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Is particle physics dead, dying, or just hard?

quantamagazine.org

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Re: Is particle physics dead, dying, or just hard?

#31

Post by throw_m239339 »

bananaflag wrote: post #7

It's basically the opposite situation from 150 years ago. Back then, we thought our theory was more or less complete while having experimental data which disproved it (Michelson-Morley experiment, Mercury perihelion, I am sure there are others). Right now, we know our theories are incomplete (since GR and QFT are incompatible) while having no experimental data which contradicts them.

I find the idea that reality might be quantized fascinating, so that all information that exists could be stored in a storage medium big enough.

It's also kind of interesting how causality allegedly has a speed limit and it's rather slow all things considered.

Anyway, in 150 years we absolutely came a long way, we'll figure it that out eventually, but as always, figuring it out might lead even bigger questions and mysteries...

Re: Is particle physics dead, dying, or just hard?

#32

Post by JumpCrisscross »

Paracompact wrote: post #21
tasty_freeze wrote: post #15

Here is one fact that seems, to me, pretty convincing that there is another layer underneath what we know. The charge of electrons is -1 and protons +1. It has been experimentally measured out to 12 digits or so to be the same magnitude, just opposite charge. However, there are no theories why this is -- they are simply measured and that is it. It beggars belief that these just happen to be exactly (as far as we can…

Technically, the charge of a proton can be derived from its constituent 2 up quarks and 1 down quark, which have charges 2/3 and -1/3 respectively. I'm not aware of any deeper reason why these should be simple fractional ratios of the charge of the electron, however, I'm not sure there needs to be one. If you believe the stack of turtles ends somewhere, you have to accept there will eventually be (hopefully simple) c…

> you have to accept there will eventually be (hopefully simple) coincidences between certain fundamental values, no?

No. It’s almost certainly not a coïncidence that these charges are symmetric like that (in stable particles that like to hang out together).

Re: Is particle physics dead, dying, or just hard?

#33

Post by Paracompact »

XorNot wrote: post #25
Paracompact wrote: post #23

Earlier quoted context omitted.

What about underexplained cosmological epicycles like dark matter (in explaining long-standing divergences of gravitational theory from observation), or the Hubble tension?

This is your regular reminder that epicycles were not an incorrect theory addition until an alternative hypothesis could explain the same behavior without requiring them.

Sure, but in that regard dark matter is even more unsatisfying than (contemporary) epicycles, because not only does it add extra complexity, it doesn't even characterize the source of that complexity beyond its gravitational effects.

Re: Is particle physics dead, dying, or just hard?

#34

Post by jiggawatts »

tasty_freeze wrote: post #15

Here is one fact that seems, to me, pretty convincing that there is another layer underneath what we know. The charge of electrons is -1 and protons +1. It has been experimentally measured out to 12 digits or so to be the same magnitude, just opposite charge. However, there are no theories why this is -- they are simply measured and that is it. It beggars belief that these just happen to be exactly (as far as we can…

This is "expected" from theory, because all particles seem to be just various aspects of the "same things" that obey a fairly simple algebra.

For example, pair production is:

    photon + photon = electron + (-)electron
You can take that diagram, rotate it in spacetime, and you have the direct equivalent, which is electrons changing paths by exchanging a photon:

   electron + photon = electron - photon
There are similar formulas for beta decay, which is:

   proton = neutron + electron + (-)neutrino
You can also "rotate" this diagram, or any other Feyman diagram. This very, very strongly hints that the fundamental particles aren't actually fundamental in some sense.

The precise why of this algebra is the big question! People are chipping away at it, and there's been slow but steady progress.

One of the "best" approaches I've seen is "The Harari-Shupe preon model and nonrelativistic quantum phase space"[1] by Piotr Zenczykowski which makes the claim that just like how Schrodinger "solved" the quantum wave equation in 3D space by using complex numbers, it's possible to solve a slightly extended version of the same equation in 6D phase space, yielding matrices that have properties that match the Harari-Shupe preon model. The preon model claims that fundamental particles are further subdivided into preons, the "charges" of which neatly add up to the observed zoo of particle charges, and a simple additive algebra over these charges match Feyman diagrams. The preon model has issues with particle masses and binding energies, but Piotr's work neatly sidesteps that issue by claiming that the preons aren't "particles" as such, but just mathematical properties of these matrices.

I put "best" in quotes above because there isn't anything remotely like a widely accepted theory for this yet, just a few clever people throwing ideas at the wall to see what sticks.

[1] https://arxiv.org/abs/0803.0223

Re: Is particle physics dead, dying, or just hard?

#35

Post by [deleted] »

XorNot wrote: post #25
Paracompact wrote: post #23

Earlier quoted context omitted.

What about underexplained cosmological epicycles like dark matter (in explaining long-standing divergences of gravitational theory from observation), or the Hubble tension?

This is your regular reminder that epicycles were not an incorrect theory addition until an alternative hypothesis could explain the same behavior without requiring them.

[deleted]

Re: Is particle physics dead, dying, or just hard?

#36

Post by [deleted] »

klipt wrote: post #24
bananaflag wrote: post #7

It's basically the opposite situation from 150 years ago. Back then, we thought our theory was more or less complete while having experimental data which disproved it (Michelson-Morley experiment, Mercury perihelion, I am sure there are others). Right now, we know our theories are incomplete (since GR and QFT are incompatible) while having no experimental data which contradicts them.

Doesn't that imply our theories are "good enough" for all practical purposes? If they're impossible to empirically disprove?

[deleted]

Re: Is particle physics dead, dying, or just hard?

#37

Post by hackyhacky »

JumpCrisscross wrote: post #32
Paracompact wrote: post #21

Earlier quoted context omitted.

Technically, the charge of a proton can be derived from its constituent 2 up quarks and 1 down quark, which have charges 2/3 and -1/3 respectively. I'm not aware of any deeper reason why these should be simple fractional ratios of the charge of the electron, however, I'm not sure there needs to be one. If you believe the stack of turtles ends somewhere, you have to accept there will eventually be (hopefully simple) c…

> you have to accept there will eventually be (hopefully simple) coincidences between certain fundamental values, no? No. It’s almost certainly not a coïncidence that these charges are symmetric like that (in stable particles that like to hang out together).

> coïncidence

Nïce

Re: Is particle physics dead, dying, or just hard?

#38

Post by cozzyd »

Paracompact wrote: post #33
XorNot wrote: post #25

Earlier quoted context omitted.

This is your regular reminder that epicycles were not an incorrect theory addition until an alternative hypothesis could explain the same behavior without requiring them.

Sure, but in that regard dark matter is even more unsatisfying than (contemporary) epicycles, because not only does it add extra complexity, it doesn't even characterize the source of that complexity beyond its gravitational effects.

Even better, there are the "nightmare" scenarios where dark matter can only interact gravitationally with Standard Model particles.

Re: Is particle physics dead, dying, or just hard?

#39

Post by Paracompact »

JumpCrisscross wrote: post #32
Paracompact wrote: post #21

Earlier quoted context omitted.

Technically, the charge of a proton can be derived from its constituent 2 up quarks and 1 down quark, which have charges 2/3 and -1/3 respectively. I'm not aware of any deeper reason why these should be simple fractional ratios of the charge of the electron, however, I'm not sure there needs to be one. If you believe the stack of turtles ends somewhere, you have to accept there will eventually be (hopefully simple) c…

> you have to accept there will eventually be (hopefully simple) coincidences between certain fundamental values, no? No. It’s almost certainly not a coïncidence that these charges are symmetric like that (in stable particles that like to hang out together).

Whence your confidence? As they say in math, "There aren't enough small numbers to meet the many demands made of them." If we assume the turtle stack ends, and it ends simply (i.e. with small numbers), some of those numbers may wind up looking alike. Even more so if you find anthropic arguments convincing, or if you consider sampling bias (which may be what you mean by, "in stable particles that like to hang out together").

Re: Is particle physics dead, dying, or just hard?

#40

Post by libraryofbabel »

rjh29 wrote: post #22
tasty_freeze wrote: post #15

Here is one fact that seems, to me, pretty convincing that there is another layer underneath what we know. The charge of electrons is -1 and protons +1. It has been experimentally measured out to 12 digits or so to be the same magnitude, just opposite charge. However, there are no theories why this is -- they are simply measured and that is it. It beggars belief that these just happen to be exactly (as far as we can…

One argument (while unsatisfying) is there are trillions of possible configurations, but ours is the one that happened to work which is why we're here to observe it. Changing any of them even a little bit would result in an empty universe.

There’s a name for that: the Anthropic principle. And it is deeply unsatisfying as an explanation.

And does it even apply here? If the charge on the electron differed from the charge on the proton at just the 12th decimal place, would that actually prevent complex life from forming. Citation needed for that one.

I agree with OP. The unexplained symmetry points to a deeper level.

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