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Vilenkin's Tunneling from Nothing vs The Boundary Proposal

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Quantum Tunneling Origin· within family

	Vilenkin's Tunneling from Nothing Speculative	The Boundary Proposal Speculative
Proposed	1982	2024
Key figures	Alexander Vilenkin	Bjoern Hassfeld, Arthur Hebecker
In one sentence	Vilenkin proposed in 1982 that the universe quantum-tunneled into existence from a state with no space, no time, no fields, literal nothing.	An alternative to Hartle-Hawking and Vilenkin in which the universe begins with a finite spacelike spherical boundary that can dominate over the no-boundary instanton.
Predictions	[[Inflation]] begins naturally with high probability after tunneling Universe is initially small, closed, and de Sitter-like No contracting phase before the Bang	Distinct primordial perturbation spectrum from Hartle-Hawking and Vilenkin proposals Specific signatures in the CMB tied to the boundary geometry
Where it breaks	Krauss: still requires quantum laws, so not really nothing Hawking & Bousso (1995): catastrophic particle production Penrose: ignores Weyl curvature hypothesis	Requires specifying the boundary geometry as input, which some critics view as no improvement over the boundary conditions it replaces. The phenomenological implications are still being worked out and have not yet been compared to Planck data.
Key unresolved problem	The laws-from-nothing problem: the quantum tunneling that creates the universe still needs quantum laws and a space of possible states to work in, so the proposal has not truly started from nothing.	The input-geometry problem: the proposal has to be handed the size of its starting boundary surface from outside, which critics say just moves the fine-tuning problem somewhere else rather than removing it.
Reader vote	100% · 2 votes	0% · 0 votes

Vilenkin's Tunneling from Nothing

1982 · Speculative

The Boundary Proposal

2024 · Speculative

Proposed

1982

2024

Key figures

Alexander Vilenkin

Bjoern Hassfeld, Arthur Hebecker

In one sentence

Vilenkin proposed in 1982 that the universe quantum-tunneled into existence from a state with no space, no time, no fields, literal nothing.

An alternative to Hartle-Hawking and Vilenkin in which the universe begins with a finite spacelike spherical boundary that can dominate over the no-boundary instanton.

Predictions

[[Inflation]] begins naturally with high probability after tunneling
Universe is initially small, closed, and de Sitter-like
No contracting phase before the Bang

Distinct primordial perturbation spectrum from Hartle-Hawking and Vilenkin proposals
Specific signatures in the CMB tied to the boundary geometry

Where it breaks

Krauss: still requires quantum laws, so not really nothing
Hawking & Bousso (1995): catastrophic particle production
Penrose: ignores Weyl curvature hypothesis

Requires specifying the boundary geometry as input, which some critics view as no improvement over the boundary conditions it replaces.
The phenomenological implications are still being worked out and have not yet been compared to Planck data.

Key unresolved problem

The laws-from-nothing problem: the quantum tunneling that creates the universe still needs quantum laws and a space of possible states to work in, so the proposal has not truly started from nothing.

The input-geometry problem: the proposal has to be handed the size of its starting boundary surface from outside, which critics say just moves the fine-tuning problem somewhere else rather than removing it.

Reader vote

100% · 2 votes

0% · 0 votes