Theory of Everything (TOE) Without a Grand Unified Theory (GUT)

[ohwilleke]

Normally, we think about a grand unified theory (GUT) that unifies the standard model forces and particles into an overarching unified framework, as a pre-requisite to a theory of everything (TOE) which adds quantum gravity to a GUT.

But, developments of both beyond the Standard Model physics, and "within the Standard Model" physics that explain the Standard Models internal structure without modifying it, are moving forward at a glacial pace since experimental evidence continues to stubbornly refuse to deviate from Standard Model predictions and the Higgs boson mass has allowed the Standard Model to be well defined and stable up to the Planck scale.

Meanwhile, advances in astronomy observation and theory are moving the project of describing quantum gravity along at a respectable pace.

So, it seems to me, we may well have a TOE, before we have a GUT.

 

[Greg Bernhardt]

Thanks for the post! Sorry you aren't generating responses at the moment. Do you have any further information, come to any new conclusions or is it possible to reword the post?

 

[friend]

In order to have a theory of everything, we're going to have to explain why the universe is quantum mechanical and why the metric changes with energy. Are there any candidate theories that do any of that?

 

[bapowell]

In order to have a theory of everything, we're going to have to explain why the universe is quantum mechanical and why the metric changes with energy. Are there any candidate theories that do any of that?

Are we going to have to explain why there is gravity? Why there is something rather than nothing? Why electrons are negatively charged while protons are positively charged? Some aspects of the universe, including *why* certain laws are the way they are, might just be beyond explanation from within the system.

 

[nikkkom]

In order to have a theory of everything, we're going to have to explain why the universe is quantum mechanical and why the metric changes with energy. Are there any candidate theories that do any of that?

That's not exactly how science works.

A scientific theory doesn't explain "why".

A theory says "assuming that these concepts and equations govern nature, here's my predictions what we'll see in experiments". Note that theory doesn't explain why it contains those specific equations, not some other ones.

The "whys" which _are_ answered by the theory are _theorems_ which are derived from those initial concepts and equations, but initial concepts and equations are axioms, not theorems.

 

[friend]

That's not exactly how science works.

A scientific theory doesn't explain "why".

A theory says "assuming that these concepts and equations govern nature, here's my predictions what we'll see in experiments". Note that theory doesn't explain why it contains those specific equations, not some other ones.

Sure, finding reverse engineering equations that describe observation will only take you back so far on how things work.

 

[torsten]

Normally, we think about a grand unified theory (GUT) that unifies the standard model forces and particles into an overarching unified framework, as a pre-requisite to a theory of everything (TOE) which adds quantum gravity to a GUT.

But, developments of both beyond the Standard Model physics, and "within the Standard Model" physics that explain the Standard Models internal structure without modifying it, are moving forward at a glacial pace since experimental evidence continues to stubbornly refuse to deviate from Standard Model predictions and the Higgs boson mass has allowed the Standard Model to be well defined and stable up to the Planck scale.

Meanwhile, advances in astronomy observation and theory are moving the project of describing quantum gravity along at a respectable pace.

So, it seems to me, we may well have a TOE, before we have a GUT.

I agree with you, the standard model is well-established and there is no new sign for more unknwon particles required by GUT. It seems that TOE (in particular quantum gravity) will take over.

 

[friend]

I agree with you, the standard model is well-established and there is no new sign for more unknwon particles required by GUT. It seems that TOE (in particular quantum gravity) will take over.

Wouldn't a TOE by definition tell us whether there is a GUT or not?

 

[Ilja]

As an example for an approach which promises an incorporation of gravity without following the usual GUT scheme of introducing a larger gauge group see http://arxiv.org/abs/0908.0591 which obtains the SM gauge group as the maximal possible one compatible with some principles. It is compatible with the theory of gravity proposed in http://arxiv.org/abs/gr-qc/0205035 which can be easily quantized (as a field theory on a fixed background, thus, avoiding any problems related with background-freedom like the problem of time).