From: mk_thisisit
Introduction
Professor Brian Cox, a renowned physicist and popularizer of science, discusses fundamental questions about the universe, including the nature of time, the existence of life beyond Earth, and the possibilities of advanced physics. He highlights the current understanding of quantum theory, the capabilities of quantum computers, and the ongoing quest for a unified theory of everything [00:01:08].
Understanding Quantum Theory
Quantum theory describes the world at its most basic level [00:27:10]. It explains how things behave and connect [00:28:04]. A key question in physics is how quantum mechanics creates the world we perceive, which doesn’t seem to exhibit quantum properties like objects being in multiple places at once [00:26:49]. Humanity is increasingly understanding this connection [00:27:03].
Quantum Clocks
Research into the fundamental nature of time explores “minimal clocks” [00:12:34]. One such theoretical clock consists of three atoms, where its “ticking” relates to the emission of light as electrons jump between energy levels [00:12:44]. These “clocks” behave as thermodynamic machines, measuring the flow of entropy [00:13:13].
Quantum Computers
Quantum computers are devices that operate according to the laws of quantum mechanics [00:29:51]. Concepts like quantum entanglement, once purely theoretical, are now becoming experimental and even engineered into systems [00:29:57]. These technologies are enabling a significant leap in our understanding of quantum theory and its impact on the world [00:29:26].
The Theory of Everything
Many physicists believe that explaining the theory of everything is within reach [00:28:06]. This involves connecting quantum physics with classical physics [00:26:11].
Connecting Classical and Quantum Physics
There is ongoing work to bridge the gap between quantum physics and classical physics [00:26:11]. A Polish scientist at Los Alamos Laboratory co-created a theory of decoherence, aiming to connect these two realms [00:26:18]. The holographic principle, and specifically the AdS/CFT correspondence discovered by Juan Maldacena, is another promising area of research that seeks to represent space and time as entangled [00:27:18].
Black Holes and Information Paradox
The study of black holes has led to the development of quantum gravity theories, which suggest that space and time emerge from a deeper, more fundamental theory that does not inherently include them [00:14:32].
A significant challenge in physics, known as the “information paradox” of black holes, questions what happens to information that falls into a black hole [00:20:36]. While the laws of nature generally suggest that information is preserved and cannot be destroyed [00:21:21], Stephen Hawking’s initial calculations on Hawking radiation suggested that information would be lost when a black hole evaporates [00:22:39].
The current scientific consensus, however, is that information is ultimately preserved and eventually emerges from the black hole in a highly mixed form, recorded in the radiation [00:23:17]. This emerging radiation, according to Hawking’s theory, comes from the event horizon and the vacuum of space, rather than from the objects that fell in [00:24:09]. One speculative interpretation suggests that information exits through a type of “space-time tunnel” that opens from inside the black hole to the outside [00:24:55]. This highly speculative idea offers a glimpse into a deeper theory of space-time [00:25:20].
The Nature of Time
The fundamental nature of time remains an active area of research [00:09:47]. In Einstein’s theory of relativity, space and time are interwoven into the “fabric of the universe,” known as space-time [00:09:53]. Time, in this context, is measured by a clock, representing the distance traveled in space-time during a lifetime [00:10:27]. The age of the universe is defined by the time measured on a freely falling clock that started at the Big Bang [00:10:41].
However, the definition of time itself is complex [00:11:00]. While the laws of nature are symmetrical, allowing for situations to be recreated forward or backward in time [00:11:20], the observed asymmetry of past, present, and future is linked to the Big Bang being an extremely orderly, low-entropy event [00:11:56]. The second law of thermodynamics states that entropy always increases, meaning things become more disordered, which defines the direction of the future [00:12:10]. This concept is referred to as “thermodynamic time” [00:12:23].