Minute Physics
#AstronomyTermOfTheDay @MinutePhysics
Astronomy Term of the Day
Suppose a person looks into the sky in West direction, 10 billion light years away and after that 10 billion light years away in the exactly opposite direction. He will observe that the universe is homogeneous. The cosmic background temperature is same. But the distance between the two points is 20 billion light years. So information from one end will take 20 billion years to reach the other end. Since the universe is 13 billion years old, to us it seems that the two ends were never in contact. Then how come they are similar? Homogeneous? That's an overview of the horizon problem.
The solution proposed is the inflation. The two parts were indeed in contact with each other after the big bang. In the inflationary epoch, the universe expanded exponentially, at a rate greater than speed of light for a few moments. Thus to us it seems, after 13 billion years, that they were never in contact.
The exact particle physics of inflation is unknown. It was proposed by Alan Guth.
Some Physicists place Inflation after the GUT epoch while others place it after the Electroweak epoch.
Suppose a person looks into the sky in West direction, 10 billion light years away and after that 10 billion light years away in the exactly opposite direction. He will observe that the universe is homogeneous. The cosmic background temperature is same. But the distance between the two points is 20 billion light years. So information from one end will take 20 billion years to reach the other end. Since the universe is 13 billion years old, to us it seems that the two ends were never in contact. Then how come they are similar? Homogeneous? That's an overview of the horizon problem.
The solution proposed is the inflation. The two parts were indeed in contact with each other after the big bang. In the inflationary epoch, the universe expanded exponentially, at a rate greater than speed of light for a few moments. Thus to us it seems, after 13 billion years, that they were never in contact.
The exact particle physics of inflation is unknown. It was proposed by Alan Guth.
Some Physicists place Inflation after the GUT epoch while others place it after the Electroweak epoch.