Albert Einstein introduced the cosmological constant in the theory of relativity almost a century ago. It is definitely not a precise estimation as the difference in the theoretical model and the value based on astronomical measurements is of order 10^{121}. Hence, this is known as the worst estimate in the entire history of physics.

A researcher from the **University of Geneva**, Switzerland has proposed a method to resolve this difference. **Lucas Lombriser**, professor of Theoretical Physics and the article’s sole author states that it is to be accepted that the universal constant of gravitation G, which is also a part of the relativity equation may vary. It has been received positively by the scientific world however deeper work for confirmation of this theory is still pending. The work appears in Physics Letters B.

Lombriser says that his approach consists of a different way to mathematically manipulate the general relativity equations which help in merging the gap between theory and actual observation for the cosmological constant. The cosmological constant, lambda was introduced to maintain Einstein’s assumption for his theory that the universe is static. But it was refuted by Edwin Hubble in 1929 when he discovered that galaxies have been separating from each other indicating the expansion of the universe. On knowing this, Einstein termed the introduction of the cosmological constant as his greatest blunder.

Analysis of distant supernovae in 1998 showed that the universe’s expansion rate is not constant but accelerating. The cosmological constant was then used to define “vacuum energy” for the unknown energy which is actually responsible for the acceleration in the expansion of the universe. Observations of the cosmic microwave background which is the microwave radiation from all over the sky and a leftover of the Big Bang helped in measuring the cosmological constant. It is a small figure which explains the expansion of the universe.

The theoretical value of the cosmological constant is calculated using quantum field theory which considers that particle pairs at a very small scale are created and destroyed simultaneously at all points in the space at any moment. When the energy of “vacuum fluctuation” is used for calculating the value of cosmological constant then the result turns out to be incompatible with the value obtained from observation. It is the largest gap ever obtained between experiment and theory.

This problem is being approached by researchers all over the world with their own ideas however no consensus has been reached yet.

Previously Professor Lombriser had this idea to introduce a variation in G(universal gravitation constant) in the equations of Einstein. This means that our universe is a single case among an endless number of theoretical possibilities. Through this approach, it is possible to calculate **ΩΛ,** a different way of expressing the cosmological constant but easier to manipulate. It also expresses the fraction of the universe which consists of dark energy. The number comes to 70.4% which is close to the experimental value of 68.5 percent. Further analyses are needed to confirm the framework of Lombriser but it has been already taken in a positive way by the scientific community.

Journal Reference: Physics Letters B.

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