RationalWiki's 2020 Fundraiser

There is no RationalWiki without you. We are a small non-profit with no staff – we are hundreds of volunteers who document pseudoscience and crankery around the world every day. We will never allow ads because we must remain independent. We cannot rely on big donors with corresponding big agendas. We are not the largest website around, but we believe we play an important role in defending truth and objectivity.

If everyone who saw this today donated $5, we would meet our goal for 2021.

Fighting pseudoscience isn't free.
We are 100% user-supported! Help and donate $5, $20 or whatever you can today with PayPal Logo.png!

Donations so far: $1680Goal: $3500

Dark energy

From RationalWiki
Jump to: navigation, search
Acceleration of the Universe
The poetry of reality
Icon science.svg
We must know.
We will know.
A view from the
shoulders of giants.

Dark energy is the final chapter of Half-Life 2 the term for a proposed form of energy that is thought to permeate all space. Dark energy has a repulsive effect, much weaker than gravity, but its permeating all of space means that falling off is irrelevant. The true nature of dark energy is one of the current unsolved problems in physics.

The abundance of dark matter is 26.8% of the total mass of the Universe, which is far larger than the 4.9% of mass represented by ordinary matter, such as interstellar gas. But 68.3% of the mass of the Universe is bound up in the mass-equivalence of dark energy.


Not only is the Universe expanding, its rate of expansion is increasing with time. Dark energy is the name given to the mysterious "something" that is fueling this universal inflation. Such energy is necessary only if the universe is flat; an "open" universe (an "anti-de Sitter spacetime", one with hyperbolic geometry--negative scalar curvature universally) experiences an accelerating metric expansion anyway. However, our observations suggest the universe is flat (a "minkowski" spacetime, euclidean geometry, zero scalar curvature universally), and an anti-de Sitter spacetime is unstable and thus cannot be a description of our universe anyway.[1]

Dark energy is the successor to such past scientific gap-fillers as caloric, phlogiston, aether and Einstein's "biggest blunder" — the cosmological constant (it's really more of a reinterpretation than a successor; dark energy appears in the Einstein Field EquationsWikipedia as a cosmological constant, using the same symbol Einstein did). Whether it stays as it is, becomes modified into a more concrete form, or is replaced by an even stranger space filler remains to be seen.

See also[edit]

External links[edit]

  1. Moschidis, Georgios (2018-12-11). "A proof of the instability of AdS for the Einstein--massless Vlasov system". arXiv:1812.04268