Cosmological Constant and Conservation of Energy

[Jack21222]

The cosmological constant, or dark energy if you prefer, can be thought of as energy inherent in free space. This energy density is thought to be constant, and the volume which it occupies grows as space expands. The more this happens, the more dark energy comes to dominate the universe.

Where does all of this energy come from? Energy is always conserved, but we have this term accumulating more and more energy. What am I missing?

 

[Chalnoth]

The cosmological constant, or dark energy if you prefer, can be thought of as energy inherent in free space. This energy density is thought to be constant, and the volume which it occupies grows as space expands. The more this happens, the more dark energy comes to dominate the universe.

Where does all of this energy come from? Energy is always conserved, but we have this term accumulating more and more energy. What am I missing?

That energy is always conserved. In General Relativity, conservation of energy isn't a law that is always followed. Instead, the conserved quantity is the stress-energy tensor, and under certain conditions, conservation of the stress-energy tensor forces non-conservation of energy. Here's a more detailed look:
http://www.xs4all.nl/~johanw/PhysFAQ/Relativity/GR/energy_gr.html