Alternatives to GUT and GUT Epoch

In summary, the conversation revolved around the concept of Grand Unified Theories (GUTs) and their role in the early universe. The discussion questioned the validity of GUTs, particularly SU(5), due to the lack of evidence for proton decay, which is a crucial aspect of GUTs. The conversation also mentioned the possibility of other alternatives beyond the standard model and the role of gauge symmetry in unifying the strong and electroweak forces. There was also a mention of Loop Quantum Gravity as a potential theory that does not unify the forces but rather explains gravity in a quantum framework. The conversation ended with a debate on the logic behind testing the theory of proton decay and the experimental constraints on its half-life.
  • #1
kye
168
2
I went to a science museum last weekend and saw timeline of the big bang. There is a "GUT Epoch" mentioned at the beginning but then how can this be when GUT (Grand Unified Theories) was not proven due to lack of proton decay, etc. What other alternatives beyond the standard model if the strong force and electroweak was not really combined force early in the universe? Do you think this is more possible than symmetry unifying them? Would Big Bang no longer be so if they indeed came off separately? What is the list of ideas or scenerios about this in arxiv, etc.? What candidates of the mechanism?

Without gauge symmetry unifying the strong and electroweak force. How do you think (or possible scenerios) how they separately came to be? I'm sure Loop Quantum Gravity people prefer this as their theory doesn't unify the forces but just cooking up quantum version of gravity.
 
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  • #2
Something's not right. Proton in GUT is supposed to decay in 10^72 years.. more than the lifetime of the universe... so what scientists do is to put 10^72 protons in experiments and see if one would decay. Since it didn't, then GUT as least SU(5) is falsified. Does the logic hold? It's like saying that there is a 1/10^72 chance a prisoner can quantum tunnel outside a prison cell and by creating 10^72 prisoners, one of them can indeed tunnel... does this makes sense?

If it didn't, then Proton can decay in 10^72 years, isn't it and GUT at least SU(5) is still promising.
 
  • #3
The current experimental constraints on the minimum proton half-life are between 10^33 and 10^34 years. This rules out SU(5) at (at least) 90% confidence. Other GUTs predict longer half-lives.
 
  • #4
Only SU(5) GUT - which is the simplest but not the favorite GUT - has been ruled out by proton decay experiments.
 
  • #5
kye said:
Something's not right. Proton in GUT is supposed to decay in 10^72 years.. more than the lifetime of the universe... so what scientists do is to put 10^72 protons in experiments and see if one would decay. Since it didn't, then GUT as least SU(5) is falsified. Does the logic hold? It's like saying that there is a 1/10^72 chance a prisoner can quantum tunnel outside a prison cell and by creating 10^72 prisoners, one of them can indeed tunnel... does this makes sense?

If it didn't, then Proton can decay in 10^72 years, isn't it and GUT at least SU(5) is still promising.

First, the Number is 10^30ish. Not 10^72. 2nd, Yes, by increasing the sample size even very unlikely events ought to be observed.
 

Related to Alternatives to GUT and GUT Epoch

1. What are alternatives to the Grand Unified Theory (GUT)?

Some alternatives to GUT include String Theory, Loop Quantum Gravity, and the Multiverse Theory. These theories attempt to reconcile the inconsistencies of GUT and explain the fundamental forces of the universe in a different way.

2. How do these alternative theories differ from GUT?

While GUT attempts to unify all of the fundamental forces, these alternative theories take a different approach. String Theory, for example, proposes that particles are made up of tiny vibrating strings, while Loop Quantum Gravity suggests that space and time are made up of discrete, indivisible units.

3. Is there any evidence to support these alternative theories?

Currently, there is limited evidence to support these alternative theories. However, some experiments, such as the Large Hadron Collider, are searching for evidence that could support or disprove these theories.

4. Are there any drawbacks to these alternative theories?

One major drawback of these alternative theories is that they are highly complex and difficult to test. Additionally, they often require new mathematical frameworks and concepts that are not yet fully understood.

5. How do these alternative theories impact our understanding of the early universe?

These alternative theories propose different explanations for the early universe, such as the idea of a Multiverse or the concept of a pre-Big Bang universe in String Theory. These theories continue to be studied and debated in order to gain a better understanding of the origins of our universe.

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