# What's in all the empty space in an atom? **URL:** \ **Category:** Factual Questions\ **Created:** [November 10, 2002, 10:32am UTC](https://boards.straightdope.com/t/whats-in-all-the-empty-space-in-an-atom/136125 "2002-11-10T10:32:26Z")\ **Posts on this page:** 4\ **Page:** 3
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [November 13, 2002, 12:57pm UTC](https://boards.straightdope.com/t/whats-in-all-the-empty-space-in-an-atom/136125/41 "2002-11-13T12:57:57Z")
This Board is an educational one, no doubt about it. I’ve learned several things on it over the years, esp. about physics. Nevertheless, a lot of the argument about “real” vs. “virtual” particles strikes me as more philosophy and verbal sleight-of-hand than reality (an understandable confusion at the quantum level). From this site: > **[Research](https://www6.slac.stanford.edu/research)** > >   > > SLAC research explores the structure and dynamics of matter and the properties of energy, space and time at the smallest and largest scales, in the fastest processes and at the highest energies. These studies address questions of major... > [@](#): > > Particle physicists talk about these processes as if the particles exchanged in the intermediate stages of a diagram are actually there, but they are really only part of a quantum probability calculation. It is meaningless to argue whether they are or are not there, as they cannot be observed. Any attempt to observe them changes the outcome of the process. So the particles can’t be observed because if you do so they change the outcome. But if you don’t insist on the outcome being unchanged, and merely observe the situation, and the particles _do_ interact, then you can observe the ouitcome, and say that real particles interacted. So the particles are observable. They don’t obey the energy law because the amount of energy they have violates the energy balance by the amount allowed by the uncertainty relation. But if you observe it after the interaction everything seems to balance perfectly, provided you don’t insist that everything happen the way it would have if the interaction wasn’t observed. ---
**Author:** ![Ring](https://avatars.discourse-cdn.com/v4/letter/r/6a8cbe/32.png) [@Ring](https://boards.straightdope.com/u/Ring)\ **Post date:** [November 13, 2002, 3:15pm UTC](https://boards.straightdope.com/t/whats-in-all-the-empty-space-in-an-atom/136125/42 "2002-11-13T15:15:44Z")
> [@](#): > > \*Originally posted by CalMeacham \* > Nevertheless, a lot of the argument about “real” vs. “virtual” particles strikes me as more philosophy and verbal sleight-of-hand than reality (an understandable confusion at the quantum level). Truer words have never been spoken. > [@](#): > > From this site: > [http://www2.slac.stanford.edu/vvc/theory/virtual.html](http://www2.slac.stanford.edu/vvc/theory/virtual.html) > > So the particles can’t be observed because if you do so they change the outcome. But if you don’t insist on the outcome being unchanged, and merely observe the situation, and the particles _do_ interact, then you can observe the ouitcome, and say that real particles interacted. So the particles are observable. Yes, that’s the whole point. You can change the experiment, but when you do you are no longer attempting to observe _virtual_ particles. You’re now observing _real_ particles. Virtual particles can never be detected. ---
**Author:** ![FriendRob](https://avatars.discourse-cdn.com/v4/letter/f/ecc23a/32.png) [@FriendRob](https://boards.straightdope.com/u/FriendRob)\ **Post date:** [November 13, 2002, 3:38pm UTC](https://boards.straightdope.com/t/whats-in-all-the-empty-space-in-an-atom/136125/43 "2002-11-13T15:38:23Z")
Particle interactions are described in terms of quantum _fields_. Virtual particles are a sometimes-convenient way of talking about those fields. They do things real particles can’t do, like traveling faster than light (at times). You can never catch them in the act (unless you add enough energy to promote them to real particles, as **Ring** said). ---
**Author:** ![barbitu8](https://avatars.discourse-cdn.com/v4/letter/b/839c29/32.png) [@barbitu8](https://boards.straightdope.com/u/barbitu8)\ **Post date:** [November 13, 2002, 10:28pm UTC](https://boards.straightdope.com/t/whats-in-all-the-empty-space-in-an-atom/136125/44 "2002-11-13T22:28:01Z")
> [@](#): > > \*Originally posted by CalMeacham \* > \*\*So the particles can’t be observed because if you do so they change the outcome. But if you don’t insist on the outcome being unchanged, and merely observe the situation, and the particles _do_ interact, then you can observe the ouitcome, and say that real particles interacted. So the particles are observable. They don’t obey the energy law because the amount of energy they have violates the energy balance by the amount allowed by the uncertainty relation. But if you observe it after the interaction everything seems to balance perfectly, provided you don’t insist that everything happen the way it would have if the interaction wasn’t observed. \*\* \*\* Enderw24 \*\*, take that paragraph to your English teacher. 🙂 [Previous page](https://boards.straightdope.com/t/whats-in-all-the-empty-space-in-an-atom/136125.md?page=2)