Recent content by ohad

I looked around for this issue a while ago and the problem with cosmology treatment of this issue is that the timescales of close encounters is very large in relation to the evolution time. When such limitation is imposed, it means that waves are propagated dispersively. I remember that I...

In the following lecture of Leonard Susskind: at minute 30 +- 1 he says that every unified theory predicts baryon number violation.

in the example of spin-0 - rotations, the symmetry is rotation. singlet is relative abstract mathematical notion, so the answers will be usually abstruct.

A very general statement would be that a singlet (with regard to specific symmetry) is a state that is not affected by operations (that keep the symmetry) it is like a scaler. A good examples are: 1) spin-0 particles are singlets with regards to rotations 2) uncharged particles are singlets with...

Classical physics cannot describe photons, at least not most of the interactions it does. Quantum Physics describe photon as the electromagnetic field itself. You cannot think of it as point particle and not as a simple wave. it has the particle-wave duality and it has quantum amount of energy...

Gauge invariance is about local symmetry of a field. If you have any field and there is some global symmetry which is preserved by the lagrangian, than requiring this symmetry to be local (i.e. to be position dependent) usually breaks the symmetry, for that you need to introduce the gauge field...

They do not contradict. the system has symmetry, but the ground state breaks it. you can check the following example: ferromagnetic Iron, you heat it up and there is no magnetic field. Than you start to cool it down, the system has rorational symmetry so the magnetic pole can be in any...

Looks like quantum network is already operational: https://en.wikipedia.org/wiki/Quantum_network

Entanglement can only happen between quantum numbers. One of the particles can interact with very limited part of the macro object, by that the information is lost because you cannot know which particle is the entangled one. If you do know which is the new entangled particle than you go back to...

There is no conclusion that observer's consciousness causes a collapse of wavefunctions. The foundations of QM claims that measurement cause it. And not just any measurement but measurement that has enough precision. If for example, in the famous double slit experiment, you are measuring the...

ohwilleke, thank you for the very detailed explanation. I learned a lot from it.

Hi cube137, As I understand it the problem of 120 oom is not within GR to explain but it is a problem in QFT. QFT vacuum energy is much higher than the measured cosmological one.

My question is about system of infinite number of point like particles with gravitation interaction (classic Newtonian interactions). If the infinite system can be considered to be in equilibrium, uniform density, in 3D, did anyone analyzed this system with regard to propagation of density...

An object of 1kg mass (the speed is negligible here) has a huge amount of energy stored within by the E=mC^2 famous formula. However you cannot access this energy because this structure is very very stable. Only in very extreme scenarios of fusion or fission you will be able to access small...

Hi, After you manage to use the angular momentum conservation, you need to do variable change from r to u = 1/r. Also there are many online texts which solve this problem. BR, Ohad