Table of Contents
Why can we see 46 billion light years?
The universe is about 13.8 billion years old, so any light we see has to have been travelling for 13.8 billion years or less – we call this the ‘observable universe’. However, the distance to the edge of the observable universe is about 46 billion light years because the universe is expanding all of the time.
How can the universe be bigger than its age?
This can happen in strong gravitational potentials, or in, say, an expanding universe. So yes, objects in the Universe can travel faster than c away from us due to the expansion of the Universe, and the Universe itself can be much larger than expected given its age and the speed of light.
Is the Universe 155 billion years old?
The Universe is 13.7 billion years old. About five billion years ago, an energy field that we call dark energy became important. Dark energy is a repulsive form of gravity, which means that the expansion of the universe isn’t slowing down, it’s accelerating.
How many light-years is 13.8 billion years?
46.1 billion light-years
And today, 13.8 billion years after the Big Bang, the farthest thing we could possibly see, corresponding to the light emitted at the first moment of the Big Bang, is 46.1 billion light-years distant. Given the contents of our Universe, it couldn’t have turned out any other way.
Why did primordial nucleosynthesis stop?
By the time the Universe had cooled to a temperature of about 3 × 108 K after 1000 s, the particles had insufficient energy to undergo any more reactions. The era of primordial nucleosynthesis was at an end, and the proportion of the various light elements was fixed.
How big is the universe?
You might think, in a Universe limited by the speed of light, that would be 13.8 billion light years: the age of the Universe multiplied by the speed of light. But 13.8 billion light years is far too small to be the right answer. In actuality, we can see for 46 billion light years in all directions, for a total diameter of 92 billion light years.
Is 92 billion light years big enough?
And so 92 billion light years might seem like a large number for a 13.8 billion year old Universe, but it’s the right number for the Universe we have today, full of matter, radiation, dark energy, and obeying the laws of General Relativity.
How old is the universe?
You might think, in a Universe limited by the speed of light, that would be 13.8 billion light years: the age of the Universe multiplied by the speed of light. But 13.8 billion light years is far too small to be the right answer.
What is the radius of the observable universe?
Since the radius of the observable universe is defined by the greatest distance from which light would have had time to reach us since the Big Bang, you might think that it would lie at a distance of only 14 billion light years, since x = c t for motion at a constant velocity c. However, a relation like x = c t is only valid in special relativity.