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I am a highly interested layperson in Germany focusing on the fundamental principles that govern our everyday reality.

I have a specific question regarding the permanence of the basic forces of nature. My core question is:

What physical mechanisms or theoretical concepts guarantee the long-term stability of the Strong and Weak Nuclear Forces?

For example, what assures us that the strong interaction coupling constant will not spontaneously change over cosmological timescales?

Are these constants seen as truly immutable within the Standard Model, or are there experimental or theoretical constraints that limit the possible variation of these parameters?

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Leyla Katharina is a new contributor to this site. Take care in asking for clarification, commenting, and answering. Check out our Code of Conduct.
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  • $\begingroup$ You might well be asking a question on grand unification, linked to this one... $\endgroup$ Commented 2 days ago
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    $\begingroup$ Time-variation of fundamental constants $\endgroup$ Commented 2 days ago
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    $\begingroup$ @David_h No, it’s a question for physics. Distant quasars let us observe whether fundamental constants have changed over billions of years. $\endgroup$ Commented 2 days ago
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    $\begingroup$ @Ghoster Sure, that's probably the best answer this question can get, but that's the past. The question asks whether they will change, not whether they have changed and it speaks of assuring they will not change. That's not something physics can do, because that's the problem of induction. $\endgroup$ Commented 2 days ago
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    $\begingroup$ If we’re in a false vacuum state, everything could change at any moment. $\endgroup$ Commented yesterday

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The standard model assumes they are constant. Cosmological models for before a tiny fraction of the first second of the universe do explicitly model changes in the interactions. But nothing guarantees the permanent stability of any interactions. It’s just that we don’t observe them changing now. Physics tries to describe what we observe as accurately as possible. No one has any idea why the universe even has fixed laws, except that’s what we see, and if it didn’t we wouldn’t be around to observe. But really that is philosophy (unfortunately for the credibility of the field of philosophy)

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  • $\begingroup$ How do physicists manage when they reach the limits of science, because they cannot answer the 'why'? This somehow triggers anxieties in me, and I don't understand how physicists can live with it, because they are confronted more than I am every day with the fact that we don't have 100% confirmation that we can rely on these constants like the nuclear and gravitational forces. $\endgroup$ Commented yesterday
  • $\begingroup$ @LeylaKatharina I suspect they echo N. David Mermin: Shut up and calculate! $\endgroup$ Commented yesterday
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    $\begingroup$ @LeylaKatharina This somehow triggers anxieties in me. There are so many alarming things happening in the world today that this is the least of my worries. However I’ve dealt with anxiety on other issues and I know it can be very difficult; group therapy was helpful for me. Try to take comfort in the fact that the universe has lasted almost 14 billion years so it is statistically very unlikely to change its physics in your lifetime. $\endgroup$ Commented yesterday
  • $\begingroup$ @LeylaKatharina You can't keep asking "why" forever. At some point, we accept certain axioms that have not yet been proved false. $\endgroup$ Commented 3 hours ago
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When we look at particles at CERN and similar places, we are only looking at the present values of these "constants", of course.

One could imagine running experiments over so many years that any change would be apparent, but we are hardly there yet. Cosmological times scales are long, human time scales are short.

Fortunately we have a sneaky shortcut.

We can look at stars and galaxies far away. When looking at something ten billion light years away, we are in effect looking at how physics worked ten billion years ago. And that was only a few billion years after the Big Bang. Surely any difference would be easy to see.

But what do we see? We see stars that behave just like the stars nearby, we see galaxies behaving just like our own.

Now, we don't see very much at those immense distances, but light spectra can tell you a lot about both how much there are of each element and how those elements are behaving.

Everything looks normal.

Moving closer to the Big Bang we have the hydrogen and helium percentage of the universe. It is assumed (for good theoretical reasons) that an equal number of protons and neutrons were created at the Big Bang. Then some neutrons decayed into protons. After a few minutes everything had cooled down enough that protons and neutrons could combine in helium. Unlike bare neutrons, helium is stable. Because of neutron decay there is a surplus of protons, which is also called hydrogen.

Physicists have calculated how much helium and hydrogen there should be based on the present values of the "constants", and the results match what we see around us.

As @kangermu wrote, cosmologists consider the possibility of a change in the "constants" for the very first fraction of a second after the Big Bang.

That is possible. We will probably never know for sure. Some people might find that unsettling, but what can one do? It is better to shrug and get on with life.

As for the future, these "constants" have been very close to constant for billions of years. We can expect them to hold for our life times.

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