Undergrad How do I show a skeptic that atoms/molecules actually exist?

[Stavros Kiri]

This is not entirely true. Science ...
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...
Lastly, from a rather philosophical perspective, your friend is inherently wrong by contradicting himself since if science does work (as he himself says), and even if he only speaks of technology, this inherently means that science can actually tell things about the reality otherwise those technologies he speaks about could not have been invented (most of them were not invented purely by trial and error). And an even more profound counter-argument to your friend's one is that these technologies were not part of reality before they were invented, but afterwards, they were part of reality, and if your friend agrees that science works with those technologies, it can also explain them and how they work, and therefore, tell things about reality.

See also posts #26 & 18

P.S. Welcome to PF!

 

[Stavros Kiri]

They want to know what there is really and that is why they do it, not just to be some kind of an modeler or experimenter all their life.

I am shocked that Physics Forum Mentor don't get this.

A) No, the mentors surely realize that reality is the subject and the goal of science, but that doesn't come or happen magically "overnight"; that's what I think they are trying to explain to you. So they are describing to you the scientific method etc.
Or, as also said (emphasis in bold mine):

Sophiecentaur, Dale and Drakkith are right. Science is about finding models that work, and all of these models are tentative and subject to replacement as more is learned. There was a time when we thought atoms were indivisible. Now we don't.

It is, however, the case that some models have undergone such thorough testing that disbelieving them is not rational. However, this doesn't mean the models cannot be superseded. It means that the model that supersedes them needs to make every prediction of the old model and then some. As in Dale's example.

B)

These aren't terribly convincing arguments. And the capitalization doesn't help.

Lol! ...
For @Michael Scott : with solid arguments in replying to a discussion, characterizing other people's replies as irrational or something (etc.) is at least redundant, and should (IMO) be avoided, but rather we should just be focussing on secure valid arguments etc. for a healthy, fruitful, productive discussion. Or better yet, [or at the same time] provide valid PF accepted references ...
(But personally I don't think you did too bad for first day here. That's just my own view [about the quality of this discussion here etc.], and I am not a mentor.)

 

[sophiecentaur]

His argument is that although science works (that is the technology part), science cannot actually tell anything about "reality".

Your friend is doing a good job of winding you up with this opinion. But he is introducing the word "reality" in order to justify his lack of knowledge about the terms of serious Science. He would rather 'take sides' against Science and argue against it without actually learning the basic ideas that we use to describe the World around us and learning what the aims are of serious Science..
Everything about Science is 'near enough' and we can't expect any more. That doesn't mean that Science is 'wrong' or that the images of atoms that have been produced are not believable. Those fuzzy shapes we say are telling us that something is going on in that place we are looking and that we are justified in identifying them as "atoms".

 

[Dale]

Because "reality" cannot have 2 descriptions right??

Why not? I can be accurately described as a mentor on PF. I can also be accurately described as an employee of my company. I can be described by my physical characteristics. Etc. if there can be multiple correct descriptions of me, why not of reality.

Furthermore, if we use math in our descriptions, then we can provide many different but equivalent descriptions (as with natural language too). For example, Newtonian mechanics, or Lagrangian mechanics, or Hamiltonian mechanics. All can correctly describe the same situation despite being very different descriptions.

Like it or not, the force picture of gravity is still a valid description of much of reality. Many experiments verify it. By choosing to reject it you effectively concede your friends point and then his argument follows. This is the reason you are having trouble in your argument. You accept the premise, and then cannot logically reject the conclusion. I am telling you that his premise is wrong.

So, the reason why objects fall to the ground (i.e. reality) cannot be due to both, a force or space-time curvature, right?

Only one of them has to be correct. That is my understanding.

They certainly can both be correct whenever both accurately predict the outcome of experiments. In fact, in the domain where they both apply, you can actually derive the force model from the spacetime curvature model. The force model is part of the curvature model, so the force cannot be wrong if the curvature is right.

No matter how you approach it, we are essentially guaranteed that there will be multiple correct descriptions of nature.

 

[Dale]

The core of science as I see it is indeed to try and explain the forces governing the universe

The core of science is the scientific method

 

[A.T.]

That is CRAZY.

This is completely NUTS!

Given your reactions, I assume your friend is just winding you up for fun.

I went to Wikipedia Science page which says this:

Working scientists usually take for granted a set of basic assumptions that are needed to justify the scientific method: (1) that there is an objective reality shared by all rational observers; (2) that this objective reality is governed by natural laws; (3) that these laws can be discovered by means of systematic observation and experimentation.[10] Philosophy of science seeks a deep understanding of what these underlying assumptions mean and whether they are valid.

The belief that scientific theories should and do represent metaphysical reality is known as realism. It can be contrasted with anti-realism, the view that the success of science does not depend on it being accurate about unobservable entities such as electrons. One form of anti-realism is idealism, the belief that the mind or consciousness is the most basic essence, and that each mind generates its own reality.[m] In an idealistic world view, what is true for one mind need not be true for other minds.

Note that this is explicitly about "philosophy" and "beliefs".

 

[Stavros Kiri]

The core of science as I see it is indeed to try and explain the forces governing the universe and the components from which it is made.

I agree with Dale on that one

The core of science is the scientific method

... studying reality (or the world we live in)

 

[russ_watters]

Because "reality" cannot have 2 descriptions right?? There can be only 1 description of reality, right??

So, the reason why objects fall to the ground (i.e. reality) cannot be due to both, a force or space-time curvature, right?

Only one of them has to be correct. That is my understanding.

No, that's wrong. Your're still looking for something exact, when something close is still a good description. It's not an all or nothing proposition.

 

[Dale]

Your're still looking for something exact,

And because of how math works even an exact model would have multiple different formulations/descriptions, and would necessarily contain all of the approximate models in their appropriate domains of applicability.

 

[OfekA]

The core of science is the scientific method

The scientific method is the methodology and means by which we can get to better and better models and explanations of the universe. People don't practice science because of the scientific method but rather it is the tool with which they practice it. Perhaps I should've used the word "aim" instead of "core", but yet you can think about it like digging a hole in the ground in order to find the underneath buried "gems" (=answers) that we seek. Now to dig that hole we use a shovel that also breaks each stone resembling a gem but does not break the gems thus "proving" which answers are valid and which are not, this shovel is the scientific method. However, we could also dig the ground with our hands (i.e. try to find answers without the scientific method) but it would take longer to find the gems and even when we find them we would have no way of knowing if these are stones resembling gems or actual gems so this whole method would be terribly ineffective. Nevertheless, in both cases, using both methods, we try to do the same thing (i.e. the "core" of what we're trying to do is the same = find gems. Not using a shovel or hands). Moreover the scientific method and especially research methods have gone through several "upgrades" that allows an even more efficient way to do our task, so now we are digging with a bulldozer and using a gem filter and yet, the core of what we're doing is the same, seeking for precious gems which are the answers to the questions we have about the natural world.

 

[Dale]

People don't practice science because of the scientific method but rather it is the tool with which they practice it. Perhaps I should've used the word "aim" instead of "core",

I would accept “aim of scientists”. But the motivations of the people that practice science is not what defines science itself. Particularly since those motivations are shared with other groups.

 

[hilbert2]

Is there a way to actually see sub-atomic particles, atoms or molecules?? Can we actually see these things with our naked eye through a powerful telescope?? Maybe if I can show a actual picture of an atom or molecule he might be convinced that they do actually exist.

The biological senses of a human being don't give the person any more direct information about their surroundings than a technical measuring device does. Any visual or auditory stimulus goes through a whole lot of neural processing before it becomes a conscious experience, and even after that you can misinterpret it. A philosophical theory called solipsism actually states that we can't even know for certain that anything outside our own mind exists at all.

One really convincing piece of evidence for the existence of atoms and molecules is Brownian motion, the apparently random motion that small dust particles go through when immersed in liquid. The cause of the motion is that some of the molecules of the liquid substance randomly have a significantly larger than average kinetic energy and therefore substantially change the state of motion of the particle when colliding with it. It would be very difficult to explain with a continuum model of matter where internal energy is uniformly distributed in the liquid as classical thermodynamics assumes.

 

[OfekA]

I would accept “aim of scientists”. But the motivations of the people that practice science is not what defines science itself. Particularly since those motivations are shared with other groups.

Well, I can agree with you on that. I think the conflict here arises from that the phrase: "the core of science" is rather ambiguous. You can't really discern if it means "How science is conducted" or "For what reason is science conducted". The thing driving people to practice science is curiosity. However curiosity drives people to do a whole bunch of things other than science. The scientific method is what distincts science from those other things so yeah, I got your point :)

 

[Lord Jestocost]

Ok ok I got it now.

I went to Wikipedia Science page which says this:
Working scientists usually take for granted a set of basic assumptions that are needed to justify the scientific method: (1) that there is an objective reality shared by all rational observers; (2) that this objective reality is governed by natural laws; (3) that these laws can be discovered by means of systematic observation and experimentation.[10] Philosophy of science seeks a deep understanding of what these underlying assumptions mean and whether they are valid.

The belief that scientific theories should and do represent metaphysical reality is known as realism. It can be contrasted with anti-realism, the view that the success of science does not depend on it being accurate about unobservable entities such as electrons. One form of anti-realism is idealism, the belief that the mind or consciousness is the most basic essence, and that each mind generates its own reality.[m] In an idealistic world view, what is true for one mind need not be true for other minds.

So, there is actually many "schools of thought" about this. You guys are clearly anti-realists, right??

There are working scientists who take an instrumentalist’s point of view, a very pragmatic approach. Various experiments produce clumps of data that might be gathered under the heading “that’s an atom” or “that’s a molecule” and so on. And these data can be used to predict other sets of experimental readings when performing other experiments. But that’s it. For an instrumentalist, there is no reason whatsoever to believe that “atoms“ or “molecules“ are real, existing objects. Using such terms is merely a matter of convenience. Instrumentalists are aware that classical ideas like “objective physical reality” may merely based upon psychological feelings of what “should be out there”.

 

[Al_]

To answer the original question of the topic - how about Brownian Motion? A good optical microscope should be able to show it, in a little smoke trapped in a transparent container.

Other evidence might come from crystals, with a little reasoning.

And to add weight to the reasoning, perhaps a bit of chemistry, where exact ratios of masses of chemicals are seen to react.

 

[ZapperZ]

As someone who has been in physics for way too long, I've been asked this type of question many times! (If only I get $1 for every...) It is one reason I wrote on the shortcomings of our human eyesight, because many people who asked me such questions always used the fact that these things can't be "seen". And I find it interesting that the logical fallacy that is inherent in this question is either missed, or has not been used.

I may have read too many Martin Gardner's mathematical games book, but this is nothing more than the Liar's Paradox. The Liar's paradox tells a story of a liar who says "Everything I say is a lie".

So then, if that statement is true, then his claim that "Everything I said is a lie" must also be a lie, and that means that he's been telling the truth. But if he's been telling the truth, then "Everything I say is a lie" must be true, so he has been lying... and so on and so on.

How does this apply here? So someone comes up to me and says "What we all know isn't real. Nothing in this world reflects the actual reality."

If that statement is true, then by its own rule, the claim that "What we all know isn't real. Nothing in this world reflects the actual reality" is also not the reality. Consequently, it means that what we know is real and that there is reality, which allows that statement to be true,... and so on and so on.

Somehow, when you explain this paradox to these people, I don't think they get it.

The other issue, and this is a very common issue, that is related to this is the issue of defining when something "exist". I think most people do not realize that everything that we detect is based on a series of properties. We define an electron by its mass, charge, spin, etc... so a series of characteristics define an entity to be an electron. You can do the same with, say, your mother. Based on your visual observation of her features, her voice, her demeanor, etc...etc., you conclude that that entity is your mother. This is the ONLY means that we have to say that something exists.

So what does it mean when these people say that something isn't real, or doesn't exist? Are they denying that when I release a ball from the ceiling of my house, that the ball doesn't fall to the floor? That this isn't real? How would someone know that there is another underlying reality beyond what we can physically access? Isn't such a statement based on speculation that isn't supported by any physical evidence in the first place? Isn't it a cruel and an unusual punishment to attack science using an unverified conjecture?

Seeing something with your eyes isn't the criteria for something to exist, even though having a single trapped strontium atom emitting visible light is very convincing and very cool. Whenever we get question like this, it is necessary that we question the questioner back, because higlighting these vague, undefined, and logically-problematic aspect of the question is exactly how the question should be tackled.

Zz.

 

[jtbell]

how about Brownian Motion? A good optical microscope should be able to show it, in a little smoke trapped in a transparent container.

Or milk diluted in water:
https://arxiv.org/abs/physics/0303064
IIRC it was the analysis of Brownian motion and related phenomena that convinced the last scientists who were holdouts against the atomic model, in the early 1900s.

 

[hilbert2]

I may have read too many Martin Gardner's mathematical games book, but this is nothing more than the Liar's Paradox. The Liar's paradox tells a story of a liar who says "Everything I say is a lie".

So then, if that statement is true, then his claim that "Everything I said is a lie" must also be a lie, and that means that he's been telling the truth. But if he's been telling the truth, then "Everything I say is a lie" must be true, so he has been lying... and so on and so on.

This is a really clever thing to point out in this context... So we're kind of left with a vaguely defined nonzero "expectation value" of how much we actually know.

 

[CWatters]

A lot of experiments have been done that support our models of the atom so for me the existence of atoms has been proven using the scientific method. Your friend would have to find consistent alternative explanations for the results of all these experiments.

Some background in here...

http://www.bbc.co.uk/earth/story/20151120-how-do-we-know-that-things-are-really-made-of-atoms

Some years ago IBM wrote IBM in individual atoms of gold and used an atomic force microscope to take a picture of it. These days they can move individual atoms around and make a movie...

http://www.research.ibm.com/articles/madewithatoms.shtml#fbid=tPg_64HbyyY

 

[Dale]

I think the conflict here arises from that the phrase: "the core of science" is rather ambiguous. You can't really discern if it means "How science is conducted" or "For what reason is science conducted"... so yeah, I got your point :)

Well said, I got your point too!

 

[Stavros Kiri]

Everything about Science is 'near enough' and we can't expect any more.

Well it doesn't hurt to expect more ... some day perhaps ... , but (in the meantime) it doesn't mean that temporary relative knowledge that happens to be not 100% accurate is not science ...

 

[rsk]

Because "reality" cannot have 2 descriptions right?? There can be only 1 description of reality, right??

Why? (Asking for a friend ;) )

 

[nomadreid]

One thing that was overlooked in all these wonderful exchanges is: what does the OP's "skeptic" friend mean by the words, "molecules", "atoms", and "exist"? A bit of a mathematician's approach: get the definitions down first, and often that is enough that the answer comes out in the wash. According to her definitions, the statement "molecules and atoms exist" may or may not be true. While you are at it, the OP could ask the friend whether her question is real (that is, she is ready to admit that the question might have one or the other answer, and is not just being dogmatic), and if so, what the criteria would be that she would allow to decide the question. Of course, if the OP's friend is asking just to wind the OP up, then she is doing a good job.

 

[Stavros Kiri]

A)

A bit of a mathematician's approach: get the definitions down first, and often that is enough that the answer comes out in the wash. According to her definitions, the statement "molecules and atoms exist" may or may not be true.

What makes you think it's a "she"?

His argument is that although science works (that is the technology part), science cannot actually tell anything about "reality".

He sites for example

Other than that, I agree.

B)

Why? (Asking for a friend ;) )

We all call it "a friend" now ... don't we?

 

[TheOldFart]

His argument is that although science works (that is the technology part), science cannot actually tell anything about "reality".

I've been online since the days of dial-up BBS systems and USENET.

I can guarantee you that you cannot change the mind of dogmatic people like that.

I can even give you a simple way to prove that is the case.

Ask him this question: What *specific* testable evidence would it take to convince you that atoms and molecules are real?"

That question works no matter what the dogma is, and it works in both directions - it will always show when someone else is being dogmatic, and it will always show when you are being dogmatic.

You can just substitute whatever pseudoscience or science denial you're dealing with.

What *specific* testable evidence would it take to convince you that climate change is real?
What *specific* testable evidence would it take to convince you that biological evolution is real?
What *specific* testable evidence would it take to convince you that the Earth is a sphere?
What *specific* testable evidence would it take to convince you that astrology is real?

Rational people know that astrology isn't real, but are you being rational about it or dogmatic about it? That last one will tell you.

You will never change his mind from the outside. Only he can change his mind, and the only way he's going to do it is to be forced into admitting to himself that he's being dogmatic/dishonest about it.

 

[nomadreid]

A)
What makes you think it's a "she"?

Touché. "She" comes from the combination of not noticing the use of "he" and "his" in the OP's posts with the habit of being "politically correct", or avoiding conflict with people who think that the earlier English convention of applying masculine pronouns to persons of unknown gender is sexist (oddly enough, the same argument could be brought about a convention of applying female pronouns, but no one does). Alternatively, I could have used (while being mistaken that the reference was to a male friend) the other convention and write "they", whereupon you could ask why I think the reference is to more than one friend.

 

[Stavros Kiri]

Ask him this question: What *specific* testable evidence would it take to convince you that atoms and molecules are real?"

That question works no matter what the dogma is, and it works in both directions - it will always show when someone else is being dogmatic, and it will always show when you are being dogmatic.

What if he tells you that he actually wants to sit on top of a real molecule or atom, travel with it, test it and see that it is composed of electrons, protons (thus quarks etc.). Now how he does that is his problem ... , but ... he's not being dogmatic. So, I think, your argument/method is also defeasible ...

 

[DET]

Tell him you'll be happy to answer his objections as soon as he proves to you that he exists.

 

[votingmachine]

Science doesn't attempt to do that. All Science attempts to do is to make a model that can be used to predict what will happen to within some accuracy. It's Non-Scientists who demand 'reality'.

This was addressed in another comment, but there is a difference between "science" and "scientists". Of course many scientists are interested in understanding reality. But science is specifically a tool that does not make a claim of such understanding. It draws a model that is illuminating, and fits the facts, and predicts.

Scientists are as willing to demand 'reality' as non-scientists. They just recognize that the process of attempting to understand reality is a theoretical journey.

I would answer the original question that there is not a specific measurement that proves current atomic models are correct. But theories have been converging on the idea of atoms for a while. Refinements of the idea of what an atom is are not getting wildly revised. We once saw a "plum pudding" model replaced by a "planetary orbit" model. But we have not seen a model that disposes of atoms and replaces them with something completely different. There is no conclusive way to prove that our current models are close to the answer "42", but there is no reason to expect a GIANT revision.

And of course as pointed out over and over, science does not say that theories are irrefutable. Including well-established and incredibly reliable ones.

 

[Stavros Kiri]

Touché. "She" comes from the combination of not noticing the use of "he" and "his" in the OP's posts with the habit of being "politically correct", or avoiding conflict with people who think that the earlier English convention of applying masculine pronouns to persons of unknown gender is sexist (oddly enough, the same argument could be brought about a convention of applying female pronouns, but no one does). Alternatively, I could have used (while being mistaken that the reference was to a male friend) the other convention and write "they", whereupon you could ask why I think the reference is to more than one friend.

The most "politically correct" way is I think "he/she" ...
[Although in the future we might have to also introduce "/it", to cover the case of A.I. or machine, in order to avoid being sued by any of them ! (for sexist language ...) ... ]