Expression "subtle energy" is used in the esoteric texts.

From representation of philosophy Dao (道) the world has arisen from initial energy chi (Qi 氣), in which energy YIN and YANG still was confound. Streams of this energy chi (similar to a wind), are influence all nature, including on the person.
The subtle energies are not be registered appliances.

In modern science - Dark energy - this assumption. This energy is present everywhere but there are no devices that can registering the dark energy.

Definitions Matter (substance) as energy, but energy that is concentrated in a limited space.
what is dark energy and dark matter



Definitions of Dark energy on the Web:

 

• In physical cosmology, astronomy and celestial mechanics, dark energy is a hypothetical form of energy that permeates all of space and tends to increase the rate of expansion of the universe.
  en.wikipedia.org/wiki/Dark_energy
• A mysterious (and as yet hypothetical) form of energy which is spread out uniformly throughout space (and time) and which
  has anti-gravitational properties: it is one of the possible explanations
  for the current accelerating rate of expansion of the universe, and it is
  estimated to account for ...
  en.wiktionary.org/wiki/dark_energy
• an additional energy needed to make the universe's overall curvature flat. It may be the cosmological constant.
  www.astronomynotes.com/glossary/glossd.htm
• A mysterious force that seems to work opposite to that of gravity and makes the universe expand at a faster pace.
  www.aerospaceguide.net/glossary/index.html
• “Negative gravity” that plays a part in the acceleration of universal expansion.
  www.darkskycast.com/astronomyglossary.html

And evidences also indicate that the universe is flat.



Definitions of Subtle energy on the Web:

• The term energy has been widely used by writers and practitioners of various esoteric forms of spirituality and
  alternative medicine to refer to a variety of phenomena, sometimes
  supposed to be directly perceptible to some observers, who have usually
  undergone some form of training or initiation ...
  en.wikipedia.org/wiki/Subtle_energy
• 
  High frequency energy beyond the known EM spectrum.
  Subtle energy fields, such as the etheric, are said to interpenetrate the human body. ISSSEEM (Richard Gerber, Barbara Brennan)

Subtle energy