Yes, and there are evidences of their existence too.
If only that were true... Yes,the existence of dark energy, aka the cosmological constant, can be confirmed due to it being the lone logical explanation for the observed metric expansion of our universe! Dark matter however, IMO, is simply a manifestation of the wishful thinking, behind the attempted covering up of the misconception that gravitation is some kind of attractive force. even though Einstein specifically told us that gravitation is not a force, it is an effect of the presence of mass curving space-time. This topic fascinates me so much, that I tend to waffle and not make the point I am trying to make. so, please bear with me..
The observed motion of the stars withinin galaxies is inconsistant with the estimated mass/gravitation of those galaxies. Meaning either the theory of gravitation is wrong, or, galaxies are surrounded by immense haloes of invisible matter which gravitationally effects the baryonic matter in those galaxy. I prefer the former of the two options, and I believe Le'sage put forward a theory which actually explains gravitation rather than just stating as Einstein did that mass curves space time and the curvature of space influences the way matter moves Or... were Le'Sage and Einstein both putting forward the same basic theory with different wording?
In Le' Sages version of gravitation the universe is filled with particles he called ultra mundane corpuscles. These particles exert an outward pressure-like effect, simultaneously in all directions, (Hmm sounds rather like dark energy or Einsteins cosmological constant to me.)
Le'Sage proposed that these particles (corpuscles) didnt pass easily through matter, so most corpuscles would be blocked thus creating a shadow effect that would form a halo of quasi-low-pressure around an object made of baryonic matter. the larger and denser the object, the more pronounced the shadow effect would be.
The shadow effect would also diminishes with distance at the same rate as is dictated by the invese square law.
When there are multiple objects with mass in one vicinity the shadowing effect can merge into a three dimensional geometry , not unlike a three dimensional version of a barometric chart
Any two massive objects in the the same vicinity experience a reduced amount of quasi-pressure between them and are consquently pushed together by the surrounging higher quasi-pressure of the corpuscles.
In some ways cosmologists have been stuck in an inescapable rut by not acknowledging that there is something wrong with the way we percieve gravitation, Time is likely the precursor of dark energy and dark energy replaces the ultra mundane corpuscles of Le'sages theorum, other than that... What can be said other than "Well done LeSage ." Or, Well done to whoever formulated the theory, if the rumours of plagiarism by le'Sage are true.
I love simplicity so making dark energy responsible for both cosmic expansion and gravitation certainly ticks a box with me.
No need for gravitons!
No need for dark matter!
Just dark energy! Which is an effect of space-time.