Dark Energy

What is Dark Energy?

  • While it is established that the universe is expanding the question is at what rate is it expanding and does the rate of expansion remain the same?
  • Because there is matter in the universe, and because gravity tends to pull the bits of matter in the universe toward one another, we would expect that the expansion should slow down with time.
  • However calculations show that the universe is expanding at an accelerating rate .i.e. universe is expanding faster than before.
  • It turns out universe is filled with some unknown energy that is responsible for this accelerating expansion of universe. This is called dark energy.
  • In fact, we are living in a ‘dark energy-dominated’ universe. About 76% of the universe is filled with dark energy.

Characteristics of dark Energy

  • Dark energy is like a form of anti-gravity. i.e. while gravity tends to make objects attract, dark energy would pull them apart by increasing the space between them.
  • Normally as universe expands the density of mass and radiation in it decreases. (same amount of mass in more area)
  • However the density of dark energy remains constant throughout.
  • This means the dark energy in the universe is ever increasing in order to keep the energy-density constant.
  • Thus dark energy should be energy inherent in the fabric of space itself.

Dark Energy Observatories


  • ESA’s infra-red space telescope to detect dark energy and dark matter.
  • Planned launch in 2023.

Roman Space Telescope (Nancy Grace Roman Telescope)

  • NASA’s next-gen space telescope in infra-red range to detect dark energy and dark matter
  • Planned launch in 2027.
  • Studies dark energy and dark matter using gravitational lensing of light by supernovae focused at an infra-red telescope placed in space.
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