Is cosmic expansion happening on microscopic scales? (Advanced)

I'm not sure if this is an astrophysics question or a quantum physics question, or something totally stupid, but here goes...

If the universe is expanding (Hubble), and therefore space in general is expanding, then does it make sense to conclude that the space immediately around us (people, dogs, cats, chairs, etc) is also expanding, but at an imperceptible rate? In other words, is my right eye moving away from my left eye at some infinitesimally small rate due to universal expansion?

If so, then it must also be happening at a microscopic level. Does this microscopic expansion have any effect on atomic and/or quantum calculations? Do mathematicians and physicists include an expansion constant in their formulas when developing quantum theory?

Cosmic expansion is happening on a microscopic level, as you surmise, but at such a small rate that you would never notice it. On such scales other forces are so strong that while theoretically space is expanding, the particles in it are held together and do not move. Indeed, your right eye would be expanding away from your left eye due to this effect, except that they are held in place by all the bones and ligaments in your skull.

Cosmic expansion is not included in quantum calculations. The effect is far, far, FAR too small.

There is really only one place a calculation like you suggest would come in handy: calculating the energy density in a vacuum. As the vacuum expands, you get more total vacuum energy.

Thanks for a cool question!

This page was last updated June 27, 2015.

About the Author

Karen Masters

Karen Masters

Karen was a graduate student at Cornell from 2000-2005. She went on to work as a researcher in galaxy redshift surveys at Harvard University, and is now on the Faculty at the University of Portsmouth back in her home country of the UK. Her research lately has focused on using the morphology of galaxies to give clues to their formation and evolution. She is the Project Scientist for the Galaxy Zoo project.

Twitter:  @KarenLMasters

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