Take the 2-minute tour ×
Physics Stack Exchange is a question and answer site for active researchers, academics and students of physics. It's 100% free, no registration required.

Regarding conservation of mass-energy Wikipedia says: "this is an exact law, or more precisely, has never been shown to be violated."

However, regarding quantum fluctuations, Wikipedia says here: "That means that conservation of energy can appear to be violated, but only for small times".

I thought to resolve the two conflicting statements by proposing that the virtual particles from quantum fluctuations are created/destroyed from the "noise energy" of the uncertainty principle. Hence, the energy is already there. Is this correct?

If this is incorrect, how can we resolve the two?

share|improve this question

1 Answer 1

In the four dimensional spacetime of field theory, which is where virtual particles live, Energy is one of the four momentum components: p_x, p_y,p_z,E . In this fourvector space , actually a pseudovector space because a minus sign enters between the fourth and the rest of the coordinates:

the dot product of the vector with itself is its scalar measure, analogous to the length of the three dimensional vector in the normal three dimensional space. This scalar number in "real" space is fixed and unchangeable. In "virtual" space it can change according to the mathematical formulations of the Feynman diagrams describing the interaction.

Virtual space is a mathematical tool for complicated calculations and is constrained only by mathematics, not physics laws like energy conservation. This is because one can never do an experiment in virtual space, by construction.

As @DavidH comments to you the HUP is another story, it is a general uncertainty in the possibility of measuring some pairs of variables, well defined, as for example energy and time. If you measure the energies before an interaction well the energy should be conserved after the interaction. The HUP would just constrain the knowledge of how long the interaction took within the uncertainty limits. It is not the HUP that is generating virtual particles, but the specific calculations of interactions.

You may be thinking of vacuum fluctuations, but these are virtual, unless there is an interaction, i.e. energy is supplied by an interacting particle. Otherwise we would be able to get energy out of the vacuum :).

share|improve this answer

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.
{"cc_re__cc_re__cc_by_sa_3_0": ["                  <li><a href=\"//area51.stackexchange.com\" title=\"proposing new sites in the Stack Exchange network\">Area 51</a></li>\r\n                        <li><a href=\"//careers.stackoverflow.com\">Stack Overflow Careers</a></li>\r\n                    \r\n                </ol>\r\n            </td>\r\n    </tr>\r\n</table>\r\n                </div>\r\n            </div>\r\n\r\n            <div id=\"copyright\">\r\n                site design / logo &#169; 2015 stack exchange inc; user contributions licensed under <a href=\"http://creativecommons.org/licenses/by-sa/3.0/\" rel=\"license\">cc by-sa 3.0</a> \r\n                with <a href=\"http://blog.stackoverflow.com/2009/06/attribution-required/\" rel=\"license\">attribution required</a>\r\n            </div>\r\n            <div id=\"svnrev\">\r\n                rev 2015.3.26.2411\r\n            </div>\r\n            \r\n        </div>\r\n    </div>\r\n    <noscript>\r\n        <div id=\"noscript-warning\">Physics Stack Exchange works best with JavaScript enabled<img src=\"http://pixel.quantserve.com/pixel/p-c1rF4kxgLUzNc.gif\" alt=\"\" class=\"dno\"></div>\r\n "], "copyright__copyright__copyright": ["rtual particles, but the specific calculations of interactions.\n\nYou may be thinking of vacuum fluctuations, but these are virtual, unless there is an interaction, i.e. energy is supplied by an interacting particle. Otherwise we would be able to get energy out of the vacuum :).\n\nshare|improve this answer\n\nYour Answer\n\n\u00a0\ndiscard\n\nBy posting your answer, you agree to the privacy policy and terms of service.\n\nNot the answer you're looking for? Browse other questions tagged or ask your own question."]}