Dark Energy: Study Notes

General Science July 28, 2025 4 min read

What is Dark Energy?

Definition: Dark energy is a mysterious form of energy that makes up about 68% of the universe. It is responsible for the accelerated expansion of the cosmos.
Discovery: First inferred in 1998 from observations of distant Type Ia supernovae, which showed the universe’s expansion rate is increasing.

Supernova Observations: Distant supernovae appear dimmer than expected, indicating faster expansion.
Cosmic Microwave Background (CMB): Measurements from satellites like Planck show patterns consistent with dark energy.
Large Scale Structure: Distribution of galaxies and galaxy clusters matches models that include dark energy.

Dark energy is not the same as dark matter.
Dark matter interacts gravitationally and helps form galaxies; dark energy drives cosmic expansion.
The energy density of dark energy remains nearly constant over time.
Unlike matter and radiation, the amount of dark energy per unit volume does not decrease as the universe expands.
The fate of the universe depends on dark energy.
If dark energy continues as it is, the universe will expand forever, possibly leading to a “Big Freeze.”

2023: Astronomers used the Dark Energy Spectroscopic Instrument (DESI) to map over 14 million galaxies, refining measurements of cosmic expansion and dark energy’s effects.
2022: The Euclid mission (ESA) launched to study dark energy by observing billions of galaxies and measuring their shapes and distances.
2020: A study published in Nature Astronomy (Abbott et al., 2020) used gravitational lensing data to constrain dark energy’s properties more tightly than ever before.

Cosmological Constant (Λ): Einstein’s concept; dark energy is a constant energy density filling space.
Quintessence: A dynamic field that changes over time.
Modified Gravity: Some theories suggest gravity itself behaves differently on large scales.

Build a Model Universe Simulation

Use Python and the matplotlib library to simulate the expansion of the universe under different dark energy scenarios (cosmological constant, quintessence).
Compare simulated galaxy distributions to real data from DESI or Euclid.
Present findings in a science club meeting.

Indirect Connection: Understanding dark energy requires advanced mathematics, physics, and computing. Research in these fields drives technological innovation, which can benefit medical imaging, diagnostics, and data analysis.
Cognitive Health: The human brain’s complexity (more connections than stars in the Milky Way) mirrors the complexity of cosmic phenomena. Studying such topics stimulates critical thinking and problem-solving skills, promoting cognitive health.

Abbott, T.M.C. et al. (2020). “Dark Energy Survey Year 1 Results: Cosmological Constraints from Galaxy Clustering and Weak Lensing.” Nature Astronomy. Link