https://news.mit.edu/2014/profile-larry-guth-0527
Guth的父亲是Alan Guth，麻省理工学院的Victor F. Weisskopf物理学教授，也是宇宙膨胀理论的创始人，该理论描述了大爆炸后宇宙的快速膨胀，由排斥引力引起。
王虹的博士生导师MIT 数学教授Larry Guth，父亲是宇宙膨胀论创始人
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Re: 王虹的博士生导师MIT 数学教授Larry Guth，父亲是宇宙膨胀论创始人
什么是排斥性引力？
A repulsive gravitational force is a phenomenon predicted by Einstein’s General Relativity in certain exotic energy conditions where gravity acts outward, pushing space apart, instead of pulling matter together.
A repulsive gravitational force is an outward‑pushing effect of gravity caused by uniform energy distributions (like dark energy), leading to cosmic acceleration rather than attraction.
Why gravity can become repulsive
Why gravity can become repulsiveIn General Relativity, gravity is not just caused by mass—it is caused by the entire stress–energy tensor, including:
- energy density
- pressure
- momentum flow
Under certain conditions, pressure itself can gravitate, and if the pressure is sufficiently negative, the resulting curvature of spacetime becomes repulsive.
This happens when the equation of state satisfies:
\[
\rho + 3p < 0
\]
where \( \rho \) is energy density and \( p \) is pressure.
Where repulsive gravity appears
Where repulsive gravity appears1. Dark energy
The cosmological constant \( \Lambda \) has negative pressure, causing the universe’s expansion to accelerate.
2. Inflation
During the early universe, a uniform scalar field created enormous repulsive gravity, driving exponential expansion.
3. Cosmological constant term
Einstein added \( \Lambda g_{\mu\nu} \) to his field equations, which mathematically acts as a repulsive gravitational component.
How it differs from normal gravity
How it differs from normal gravity| Concept | Normal Gravity | Repulsive Gravity |
|---|---|---|
| Effect | Pulls matter together | Pushes space apart |
| Source | Positive mass-energy | Uniform energy with negative pressure |
| Theory | Classical GR | GR with cosmological constant or scalar fields |
| Example | Planets orbiting the Sun | Accelerating expansion of the universe |
