of fresh material in galaxies, where they can grasp this gas into new stars. But why was the tip at that time, so long? Why did star formation decrease so fast? Or maybe why stars persisted so long, despite the collapse of their one-great empire?
Difficult questions without easy answers. At the moment, at least, we are still in the fog.
Read more: "Gamma radiation determination of the stars' history of the Universe"