New Idea Solves Three Physics Mysteries at Once: Post Quantum Gravity

Sabine Hossenfelder
12 Mar 202406:59
EducationalLearning
32 Likes 10 Comments

TLDRFor the first time in decades, physicists have found a new approach to combining quantum physics with gravity, called 'Postquantum Gravity,' proposed by Johnathan Oppenheim. This theory introduces randomness to gravity, explaining dark matter and dark energy without contradictions. While promising, some believe it may not work due to the linear nature of the equations involved. Despite skepticism, the theory has sparked interest in the scientific community. For more on this and other scientific developments, the video recommends checking out Nautilus magazine, which covers a wide range of scientific topics.

Takeaways
  • 🧠 For the first time in 40 years, physicists have a new approach to combining quantum physics with gravity called 'Postquantum Gravity'.
  • 🧩 This new approach is suggested by Johnathan Oppenheim and his collaborators, and it also aims to explain dark matter and dark energy.
  • 🔍 Quantum physics is non-deterministic with built-in uncertainty, while gravity, described by Einstein's General Relativity, is deterministic.
  • 🧪 Many attempts to unify quantum physics and gravity have been made, such as string theory and loop quantum gravity, but none have succeeded so far.
  • 🔄 Oppenheim's Postquantum Gravity introduces randomness as a fundamental ingredient in gravity, similar to the randomness in quantum mechanics.
  • 🔗 This theory combines the mathematics of both quantum and gravity randomness into a single framework, allowing them to interact without contradictions.
  • 🌌 The randomness in gravity affects objects with small acceleration, potentially explaining phenomena attributed to dark matter, similar to Modified Newtonian Dynamics (MOND).
  • 💫 The theory predicts changes in the law of gravity under certain circumstances, specifically at small accelerations, matching observations of dark matter effects in galaxies.
  • 📈 Oppenheim and Russo's equation shows gravity getting stronger at small accelerations, which aligns with MOND and suggests a term resembling dark energy.
  • 👀 Despite the promising theory, some experts are skeptical about its practical application, particularly due to the linear nature of their equation in the Newtonian potential.
Q & A
  • What is the main problem that physicists have been trying to solve for almost a century?

    -The main problem is how to combine quantum physics with gravity, as these two theories have been historically incompatible.

  • What is the new approach to solving the quantum-gravity problem called?

    -The new approach is called 'Postquantum Gravity', proposed by Johnathan Oppenheim and his collaborators.

  • What are the fundamental differences between quantum physics and gravity as described in the script?

    -Quantum physics is non-deterministic with a random element and built-in uncertainty, while gravity as described by Einstein's General Relativity is deterministic, with the future following from the past.

  • What are some of the well-known approaches to unifying quantum physics and gravity?

    -Some well-known approaches include string theory, loop quantum gravity, and asymptotically safe gravity, all of which give quantum properties to gravity.

  • How does Postquantum Gravity differ from other approaches to unifying quantum physics and gravity?

    -Postquantum Gravity differs by giving a random element to gravity itself, treating this randomness as a fundamental ingredient, similar to the inherent randomness in quantum mechanics.

  • What is the innovative aspect of Oppenheim's Postquantum Gravity theory?

    -The innovation is the combination of the mathematics of both types of randomness (quantum and gravitational) into one framework, allowing for a non-quantum gravity and quantum particles to interact without contradictions.

  • How does the Postquantum Gravity theory relate to the concept of dark matter and dark energy?

    -In the Postquantum Gravity theory, the randomness can change the law of gravity under certain circumstances, such as very small accelerations, which could potentially explain the phenomena attributed to dark matter and dark energy.

  • What is Modified Newtonian Dynamics (MOND), and how does it relate to the Postquantum Gravity theory?

    -MOND is a modification of Einstein's gravity that becomes noticeable at small accelerations and is a competitor to the dark matter hypothesis. The Postquantum Gravity theory shows similar behavior at small accelerations, suggesting a possible connection.

  • What is the main criticism of the Postquantum Gravity theory as presented in the script?

    -The main criticism is that the equation derived in the theory is linear in the Newtonian potential, whereas a non-linear equation is needed to correctly scale the asymptotic velocity with the mass of galaxies, as in MOND.

  • What is Nautilus magazine, and how does it relate to the script?

    -Nautilus is a science magazine that covers a wide range of topics and often features contributions from scientists. The script recommends it as a source for learning about recent scientific developments, including theories like Postquantum Gravity.

  • What is the speaker's personal opinion on the Postquantum Gravity theory?

    -The speaker expresses skepticism about the theory, stating that they believe it will not work due to the linear nature of the equation in the Newtonian potential, but also acknowledges the possibility of being proven wrong.

Outlines
00:00
🔬 Postquantum Gravity: A New Approach to Unifying Quantum Physics and Gravity

Physicist Johnathan Oppenheim introduces a groundbreaking theory called 'Postquantum Gravity,' which aims to reconcile quantum physics with gravity—a challenge that has persisted for nearly a century. Traditionally, quantum physics, characterized by its inherent randomness and uncertainty, has been at odds with the deterministic nature of gravity as described by Einstein's General Relativity. Oppenheim's innovation lies in attributing a fundamental randomness to gravity, allowing it to coexist with quantum randomness within a unified framework. This theory suggests that the two realms communicate through the influence of gravity on particles, fitting together without contradiction. Furthermore, the paper by Oppenheim and co-author Russo proposes that this inherent randomness in gravity could potentially explain dark matter and dark energy, particularly under conditions of very small object acceleration, drawing parallels with Modified Newtonian Dynamics (MOND), which also becomes evident at low accelerations. The authors claim their theory can account for the universe's expansion and galactic rotation without invoking dark matter or dark energy.

05:04
🤔 Skepticism Surrounding Postquantum Gravity's Viability

Despite the excitement surrounding the Postquantum Gravity theory, the narrator expresses skepticism about its practical viability. They argue that for a modified gravity theory to be successful, such as MOND, it requires a non-linear equation in the Newtonian potential, which is not present in Oppenheim's model. The narrator anticipates issues with the scaling of asymptotic velocity with the mass of galaxies, suggesting that the theory may not align with observed phenomena. They acknowledge their own predisposition to doubt and invite viewers to stay tuned for potential updates or public corrections. The narrator also recommends Nautilus magazine as a valuable resource for staying informed about current scientific discussions, including their own contributions on Oppenheim's theory, and offers a discount link for subscriptions.

Mindmap
Keywords
💡Quantum Physics
Quantum physics is a fundamental theory in physics that describes nature at the smallest scales of energy levels of atoms and subatomic particles. It is characterized by non-deterministic behavior, meaning there is an inherent randomness and uncertainty in the properties of particles. In the context of the video, quantum physics is contrasted with gravity, which is deterministic, and the script discusses the challenge of combining these two theories into a unified framework.
💡Gravity
Gravity is the force that attracts two objects with mass towards each other and is described by Einstein's General Theory of Relativity. It is deterministic, meaning the future state of a system is completely determined by its past state. The video script discusses the difficulty of integrating gravity with quantum physics, as they have fundamentally different properties.
💡Postquantum Gravity
Postquantum Gravity is a novel approach proposed by Johnathan Oppenheim to unify quantum physics with gravity. It introduces a random element into gravity, similar to the inherent randomness in quantum mechanics, and combines the mathematics of both types of randomness into a single framework. The script highlights this new idea as a potential solution to the long-standing problem of reconciling quantum mechanics with gravity.
💡Dark Matter
Dark matter is a hypothetical form of matter that is thought to account for approximately 85% of the matter in the universe. It does not emit or interact with electromagnetic radiation, making it invisible to telescopes but detectable through its gravitational effects. The video script suggests that Postquantum Gravity might offer an alternative explanation for phenomena attributed to dark matter.
💡Dark Energy
Dark energy is the unknown form of energy that is hypothesized to permeate all of space and accelerate the expansion of the universe. The video script mentions that Postquantum Gravity also attempts to explain dark energy, in addition to dark matter and the unification of quantum physics with gravity.
💡General Relativity
General Relativity is a theory of gravitation proposed by Albert Einstein, which describes gravity not as a force but as a curvature of spacetime caused by mass and energy. The script contrasts General Relativity, which is deterministic, with the indeterministic nature of quantum physics.
💡String Theory
String Theory is a theoretical framework in which the point-like particles of particle physics are replaced by one-dimensional objects called strings. It is one of the best-known approaches to quantum gravity, attempting to reconcile quantum mechanics with gravity by giving quantum properties to gravity. The script mentions it as one of the attempts to unify these two areas of physics.
💡Loop Quantum Gravity
Loop Quantum Gravity is a quantum gravity theory that attempts to quantize the fabric of spacetime itself. It is mentioned in the script as another approach to unifying quantum mechanics and gravity, distinct from String Theory and Postquantum Gravity.
💡Asymptotically Safe Gravity
Asymptotically Safe Gravity is a theoretical framework that suggests that gravity becomes non-perturbatively renormalizable at high energies, thus offering a way to unify it with quantum mechanics. The script lists it among the less common approaches to the problem of quantum gravity.
💡Modified Newtonian Dynamics (MOND)
Modified Newtonian Dynamics is an alternative to dark matter that modifies Newton's laws of motion at very low accelerations to account for the observed motion of stars in galaxies without invoking dark matter. The script connects the changes in the law of gravity due to randomness in Postquantum Gravity to the effects seen in MOND.
💡Newtonian Potential
The Newtonian potential is the potential energy in a gravitational field as described by Newtonian mechanics. It is used in the script to describe how the randomness in Postquantum Gravity affects the law of gravity, particularly at low accelerations, and how it relates to MOND.
Highlights

Physicists have discovered a new approach to solving the almost century-old problem of combining quantum physics with gravity, called 'Postquantum Gravity'.

Postquantum Gravity introduces randomness as a fundamental ingredient to gravity, similar to the inherent randomness in quantum mechanics.

Johnathan Oppenheim and his collaborators propose that Postquantum Gravity not only unifies quantum physics with gravity but also explains dark matter and dark energy.

Quantum physics and gravity are fundamentally at odds, with the former being non-deterministic and the latter deterministic.

Previous attempts to unify quantum physics and gravity have included string theory, loop quantum gravity, and asymptotically safe gravity.

Postquantum gravity suggests that gravity remains non-quantum while particles remain quantum, with the two sectors interacting through gravity's influence on particles.

The theory's innovation lies in combining the mathematics of both types of randomness into a single framework without contradictions.

In Postquantum gravity, changes to the law of gravity occur under certain circumstances, specifically when an object's acceleration is very small.

The modification of gravity at small accelerations is reminiscent of Modified Newtonian Dynamics (MOND), a competitor to the dark matter hypothesis.

The proposed changes in Postquantum gravity can explain galactic rotation without the need for dark matter, similar to MOND.

The derived equation in Postquantum gravity has unusual contributions that resemble those of MOND, challenging the dark matter explanation.

The theory also suggests a term that resembles dark energy, potentially explaining the universe's expansion.

Despite the promising aspects of Postquantum gravity, the speaker expresses skepticism due to the linear nature of the derived equation in the Newtonian potential.

The speaker anticipates that the scaling of the asymptotic velocity with the mass of galaxies may not align with observations, indicating potential flaws in the theory.

The speaker acknowledges her skepticism may be unfounded, leaving room for the possibility of a breakthrough in the understanding of quantum gravity.

Nautilus magazine is recommended for readers interested in staying updated on relevant scientific topics, including theories like Postquantum gravity.

A discount is offered for Nautilus magazine subscriptions through a custom link provided by the speaker.

Transcripts
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