The old grandmother of 15th century comes back to see her grand … grandson, the Apple boy. The following is the conversation about this unnaturalness issue.
Apple boy: G-grandmother, I just read a great article about the unnaturalness of Nature. Every argument in it makes sense. But put all together, it just doesn’t make sense to me. How can Nature be unnatural? You have sat right beside of Nature for the past 500 years. Can you help me on this?
G-grandmother: Oh, the only thing unnatural to me during my last visit in the 17th century was seeing a man who walked on a rope 100 feet above the ground.
Apple boy: It is unnatural to an average person in their ability to perform such a stunt. But, it is simply allowed by the laws of Nature.
G-grandmother: Well, I really see some unnatural things in this visit. When I came down from upstairs, I saw many people in a bird-like metal box flying in the sky. Then, I saw many people talking from inside of a hand-held plate.
Apple boy: Indeed, they are some kinds of unnatural as they were invented by humans. We call them artificial inventions. Yet, they are still parts of Nature as only laws of nature allow their existences.
G-grandmother: Last night, I saw a video about Ptolemy model of the universe, and all stars are dancing in different patterns. How can a star dance like a dancer? It is truly unnatural.
Apple boy: That model put the *center* of the universe at Earth, and it is an unnatural way of doing it. Indeed, that model is unnatural which means *wrong* today.
G-grandmother: Hi, boy, you seemingly know all answers. Then, what is your question?
Apple boy: Matt showed a vase/table analogy and said that our universe sits at the unnatural situation (the rightmost picture).
G-grandmother: Why is it unnatural? For a few hundred years, I have travelled with my nephew Jedi all over this universe. And, most of the time (99.9999…%), the vase are not sitting in the natural cases as described in his analogy. His saying is true only when my spaceship landed on Earth. There must be some unnatural force around Earth.
Apple boy: Okay, okay. No analogy. But, please read the entire article. The argument is very strong individually, especially about the Standard Model.
G-grandmother: Hi, boy, it took me awhile to read it. No big problem, but a major confusion. There are only two questions.
a. Standard Model is unnatural (meaning, it is wrong).
b. Nature is unnatural (meaning, … nuts).
Apple boy: The issue is more subtle than that. The Standard Model has three parts.
Part A — A zoo of particles (especially the 48 matter particles) which are verified by tests.
Part B — A set equations which *fits* the test data by hand-put many parameters into the equations.
Part C — A reverse-engineering which produced Higgs mechanism.
If Standard Model is wrong (unnatural), which part is wrong?
G-grandmother: Part A is message directly from Nature. Part B is artificial but works for Nature. Only part C is the suspect of the problem.
Apple boy: But, Higgs boson was *discovered* on July 4th 2012.
G-grandmother: Indeed, LHC found *something* on July 4th 2012. But, 14 months later, we haven’t even officially established evidence for the Higgs to bottom quark pair decay (which is one of the *golden channel*) at all.
Matt’s argument is all about the *mass* of that something (he calls it Higgs boson) vs the *vacuum energy* (he calls it Higgs field) of the empty space.
In one other model, the mass of that-thing should be [(1/2) of the vacuum energy + some transformation barrier], as that-thing is a blob of [a vacuum state to a new vacuum state] transformation.
This is an unsettled issue and thus no need to go into any further.
Apple boy: Okay, let’s put the Higgs issue aside. The unnaturalness can still arise in the case of *multiverse*.
G-grandmother: *Possible universes* was a very old philosophical topic. The evolution *pathways* for the universe are zillions (infinite to be exact), but the *history* of the universe is unique, only one history. That is, there is only *one set* of laws of universe.
The *multiverse* in the article is about having many different sets of laws of nature. They got this idea from the concept of *fine-tuning*. If a set of laws can be tuned, it becomes many different sets.
Apple boy: *Fine-tuning* is definitely a part of nature. If we change the nature constants very slightly, this universe will be dramatically different.
G-grandmother: Well, this is another major confusion. Nature is very, very precise, locked by Alpha (a dimensionless pure *number*). That is, no *dimension* of any kind can change it. Preciseness looks very much like fine-tuning but cannot be tuned.
Apple boy: Thanks G-grandmother. Now I understand the issue which has only two questions.
1. Which one is unnatural —- Nature or the Standard Model?
2. Can preciseness be tuned?
But, I think that you have swept three very important points off the table by questioning about the Higgs mechanism, didn’t you?
1. Three Higgs (or other) field classes (on, off, on/small)
2. Quantum fluctuations of quantum fields, and the energy carried in those fluctuations (the vacuum energy)
3. Why It Isn’t Easy to Have the Higgs (or Higgs-like) Particle’s Mass Be Small (the summation of all different fields and the magic cancellation)
G-grandmother: I was a farm lady, you know. I know everything about *fields*, the corn field, the potato field, the sheep field, the dog field, the fish field, … the ocean field, etc..
Apple boy: Come on, G-grandmother. A herd of sheep, a pack of dogs and a school of fish, not fields.
G-grandmother: Okay, my bad. Just exclude those then. But, for all other fields (corn or the whatnot), I could turn them on or off as I please, by plowing them out or seeding them in. If you can move this Earth into Mercury’s orbit, I can even turn the ocean field off.
Apple boy: What is your point?
G-grandmother: Just a bit Buddhism here. All those fields are transient phenomena. Their on or off have no importance for the eternal reality. For me, there was only *one* field, the surface of the Earth, and it cannot be turned on or off (so to speak). And, this true field is a tad bigger than all those *fields* add together. So, those summation operations of all those different fields (top quark field, etc.) do not make any difference for the true Daddy field which cannot be turned on or off. By the way, if a field can be turned on or off, it cannot be the true Daddy field.
Apple boy: What is the true Daddy field for this universe?
G-grandmother: Now, you ask a right question. It is the space-time sheet (field). All matter particles are protrusions from the space-time field, just similar to the corns and potato on the Earth field. When an electron protrudes, it forms an electric field.
Apple Boy: So, Higgs field is not space-time field. Is there anything wrong with the Higgs field argument in this unnaturalness issue?
G-grandmother: This is the whole problem. The argument implies that the Higgs field is the true Daddy field which affects the entire universe. You know, only the true Daddy field (the space-time-sheet) carries the *vacuum energy*. Any other fields also carry energy, but not vacuum energy.
Apple Boy: Come on, everyone knows that the vacuum energy is the result of quantum fluctuations of quantum fields.
G-grandmother: No, the quantum fluctuations of electric field are not vacuum energy. This is a linguistic issue, you know. Vacuum is referring to lacking of matter in *space*. So, vacuum energy is about the energy carried by space-field (space-time-sheet to be exact). If Higgs field carries some energy, it should not be called the *vacuum energy*, unless the Higgs field is the space-time filed.
Apple Boy: Well, besides of not being turned on or off, what is the other reason that the Higgs field cannot be the space-time-sheet?
G-grandmother: The space-time –sheet houses *all* fields (including the gravity field), the same as the Earth field houses all plant fields and those herds, packs and schools, you know. If Higgs field does not house all fields, its being on or off does not truly make any difference to the space-time-sheet. If it does house all fields, then it cannot be turned on or off. All those calculations are just games on the paper.
Apple Boy: Okay, let’s put this Higgs field vs vacuum energy issue aside. The point that the vacuum energy is the result of quantum fluctuations is still important, isn’t it?
G-grandmother: Wow, you got a key question again. We know three facts.
a. Quantum principle (fluctuations) is a fact.
b. Vacuum energy is not zero.
c. The above two facts (a and b) are related.
But, what kind of relation are they, the cause/effect or the fundamental/emergent? There are two possibilities.
1. Quantum principle (fundamental) causes the nonzero vacuum energy (emergent).
2. Nonzero vacuum energy (fundamental) causes the quantum principle (emergent).
Apply Boy: Come on, everyone knows that #1 is the answer. But, what is the big deal here?
G-grandmother: This is *the* issue. By selecting #1 as the answer, we are facing the unnaturalness issue. By selecting #2 as the answer, the Nature cannot be unnatural. But, this issue is very deep and cannot be discussed any further here.
The above is also available at http://profmattstrassler.com/articles-and-posts/particle-physics-basics/the-hierarchy-problem/naturalness/#comment-84640