Dark Energy, the Swampland and the Equivalence Principle

Understand

It has recently been argued that string theory does not admit de Sitter vacua.

• This would imply that the current accelerated expansion of the universe is not driven by a cosmological constant (or vacuum energy) but by other means such as a quintessential scalar field.
• Such a scalar field is in general expected to couple to at least some matter species, such as dark matter.
• Cosmological observations already constrain such dark matter couplings strongly.