Uniting of the forces

[Copernicus]

I was wondering if physics theories are set on the forces uniting at a certain condition or time or if the forces are separate and generated from separate but connected entities.

[KiwiBiggles]

I'm only a lay science reader Copernicus, but here's my take on it:

Maxwell unified electricity and magnetism in 1873, which seems to have got the unification ball rolling.

The electroweak interaction unified electromagnetism and the weak nuclear force at high energy (such as existed momentarily after the Big Bang). Weinberg, Glashow and Salam won the Nobel Prize in 1979. As I understand it, this is where we're at right now with the Standard Model.

A successful Grand Unified Theory would merge the electroweak and strong nuclear forces at even higher energy (even earlier Big Bang epoch) and might be considered the next evolution of particle physics beyond the Standard Model?

Beyond that again is the so-called Theory of Everything which would unify gravity, the remaining of the four fundamental forces, presumably at higher energies still.

I don't know how others see it, but I think Einstein’s insights into unifying space and time have also added to the appeal of models that include the quality of unifying existing phenomena. 'Symmetry' as being examined at the LHC experiments is another example, and there are others all over science. 'Symmetry Breaking' as I understand it is the separation of these unified forces as the early universe evolves, and is invoked in some models of Big Bang inflation for example.

I've read some scientists who think this interest in an underlying simplicity and 'beauty' to nature is misguided - they suspect nature will eventually turn out to be more or less arbitrary, or that our universe is just a random example of a 'landscape' of possible and actual universes - but I think most scientists do harbour a hope that nature is indeed 'beautiful'.

Personally, I like that almost spiritual quality that simplicity and beauty brings to science... so I'm hoping for unification to win through!

[Cougar]

I was wondering if physics theories are set on the forces uniting at a certain condition or time or if the forces are separate and generated from separate but connected entities.

Prior to modern inflationary cosmology, it was not "set" but speculated upon that all the forces were joined into a single force way back around the Planck epoch. Apparently, inflation changes all that. Basically, we didn't know before, and now we really don't know.

[Cougar]

Basically, we didn't know before, and now we really don't know.

This is surely overstating our ignorance. As I recall, there were, and probably still are, good reasons for the four forces to have split off at different, specific times/temperatures/states during the earliest of fractions of the first second after the beginning of the expansion. Apparently inflation has to be considered in the mix, but it also is figured to have occurred in the briefest of instants. The so-called grand unification energy of 10¹⁶ Gev still doesn't include gravity. But I think most agree that whatever happens with these 'phase transitions', it's all over after the first second -- the forces are like they are today. Is that close enough?

[m74z00219]

I was wondering if physics theories are set on the forces uniting at a certain condition or time or if the forces are separate and generated from separate but connected entities.

It seems there has been a significant development in the mathematics of field theory: a simplification. It's an interesting read if you can get a hold of this past May's issue of Scientific American. Here is a link to a preview:

http://www.scientificamerican.com/ar...or-new-physics



M74

[Copernicus]

This is surely overstating our ignorance. As I recall, there were, and probably still are, good reasons for the four forces to have split off at different, specific times/temperatures/states during the earliest of fractions of the first second after the beginning of the expansion. Apparently inflation has to be considered in the mix, but it also is figured to have occurred in the briefest of instants. The so-called grand unification energy of 10¹⁶ Gev still doesn't include gravity. But I think most agree that whatever happens with these 'phase transitions', it's all over after the first second -- the forces are like they are today. Is that close enough?

That is what I thought, but I think it would be better to seek for a unification of force origin, rather than unification of forces. It might help find the final theory.

[Shaula]

That is what I thought, but I think it would be better to seek for a unification of force origin, rather than unification of forces. It might help find the final theory.

That is being worked on in terms of understanding the symmetry groups the forces belong to. The electroweak unification is a brilliant example of that. But if you are looking for a 'why', well we don't know 'why' a force so it is not that productive to ask 'why' a unification.