# Q & A: What's the frequency of dark energy?

Q:
Using e= (mc2) and e= hf, then mc^2 = hf, then f= (mc2)/h. c^2= (299,792,458 meteres/second) squared h= 6.626075 x 10^-34 Js (joule seconds) If these are correct, then Frequency= Mass x [8.987551787 x 10^16 (m/s)squared]/6.626075 x 10^-34 Joule seconds. A Joule is a kg-m^2/s^2. Given these formulae, and the density of Dark Energy measured at 10^-29 grams per cubic centimeter, can the frequency of Dark Energy be determined?
- Jim (age 58)
Batesville, AR, USA
A:
Your idea that energy/mass/frequency are all really the same thing in different units is correct. Assuming that the general dark energy model is correct, however, that doesn't give a single frequency for dark energy. Rather, one gets a frequency that's proportional to the volume of space involved. Taking your numbers (Your value for c2 is a little off, but not much.), that gives about  1018 Hz/cm3.

Does this have much direct significance? None that I know of.

Mike W.

(published on 07/16/2012)

## Follow-Up #1: the sound of dark energy?

Q:
If dark energy could be defined as a frequency, why is everyone looking for matter instead of listening? Is it possible that the movement of the things we can see in space are reacting to 'sounds' instead of a dark matter physically moving it? Supposedly there is no sound in space? Why not? And if there were, wouldn't it look allot like dark energy?
- Shawn Hunter (age 48)
Gentrt, Ark USA
A:

I think you've got a few things jumbled together. The seacrhes for matter particles are looking for, among other things, the constituents of "dark matter". That's the stuff that lumps up gravitationally with familiar matter in galaxies. Or at least it looks like that's what is happening. Since this looks like pretty ordinary lumpy stuff that happens not to interact strongly with our particular type of lumpy stuff, it makes sense to search for weakly interacting particles.

"Dark energy" on the other hand, is the standard way of describing something very different, an energy that uniformly pervades all of space. Unlike regular stuff, including dark matter, dark energy does not get more dilute as space expands. The density stays constant. Explanations are usually made in terms of some space-filling field. That wouldn't be at all sound-like, but in principle it could support some sort of sound-like vibrations. A parallel example would be the Higgs field, which can be twanged hard enough to have little Higgs particle waves stirred up.

With regard to our old answer, we said there is no particular frequency associated with the dark energy.

Mike W.

(published on 02/22/2015)