Well, the answer is #3. There it was, just hanging there.
Somehow I suspect you don’t believe me. Or at least, if you do believe me, you probably are assuming there must be some complicated explanation that I’m about to give you as to how this happened. It can’t possibly be that two young kids were playing wildly in the room and somehow managed to get the vase into this extremely precarious position just by accident, can it? For the vase to end up
just so — not firmly on the table, not falling off the table, but just in between — that’s …
that’s not natural!
There must (mustn’t there?) be an
explanation.
Maybe there was glue on the side of the table and the vase stuck to it before falling off? Maybe one of the kids was hiding behind the table and holding the vase there as a practical joke on his mom? Maybe her husband had somehow tied a string around the vase and attached it to the table, or to the ceiling, so that the vase couldn’t fall off? Maybe the table and vase are both magnetized somehow…?
Something so unnatural as that can’t just end up that way on its own… especially not in a room with two young children playing rough and throwing things around.
The Unnatural Nature of the Standard Model
Well. Now let’s turn to the Standard Model, combined with Einstein’s theory of gravity.
Fig. 2: Imagine a lot of different possible universes, each one described by equations similar to our own universe, but with small adjustments.
I want you to imagine a universe much like our own, described by a complete set of equations — a “theory”, in theoretical-physics speak — much like the Standard Model (plus gravity). To keep things simple, let’s say this universe even has all the
same elementary particles and forces as our own. The only difference is that the
strengths of the forces, and the strengths with which the
Higgs field interacts with other known particles and with itself (which in the end
determines how much mass the known particles have) are a little bit different, say by 1%, or 5%, or maybe even up to 50%. In fact, let’s imagine ALL such universes… all universes described by Standard Model-like equations in which the strengths with which all the fields and particles interact with each other are changed by up to 50%. What will the worlds described by these slightly different equations (shown in a nice big pile in Figure 2) be like?
Among those imaginary worlds, we will find three general classes, with the following properties.
- In one class, the Higgs field’s average value will be zero; in other words, the Higgs field is OFF. In these worlds, the Higgs particle will have a mass as much as ten thousand trillion (10,000,000,000,000,000) times larger than it does in our world. All the other known elementary particles will be massless (up to small caveats I’ll explain elsewhere). In particular, the electron will be massless, and there will be no atoms in these worlds.
- In a second class, the Higgs field is FULL ON. The Higgs field’s average value, and the Higgs particle’s mass, and the mass of all known particles, will be as much as ten thousand trillion (10,000,000,000,000,000) times larger than they are in our universe. In such a world, there will again be nothing like the atoms or the large objects we’re used to. For instance, nothing large like a star or planet can form without collapsing and forming a black hole.
- In a third class, the Higgs field is JUST BARELY ON. It’s average value is roughly as small as in our world — maybe a few times larger or smaller, but comparable. The masses of the known particles, while somewhat different from what they are in our world, at least won’t be wildly different. And none of the types of particles that have mass in our own world will be massless. In some of those worlds there can even be atoms and planets and other types of structure. In others, there may be exotic things we’re not used to. But at least a few basic features of such worlds will be recognizable to us.
Now: what fraction of these worlds are in class 3? Among all the Standard Model-like theories that we’re considering, what fraction will resemble ours at least a little bit?
The answer? A ridiculously, absurdly tiny fraction of them (Figure 3). If you chose a universe at random from among our set of Standard Model-like worlds, the chance that it would look vaguely like our universe would be spectacularly smaller than the chance that you would put a vase down carelessly on a table and end up putting it right on the edge of disaster, just by accident.
much more at the link...
https://profmattstrassler.com/artic...ics-basics/the-hierarchy-problem/naturalness/
