
There are no particles, there are only fields (2012) - monort
https://arxiv.org/abs/1204.4616
======
ptrincr
This only clicked for me a few weeks ago, but it finally gave me an
understanding of the Higgs field, and the Higgs-boson.

So the Higgs field is everywhere, like the electron field and the
electromagnetic field (all elementary particles are thought to have their own
field, as I understand it).

As excitations of one field (electrons etc) interact with the Higgs field,
they experiance a kind of drag and this interaction gives them mass.

So how about this Higgs-Boson then? Well if you produce enough energy, like
smashing two protons together at huge speeds, this energy is released and some
of it ends up in the higgs field, producing an excitation of the field, which
we detect as the Higgs Boson. It's unstable and quickly releases it's energy
which dissipates into other fields, producing more excitations which we see as
more particles.

Before I understood this, I was trying to work out how if the Higgs-Boson was
responsible for mass, why it needed so much energy for it to appear. All makes
sense when you think about it as a field.

~~~
blablabla123
The professor I wrote my diploma thesis at said to me: quantum fields and the
corresponding operators are just mathematical crutches because that stuff
can't be described otherwise.

------
atemerev
And in another 100 years or so, this will finally make it to textbooks...

Quantum field theory is weird, but there are much more compelling analogies in
classical world than particles. (Feynman was a fan of particles, but I presume
he was aware of the problems with this representation).

When you speak of fields and wave packets, you eliminate the uncertainty
principle, and double-slit experiment is no longer a paradox — no small feat
to achieve.

~~~
tim333
The trouble with explaining the double slit experiment with spread out waves
is the electrons hit the screen at points leaving you to explain how that
works. Video of it happening
[https://www.youtube.com/watch?v=ToRdROokUhs](https://www.youtube.com/watch?v=ToRdROokUhs)

~~~
ars
Because charge is quantized, and not splittable.

Once it interacts with something all of it gets "sucked in" to one spot, and
the entire electron interacts. The exact place it does that is randomized with
varying probability at different spots.

But once a place is "picked" all of the charge goes there.

It's the quantization that is fundamental, and it's the quantization that
makes fields look like particles, not the other way around.

~~~
hasenj
If I understand correctly, there's currently no explanation of how one
electron gets picked out of all the gazillions of electrons available; am I
correct? Would that just be considered a fundamental randomness in nature?

~~~
ars
I don't understand your question, can you rephrase?

In the experiment here they fire one electron at a time, so you don't have to
pick one electron. Rather the final location of that electron is what's
random.

~~~
srtjstjsj
That's the question: how is the location picked?

You roll a fair die, 1-6. It lands on 4 _this time_. Why 4, and not 5? How was
the 4 chosen? In classical mechanics, it's a horrendously complicated but
fundamentally simple computation. In QM, no one knows.

~~~
dogma1138
Pilot wave theory :)

~~~
naasking
aka Bohmian mechanics, aka the de Broglie-Bohm interpretation of QM. It
definitely doesn't get enough serious attention IMO.

~~~
dogma1138
It's been getting more and more attention especially since many recent QM
simulation experiments kinda show that pilot waves are a real phenomena.

------
okket
Sean M. Carrol always mentions this fact when he talks about QFT, which can be
very entertaining like this one from 2013

"Particles, Fields and The Future of Physics"

[https://www.youtube.com/watch?v=gEKSpZPByD0](https://www.youtube.com/watch?v=gEKSpZPByD0)

(Audio starts at 19 sec, Lecture starts at 2:00)

~~~
IANAD
Just read this post from him recently, which, along with the referenced paper,
was pretty enlightening: "Space Emerging from Quantum Mechanics"
[http://www.preposterousuniverse.com/blog/2016/07/18/space-
em...](http://www.preposterousuniverse.com/blog/2016/07/18/space-emerging-
from-quantum-mechanics/)

paper "Space from Hilbert Space: Recovering Geometry from Bulk Entanglement":
[https://arxiv.org/abs/1606.08444](https://arxiv.org/abs/1606.08444)

------
ScottBurson
Interesting that the paper starts by attacking "quantum mysticism". Seems to
me that the argument it's making renders quantum mysticism _easier_ to believe
rather than harder. The concept of particles, after all, appeals to our
Newtonian "billiard ball" intuitions; particles are the essence of locality,
and our intuitions suggest that a particle universe should be deterministic.

On the other hand, if particles are epiphenomenal, and everything is really
infinite fields which only have a certain probability of interacting in
certain ways, it seems like, intuitively, there's a lot more room for
consciousness to influence those fields in a nonlocal manner. No?

Just playing devil's advocate here :-)

~~~
Houshalter
Not at all. Fields are a precise mathematical model that could, in principle,
be simulated on a computer to arbitrary precision. There's no room for
mysticism or "consciousness" nonsense.

~~~
danharaj
> Fields are a precise mathematical model

Let's not get ahead of ourselves here; unless you've solved a millennium
problem!

~~~
joelthelion
Which one is it?

------
datihein
This article did get published in the American Journal of Physics, and there
was some back and forth discussion also published in the Journal.
Unfortunately, the published version and the ensuing discussion is effectively
inaccessible ... they want 30 USD from me to read each published response.

~~~
monort
[http://physics.uark.edu/hobson/pubs/13.09.a.AJP.pdf](http://physics.uark.edu/hobson/pubs/13.09.a.AJP.pdf)

------
Ono-Sendai
Generally I think the field idea is more plausible than the particle idea. But
I think there are some things that the field can't explain yet (to my
satisfaction at least). Why, whenever we measure the charge of an electron, do
we measure the same value? Why not one half, or one third of that charge
sometimes? After all, if an electron is just a disturbance in a field, why
might we not capture just part of that field in our measuring apparatus?

This is of course trivially explained by the particle idea.

~~~
taneq
Why do gliders
([https://upload.wikimedia.org/wikipedia/commons/9/96/Animated...](https://upload.wikimedia.org/wikipedia/commons/9/96/Animated_glider_emblem.gif))
always have a 'weight' of 5 cells? Why not 4 or 6?

~~~
platz
Space itself cannot be quantized into a grid because it totally fails under
special relativity.

~~~
taneq
I seem to remember reading somewhere recently that you can in fact quantize
space in a hexagonal grid in a way consistent with quantum mechanics, but I
can't find a link now.

~~~
platz
quantization consistent with QM is tautology; issue is this can't be made
consistient with GR. see raattgift's comment in thread.

------
WhitneyLand
Here another physicist challenges Hobson for not respecting realism, and he
has a pretty good come back:

[http://physics.uark.edu/hobson/pubs/13.09.a.AJP.pdf](http://physics.uark.edu/hobson/pubs/13.09.a.AJP.pdf)

------
andrewflnr
That was eye-opening, and not just with regard to the titular subject. I'd
never thought of energy stored in fields as a consequence of energy
conservation.

------
kkylin
The abstract already lost me: "Thus the Schroedinger field is a space-filling
physical field whose value at any spatial point is the probability amplitude
for an interaction to occur at that point." But the wave function lives on the
configuration space of the system: if you have $N$ particles, the wave
function lives on $R^{3N}$. In what way is this a "space-filling physical
field"? Admittedly I haven't had time to do more than skim the article;
perhaps it's explained more carefully later on.

(Off-topic, but since this has come up a number of times on HN: this point is
also where Bohmian pilot wave theory has never been wholly satisfying for me.
If you accept the pilot wave picture, then the double slit loses a little bit
of its mystery, but many-body theory still seems just as weird as before.)

~~~
zeroer
If there are no particles, then how do you know what $N$ should be?

------
gpsx
From the paper, at the top of page 10 of the PDF, at the end of section A:

"Some authors conclude, incorrectly, that the countability of quanta implies a
particle interpretation of the quantized system. Discreteness is a necessary
but not sufficient condition for particles. Quanta are countable, but they are
spatially extended and certainly not particles. Eq. (3) implies that a single
mode's spatial dependence is sinusoidal and fills all space, so that adding a
monochromatic quantum to a field uniformly increases the entire field's energy
(uniformly distributed throughout all space!) by hf. This is nothing like
adding a particle. Quanta that are superpositions of different frequencies can
be more spatially bunched and in this sense more localized, but they are
always of infinite extent. So it's hard to see how photons could be
particles."

As mentioned above, you can take linear combinations of these different single
particle states at different energies and come up with various energy/location
spreads. Doesn't one such combination have a spatial spread of zero? This
would correspond to a single quanta at a single location in space.

My physics may be a bit rusty since I have been out for a while. Combining the
different frequency components from the different field configurations is not
_exactly_ the same as simple Fourier analysis, on the face of it. However, the
individual contribution from a given field configuration (meaning a single
frequency) is very small since there are so many different field
configurations contributing (an infinite number). I believe the Fourier result
does apply to the expectation value of the particles location here.

If I am thinking correctly this seems to be a very critical error in the
paper. Someone correct me if I am wrong.

* * *

EDIT: I believe I said something incorrectly. Where I said "I believe the
Fourier result does apply to the expectation value of the particle's location
here." I meant to make a stronger statement, "I believe the Fourier result
does apply to the effective value of the particles wave function in this
location in this case." (The expectation value being zero would not bean the
field does not extend to that location.)

~~~
rrmm
(Not a physics person, but) As I read it, he is just arguing against the
implication that Countability implies Particles. So he is saying that adding a
quantum that is monochromatic has an effect across all space (which is clearly
a non-particle like effect). Then he admits that you can get localization
through superpositions of quanta.

Since he is arguing against a logical implication he only needs to show a
counterexample exists.

The problematic part in choosing a single mode like this is that it can lead
to a non-normalizable integral at some point (ie, it won't be a member of the
Hilbert space).

QFT always made more since to me. Everything flows more naturally than in QM,
where out of the blue, they introduce wave packets.

The paper does feel a bit shaky though especially as it is essentially taking
a pedagogical point (start teaching from a QFT viewpoint) and making it into
an argument about the foundations of physics. The non-relativistic QM view
point is taught because it represents a smooth departure point from classical
thinking without requiring the full mathematical complexity of field theory.

~~~
gpsx
I think the general assumption is that QFT is true, it is just whether you can
call the physics it creates as being particles. At least that is how I
interpret it. QFT is QM, but it just has a lot more degrees of freedom
(infinite) than what you are talking here about when you say QM. You can write
a Schroedinger's equation for a field. Rather than the wave function being a
function of X, the wave function is a function of F(X) where F(x) is a field
configuration over space.

I would say some of his argument comes down to semantics because by his
definition in order for something to be a particle it can't have spatial
extent. I think a lot of people don't include this in the definition of a
particle. They do associate the number of "Quanta" with the number of
particles, at least in a field theory.

What I was saying above is that I believe you can create an object by the
"Quanta" definition in QFT that has no spatial extent. His argument is based
on the fact that this is not possible.

Adding these Quanta together to form a zero extent object is similar to saying
in Fourier analysis you can take a number of different frequencies (like the
quanta at different wave lengths) and create a delta function (which has no
spatial extent). The thing is, even though we are dealing with adding a bunch
of frequencies together, it is not exactly the same as a Fourier series
because we are adding them together in a different way.

You make a good point about people first teaching the simple Schroedinger's
equation of particles because it is a lot easier. I think what is so hard
about quantum mechanics is relating it to the real world, and not the axioms
themselves. The simple form is much easier to relate to the real world.

~~~
rrmm
Yeah, I just meant QM as meaning the semi-classical version. Making QM work
with SR requires moving to QFT/"second quantization".

You can presumably create particle-like quanta with a creation operator that
creates particles in position space vs momentum space. The particle then won't
have a definite momentum in that case, so there's still an extent problem at
least in configuration space. If there is an ultraviolet energy cut-off then
you end up with problems as well.

I think we perceive living in a position space more than we feel we live in a
momentum space. We would prefer things to have a definite position more than
we care about them having a definite momentum. The fact that they are
conjugate observables is the troubling part.

------
dschiptsov
Particles is just result of [self-centric] human perception bias and the
resulting naive concept of matter or a substance as perceptual conditioning,
evolved in a certain physical environment (everything what we are, including
our mind and consciousness is shaped by the environment, and our perception of
reality, in turn, is shaped by our mind, conditioned by perception).

We think that there are solids and atoms - grains of matter - basic building
blocks. This model corresponds to what our sense organs give us. It is hard to
convince oneself that there is no matter at all, only energy and our
perception grossly zoomed out of what is really going on.

Matter is an appearance to perception. A wrong model due to limitation of the
sensory system. There is no matter when there is no observer, only states of
energy, or fields, which is a better concept, but still mere concept. We could
say that atoms are "stable" fields, but it is much better to do not apply
"human" predicates to the nature.

Particles is a good-enough model, which allowed us to sequence a genome or
build a CPU, but it is only a crude model nevertheless.

------
erdevs
Total aside and this may be too late into a crowded thread for anyone to
notice this. But have physicists ever rigorously examined the idea that
quantum "duality" is explained by computational complexity?

I know it's more metaphysics/interpretation, but that's what we're talking
about here. I also know that universe-as-simulation is a very popular notion
among laypeople (particularly programmers) who look at physics. I'm just
wondering if any physicists have rigorously studied the idea, and if there are
falsifiable propositions we could make about this.

In game programming, one often cannot compute every detail of every component
of a simulation. So, what you often do is focus more precise computation on
areas around a player, or what the player is actually observing. The rest are
often modeled stochastically or via computationally efficient functions. This
has always mapped well in my (very surface-level, entirely layman)
understanding of QM and QFT.

Note that there are, in my mind at least, two different notions here. One is
actually the concept of a simulation with observer-dependencies directing the
fidelity of the simulation. The other doesn't imply a "simulation" nor is it
directly dependent on any "observer": perhaps computational complexity is
related to the fundamental physics of the universe and nature prefers to use
imprecise probability estimates wherever possible and it is only when precise
interactions need to be resolved that more precise or definite calculations
are performed.

I know these are sloppy notions as presented here and I'm not taking the time
to phrase these questions very well, or very precisely. Busy atm, sadly. Just
wondering if any well-reputed physicists have studied this possibility
rigorously, or if it has been rejected for an obvious reason, etc.

------
kmm
I always enjoy a discussion about semantics, but only when both parties are
very clear about the fact that it's semantics they're talking about, and not
fundamental nature of existence. I'm very wary of people trying to use physics
to further an ontology, as physics almost by definition allows for multiple,
completely equivalent descriptions of reality. That's not to say I think
physics teaches us nothing about how the universe really works, but I don't
think you can conclude from his interpretation of the mathematics of QFT that
particles (whatever they are) don't exist, just as much as the Fermat
principle[0] doesn't imply that light has a sentient mind which seeks out the
shortest path. There exists a consistent, fully equivalent interpretation of
(non-relativistic or relativistic) quantum mechanics that includes particles
at the core of its ontology, Bohmian mechanics[1]. I'm personally not an
adherent of it, but it shows that by nature, it's very hard to use physics to
show what something fundamentally is.

Besides, the article doesn't define clearly what it means by particle, which
is a priori just an English word, nor does it justify it well. I don't share
the authors' problem with the excitations of a field being spread out all over
the universe (by virtue of them being momentum-eigenstates). It's discrete,
has a mass, has a momentum, and energy and interacts as a whole. The article
calls these properties necessary but not sufficient, but doesn't explain why
this doesn't suffice.

Particles are at least a useful abstraction. They emerge naturally at the
classical level, interactions between fields are even at extremely high energy
levels still very localised, electrons "scatter" a lot like they're bouncing
off other particles, they leave neat tracks in bubble chambers, excitations of
fields are discrete even at the lowest level, ... Feynman diagrams[2] are
extremely handy, even if they don't "actually" happen, but are just a term in
the series expansion of an interaction Hamiltonian between two fields.

What's the use of contorting oneself to the limit to fit every observation in
a single mold, a field. Sure, classical particles are nothing like what we see
at the quantum level, but classical fields are absolutely nothing like the
fields in quantum field theory either. Why pick one term over the other?

0:
[https://en.wikipedia.org/wiki/Fermat%27s_principle](https://en.wikipedia.org/wiki/Fermat%27s_principle)
1:
[https://en.wikipedia.org/wiki/De_Broglie%E2%80%93Bohm_theory](https://en.wikipedia.org/wiki/De_Broglie%E2%80%93Bohm_theory)
2: [https://upload.wikimedia.org/wikipedia/en/f/fb/Feynman-
diagr...](https://upload.wikimedia.org/wikipedia/en/f/fb/Feynman-diagram-ee-
scattering.png)

~~~
TheOtherHobbes
I think it's been proven fairly comprehensively that particles don't really
exist in QFT in any useful sense. See e.g.

[http://arxiv.org/pdf/1304.7469.pdf](http://arxiv.org/pdf/1304.7469.pdf)

[http://www.sciencemag.org/news/2016/07/massive-neutrino-
expe...](http://www.sciencemag.org/news/2016/07/massive-neutrino-experiment-
undermines-our-sense-reality)

Particles may be a useful abstraction, but they're also a very misleading one.

It looks a lot as if what really happens is best described by a Two State
Vector/Transactional interpretation.

Which is _very_ weird, because those are both time symmetric. And that's not a
feature you'll find in any particle-oriented theory.

~~~
tachyonbeam
Newbie question: if there are no particles, then why are there quantized
packets of energy such as photons?

~~~
slacka
I'm am not a physicist, but interested in QM. Photons behavior cannot be
completely explained by treating them solely as particles. The simples counter
example (one you can perform yourself with a laser pointer), is the double-
slit experiment. If photons behaved classically (like billiard balls) they'd
never interfere with themselves.

If you'd like a good intro to QM, youtube is full of great material. Here are
some of my favorites:

NOVA - The Fabric of the Cosmos:
[https://www.youtube.com/watch?v=NbIcg0XsbFQ](https://www.youtube.com/watch?v=NbIcg0XsbFQ)

The Secrets of Quantum Physics:
[https://www.youtube.com/watch?v=VgDlzGZAPcY](https://www.youtube.com/watch?v=VgDlzGZAPcY)

Particle Fever: [https://vimeo.com/125987472](https://vimeo.com/125987472)

~~~
jostylr
Particles can interfere with themselves in the double-slit experiment if they
are being guided by a wave. This explains wave behavior and particulate events
as in Bohm's theory.

Sadly, there are issues with photons as particles as their wave equations do
not seem to allow for an easy particle interpretation unlike, say, electrons.
Of course, the flexibility of QM allows for electrons to have a particle
existence and photons to not: [http://arxiv.org/abs/quant-
ph/0404134](http://arxiv.org/abs/quant-ph/0404134) (I am a coauthor of that
paper)

And some videos to answer questions about BM: [http://www.bohmian-
mechanics.net/videos_faq.html](http://www.bohmian-
mechanics.net/videos_faq.html)

------
platz
as water waves are 'epiphenomena'/emergent from the underlying form, are the
'waves' that are used to describe light also epiphenomena (i.e. emergent) or
are light waves the EM field exactly ? If the latter, I don't see how to
interpret the photoelectric effect.

~~~
Retra
All phenomena are emergent. That word means nothing.

The photoelectric effect is not complicated any way you slice it. An atom
absorbs some quantum of energy from the field. This doesn't require any
understanding of what model you use to describe the energy in the field. The
interaction is quantized either way.

~~~
platz
not quite. 'emergent' in theoretical physics typically means 'arising from a
composition of the more fundamental physical state'. 'All phenomena are
emergent' with this definition of the word would mean you could always
represent something with something else that is more basic, _ad infinitum_ \-
I don't think that is the accepted view among physicists.

~~~
Retra
I'm not sure the term "emergent" is a term in theoretical physics. I've
certainly never seen it.

>'All phenomena are emergent' with this definition of the word would mean you
could always represent something with something else that is more basic, ad
infinitum

No, what it means is that at some point, you've broken your model down into
something that is not ' _phenomena_ ' in any meaningful sense. Which is
something physicists do all the time.

------
nobrains
The day I understood this, it was a awe moment. The realization that if we
zoom in very very deep, we will not see marble-like particles, rather we will
see nothing. Its only through the interaction of the excitation in these
fields do our pseudo-particles form.

------
amai
There are followup comments to this paper:

* [http://physics.uark.edu/hobson/pubs/13.09.a.AJP.pdf](http://physics.uark.edu/hobson/pubs/13.09.a.AJP.pdf)

* [http://physics.uark.edu/hobson/pubs/13.09.b.AJP.pdf](http://physics.uark.edu/hobson/pubs/13.09.b.AJP.pdf)

------
Animats
There is only the mathematics. "Shut up and calculate", as one physicist put
it.

Here's Feynman talking about it.[1] "We interpret the intensity of the wave as
the probability of finding a photon".

[1]
[https://www.youtube.com/watch?v=_7OEzyEfzgg](https://www.youtube.com/watch?v=_7OEzyEfzgg)

~~~
daxfohl
I feel this approach is flawed. In theory it'd have been possible to come up
with Relativity by recognizing the Lagrangian transforms that match
experimental outcomes and say "That's just how it is". Einstein provided an
insight as to _why_ that's far more enlightening.

To me, QM is still in the former state, detailed equations looking for a soul.

------
Gnarl
Nothing new. This guy published a book about it in 2006:
[http://transfinitemind.com/tapestryindex.php](http://transfinitemind.com/tapestryindex.php)

------
virtualritz
"Physicists are still unable to reach consensus on the principles or meaning
of science's most fundamental and accurate theory, namely quantum physics. An
embarrassment of enigmas abounds concerning wave-particle duality,
measurement, nonlocality, superpositions, uncertainty, and the meaning of
quantum states. After over a century of quantum history, this is scandalous."

What is also scandalous that in this age of systems that do this work for you
automagically (e.g. Tex) typesetting and microtypography in scientific
publications seem to deteriorate. This one is a fine example of this trend.
;-)

------
rrggrr
Can someone ELI5 or possibly 15 on this for me?

------
fu9ar
the map is not the territory.

the model is not Absolute, but it gives us a really, really good idea.

------
dmfdmf
Platonism and Kantianism are still alive and strong in Western thought.

~~~
corecoder
What's wrong with Kantianism?

~~~
dmfdmf
Its just a modernized version of Platonism.

------
snarfy
I never understood why interpretations of QM which violate non-locality like
pilot wave theory are frowned upon. Fields are non-local by definition.

------
johndoe4589
is this essentially a reminder that the materialistic view of the universe /
reality is outdated, or am I reading too much into it?

------
S_Daedalus
It's either this, or something like objective collapse really does happen,
physically, which seems less likely.

------
sbussard
Anyone who's studied beginning grad level physics should know that. I don't
get why it's trending on HN

~~~
joeberon
Yeah I'm being taught QFT in my undergrad. Any theoretical physicist would be
expected to know this concept well. I guess people here aren't theoretical
physicists though! However I do think the quality of physics commentary here
is generally quite poor. I see a lot of crackpot theories or just ignorance in
general. Especially with anything involving quantum mechanics, that seems to
drive people crazy. I don't think that many people realise that in physics we
don't talk about the philosophical implications at all, we're just trying to
find good models, that's it...

~~~
gpsx
I agree that many people who are not experts often misunderstand quantum
mechanics. It is a very difficult field to learn. It takes a long time. I
disagree about physicists not talking about philosophy. At least some people
do in theoretical physics. That is probably why this paper is published in the
area of "History and Philosophy of Physics".

~~~
joeberon
I mean in general. Of course there are physicists at some universities that
write about philosophy, but not a single one in my theory department.

