Really? Clearly I have killed way too many brain cells over the years, because I can’t grasp that concept. Could you either elaborate or link to a straightforward explanation for me?
How does saying “X is possible” require that there be a reality in which “X is not possible”? If that is true, did the agnostics kill god?
I couldn’t agree with your last statement more, but just to be perverse, Brownian motion could be caused by pixies (invisible just like atoms are) with a malicious sense of humor. In fact, pixies can explain anything. The reason we rule them out, I think, is that you need a special pixie for each purpose and the atomic theory allows just one generalization to replace a plethora of pixies. Occam’s Razor and all that.
I also believe atoms exist, but given that between measurements they behave as a wave I would have to say their existence is of a somewhat different nature than that of a keyboard–micro versus macro.
It’s most definitely due to the wave nature of quantum particles. You may find it interesting that you can get the same effect with a taut string and sets of parallel bars.
David S, I believe you’re just a smidge off there.
It is, of course, brownies that cause Brownian motion.
Pixies, as is well known, cause pixelation.
I got a C in brownies, so you could be right. And I got an A in pixies. So obviously I would much rather talk about pixies.
Wikipedia has a pretty good overview of the concept:
As to this in particular:
Something got truncated in that. Saying that X is possible (along with committing X ontologically) requires that there be a reality in which NOT X is not possible. In other words, X must exist somewhere.
Lib, you have hit a new low, pimping out your ontological/modal logic in a debate about atoms, you are falling off the deep end old boy.
Actually, everything behaves as a wave between measurements. Jupiter has a wavelength (which is some fraction of a nanometer larger than the diameter of Jupiter, so it’s mostly safe to think of Jupiter as being where we think it is). It’s just more noticeable the smaller you get, so that electrons and photons tend to behave more like waves than particles (because their wavelengths are considerably larger than the size of their particles).
Epimetheus, please watch your comments. You are in GQ.
-xash
General Questions Moderator
whether or not something exists is not a question that can have a good answer imho.
as far as i know there is no evidence that theory about atoms is wrong, that means to the best of our knowledge they exist
a more relevant question would be - what ARE they ?
when you say that your keyboard exist what you really mean is you can interact with it, like bang it on your monitor. well you can also interact with atoms similarly, you can move individual atoms. that doesnt explain what they are though too well.
Wow. What a clear answer. With all your fancy book learning I assumed you could answer this in a clear way.
Just kidding. 
However, I am now even more confused. I don’t think I should have used the word “exist” in my question. Maybe a better way to ask my question is:
Can an atom be observed directly like a “keyboard” or an “apple”?
Member js_africanus currently has this as his sig:
You can only see objects that are larger than the wavelength of visible light. So that’s about 10[sup]-6[/sup]m. An atom is about 10[sup]-10[/sup], so no you could never “see” an atom. You can “see” them if you use X-ray diffraction but that’s a complicated process.
Given that the DeBrogie wavelength = h/p I’m curious as to how exactly you came up with the above?
According to the Bill Bryson book I’m reading at the moment though A Short History of Nearly Everything:
The common idea of an atom is of a central nucleus with electrons spinning round it like planets orbiting a sun but this is actually wrong. Due to the uncertainty principle, the electrons are everywhere all at the same time so if you could see an atom it would look more like a fuzzy tennis ball. You wouldn’t see the nucleus just the outside shell - the spinning electrons.
Another interesting thing he says is that nothing ever really touches anything else. Although you think you are sitting on a chair you aren’t really. The negatively charged electrons of the atoms on your bottom are repelling the negatively charged electrons of the atoms of the chair and vice versa - they are repelling each other. So you are actually levitating above the chair.
Nice article that’s kinda sorta related to the OP
google for “IBM logo flypast” you will find a short mpeg movie showing an image of an IBM logo created by pushing around individual atoms.
it was created at an IBM research center.
the 3-D flypast motion is simulated but the basis for it is the actual microscope image.
In order to forestall any misconceptions, the picture of the atoms that IBM “pushed around” to spell “IBM” isn’t an optical microscope picture of atoms. It is a pseudo image made by using the tunneling current from a probe very, very, very close to the surface to vary the intensity of the beam of a cathode ray tube or similar device.
Again, I think you oversimplify and walk right into scientific realism which, in fact, suggests that no atoms exist, even though the scientific theory says they do. Neat, huh?
Anyway, my problem is with your insistence that you detect the presence of your keyboard with the interaction of EM fields–you don’t. You touch it. You explain the sensation of touching, scientifically, with EM fields–which are just as speculative as atoms themselves. You believe that science is explaining what is “really” happening, so you suggest that there is an equivalence between the two. I find that to be a dangerous assumption.
The answer to the question, “How do you explain these experimental results?” is, “With atoms”–we both agree here, it seems. At least, this is definitely my answer. To get to “atoms exist” we need to suggest that scientific explanations are a true picture of reality. To get to “keyboards exist” we need to suggest that “perception gives a true picture of reality.” Depending on how one qualifies that second remark, one arrives at my own position.
Generally speaking, we do not disagree with science (if we did, why would we do it?), so it is safe to say that we’ve long since stopped questioning whether atoms exist and simply act as if they do. If this is the only requirement of existence, then atoms exist–simple as that. This is my original response.
The alpha particle is a helium nucleus. Helium, of course, comes in atoms. Using an atom to prove the existence of atoms is not very impressive. 