What does the cosmological constant tell us about the universe?
Figure 1: The cosmological constant was originally introduced by Einstein in 1917 as a repulsive force required to keep the Universe in static equilibrium. In modern cosmology it is the leading candidate for dark energy, the cause of the acceleration of the expansion of the universe.
What is the meaning of cosmological constant?
Definition of cosmological constant : a constant term used in the relativistic equations for gravity to represent a repulsive force which may account in part for the rate of expansion of the universe.
What is meant by a flat universe?
The universe could be flat, like a sheet of paper. In a flat universe, Euclidean geometry applies at the very largest scales. This means parallel lines will never meet, and the internal angles of a triangle always add up to exactly 180 degrees—just like you’re used to.
Why is flatness a problem in cosmology?
The flatness problem (also known as the oldness problem) is a cosmological fine-tuning problem within the Big Bang model of the universe. This value affects the curvature of space-time, with a very specific critical value being required for a flat universe.
Is the cosmological constant actually constant?
The cosmological constant is usually assumed to be, well, a constant. If it isn’t, it can be more generally referred to as ‘dark energy. ‘ If our current theories for the cosmos are correct, our universe will expand forever into a cold and dark future.
Is anything in the universe constant?
Everything ages, even the universe. One true constant in the universe—change. There are fundamental physical constants, like the charge on an electron, the permeability of free space, and the speed of light. The structure of atoms is always going to be the same, isotopes not withstanding.
Did Einstein think the universe was static?
Albert Einstein accepted the modern cosmological view that the universe is expanding long after his contemporaries Until 1931, physicist Albert Einstein believed that the universe was static.. For example, in 1922, Russian physicist Alexander Friedman showed that Einstein’s equations were viable for dynamical worlds.
Is the universe flat or round?
Most cosmological evidence points to the universe’s density as being just right — the equivalent of around six protons per 1.3 cubic yards — and that it expands in every direction without curving positively or negatively. In other words, the universe is flat.
How can the universe be flat and accelerating?
A universe with too much density collapses in on itself, a critical density universe stays static, while a universe with not enough density keeps expanding at a steady (coasting) rate. However, today’s cosmology puts emphasis upon the cosmological constant, which gives an accelerating expansion.
How does inflation explain the fact that our universe is flat?
The inflation theory predicts that the ultra-fast inflation would have expanded away any large-scale curvature of the part of the universe we can detect. The small universe inflated by a large amount and the part of the universe you can observe appears to be nearly flat. That solves the flatness problem.
Was Einstein a cosmologist?
Einstein himself lost little time in abandoning his static cosmology at that point. In the early 1930s, he published two distinct models of the expanding universe, one of positive spatial curvature and one of Euclidean geometry.