# Do atoms really exist? **URL:** \ **Category:** Factual Questions\ **Created:** [March 27, 2004, 8:26am UTC](https://boards.straightdope.com/t/do-atoms-really-exist/236714 "2004-03-27T08:26:58Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![sturmhauke](https://avatars.discourse-cdn.com/v4/letter/s/e47c2d/32.png) [@sturmhauke](https://boards.straightdope.com/u/sturmhauke)\ **Post date:** [March 27, 2004, 8:00pm UTC](https://boards.straightdope.com/t/do-atoms-really-exist/236714/21 "2004-03-27T20:00:14Z")
> [@DarrenS](#): > > My thinking was, given the nature of the images, it would seem that we know the position with very little uncertainty, meaning there must be a _huge_ uncertainty in the momentum. Therefore, why aren’t the atoms flying off in all directions? I’m thinking the problem is I’m a little fuzzy on what it means for there to be a “huge uncertainty in momentum” - does that mean they could be moving at anything from 0 mph to close to the speed of light? Are these pictures then just an instantaneous snapshot, after which the atoms fly off in different directions? If not, it would seem we’ve nailed down the position (“right there, row 3, column 4”) of an atom as well as its momentum (0, since they’re apparently stationary) in violation of the UP. “Huge uncertainty” is relative. The grid of atoms in that picture has some temperature, and so each atom vibrates randomly. But the atoms are bound together into a solid, so they only vibrate within those bonds rather than flying off somewhere. Because of that constraint, the atom’s position is known well enough to do manipulations; if you had a gas at the same temperature it wouldn’t work. If you cool matter down to a few billionths of a Kelvin, the atoms momentum becomes very well known (close to zero), and so their position becomes less and less distinct from that of nearby atoms. The result is a [Bose-Einstien condensate](http://encyclopedia.thefreedictionary.com/Bose-Einstien%20condensate), a glob of dense matter where you can’t pick one atom apart from another any longer. In fact the whole thing acts like one atom. ---
**Author:** ![astro](https://avatars.discourse-cdn.com/v4/letter/a/9dc877/32.png) [@astro](https://boards.straightdope.com/u/astro)\ **Post date:** [March 27, 2004, 8:04pm UTC](https://boards.straightdope.com/t/do-atoms-really-exist/236714/22 "2004-03-27T20:04:51Z")
> [@MonkeyMensch](#): > > I disagree with your ultimate sentence. I would say that I speak of atoms in _exactly_ the same way that I speak of keyboards. I use the same physical methods to determine the existence and physical properties of both. Doubting the existence of atoms brings up the metaphysical questions of existence and perception mentioned above. But if you think your keyboard exists I’m going to put you in the “atoms exist” camp. > > Also, **astro** , there is no borderline between the quantum world and non-quantum world simply because the latter does not exist. I carry three polarizing filters in my wallet at all times to demonstrate this very fact to folks I can manage to trap in conversation… Filters!? …and here all the ladies were thinking you were a responsible man about town. So… out of curiosity, how are you going to use this magic polarizing filters to prove this fact re the seamlessness of the quantum continuum? Splain’ me! ---
**Author:** ![erislover](https://avatars.discourse-cdn.com/v4/letter/e/71e660/32.png) [@erislover](https://boards.straightdope.com/u/erislover)\ **Post date:** [March 27, 2004, 8:25pm UTC](https://boards.straightdope.com/t/do-atoms-really-exist/236714/23 "2004-03-27T20:25:57Z")
> [@MonkeyMensch](#): > > I disagree with your ultimate sentence. I would say that I speak of atoms in _exactly_ the same way that I speak of keyboards. I use the same physical methods to determine the existence and physical properties of both. That would be very surprising. > [@](#): > > Doubting the existence of atoms brings up the metaphysical questions of existence and perception mentioned above. But if you think your keyboard exists I’m going to put you in the “atoms exist” camp. Well there are certainly instruments behaving in a way and phenomena that we’ve explained with atoms. I don’t think I’ve ever explained anything by positing a keyboard other than the sensation of a keyboard, and even that is speculative (to me, but this is the wrong forum for that). Admittedly, I am not the most worldly fellow, but I’d think by now I’d have come across such an explanation if one was about. ---
**Author:** ![astro](https://avatars.discourse-cdn.com/v4/letter/a/9dc877/32.png) [@astro](https://boards.straightdope.com/u/astro)\ **Post date:** [March 27, 2004, 8:36pm UTC](https://boards.straightdope.com/t/do-atoms-really-exist/236714/24 "2004-03-27T20:36:41Z")
> [@erislover](#): > > That would be very surprising. > Well there are certainly instruments behaving in a way and phenomena that we’ve explained with atoms. I don’t think I’ve ever explained anything by positing a keyboard other than the sensation of a keyboard, and even that is speculative (to me, but this is the wrong forum for that). Admittedly, I am not the most worldly fellow, but I’d think by now I’d have come across such an explanation if one was about. Regarding musical instruments, [apparently guitars can be understood on the quantum level.](http://www.oddmusic.com/gallery/om22000.html) ---
**Author:** ![erislover](https://avatars.discourse-cdn.com/v4/letter/e/71e660/32.png) [@erislover](https://boards.straightdope.com/u/erislover)\ **Post date:** [March 27, 2004, 8:43pm UTC](https://boards.straightdope.com/t/do-atoms-really-exist/236714/25 "2004-03-27T20:43:27Z")
How is that in response to my post? ---
**Author:** ![MonkeyMensch](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@MonkeyMensch](https://boards.straightdope.com/u/MonkeyMensch)\ **Post date:** [March 27, 2004, 8:44pm UTC](https://boards.straightdope.com/t/do-atoms-really-exist/236714/26 "2004-03-27T20:44:02Z")
> [@astro](#): > > Filters!? …and here all the ladies were thinking you were a responsible man about town. > > So… out of curiosity, how are you going to use this magic polarizing filters to prove this fact re the seamlessness of the quantum continuum? Splain’ me! I do the counter-intuitive whang-doodle demonstration (It’s an industry term.) The sort of classical explanation of polarizing filters is that they are like venetian blinds, or Levelors to anyone under forty. They only pass light whose direction of polarization is aligned with the axis of the filter. If you take two filters and align their axes at right angles virtually no light is transmitted. And this I do with the first two filters after I put the condom to one side. I then take the third filter and align it at a 45 degree angle to the other two. I hold it on one side of the pair and then the other. Still no light is transmitted. Then I slip it in between the first two. Light then slips right through, in spite of the fact that the outside filters are still aligned at right angles to each other. I’m still learning QM, but I think it’s related to the _probability_ of wave orientation that is being passed by the filter. I bet I’ve got the physics mucked up but it’s still a terrific field demonstration. If I could carry some helium II in a litlle dewar flask I’d be doing the zero viscosity demo at the local pub… ---
**Author:** ![Headcoat](https://avatars.discourse-cdn.com/v4/letter/h/6bbea6/32.png) [@Headcoat](https://boards.straightdope.com/u/Headcoat)\ **Post date:** [March 27, 2004, 9:03pm UTC](https://boards.straightdope.com/t/do-atoms-really-exist/236714/27 "2004-03-27T21:03:08Z")
Is it theoretically possible for us to one day see an atom through a powerful microscope? If so, when? ---
**Author:** ![MonkeyMensch](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@MonkeyMensch](https://boards.straightdope.com/u/MonkeyMensch)\ **Post date:** [March 27, 2004, 9:16pm UTC](https://boards.straightdope.com/t/do-atoms-really-exist/236714/28 "2004-03-27T21:16:56Z")
> [@erislover](#): > > That would be very surprising. I was speaking grossly, of course. To detect the existence of my keyboard I hurl some matter at it, usually my fingertips. To detect the existence of an atom I hurl some matter at it, usually protons but occasionally alpha particles. Sometimes I use EM radiation to detect the keyboard: I’ll turn on the room light. For atoms I turn the dimmer switch to eleven and see what X-rays can tell me. ---
**Author:** ![Liberal](https://avatars.discourse-cdn.com/v4/letter/l/848f3c/32.png) [@Liberal](https://boards.straightdope.com/u/Liberal)\ **Post date:** [March 27, 2004, 9:26pm UTC](https://boards.straightdope.com/t/do-atoms-really-exist/236714/29 "2004-03-27T21:26:58Z")
> [@](#): > > To detect the existence of my keyboard I hurl some matter at it, usually my fingertips. How is that a detection of the keyboard’s existence? All you’ve detected, if anything, is the existence of nerves in your fingers. ---
**Author:** ![MonkeyMensch](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@MonkeyMensch](https://boards.straightdope.com/u/MonkeyMensch)\ **Post date:** [March 27, 2004, 9:37pm UTC](https://boards.straightdope.com/t/do-atoms-really-exist/236714/30 "2004-03-27T21:37:52Z")
> [@Libertarian](#): > > How is that a detection of the keyboard’s existence? All you’ve detected, if anything, is the existence of nerves in your fingers. I refer the right honorable gentleman to my answer given previously (God, I’ve always wanted to say that :)) I was only showing the methods of detection of keyboard and atoms to be the same. The question of perception and reality is the epistemological quagmire referred to above. _I don’t think I’m subscribing until April 19 or 20. I’ve never got so much interaction on the boards and I think the anonymity of my post count has something to do with it_ ---
**Author:** ![astro](https://avatars.discourse-cdn.com/v4/letter/a/9dc877/32.png) [@astro](https://boards.straightdope.com/u/astro)\ **Post date:** [March 27, 2004, 9:52pm UTC](https://boards.straightdope.com/t/do-atoms-really-exist/236714/31 "2004-03-27T21:52:36Z")
> [@erislover](#): > > How is that in response to my post? Sorry Sgt. Friday. I thought you might find the nano-guitar amusing. ---
**Author:** ![erislover](https://avatars.discourse-cdn.com/v4/letter/e/71e660/32.png) [@erislover](https://boards.straightdope.com/u/erislover)\ **Post date:** [March 27, 2004, 10:03pm UTC](https://boards.straightdope.com/t/do-atoms-really-exist/236714/32 "2004-03-27T22:03:04Z")
> [@MonkeyMensch](#): > > To detect the existence of my keyboard I hurl some matter at it, usually my fingertips. To detect the existence of an atom I hurl some matter at it, usually protons but occasionally alpha particles. I simply don’t understand how you find these two methods comparable without assuming the answer to the question asked in the OP (especially wrt alpha particles). I’m not trying to be really nitpicky or excessively philosophical, but the way humans interact with keyboards seems so far removed from particle physics that I’m really at a loss. ---
**Author:** ![erislover](https://avatars.discourse-cdn.com/v4/letter/e/71e660/32.png) [@erislover](https://boards.straightdope.com/u/erislover)\ **Post date:** [March 27, 2004, 10:04pm UTC](https://boards.straightdope.com/t/do-atoms-really-exist/236714/33 "2004-03-27T22:04:20Z")
> [@astro](#): > > Sorry Sgt. Friday. I thought you might find the nano-guitar amusing. 😕 I did. But I didn’t realize it was off the cuff, it looked like you were _responding_ to me, and so I wondered. That’s all. 🙂 ---
**Author:** ![MonkeyMensch](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@MonkeyMensch](https://boards.straightdope.com/u/MonkeyMensch)\ **Post date:** [March 27, 2004, 10:24pm UTC](https://boards.straightdope.com/t/do-atoms-really-exist/236714/34 "2004-03-27T22:24:46Z")
> [@erislover](#): > > I simply don’t understand how you find these two methods comparable without assuming the answer to the question asked in the OP (especially wrt alpha particles). I’m not trying to be really nitpicky or excessively philosophical, but the way humans interact with keyboards seems so far removed from particle physics that I’m really at a loss. Well I detect the presence of my keyboard with the interaction of EM fields. (I ain’t going QM 'cause I just am not conversant with it, yet.) And the way that humans interact with keyboards _is_ far removed from particle physics. But the rules and participants are the same in both cases. The alpha particle reference was a nod to Ernest Rutherford, the Kiwi physicist who shot 15" shells at a piece of tissue paper and noticed that some of them bounced back. ---
**Author:** ![Skott](https://avatars.discourse-cdn.com/v4/letter/s/b4bc9f/32.png) [@Skott](https://boards.straightdope.com/u/Skott)\ **Post date:** [March 27, 2004, 11:46pm UTC](https://boards.straightdope.com/t/do-atoms-really-exist/236714/35 "2004-03-27T23:46:26Z")
> [@MonkeyMensch](#): > > And this I do with the first two filters after I put the condom to one side. I then take the third filter and align it at a 45 degree angle to the other two. I hold it on one side of the pair and then the other. Still no light is transmitted. Then I slip it in between the first two. Light then slips right through, in spite of the fact that the outside filters are still aligned at right angles to each other. Like [this](http://www.lhup.edu/~dsimanek/scenario/pola3.gif)? ---
**Author:** ![Jon\_the\_Geek](https://avatars.discourse-cdn.com/v4/letter/j/bbce88/32.png) [@Jon\_the\_Geek](https://boards.straightdope.com/u/Jon_the_Geek)\ **Post date:** [March 28, 2004, 12:19am UTC](https://boards.straightdope.com/t/do-atoms-really-exist/236714/36 "2004-03-28T00:19:11Z")
(I apologize if this has been addressed, I didn’t make it through the entire thread) > [@EvilAsh](#): > > Well, as a chemistry professor explained it (long ago, but the imagery has always stuck with me): An individual atom is largely nothing. Imagine an atom the size of the Astrodome (or any domed stadium). The nucleus (protons and neutrons) would be the size of a baseball in the center of the stadium, while the electrons in their various shells would be the size of grains of sand orbiting out to the size of the stadium. > > I don’t know if this model is still in favor (or is even that accurate as far as proportions and what-not), but like I said, it has always stuck with me. > > I hope this helps. ACTUALLY, that analogy is used in many, many textbooks… and it’s off by an order of magnitude or two (I worked on a textbook, and we worked out the math to check it, and were surprised to find how far off it was). A better analogy is if an atom of hydrogen were the city of Las Vegas, the nucleus would be a lightbulb in the center of Las Vegas. As for the electron… it’s best not to think of it as anything orbiting around Las Vegas. It’s better to think of it as occupying the sphere that Las Vegas is enclosed in… but not any specific part of that sphere. The wavelength of the electron would be about equal to the diameter of that sphere, meaning it would essentially be in the entire sphere at the same time. Kinda. 🙂 If you were able to isolate it at any instance in time, it would be about the mass of a grain of sand (actually considerably lighter compared to that lightbulb nucleus, I’d guess… but we never did that calculation, and I don’t have the numbers in front of me)… ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [March 28, 2004, 12:21am UTC](https://boards.straightdope.com/t/do-atoms-really-exist/236714/37 "2004-03-28T00:21:05Z")
I find the idea that [something can exist but not have shape] rather perplexing; constant changes in shape, I can cope with, shape that is too small to be determined likewise, but if something occupies space, it must have shape, mustn’t it (that’s what ‘occupies space’ means, isn’t it?). ---
**Author:** ![Liberal](https://avatars.discourse-cdn.com/v4/letter/l/848f3c/32.png) [@Liberal](https://boards.straightdope.com/u/Liberal)\ **Post date:** [March 28, 2004, 12:56am UTC](https://boards.straightdope.com/t/do-atoms-really-exist/236714/38 "2004-03-28T00:56:36Z")
> [@MonkeyMensch](#): > > I refer the right honorable gentleman to my answer given previously (God, I’ve always wanted to say that :)) > > I was only showing the methods of detection of keyboard and atoms to be the same. The question of perception and reality is the epistemological quagmire referred to above. > > _I don’t think I’m subscribing until April 19 or 20. I’ve never got so much interaction on the boards and I think the anonymity of my post count has something to do with it_ It is indeed a question of perception, but it isn’t just an epistemological quagmire — it’s an ontological quagmire. There are epistemic possibilities and metaphysical possibilities. For example, if you say, “It’s possible that it’s raining outside,” you might mean one of two things: (1) It is possible that it is raining outside _for all I know_, or (2) It is possible for it to rain outside. The first sort of possibility is epistemic. It’s not making any ontological commitment. But the second possibility is making a massive ontological commitment. It is saying that that there must be some world — some circumstance, context, or contingency — in which it is not possible that it is not raining outside. In asking whether atoms exist, it is clear that existence makes an ontological commitment. Given the premise that it is possible for atoms to exist, along with one or two other reasonable premises that make a massive ontological commitment, it can be proved that atoms cannot not exist. But that conclusion is contradicted by proof using more stable and less controversial premises that there are conditions (contingencies) in which atoms cannot exist. For example, in the brand new universe at temperatures too high for atomic cohesion. Since the conclusion is overturned in our proof of atoms, so is the premise. (By modus tollens or contraposition, depending on how the assertion is constructed.) It is therefore impossible for atoms to exist. ---
**Author:** ![MonkeyMensch](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@MonkeyMensch](https://boards.straightdope.com/u/MonkeyMensch)\ **Post date:** [March 28, 2004, 1:09am UTC](https://boards.straightdope.com/t/do-atoms-really-exist/236714/39 "2004-03-28T01:09:27Z")
> [@Mangetout](#): > > I find the idea that [something can exist but not have shape] rather perplexing; constant changes in shape, I can cope with, shape that is too small to be determined likewise, but if something occupies space, it must have shape, mustn’t it (that’s what ‘occupies space’ means, isn’t it?). Hey, you demi-goddish omnivore, you. I think this is the first time I’ve had occasion to reply. I think about shape as a function on the space the object is in. Any point in that field has certain values. I just don’t look at keyboard=here as a binary function. It’s all a sliding scale. My keyboard, for example, looks like it has a shape. But once I get the God’s-Own-Microscope pointed at it I can see all that froth of electrons changing states, and photons doing God-knows-what, and whatever else the guys at the ITP are going to think of next. ---
**Author:** ![Lumpy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lumpy/32/446_2.png) [@Lumpy](https://boards.straightdope.com/u/Lumpy)\ **Post date:** [March 28, 2004, 3:41am UTC](https://boards.straightdope.com/t/do-atoms-really-exist/236714/40 "2004-03-28T03:41:09Z")
After Dalton proposed the first modern atomic theory at the beginning of the nineteenth century, the question of whether atoms are real was roundly debated through most of that century. Dalton proposed that chemical combination only occurs in fixed proportions by weight, and that all chemical reactions will consistantly behave in a manner explainable by presuming irreducable units of different “elements”, which he labled atoms. A century of investigation in chemistry confirmed this (although many of Dalton’s original postulates were discovered to be oversimplifications). In addition, the classical physics of the nineteenth century discovered more and more phenomena could be explained by “atomic theory”: heat could be considered the random motion of atoms and molecules; stereoisomerism (two substances apparently identical except for how they polarize light) by presuming mirror versions of molecules; crystallography could account for all possible crystal symmetries in terms of three-dimensional arrangements of atoms; and many others. Still, there were some holdouts. They said “all the above simply shows that matter behaves _as if_ it were atomic. But are there really tiny spheres of a definite size and weight?” A proof of the reality of atoms was produced by none other than Albert Einstein at the end of the century. Earlier, the phenomenon of Brownanian motion had been discovered. Tiny particles suspended in liquid will continually jiggle and bounce around, and the smaller they are the more they’ll move. This was eventually interpreted as caused by random thermal movement of molecules in the liquid: atoms are so small that a macroscopic object is struck by effectively identical numbers of them on all sides. But a very small object might be struck by, say, one million on one side and one million and one on the other, jiggling it about a little. An even smaller particle might be hit by ten thousand on one side and ten thousand and one on the other, being jiggled more strongly; and so forth. What Einstein did (in addition to Relativity and the photon theory of light) was to produce a mathematical analysis that exactly predicted how Brownanian motion would diffuse small suspended particles throughout a liquid, presuming that the molecules of the liquid were a certain finite mass. In fact, his paper produced the first method of directly calculating exactly what a molecule actually weighed. Of course, all this was done just as classical physics collapsed, but leaving out quantum physics: yes atoms are real, as real as anything is. [Previous page](https://boards.straightdope.com/t/do-atoms-really-exist/236714.md?page=1) [Next page](https://boards.straightdope.com/t/do-atoms-really-exist/236714.md?page=3)