Dark matter, dark energy, and alternate models: A review

Understand

The nature of dark matter (DM) and dark energy (DE) which is supposed to constitute about 95% of the energy density of the universe is still a mystery.

• There is no shortage of ideas regarding the nature of both.
• While some candidates for DM are clearly ruled out, there is still a plethora of viable particles that fit the bill.
• In the context of DE, while current observations favour a cosmological constant picture, there are other competing models that are equally likely.