What is total energy of Universe ?
Have you ever wonder, what is total energy of universe ? Before answering this question , we should know where is energy in universe ? The total energy of universe has been calculated assuming that it is the sum of the contributions from the matter part and gravitation part of universe . And after a calculation ,scientists have arrived that total energy of universe is exactly zero .
Classical points of view :-
Total energy of universe = ( matter part. + gravitational part)
Matter parts could contain positive energy and negative energy could be in form of gravity . Positive energy of universe is exactly cancelled out by negative energy and thus total energy in universe is exactly zero .This is called “Zero Energy Hypothesis “. The calculation of it involves the use of Einstein pseudotensor. Calculation have been carried out in specific examples of spacetime geometries . In some cases the total energy is indeed zero confirming previous results but in other cases the total energy is nonzero. So Rosen’s idea that the pseudotensorial calculations will lead to the result that the total energy of the universe is zero, is very much model dependent.In the present work, we examine the calculation of the total energy on the basis of
pseudotensor a bit critically. Pseudotensorial calculations are always dangerous as they
are very much coordinate dependent and thus may lead to ambiguous results except,
however, in asymptotically flat spacetimes if one is using quasi-Minkowskian coordinates
. Rosen’s idea was that the Einstein pseudotensor gives the gravitational energy and
together with the matter part yields the result that the total energy of the universe is zero.
In what follows, we test Rosen’s idea against some examples. Some anisotropic
cosmological models are considered, in which the nonzero components of the
pseudotensor are used to calculate the total energy of the universe following Rosen’s
idea. It is interesting to note that although in some cases the total energy indeed comes
out to be zero, in some other cases the energy integral is in fact nonzero
Modern views on total energy of universe :-
On the basis of some descriptions of origin of the universe , group of cosmologists and astrophysicists have hypothesized that total energy of universe is zero. Several investigations and experiments showed that space is not exactly empty but it contains energy which comes out from continuous pops out of fluctuating particles in form of matters and antimatters . Investigations of
Albrow  and Tyron  assume that the universe might have arisen as a quantum
fluctuation of the vacuum. After the success of the inflationary cosmological models in
solving some outstanding problems in standard cosmology, the idea of vacuum
fluctuations has been developed further. Inspired by these results, there have been
attempts to show that the total energy of the universe is zero even from a purely classical
point of view. The total energy of the universe, however, is not really zero if it is
calculated on the basis of the matter part alone. Recently, there have been several
attempts to include the gravitational energy along with the matter part so that the total
energy is zero
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