Still confused about matter not being solid !

[Swift]

Though coming back to individual particles, they are real physical entities. I see them as tiny points with no inner structure. If they are real then they must have a size.

Electrons and their relatives can be described as point particles with no inner structure. But this would not be a good description of protons and neutrons. They do have a size (there have been measurements of them) and they are made of even smaller particles (quarks) so they do have a structure, though I don't think I would call them "solids".

By the way (completely off topic), but what the heck is your new avatar?

[kevin1981]

Kevin, you've demonstrated how useful it is when someone asks a seemingly simple (but actually quite deep) question, clearly listens to the answers, asks follow-up questions, and so on. This is so refreshing after having sat through several recent threads where someone makes a wrong assertion and then ignores key questions and counter-evidence.

Thanks Paul and AndreH for your comments. I am here to learn and have an inquisitive nature. I like to know how things work, especially
in nature. There are obviously many people on this board who have a much better, deeper, understanding about these subjects than me.
So i take the answers i get seriously and trust there judgement.

I am not too sure where to go now as i do not want to keep repeating myself. It would seem to me that the question of, is fundamental
matter solid, is a tricky question.
The answer seems to be, no, it is not. The solid world we see is due to interaction of forces. We can not really think of them as very tiny
snooker balls because that is a misinterpretation. What ever they really are is outside of our every day common experience so trying to
make sense of them or visualize them is all ways going to come up short. It is rather unsatisfactory, but that is the way it is.

[kevin1981]

By the way (completely off topic), but what the heck is your new avatar?

haha I was hoping for that sort of reaction ! It is a smiling pumpkin !

[AndreH]

BTW: Here is maybe a helpful link to a Wikipedia page. It is concerning the so called "Copenhagen interpretation" of QM. As you see, physicists have been struggling with the philosphical implications of QM since the very beginning. As you may notice from my posts, I have never liked this interpretation but everything is pointing into the direction it is maybe all we will ever have.
http://en.wikipedia.org/wiki/Copenhagen_interpretation

[Jeff Root]

I disagree that the quantum world is counterintuitive. What is
intuitive is what you are accustomed to. I've been hearing and
reading about quantum mechanics my entire life, and the rules
which describe quantum interactions seem natural to me. They
make sense to me-- as I interpret them. Some interpretations
of QM do not make sense or seem natural to me. I'd say that
those interpretations are either wrong or misleading.

In the thread which led to this one, I said that a fundamental
particle is its properties. Same as Strange said here in post 29.
An electron is the properties of an electron, which are centered
on a location which your intuition makes you want to think of as
the electron itself. That location is just a location, nothing more.

The assertion that an electron is a cloud of probabilities is an
interpretation which I think is not wrong, but very misleading.
If you understand it, it makes perfect intuitive sense. If you
misunderstand it-- which is almost unavoidable-- it is crazy.
Absurd. Ridiculous. Complete nonsense. Although learning
the math necessary to be able to work out quantum calculations
is beyond my ability, I understand the ideas sufficiently for them
to make sense to me, so I know it can make sense to you, too.

I reject the notion that we can't describe quantum behavior in a
way that makes sense, is meaningful, and is explanatory. I think
the idea that quantum behavior is beyond comprehension is a
consequence of it being so different from classical physics that
it seemed that way to people accustomed to classical physics,
and the idea hasn't yet died out. Most people have such a
superficial knowledge of QM that they have not developed an
intuitive feel for it. That is, they don't understand it yet, so they
generally misunderstand it, and the interpretation they have is
nonsensical. Nonsense often makes people lose interest. But
it also often makes people wonder, and ask good questions.

-- Jeff, in Minneapolis

[Shaula]

Some interpretations of QM do not make sense or seem natural to me. I'd say that those interpretations are either wrong or misleading.

Wow. This is not meant in a nasty way but that is a hugely egotistical thing to say. "Any interpretation that doesn't seem natural to me is wrong". No. It may not be useful to you but to someone else it might be a perfectly valid interpretation that they can use and reason from. Sorry but that is true. You are not the arbiter of right and wrong when it comes to QM!

[Jeff Root]

Shaula,

I'll repeat what I said to someone in a PM on November 17:
Don't assume that the mainstream disagrees with you or that
you disagree with the mainstream. It is more likely a difference
in perception or description than a difference in the physics.

Do you feel that intuitive understanding of advanced physics
ideas must necessarily always be wrong?

Don't assume that because that question is ironic, it isn't
serious. I ask it in earnest.

Do you disagree with the example I gave, that the assertion
that an electron is a cloud of probabilities is an interpretation
which is not wrong, but is very misleading?

-- Jeff, in Minneapolis

[Jeff Root]

Shaula,

I just came across a good example of a misleading
interpretation in another thread in which you participated.
It is a good example because it is very simple. You agreed
with Cougar, Strange, and Grey that the term "halo" is
misleading as applied to the dark matter associated with
a galaxy. However, cjameshuff (whose comments I almost
always agree with strongly) opined that it sounds like the
perfect word for it to him. I agree with you that "halo" is
misleading. I would speculate that cjameshuff doesn't see
it as misleading because his image of what constitutes a
halo is different from mine and yours.

-- Jeff, in Minneapolis

[Shaula]

My point was that you are not the yardstick of QM. You may not like or feel comfortable with an interpretation - but to make the bold statement you made about things not being right if you didn't like them is too much.

I genuinely think that most intuitive pictures are fine if they are used where they are applicable. A huge swathe of bad physics comes about because people take an analogy that is intuitive and then try to reason with it outside where it is applicable. Ten minutes of maths is enough to show they are wrong but because for many people mathematical explanations are less intuitive than pure word ones they will cling to the verbal explanation. So short version: Intuitive models of advanced physics always fail somewhere. But they are perfectly valid if they are applied correctly and within their own limitations.

[AndreH]

......snip.... I said that a fundamental
particle is its properties. Same as Strange said here in post 29.
An electron is the properties of an electron, which are centered
on a location which your intuition makes you want to think of as
the electron itself. That location is just a location, nothing more.

We could argue a lot on that. I would insist that the properties cannot be the thing itself. But that that would not lead anywhere. To me it sounds as if you have found an explanation that you can live with. That is completely fine. But it does not mean for other'S it is the same.

....snip..... Although learning
the math necessary to be able to work out quantum calculations
is beyond my ability, I understand the ideas sufficiently for them
to make sense to me, so I know it can make sense to you, too.
I reject the notion that we can't describe quantum behavior in a
way that makes sense, is meaningful, and is explanatory. I think
the idea that quantum behavior is beyond comprehension is a
consequence of it being so different from classical physics that
it seemed that way to people accustomed to classical physics,
and the idea hasn't yet died out. Most people have such a
superficial knowledge of QM that they have not developed an
intuitive feel for it. That is, they don't understand it yet, so they
generally misunderstand it, and the interpretation they have is
nonsensical. Nonsense often makes people lose interest. But
it also often makes people wonder, and ask good questions.

As I mentioned the one or other time, it is a while since I got my degree, and today doing the math for therotical physics is completely beyond me. But at some point in my studies I could solve simple (one dimensional) wave functions. Calculate things as tunneling, partial reflection and other stuff (the Alonso Finn study book has some very good exercises). I could do operator equations to determin things like from which to which state an atom can go and so on.
I could explain what outcome the double slit experiment has and what happens if you know which way a photon (or electron goes) etc.
In other words: I could do the math, and new how to apply it in which situation on that level described above.
But I never found an intuitive way to understand what is going on. Being able to do the math or explain the outcome of an experiment never really satisfied me. At that point I subscribed to the "shut up and calculate" fraction and left the rest to the phillosophers.
Sad but true.

[AndreH]

My point was that you are not the yardstick of QM. You may not like or feel comfortable with an interpretation - but to make the bold statement you made about things not being right if you didn't like them is too much.

I genuinely think that most intuitive pictures are fine if they are used where they are applicable. A huge swathe of bad physics comes about because people take an analogy that is intuitive and then try to reason with it outside where it is applicable. Ten minutes of maths is enough to show they are wrong but because for many people mathematical explanations are less intuitive than pure word ones they will cling to the verbal explanation. So short version: Intuitive models of advanced physics always fail somewhere. But they are perfectly valid if they are applied correctly and within their own limitations.

I totally agree with that statement. The electron "cloud" model e.g. helps at some point a lot to understand chemistry. It is the same with all models. Hard balls for atoms in a gas, depicting potentials as hills and valleys and the particles as small balls rolling around and so on.

[Jeff Root]

My point was that you are not the yardstick of QM.

I think you mean that I'm not the person who decides what
QM says and does not say.

I can agree with that. But if I do, I will add that nobody holds
the job of deciding what QM says and does not say.

On the other hand, I can disagree. If I do, I will add that it
is everyone's job to decide what QM says and does not say.
Anyone posting anything about QM here on BAUT or
anywhere else necessarily does so. You are doing it when
you tell me that I can't or shouldn't do it.

You may not like or feel comfortable with an interpretation -
but to make the bold statement you made about things not
being right if you didn't like them is too much.

I didn't say such a thing, anyway. That is the second time
you misrepresented what I said. I'll grant that your version
isn't very different from what I actually said, but it is different.
What I actually said:

Some interpretations of QM do not make sense or seem
natural to me. I'd say that those interpretations are either
wrong or misleading.

Since I did not specify what interpretations I was referring
to, you have no way of assessing whether my assessments
of them are right or wrong.

The one example I gave was of something which I explicitly
said I think is not wrong, but is very misleading. So you have
no idea what I am talking about and no idea what you are
talking about when you object to my assessments of "some
interpretations of QM" being "wrong". You also have no idea
what my assessments are based on or how they are arrived
at, in contradiction to your repeated assertion that they are
based on my not liking them.

I genuinely think that most intuitive pictures are fine if they
are used where they are applicable.

And I do not think that. I think it is not a matter of an
interpretation being applicable or not being applicable.
I think it is a matter of the interpretation working or not
working.

In effect, I do not distinguish between a theory and a
correct interpretation of that theory. In my opinion they
are one and the same.

I want to reply to what you said next, but not today, and
not in this thread. So I'm skipping to ...

Intuitive models of advanced physics always fail somewhere.

1) Why?

2) What about physics which isn't "advanced"?

-- Jeff, in Minneapolis

[Shaula]

I don't want to get into a fight on this but you said:

Some interpretations of QM do not make sense or seem natural to me. I'd say that those interpretations are either wrong or misleading.

From this statement the implication is that your criteria for assessment is the 'naturalness' or 'sense' in an interpretation. If that is not the case and all you are saying is that by pure coincidence the set of all misleading or wrong interpretations (as agreed by consensus in the mainstream) happens to be identical with the set of all interpretations you don't like then I retract my comments.

In effect, I do not distinguish between a theory and a correct interpretation of that theory. In my opinion they are one and the same.

OK, disagree totally there. A theory is a predictive framework constructed in a logical language to allow for internal self-consistency checks. An interpretation is a way of relating the modelled entities to common experience in order to allow our minds to better grasp and manipulate them. Which is why interpretations are not unique and theories can be shown to be unique or transformations of one simpler statement of the theory.

1) Because they use non-rigorous models of a system to try to make predictions about it. And to be fair theories also fail if used outside their remit. Interpretations just tend to cover bits of theories and so fail multiple times within the domain a theory works in.
2) I don't really know where you draw the line, but I'd say yes. As soon as you start dealing with things by assigning them mental models which are not fully representative of them then you have an interpretation that will fail. Gas molecules don't behave like billiard balls. The only difference with the physics of the macroscopic is that generally the entities we are modelling are actually very similar to the entities we use in our heads to interpret them. So a billiard ball does act like a billiard ball.

[Jeff Root]

Some interpretations of QM do not make sense or seem
natural to me. I'd say that those interpretations are either
wrong or misleading.

From this statement the implication is that your criteria for
assessment is the 'naturalness' or 'sense' in an interpretation.
If that is not the case and all you are saying is that by pure
coincidence the set of all misleading or wrong interpretations
(as agreed by consensus in the mainstream) happens to be
identical with the set of all interpretations you don't like then
I retract my comments.

Not one extreme or the other, but somewhere between.

It is not a coincidence. What I don't like is an interpretation
which is wrong (or misleading). To the extent that I have a
good understanding of the physics, a good interpretation
(one which works) will make sense and seem natural to me,
and a bad interpretation will not. Obviously that does not
work when my understanding of the physics is wrong, and
detecting when my physics might be wrong is not an entirely
separate issue.

But when I do understand the physics correctly, then any
correct interpretation of it will naturally tend to make sense
and seem natural. If an interpretation does not make sense
and does not seem natural, then either I do not understand
the physics or the interpretation is either wrong or misleading.

In effect, I do not distinguish between a theory and a
correct interpretation of that theory. In my opinion they
are one and the same.

OK, disagree totally there. A theory is a predictive framework
constructed in a logical language to allow for internal self-
consistency checks. An interpretation is a way of relating the
modelled entities to common experience in order to allow our
minds to better grasp and manipulate them. Which is why
interpretations are not unique and theories can be shown to
be unique or transformations of one simpler statement of the
theory.

My assertion is essentially that if an interpretation says
something different from what the theory says, then it is not
a correct interpretation of the theory.

Intuitive models of advanced physics always fail somewhere.

1) Why?

1) Because they use non-rigorous models of a system to
try to make predictions about it.

I see no reason for a correct interpretation of a theory to
make predictions different from predictions made by the
theory. If predictions made by the interpretation do not
match those made by the theory, then the interpretation
is wrong.

And to be fair theories also fail if used outside their remit.

A correct interpretation would fail in the same ways that
the theory fails.

Interpretations just tend to cover bits of theories and so
fail multiple times within the domain a theory works in.

If an interpretation covers only part of a theory, then it
should accurately cover that part of the theory. It will
be a correct interpretation of that part of the theory and
should never be asserted to represent the whole theory.

For example, the interpretation of economic theory that
rarity of a commodity determines its value is correct as
far as it goes, but obviously is far from complete. Rarity
is only one factor in the determination of value. It would
be silly to think that rarity was the only factor.

2) What about physics which isn't "advanced"?

2) I don't really know where you draw the line, but I'd say
yes. As soon as you start dealing with things by assigning
them mental models which are not fully representative of
them then you have an interpretation that will fail. Gas
molecules don't behave like billiard balls. The only
difference with the physics of the macroscopic is that
generally the entities we are modelling are actually very
similar to the entities we use in our heads to interpret
them. So a billiard ball does act like a billiard ball.

A description of gas molecules which likens them to
billiard balls is an analogy, not an interpretation of a
theory. I agree that analogies always fail. A correct
interpretation of a theory should never fail except
where the theory itself fails.

-- Jeff, in Minneapolis

[Shaula]

Well if your interpretation is something that follows the mathematical model exactly then fine, it will fail with the theory. I've just never seen anyone reasoning from an interpretation alone who got the same results as the models did. YMMV.