Dark energy and mass-energy conservation

[AmongTheRull]

If dark energy is a property of space-time, and more dark energy is created as space-time increases, and the additional dark energy accelerates the expansion of space-time, what is left of the notion of the conservation of energy or of mass-energy?

Does energy conservation become a purely local property? And if so, how much volume can included in the "location"?

 

[Dale]

Hi AmongTheRull, welcome to PF!

Well, it is a non-trivial question and the answer is fairly involved. Here is the best link I know of at a reasonably non-technical level:
http://math.ucr.edu/home/baez/physics/Relativity/GR/energy_gr.html

 

[Entropia]

The notion of conservation of energy and mass-energy is a fundamental principle in physics, and it is understandable to question how it applies to the concept of dark energy. However, it is important to note that the conservation of energy and mass-energy still holds true in the case of dark energy.

Dark energy is a property of space-time, which means it is a part of the fabric of the universe itself. As space-time expands, more dark energy is created, but this does not violate the conservation of energy. This is because the total energy of the universe remains constant, with the increase in dark energy being balanced by a decrease in other forms of energy, such as matter and radiation.

In other words, dark energy is not being created out of nothing, but rather it is a redistribution of energy within the universe. This is similar to how the total energy of a closed system, such as a pendulum, remains constant even as the energy is constantly transforming between potential and kinetic forms.

Furthermore, the conservation of energy and mass-energy is still applicable on a local scale. This means that within a specific region of space-time, the total energy and mass-energy must remain constant. So, while dark energy may be increasing on a larger scale, it does not violate the conservation principle within a localized region.

The notion of energy conservation is not limited to a specific volume or location, but rather it applies to the entire universe as a whole. The concept of dark energy does not change this, but rather it adds to our understanding of the dynamics of the universe and its expansion.

In conclusion, while the presence of dark energy may challenge our understanding of energy conservation, it does not invalidate the principle. The conservation of energy and mass-energy still holds true, both on a global and local scale, and the concept of dark energy only adds to our understanding of the complex workings of the universe.