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cover of episode Wormholes
People
A
Andrew Pontzen
K
Katy Clough
T
Toby Wiseman
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Toby Wiseman: 我认为宇宙极其庞大，寻找捷径是可取的。宇宙大约有140亿年的历史，其可观测范围大约是140亿光年，这是一个极其巨大的距离。虫洞的大小可能差异巨大，小的可能就在我们周围，大的可能位于遥远的星系。我们目前只能观测到宇宙的一小部分，宇宙可能远大于我们可观测到的范围，但由于宇宙加速膨胀，我们可能永远无法观测到全部宇宙，除非有像虫洞这样的超光速旅行方式。 Andrew Pontzen: 牛顿的万有引力理论是现代物理学的基石，它统一了地球上的重力现象和天体运动，但这理论并非完全正确。牛顿的万有引力理论与后来发展起来的电磁理论不相容，爱因斯坦试图调和两者，最终导致了广义相对论的提出。广义相对论将空间和时间统一为时空，并认为时空是可以弯曲的，这与牛顿的固定网格式时空观不同。约翰·惠勒创造了“虫洞”一词，他从对核聚变的深入研究转向了天体物理学问题，并继承了爱因斯坦和罗森的研究工作。如果虫洞存在，它将表明宇宙的形状比我们想象的更复杂，时空可能被折叠。虫洞的存在将揭示奇异物质的存在，并对我们对宇宙的理解产生革命性的影响。探索看似疯狂的想法对物理学的发展至关重要，即使虫洞最终被证明不存在，这个探索过程也能帮助我们更好地理解宇宙。 Katy Clough: 量子物理学与经典物理学存在根本差异，前者是概率性的，后者是确定性的，将两者统一是当前物理学面临的主要挑战之一。爱因斯坦和罗森提出的“爱因斯坦-罗森桥”的概念是虫洞概念的起源，但其最初并非用于星际旅行，而是试图用经典方式解释粒子。黑洞的完整数学解包含虫洞，但这个虫洞无法穿越，理论上，它可以连接两个不同的宇宙，两个宇宙的人可以分别跳入黑洞并进行信息交换。虫洞在二维空间中可以想象成一个连接两个平面的漏斗，在四维时空中的样子可能不同，虫洞的长度可以任意，但为了实用，最好较短。目前没有证据表明虫洞存在，但科学家正在研究如何通过观测来探测虫洞，虫洞从外部看起来可能很像黑洞。通过对黑洞的引力波观测，我们可以尝试区分黑洞和虫洞。如果虫洞是可穿越的，从外部看它可能像一个大的肥皂泡，而不是隧道，穿越虫洞可能会到达宇宙的另一个地方，甚至另一个宇宙，理论上可以通过虫洞观察另一端的情况。计算机模拟可以帮助我们研究虫洞，探索不同奇异物质模型的后果，例如虫洞的稳定性等。研究虫洞可以帮助我们更好地理解量子物理学、经典物理学和广义相对论，即使最终证明虫洞不存在，这个过程也能让我们学到很多东西。未来对引力波的观测将为我们提供更多关于宇宙的信息，这可能会带来意想不到的发现。

Deep Dive

Key Insights

How large is the universe, and why might wormholes be desirable?

The universe is approximately 14 billion years old and spans tens of billions of light years. Wormholes could act as shortcuts, allowing travel across vast distances that would otherwise take billions of years to traverse.

What is the relationship between black holes and wormholes?

The full mathematical solution for a black hole includes a wormhole, which connects two separate universes. However, it is a one-way trip, as anything entering the black hole would be torn apart by tidal forces before reaching the other universe.

What exotic matter is required to support wormholes?

Wormholes require matter with negative energy, which is not found in classical physics but is allowed in quantum mechanics. The Casimir effect is an example of quantum phenomena that can produce negative energy.

What would a traversable wormhole look like?

A traversable wormhole would resemble a large spherical portal, with extreme distortions of space around it. Light could pass through, allowing travelers to see the other side, but the destination could be another part of the universe or a completely separate universe.

Why are wormholes considered unlikely to exist?

Wormholes require exotic matter with negative energy, which has not been observed in nature. Additionally, the immense amounts of mass needed to create a wormhole large enough for human travel make their existence highly improbable.

What role do computer simulations play in studying wormholes?

Computer simulations allow researchers to explore the behavior of wormholes and exotic matter without physical experiments. They help test stability and predict observable signals, such as gravitational waves from hypothetical wormhole mergers.

What did Einstein and Rosen contribute to the concept of wormholes?

Einstein and Rosen proposed 'bridges between sheets,' now known as wormholes, as a way to explain particles in a classical framework. While their idea did not work for particles, it laid the foundation for modern wormhole physics.

How does general relativity describe space-time compared to Newton's theories?

General relativity unifies space and time into a single entity called space-time, which can be distorted by matter. Unlike Newton's fixed grid, space-time is dynamic and actively participates in the universe's structure.

What is the significance of the Casimir effect in relation to wormholes?

The Casimir effect demonstrates that quantum mechanics allows for negative energy, which is essential for the theoretical existence of wormholes. This exotic energy could support the curvature of space-time required for wormholes.

What challenges arise when trying to unify quantum physics and classical physics?

Quantum physics describes particles taking all possible paths with probabilistic outcomes, while classical physics predicts deterministic paths. Unifying these theories is difficult because general relativity, a classical theory, may need to be an approximation of an unknown quantum theory.

Shownotes Transcript

Melvyn Bragg and guests discuss the tantalising idea that there are shortcuts between distant galaxies, somewhere out there in the universe. The idea emerged in the context of Einstein's theories and the challenge has been not so much to prove their unlikely existence as to show why they ought to be impossible. The universe would have to folded back on itself in places, and there would have to be something to make the wormholes and then to keep them open. But is there anywhere in the vast universe like that? Could there be holes that we or more advanced civilisations might travel through, from one galaxy to another and, if not, why not?

With

Toby Wiseman Professor of Theoretical Physics at Imperial College London

Katy Clough Senior Lecturer in Mathematics at Queen Mary, University of London

And

Andrew Pontzen Professor of Cosmology at Durham University

Producer: Simon Tillotson

Reading list:

Jim Al-Khalili, Black Holes, Wormholes and Time Machines (Taylor & Francis, 1999)

Andrew Pontzen, The Universe in a Box: Simulations and the Quest to Code the Cosmos (Riverhead Books, 2023)

Claudia de Rham, The Beauty of Falling: A Life in Pursuit of Gravity (Princeton University Press, 2024)

Carl Sagan, Contact (Simon and Schuster, 1985)

Kip Thorne, Black Holes & Time Warps: Einstein's Outrageous Legacy (W. W. Norton & Company, 1994)

Kip Thorne, Science of Interstellar (W. W. Norton & Company, 2014)

Matt Visser, Lorentzian Wormholes: From Einstein to Hawking (American Institute of Physics Melville, NY, 1996)

In Our Time is a BBC Studios Audio Production