Imagine yourself on a boat on a small land just beyond the ocean, in a large ocean, to the far horizon. In the morning, a dense fog settled just before the dawn and along the coast. Chill, when you're in your early hour, a lighthouse from the corner of your eye, shaky through the fog.
And – yes – there! Another lighthouse, closer, the light a little stronger. More lighthouses when horizon runs, points out the dangers of distant shores.
You know this coastline, we return to the same port every year. You can know that the lanterns are made by the same production and have the same brightness maintained throughout the same year in good working order.
And so spend some time playing games. In consultation with your graphics, you know the distance to each lighthouse and how far their light goes to reach your trapped eyes. However, the light, bright and gleaming light of an open evening is constantly darkened and shaded by the mist. You know how bright they are ought You can compare this brightness with what you see when examining layers and fog layers to predict how much fog has shaken the shoreline.
It's not like there's anything better to do.
This is the procedure astronomers use recently to measure the total amount of light in the universe – of course, fog and lighthouses and salt sailors.
Our cosmic lanterns are active galaxies, the most powerful engines in the universe. Here, the substance flowing into the gigantic black holes, such as grasping, pinching and heating in the flame of radiation, before being swallowed with the event horizon. In their death, these rotating, cluttered gas piles emit more energy than millions of galaxies and pump their light through the universe.
When they are caught in the young cosmos, they appear to us as shimmering, but distant lighthouses.
Among these lanterns and telescopes thing In the universe. Most of the universe is empty empty, but filling these gaps is the accumulated light from all the star generations that have lived and died since the distant ages;
The radiation from the distant active galaxies is extremely high energy – given the strong nature of its sources, there is no surprise. And when this high-energy light explodes in the universe, it encounters the fine mist. Chance interaction, random collision as a result of random collision, high-energy radiation loses energy and scatter.
By examining the light from more than 700 active galaxies, astronomers were able to predict all the light throughout the universe and through all the star stars, just after the first stars, during the cosmic time, just 500 million years after the big explosion. near to present day. Rough count? 4 × 10 ^ 84 photons, this is very 4.
This prediction is in agreement with the other calculations of the so-called extra-galactic background light, but it is buried in the last observation, and the others are disturbing finding: our universe is dying.
By comparing the light from different active galaxies placed at different distances from us, astronomers cannot only calculate the total amount of starlight generated, but also follow the midwives and flows of this starlight throughout the billions of years of cosmic history.
And the terrible news is that the lights come out one by one. As far as we can understand, through our various observations and predictions, our universe reached its peak in star formation when it was 9 billion years ago, when it was only a quarter of the current age of the cosmos.
The exact reason still encourages us. Undoubtedly, our expanding universe has something to do with it – galaxies are moving apart on average, resulting in less mergers and less fresh material flowing into the galaxies, which can turn into new stars. But why did it take so long? Why did star formation decrease so fast? Or, perhaps, why have they continued so long despite the collapse of the great empire?
Difficult questions without easy answers. For now, at least we're still in the fog.
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