[Halc]

The conclusion? Does this mean it's been proven?

Your reading comprehension skills are exceptionally poor.

This is true only under counterfactual interpretations of quantum mechanics, and cannot be proven.

Science is about making predictions, and it is very good at that. It isn't about proof or 'knowing' about things to the extent that it could be categorized as 'truth'.

Science has no proof of anything. Proof is for the mathematicians. Science makes predictions based on evidence. It does not assert truth or demonstrate proofs.

Nothing is proven by science. It's all done by induction, not deduction, and it's only as strong as its premises.

Despite all these statements, you still ask if this thing has been proven.
No, science offers no proof of anything.
No, nothing can be demonstrated to be absolute fact.  Even 2+2=4 requires some unproven axioms as premises.
Just no.

Your insistence on reading the comments otherwise suggests that you very much want to have an excuse to claim this horrific experience, "spiralling into depression", "devastated", but you seem to require this proof, and you shall not have it, not from science at least.

The way I see it, the facts uncovered by science can have implications on our lives.

What possible implication does the finite-measurably-distinct arrangements of matter have to do with our lives? I cannot picture how that would have any practical implication.

I meant certain as in particular.

The two words are not anywhere close to being synonyms. No idea what you mean by this statement.

No. I said what I said.

So if we try to measure something it has finite states, can only be finitely arranged?

It means that only a finite set of distinct measurements can be taken. It does not in any way imply finite states, but if two states are sufficiently similar, they cannot be distinguished. Planck got into this.

So it's ok, even plausible to think that matter can be infinitely arranged in a finite space, despite whatever else people say?

I said yes to that, quite clearly I think.

I admit I do have a tendency to take statements very literally, I've learned that a single word can completely change any statement. A single sentence can change the way you look at an entire franchise.

Then it probably isn't a good idea to change what others are saying by omitting words and qualifications.

Are you made of atoms?

Seemingly so, but we've no proof of it.

[Europa]

Seemingly so, but we've no proof of it.
[/quote]

Please explain that there is no proof that iron atoms give hemoglobin the strength to bind to oxygen in the blood.

[Eternal Student]

Hi again.

Are you saying that Halc is erring on the side of limited memory but his argument for it is not very good? That I shouldn't worry because there is no proof of a limited memory capacity?

        Is limited memory also something that concerns you?  It might be possible to post a new thread in the Life Sciences section and see what they think. 

So it's ok, even plausible to think that matter can be infinitely arranged in a finite space, despite whatever else people say?

     I can't tell you what to think and you probably shouldn't believe everything people say.  However, I am not an expert in any field that would make me qualified to give that sort of advice.  It just seems like sensible advice.
     The relevant science has been discussed already.  Yes, it is reasonable to think that.  However, as a scientist you should probably also know  WHY  that is reasonable.  Science is less concerned with final answers and ultimate truths and more concerned with gaining some useful understanding.  There are several reasons WHY  it is reasonable to think that.  Here are some of those reasons:
     (i)  Atoms  -  there is no agreement on what an atom is.
     (ii) Quantum Mechanics   -   particles don't behave as you would normally expect.
     (iii) Constantly changing ideas in science.
     (iv) Outright recognition that science offers models and some limited understanding only, not absolute truth.
     
Best wishes to you.

[evan_au]

I can only ever be happy if I can say to myself that the things I fear are not true, that why I come to forums like this....
Are you saying that [insert uncertain scientific hypothesis here]?
Because I have told you how horrific I find that and there is no way I'll ever be ok with it?

This seems like a contradiction, to me.
- You want the truth
- You want certainty
- Even if that truth has no bearing on your day-to-day life
- And yet, if it turns out to be true (something that we may not answer for decades, if ever), you can't accept it?

That's the problem with the truth - it doesn't care what we think.

[Colin2B]

That's the problem with the truth - it doesn't care what we think.

A famous writer once said that “the truth is rarely pure, and never simple”, and in this case the answer is not simple.

Does this mean it's been proven? It sounds to me like this is saying matter can only be arranged a finite number of ways in a finite space.

@Halc has already told you that it isn’t the role of physics to prove anything. We make reasonable predictions based on the evidence of observations. In most cases those predictions are very accurate and the predictions about atoms are among some of the most accurate we have.

The question you are asking really depends what you mean by an arrangement.
Let’s take a very simple example. Say we have 2 coloured blocks red & blue and we are going to arrange them along a straight line. We can say that there are 2 different arrangements of these blocks: red/blue or blue/red. On the other hand we could say that if the blocks are 1mm apart that is a different arrangement from being 2mm apart and as there are an infinite number of ‘numbers’ between 1mm and 2mm then there are an infinite number of ways of arranging these blocks - ignoring for the moment the discussion on whether you can differentiate between these arrangements.
When we talk about arranging matter eg atoms we are usually talking about the first type of arrangement.
As @Eternal Student says, we cannot take photos of atoms; however we can map the electric fields they produce, which are responsible for the effect of making them appear solid. There are some excellent images on the net which show that atoms consistently arrange themselves in a limited number of ways. This is a good thing because if it were not so then our universe would never have formed, no molecules, no dna, nothing. Finite arrangements are essential for our existence.

So it's ok, even plausible to think that matter can be infinitely arranged in a finite space, despite whatever else people say?

If that makes you happy, then do so, but it has no effect on whether it is a reasonable assumption.

[Multifaceted (OP)]

The question you are asking really depends what you mean by an arrangement.
Let’s take a very simple example. Say we have 2 coloured blocks red & blue and we are going to arrange them along a straight line. We can say that there are 2 different arrangements of these blocks: red/blue or blue/red. On the other hand we could say that if the blocks are 1mm apart that is a different arrangement from being 2mm apart and as there are an infinite number of ‘numbers’ between 1mm and 2mm then there are an infinite number of ways of arranging these blocks - ignoring for the moment the discussion on whether you can differentiate between these arrangements.
When we talk about arranging matter eg atoms we are usually talking about the first type of arrangement.

That's not how Eternal Student describes atoms.

[Eternal Student]

That's not how Eternal Student describes atoms.

   Hi again.  Eternal Student here.

   There were earlier posts about how much space exists between atoms and how it's necessary to consider a larger system which is the atoms + whatever environment is forcing them together.   Reply #29 discussed neutron stars.

   Colin2B's comments aren't too different from this, except he has gone for an example where the space between atoms is larger than usual not smaller than usual.

   Atoms have no clear definition for many reasons but the radius of an atom is one thing that doesn't seem to be well defined.  It's hard, if not impossible, to say where an electron cloud ends.   Actually, discussing the radius of an atom is something that could fill a whole thread all on it's own.  There are some definitions where a definite fixed size could be determined but these often demand changing the way you imagine a "contact force" between two particles.

    I have no simple and unequivocal definition of an atom to offer you.  There are several that I am aware of.  Where the precise model of an atom or what properties an atom is assumed to have is important, then the scientist will make this clear in their writing.  It is possible to imagine or mathematically model a universe where there are no particles at all but instead there are only fields.  Some fluctuations in these fields give rise to regions of space where something that behaves like a particle would be found.

    There is no grand unified theory of everything that I am aware of at this time.  This is good news for scientists, since there are still things to discover and revisions to older theories that will be required.

Best wishes to you.

[TommyJ]

Early experiments bombarding two slits with one electron showed that it comes from both slits and makes interference with itself. Quantum physics affirms that electron 'dualism', as it can be going round the atom core only on certain orbits. And the actual position of the electron can be only described with a certain probability.
This probability issue was clearly pictured by Erwin Schrödinger with the cat phenomena.

[Multifaceted (OP)]

   Atoms have no clear definition for many reasons but the radius of an atom is one thing that doesn't seem to be well defined.  It's hard, if not impossible, to say where an electron cloud ends.   

This is going to sound really stupid and like I'm working really hard to cling onto something. But you did mean doesn't not does here right? You do mean it's hard, near impossible for atoms to be defined by science right?

It's just that, normally in this kind of situation, a person would make a statement and then use "BUT" to set up the explanation of a difference, opposition or exception.
Example "One by one the lands of Middle Earth fell to the power of the ring BUT there were some who resisted." You seem to be saying "Atoms can't be easily defined if at all BUT atoms can't be easily defined if at all."

I suppose I'm just so used to this device being used that I thought that, by talking about atoms being difficult to define then adding the word "BUT" you are making a statement going in the other direction.

By the way, I'd like to say I like your posts. I've been on several forums like this and not met many who have the open-mindedness to talk about how many grey areas there are in science.

[Bored chemist]

You do mean it's hard, near impossible for atoms to be defined by science right?

No
The radius of an atom is hard to define.
It's like trying to measure a cloud or a ball of cotton wool.
It hasn't got a well defined "surface".

[Eternal Student]

Hi @Multifaceted,

   I'm sorry for the clumsy sentence construction.  I must have edited and removed some things.

You have correctly identified the key points:

1.  There are many different definitions of what an atom is.   There are many problems defining exactly what properties an atom would have.
2.  The radius of an atom is one thing that isn't well defined.

Thanks and best wishes.

[Colin2B]

"One by one the lands of Middle Earth fell to the power of the ring BUT there were some who resisted."

You cannot expect a work of literature to be precise in its meaning. You have interpreted this one way, but there are others. The 2 statements are not mutually exclusive; eg one by one the lands fell except those who resisted, or maybe they all fell, but some continued to resist - just like the French resistance.

I suppose I'm just so used to this device being used that I thought that, by talking about atoms being difficult to define then adding the word "BUT" you are making a statement going in the other direction.

If I say that “most swans are white, BUT some are black” it it isn’t making a statement going in the other direction, it’s giving you extra information. Also, it doesn’t mean we can’t know and describe what a swan is. It’s even worse with cars, because every car has a different colour so you can’t define the colour of ‘cars’; but that doesn’t mean we don’t have a pretty good idea what cars are, or are able to define the colour of an individual car.
When we are describing a car we are describing an image formed by light reflected from it and we can describe a number of properties (physicists sometimes call them observables) such as colour, number of doors, position of headlights etc.
With atoms it is harder as we cannot ‘see’ them in the same way, we rely on measurements of electric field, mass etc and often how they behave when they interact with other atoms or particles. So we build up a definition based on a description of their properties. Some of those properties are not clearly defined, but are described by the likelihood (probability) of it being a certain value and that value can vary depending on the situation. So, no one is going to give you the sort of definition you are looking for.
Take note, however of what BC says:

You do mean it's hard, near impossible for atoms to be defined by science right?

No
The radius of an atom is hard to define.
It's like trying to measure a cloud or a ball of cotton wool.
It hasn't got a well defined "surface".

When these clouds are put together in a group they space themselves into well defined patterns and we can use devices like a scanning tunnelling electron microscope (STEM) to give us a picture of what that pattern looks like. For example here is an image of a layer of an oxide which shows the pattern of atoms - in the bottom right someone has highlighted the different types of atom in the material. From this image we can measure the distance between the centres of the atoms, but as you can see the edges are fuzzy and ill defined.
All in all we know a lot about atoms and their properties, so much so that we can predict their behaviour very accurately in various circumstances.


16F09140-5B7A-431A-A478-9316A1B626E5.jpeg (73.32 kB . 511x387 - viewed 3852 times)

[yor_on]

That's the funny thing about almost everything, from electrons to atoms. Atoms can be super positioned, electrons becomes a 'probability cloud' which also create most of a atoms 'size'. It's not until you photograph, or in some other way try to define, it that it will exist as a 'clear evidence' of it being there.

[Colin2B]

It's not until you photograph, or in some other way try to define, it that it will exist as a 'clear evidence' of it being there.

That’s an interpretation.
You have to be very clear what you mean by exist.

[Eternal Student]

Hi again.

When these clouds are put together in a group they space themselves into well defined patterns and we can use devices like a scanning tunnelling electron microscope (STEM) to give us a picture of what that pattern looks like.

    An interesting example of an emergent property.  An individual atom does not have well defined radius but a massive number of atoms put together does show properties that were not there in the fundamental components.  It is possible to find the average distance between atoms in this lattice but that still does not tell you exactly what the distance between any two chosen atoms will be (or provide a precise definition of the radius of one atom).
    There are additional complications when the idea of entropy is introduced.  Even a perfect crystal lattice has a non-zero and apparently random distribution of energy unless the temperature is reduced to 0 Kelvin.  That is impossible to do in reality.  A simple model of a crystal lattice could ("should") be considered as a dynamic object rather than a static thing.  The atoms vibrate about their equilibrium positions and the precise distance between each atom is not constant.   The electron micrograph that Colin2B provided is not a dynamic representation but instead it is inevitably just an average of the scatter or more complex interactions between electrons and atoms.  I'm not an expert in electron microscopy but in general there are a lot of detectors and a lot of things that can be detected including electrons that are given off by the atoms as a result of excitement.   This multitude of data is processed in a computer system and a final image is produced.  I'm simplifying this processing by just saying that an "average" distance between atoms is obtained.
    There is also a complication when impurities are introduced.  For example, Semiconductor substrates like silicon have significantly different properties and behaviours when an insignificant number of atoms of Gallium are present in the lattice.  These impurities are enough to make some silicon wafers act as microprocessors inside the computer device you are using now, while less impurities would have made the wafer act like sand or glass and quite incapable of processing data in a useful way.
    I don't think anyone has mentioned the Pauli exclusion principle yet.  We could use this to argue that no two atoms could have precisely the same set of quantum numbers that describe their fermions (e.g. their electrons).  In effect no two atoms can be identical at a quantum level.
    Overall, science has many models of atoms and the behaviour of atoms.  They are useful and allow many predictions to be made.  It is possible and sometimes desirable to use increasingly complicated and detailed descriptions.  Many of these descriptions go over my head.  I'm certain that there are more models and complications then you (Multifaceted) will have seen in this thread or any other forum you have used.
    There have been previous discussions on the nature of science.  It may be desirable to strive for absolute truth in science but most scientists do not realistically expect to obtain it.  We have some good models and and fair level of understanding.

Best wishes to you.

[yor_on]

Depends on how you look at it , is seems Collin. Using indirect evidence goes out from that they 'exist' even without being 'touched'. I'm not particularly convinced by that sort of reasoning, The probability cloud have a existence, it must if physics are correct, but the 'particle' getting defined needs a outcome. If we go by the Copenhagen interpretation it needs you, photographing it.
=

What I mean by that is that I doubt you getting any evidence of a outcome without a interaction, thinking of those types of 'indirect measurements' presuming that you can leave the thing you study in a pure 'indeterministic' state. If you get all parameters you either 'touched' it or you're dreaming. F.ex doing it over a time sequence on several particles doesn't change it, the way I think of it.


And to me it seems as we still haven't accepted what physics tells us, when we use indirect methods. We want them to be 'classical' so that we can treat them that way.