## Is there a particular range of frequencies at which parts of the human body (or the human body overall) normally vibrates? Because in an episode of the sci-fi TV series Fringe, they claimed that they could figure out if one character was from this universe or a parallel universe by measuring the frequency at which he was vibrating.

Asked by: Brandon Juhl from Washington

The short answer is, as far as we know: no. The idea that there is some vibration frequency of the body that is unique to our universe, and would allow us to determine whether someone is from our universe or not, sounds like a plot device that was invented for the purposes of the story.

In real life, we have no way of knowing whether there is some sort of measurable quantity that is unique to our universe, since ours is the only universe we know of. We have no other examples to serve as a basis for comparison.

It’s possible that there are other universes in existence and that they may have different physical laws than ours, but at the moment that’s pure speculation. The only universe whose existence we know about is our own.

The only real-life idea that comes to mind that might come close to the concept you mention from the story is the idea of “blackbody radiation”. This is a kind of electromagnetic radiation emitted by any object that has a non-zero temperature.

An example of an infrared photograph.
Image Credit: Ghetu Daniel

The radiation is emitted over a range of frequencies, and has its peak intensity at a particular frequency that’s related to the temperature through a physical principle called “Wien’s law”. The higher the frequency of peak intensity, the hotter the object. A common example is the burner on a stove, which emits blackbody radiation with its peak in the red part of the visible-light spectrum when the burner is on “high”, so it glows red.

We can use Wien’s law to estimate the temperature of the surface of the Sun. We find that the Sun emits blackbody radiation with the peak intensity at a frequency of about 600 terahertz. According to Wien’s law, this corresponds to a surface temperature of about 10,000 degrees Fahrenheit.

Similarly, a human body temperature of 98.6 degrees Fahrenheit corresponds to a blackbody radiation frequency of about 32 terahertz, which is in the infrared part of the spectrum. Human bodies emit infrared radiation, which is the principle behind “night vision” goggles: they convert infrared light to visible light, allowing the wearer to see warm bodies glowing in infrared light.