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Erik Verlinde | SciPost Physics | (2017)
Key Takeaways
Sample Definition And Size
The paper is a theoretical physics study by Erik P. Verlinde, focusing on emergent gravity and its implications for dark matter phenomena. It does not involve empirical data or a sample population; rather, it develops a conceptual framework and derives theoretical estimates.
Study Type
The work is a theoretical study proposing a novel emergent gravity framework, combining insights from string theory, black hole physics, and quantum information theory.
Conflicts Of Interest
No conflicts of interest are declared in the paper; none are indicated on the SciPost publication page.
Results Summary
Key findings include: (1) the proposal that positive dark energy induces a thermal volume-law contribution to entropy that overtakes the area-law at the cosmological horizon; (2) this leads to non-thermalizing de Sitter states with memory effects manifesting as entropy displacement due to matter; (3) an additional 'dark' gravitational force emerges, described as an elastic response to entropy displacement; (4) Verlinde derives an estimate for the strength of this extra force in terms of baryonic mass, Newton’s constant, and the Hubble acceleration scale a₀ = cH₀; (5) he argues that this emergent 'dark gravity force' can explain galactic and cluster-scale phenomena typically attributed to dark matter.
Abstract
Recent theoretical progress indicates that spacetime and gravity emerge together from the entanglement structure of an underlying microscopic theory. These ideas are best understood in Anti-de Sitter space, where they rely on the area law for entanglement entropy. The extension to de Sitter space requires taking into account the entropy and temperature associated with the cosmological horizon. Using insights from string theory, black hole physics and quantum information theory we argue that the positive dark energy leads to a thermal volume law contribution to the entropy that overtakes the area law precisely at the cosmological horizon. Due to the competition between area and volume law entanglement the microscopic de Sitter states do not thermalise at sub-Hubble scales: they exhibit memory effects in the form of an entropy displacement caused by matter. The emergent laws of gravity contain an additional ‘dark’ gravitational force describing the ‘elastic’ response due to the entropy displacement. We derive an estimate of the strength of this extra force in terms of the baryonic mass, Newton’s constant and the Hubble acceleration scale a_0 =cH_0 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow> <mml:msub> <mml:mi>a</mml:mi> <mml:mn>0</mml:mn> </mml:msub> <mml:mo>=</mml:mo> <mml:mi>c</mml:mi> <mml:msub> <mml:mi>H</mml:mi> <mml:mn>0</mml:mn> </mml:msub> </mml:mrow> </mml:math> , and provide evidence for the fact that this additional ‘dark gravity force’ explains the observed phenomena in galaxies and clusters currently attributed to dark matter.
There is another theory that gravity is not fundamental and instead it emerges from microscopic information stored in spacetime. So instead of needing dark matter, the extra gravitational pull in galaxies could come from how information is distributed in the fabric of spacetime itself - Emergent Gravity and the Dark Universe