Thread: CURRENT QUESTIONS ?

Sorry guys, nothing to do with electrical 'currents'.

Are there any particular BIG questions currently remaining to be answered in physics ?

Yes there must be thousands of unanswered questions but are there any in the forefront of current study/thinking ?

BARCUD

Originally Posted by BARCUD

Sorry guys, nothing to do with electrical 'currents'.

Are there any particular BIG questions currently remaining to be answered in physics ?

Yes there must be thousands of unanswered questions but are there any in the forefront of current study/thinking ?

BARCUD

Three are lots of them

1. A theory is needed that can address general relativity and quantum field theory simulatneously.

2. Although quantum electrodynamics in principle explains the fundamental laws that govern all of the physics of our everyday experience, including all of chemistry. no one can solve the equations in practical situations so as to be able to explain complex phenomena in those fundamental terms.

3. Our understanding of turbulent fluid flow is purely phenomenological. A fundamental description of turbulent fluid flow is needed.

4. There is insufficient observed matter to explain the rotation rates of galaxies, and some unseen and unknown form of matter, "dark matter" is hypothesized to explain what is observed. Observational data shows that not only is the universe expanding, the rate of expansion is accelerating. We don't know why and a repulsive force, termed "dark energy" is postulated to account for the observations. Dark matter and dark energy combine to apparently account for the vast majority of mass/energy in the universe. We have no idea what they are. An explanation is needed.

Hi DrRocket, thanks for the reply.

'A theory is needed that can address general relativity and quantum field theory simulatneously.' I've heard this before but not quite sure what the actual problem is. I think I have a basic grasp on general relativity but not so much quantum field theory.

Sorry to ask DrRocket but, can you state what the problem is in very simple terms so that I might gain some understanding of what it is ?

BARCUD

Originally Posted by BARCUD

Hi DrRocket, thanks for the reply.

'A theory is needed that can address general relativity and quantum field theory simulatneously.' I've heard this before but not quite sure what the actual problem is. I think I have a basic grasp on general relativity but not so much quantum field theory.

Sorry to ask DrRocket but, can you state what the problem is in very simple terms so that I might gain some understanding of what it is ?

BARCUD

Let's see if I can answer this simply. In GR, gravitation is seen as a curvature of space. For this to work at the sub-atomic scale, the curvature has to be smooth at this scale. QM, however, holds that things becomes "choppy" at the sub-atomic scale. This would lead to wild fluctuations of spacial curvature and gravity at these scales. So while GR works really well at macroscopic scales where the quantum fluctuations wash out, it doesn't at the really small scales where they dominate.

Thanks Janus, so are you saying that the laws of physics don't run true at both macro and micro levels ?

I have to work in pictures in my head most of the time so would I be correct in picturing a river, running choppy on the surface, yet seamingly smoothly down below?
Or am I way off target ?

BARCUD

Originally Posted by BARCUD

Hi DrRocket, thanks for the reply.

'A theory is needed that can address general relativity and quantum field theory simulatneously.' I've heard this before but not quite sure what the actual problem is. I think I have a basic grasp on general relativity but not so much quantum field theory.

Sorry to ask DrRocket but, can you state what the problem is in very simple terms so that I might gain some understanding of what it is ?

BARCUD

General relativity is a classical theory. It predicts definite outcomes, given specific boundary and initial conditions.

Quantum theories are stochastic. Only probabilities are predictable, and only probabilities are physical.

There have been attempts to formulate quantum theories of gravity. They have failed rather dramatically, because they are not renormalizable -- they tend to predict infinities that cannot be made to go away.

We have quantum field theories that are compatible with special relativity but not with general relativity. That is a major reason for an inability to describe the physics in the earliest universe, immediately after the big bang and near the singularity that is predicted by general relativity for black holes.

The unification of the quantum field theories of the electroweak force and the strong force with general relativity (gravity) is one of the foremost research problems in theoreticl physics. That is the goal of string theory/M theory, loop quantum gravity, and in part of supersymmetry theories. Success has been elusive.