
Long-sought decay of Higgs boson observed at CERN - chmaynard
https://home.cern/about/updates/2018/08/long-sought-decay-higgs-boson-observed
======
_Microft
_Furthermore, both teams measured a rate for the decay that is consistent with
the Standard Model prediction, within the current precision of the
measurement._

And now everyone: _Noooo, not again._

(Explanation: it's well-known that the Standard Model can't be completely
correct but again and again physicists fail to find an experiment
contradicting its predictions, see
[https://en.wikipedia.org/wiki/Physics_beyond_the_Standard_Mo...](https://en.wikipedia.org/wiki/Physics_beyond_the_Standard_Model)
for example)

~~~
delhanty
Sorry, I don't understand this point.

If a model of the universe was completely correct, wouldn't it have equivalent
complexity to the universe and hence not be a model?

~~~
jon_richards
No? Think of the game of life. Low model complexity, high universe complexity.

~~~
digi_owl
I think the term used is emergent complexity.

So when you go from particle physics to chemistry, new complexities emerge
that can't be explained in the realm of particle physics alone (iirc).

sadly certain "sciences" still cling to the idea that they can simply
aggregate the results from multiple of their "particles" and get a solution
for larger systems.

~~~
xoa
> _So when you go from particle physics to chemistry, new complexities emerge
> that can 't be explained in the realm of particle physics alone (iirc)._

Correct me if I'm misunderstanding, but I think you're confusing general
theory vs practical applicable models here maybe? Yes, fundamental principles
of interaction can combine at scale to create new large scale effects, but
that doesn't change the fact that they came out of fundamental principles nor
that they can't be "explained" via those principles. There is no magic that
pops into existence up the chain. The asymmetry of water molecules and the way
their electron clouds distribute create all sorts of fascinating effects in
bulk water, but they're still directly coming out of physics of course.

The issue in practice however is that the level of computing necessary to
accurately model reality at scale from fundamentals matches or exceeds
actually doing it in reality, and for us rapidly becomes absolutely, utterly
infeasible for anything but the simplest systems. "New emergent complexities"
absolutely "can be explained" from a correct lower level set of principles,
but that doesn't mean we can actually crunch the math at any scale we want. So
we need higher level bulk models too, at many levels all the way up, which are
good enough to be effective approximations to a given level of accuracy in
practical computing time. The low level fundamentals often at bulk average out
due to random variance in sufficient quantity and are irrelevant to whatever
we care about, so there is no need to do it that expensively (even if we
could). But that isn't the same thing as the fundamentals being wrong somehow
or not being at the root of everything above.

~~~
jon_richards
Right. There are roughly 10^15 atoms in a speck of dust. A terabyte is 10^12
bytes. Our inability to simulate does not mean our models are wrong.

------
mac01021
Does anyone here know of a good account (something I could read, preferably)
suitable for someone without much knowledge of modern physics of how the
Standard Model came to be constructed on the basis of experimental evidence?

Most descriptions of particle physics that I have encountered begin right away
with an enumeration of the different types of particles, and the statement
that some of them are composed of various combinations of quarks, but don't
include (at least not without investing some hours of my time) any indication
of how these things are observed, what set of data this model fits, what is
the nature(if any) of a quark independent of the hadron in which it is a
constituent, what are the laws governing quarks that cause these particles to
arise, etc.

I don't feel I'm learning much of anything by just memorizing the names of all
the members of the particle zoo. But it seems I must spend some hours doing
this before I can gain any understanding of what particle physics means, or
how particle physics is done?

~~~
jasonwatkinspdx
The book "Fields of Color" is short, math free, and largely organized by the
historical progression of discovery.

> any indication of how these things are observed

In the last 50 years or so, the bulk of the evidence has come from particle
accelerators, but there's been meaningful results from other experiments as
well. Sean Carrol organizes the current state of physics into two broad
categories: intensity experiments, like the LHC, which are attempting to reach
energy concentrations we haven't probed before, and sensitivity experiments,
which observe natural but rarely produced or interacting particles, like
neutrino detectors.

> what set of data this model fits

All the data. The standard model is the best model we've found to explain all
experiments observed in the history of physics.

> what is the nature(if any) of a quark independent of the hadron in which it
> is a constituent

Quarks and Gluons are bound together in the nucleus by the strong force. This
force is, as its name indicates, very strong, however it falls off with
distance sharply. The way it works out, the force is such that if you try to
pull two bound quarks apart, the energy you add is sufficient to create new
quarks. So lone quarks never appear, they're always bound into a composite of
two or three, and if you try to pull them apart, you just end up making a
second composite when they separate.

> But it seems I must spend some hours doing this before I can gain any
> understanding of what particle physics means, or how particle physics is
> done?

The blunt truth is fully understanding the standard model requires a lot of
non trivial mathematics. I can't work with the math, but I've read through
enough textbooks I've got some intuition for the big picture now. This isn't a
topic where you can swoop in, spend 15 minutes, and suddenly understand it
all. It's not going to just take some hours, it'll take much much more time
than that.

Some topics cannot be simplified into a tidy summary that can be skimmed in a
couple hours.

~~~
ddavis
>> what set of data this model fits

> All the data. The standard model is the best model we've found to explain
> all experiments observed in the history of physics.

This isn't the full story. The Standard Model _does not_ explain neutrino mass
(which we know exists from neutrino oscillations) or dark matter & dark
energy. These are very big open questions!

~~~
TheOtherHobbes
Or gravity, which is an even bigger open question.

~~~
rurban
Or antigravity, gravitomagnetism. This would be much cheaper to explore. you
just need fast rotating supraconductors, best on planetary scale.

~~~
drdeca
"supraconductors"?

Edit: apparently an older term for "superconductors"

~~~
rurban
Nope, just my phone autocompletion at work.

For antigravity just look up M.Taijmar's work on the Thirring-Lense effect:
[https://patents.google.com/patent/WO2007082324A1/en?inventor...](https://patents.google.com/patent/WO2007082324A1/en?inventor=Martin+Tajmar)

To understand gravity you don't need to build super-expensive devices to find
the particle-interpretation of this wave force. The Higgs makes no sense
outside the standard model. Studying the wave-interpretation as attracting
force is easier and also alignable with general relativity. Explaining an
wide-reaching attractive force as particle really makes no sense at all
(outside QM), as Heisenberg also complained.

------
jmount
Hossenfelder’s book "Lost in Math" ( One review here
[http://www.math.columbia.edu/~woit/wordpress/?p=10314](http://www.math.columbia.edu/~woit/wordpress/?p=10314)
) covers a bit of why confirming the standard model is a bit disappointing.
The rough idea is the standard model is known to be limited (problems unifying
with general relativity and ready to explain dark matter), so one wants to see
an explicit experimental-scale (non-galactic scale) exception to help find a
replacement theory.

~~~
airstrike
Thanks! That review alone is worth a HN submission and I'm not even a hobbyist
physicist by any stretch of the imagination.

------
jnurmine
Slightly off-topic and maybe this is just the way especially physics-related
press releases and layman articles are written, but they tend to often have a
part with "now that we have finally proven this, imagine what new
research/flying cars this discovery will open up for us!"

The truth is there whether attempts are made to prove it or not. Also
proving/disproving does not alter the fact. If you prove it to be true, great,
but it was true already before. Now you just have the fact formalized on
paper, so to say.

Now, couldn't one just make an educated assumption that some-particle-physics-
problem has been already proven and then see what new things can are made
possible with this assumption.

And then try some low hanging fruit enabled by this "virtually proven"
assumption. Any success would indirectly prove the assumption, too, or at
least give strong evidence in favor. Also, it might make interesting
discoveries happen faster.

------
source99
How do they use Machine Learnig to analyze the data?

~~~
nestorD
CERN did a particule tracking competition with Kaggle which illustrate at
least a use case : [https://www.kaggle.com/c/trackml-particle-
identification](https://www.kaggle.com/c/trackml-particle-identification)

~~~
kgwgk
They did another Kaggle contest four years ago:
[https://atlas.cern/updates/atlas-news/machine-learning-
wins-...](https://atlas.cern/updates/atlas-news/machine-learning-wins-higgs-
challenge)

