The Greatest Unsolved Problems in Modern Physics

[Yazata]

A Twitter thread by @PhysInHistory

https://threadreaderapp.com/thread/16715...82022.html

1. The nature of Dark Matter. The majority of the universe seems to be made of it, it's only known from its assumed gravitational effects, so is it really matter and if so, what is it?

2. The problem of Quantum Gravity - Physics' two most fundamental theories are General Relativity and Quantum Mechanics. Unfortunately, they aren't consistent with one another as they currently stand. A new theory that harmonizes them would be the long sought (but misleadingly named) Theory of Everything.

3. The Measurement Problem in QM - Quantum mechanics only predicts the outcome of measurements probabilistically. But actual observations deliver actualities. So what collapses the wavefunction, so to speak?

4. Matter-Antimatter Assymmetry - Theory says that the Big Bang should have produced equal amounts of matter and antimatter, which presumably would have annihilated each other. So why is our universe almost entirely matter?

5. The problem of neutrino masses - neutrinos have small masses that can seem to vary. So what explains neutrino masses? (I don't really understand this one. It depends on theory I don't know.)

6. Strong CP-violation - Charge parity symmetry says that the laws of physics should stay the same if particles are replaced by antiparticles and spatial coordinates inverted. So why does the strong force behave differently in this regard? (I don't really understand this one either.)

7. Cosmic Inflation - a widely accepted hypothesis claims that the universe expanded very rapidly immediately subsequent to the Big Bang. Assuming this speculation is true (I'm skeptical) what caused it?

8. The Problem of Time - Time in QM is a fundamental variable, while in Relativity time is relative and dynamical. The incompatibility in how time is conceived in our best theories is a basic problem for phyics.

[Magical Realist]

The Measurement Problem in QM - Quantum mechanics only predicts the outcome of measurements probabilistically. But actual observations deliver actualities. So what collapses the wavefunction, so to speak?

This is a biggie imo. It goes to the heart of what is the nature of consciousness and reality, and how they interact with each other. It appears one cannot exist without the other. The cat is both dead and alive until we know. But how can we know something that is inherently undecided? And how can something be decided that is not known? The dilemma is how in the world these two situations become each other.

[Ostronomos]

A Twitter thread by @PhysInHistory

https://threadreaderapp.com/thread/16715...82022.html

1. The nature of Dark Matter. The majority of the universe seems to be made of it, it's only known from its assumed gravitational effects, so is it really matter and if so, what is it?

2. The problem of Quantum Gravity - Physics' two most fundamental theories are General Relativity and Quantum Mechanics. Unfortunately, they aren't consistent with one another as they currently stand. A new theory that harmonizes them would be the long sought (but misleadingly named) Theory of Everything.

3. The Measurement Problem in QM - Quantum mechanics only predicts the outcome of measurements probabilistically. But actual observations deliver actualities. So what collapses the wavefunction, so to speak?

4. Matter-Antimatter Assymmetry - Theory says that the Big Bang should have produced equal amounts of matter and antimatter, which presumably would have annihilated each other. So why is our universe almost entirely matter?

5. The problem of neutrino masses - neutrinos have small masses that can seem to vary. So what explains neutrino masses? (I don't really understand this one. It depends on theory I don't know.)

6. Strong CP-violation - Charge parity symmetry says that the laws of physics should stay the same if particles are replaced by antiparticles and spatial coordinates inverted. So why does the strong force behave differently in this regard? (I don't really understand this one either.)

7. Cosmic Inflation - a widely accepted hypothesis claims that the universe expanded very rapidly immediately subsequent to the Big Bang. Assuming this speculation is true (I'm skeptical) what caused it?

8. The Problem of Time - Time in QM is a fundamental variable, while in Relativity time is relative and dynamical. The incompatibility in how time is conceived in our best theories is a basic problem for phyics.

Yazata,

Thank you for drawing our attention to the famous beasts of Physics conundrums. You've certainly enticed me or piqued my curiosity.