# EM jumble

In the 2014 science fiction action film Lucy, there’s a scene in a car where Lucy sees the radio frequency signals (streams) from cell phones and manipulates that part of the electromagnetic (EM) spectrum with gestures in order to listen to a call in progress.

We are forever enveloped in an EM jumble, as Feynman describes in one of his lectures.1

Try to imagine what the electric and magnetic fields look like at present in the space in this lecture room. First of all, there is a steady magnetic field; it comes from the currents in the interior of the earth—that is, the earth’s steady magnetic field. Then there are some irregular, nearly static electric fields produced perhaps by electric charges generated by friction as various people move about in their chairs and rub their coat sleeves against the chair arms. Then there are other magnetic fields produced by oscillating currents in the electrical wiring—fields which vary at a frequency of 60 cycles per second, in synchronism with the generator at Boulder Dam. But more interesting are the electric and magnetic fields varying at much higher frequencies. For instance, as light travels from window to floor and wall to wall, there are little wiggles of the electric and magnetic fields moving along at 186,000 miles per second. Then there are also infrared waves travelling from the warm foreheads to the cold blackboard. And we have forgotten the ultraviolet light, the x-rays, and the radiowaves travelling through the room.

Flying across the room are electromagnetic waves which carry music of a jazz band. There are waves modulated by a series of impulses representing pictures of events going on in other parts of the world, or of imaginary aspirins dissolving in imaginary stomachs. To demonstrate the reality of these waves it is only necessary to turn on electronic equipment that converts these waves into pictures and sounds.

If we go into further detail to analyze even the smallest wiggles, there are tiny electromagnetic waves that have come into the room from enormous distances. There are now tiny oscillations of the electric field, whose crests are separated by a distance of one foot, that have come from millions of miles away, transmitted to the earth from the Mariner II space craft which has just passed Venus. Its signals carry summaries of information it has picked up about the planets (information obtained from electromagnetic waves that travelled from the planet to the space craft).

There are very tiny wiggles of the electric and magnetic fields that are waves which originated billions of light years away—from galaxies in the remotest corners of the universe. That this is true has been found by “filling the room with wires”—by building antennas as large as this room. Such radiowaves have been detected from places in space beyond the range of the greatest optical telescopes. Even they, the optical telescopes, are simply gatherers of electromagnetic waves. What we call the stars are only inferences, inferences drawn from the only physical reality we have yet gotten from them—from a careful study of the unendingly complex undulations of the electric and magnetic fields reaching us on earth.

There is, of course, more: the fields produced by lightning miles away, the fields of the charged cosmic ray particles as they zip through the room, and more, and more. What a complicated thing is the electric field in the space around you!

Feynman continues the lecture with a section on scientific imagination.

When I talk about the fields swishing through space, I have a terrible confusion between the symbols I use to describe the objects and the objects themselves. I cannot really make a picture that is even nearly like the true waves. So if you have some difficulty in making such a picture, you should not be worried that your difficulty is unusual.

What I realize now is that when I talk about the electromagnetic field in space, I see some kind of a superposition of all of the diagrams which I’ve ever seen drawn about them. I don’t see little bundles of field lines running about because it worries me that if I ran at a different speed the bundles would disappear, I don’t even always see the electric and magnetic fields because sometimes I think I should have made a picture with the vector potential and the scalar potential, for those were perhaps the more physically significant things that were wiggling.

We are unfortunately limited to abstractions, to using instruments to detect the field, to using mathematical symbols to describe the field, etc. But nevertheless, in some sense the fields are real, because after we are all finished fiddling around with mathematical equations—with or without making pictures and drawings or trying to visualize the thing—we can still make the instruments detect the signals from Mariner II and find out about galaxies a billion miles away, and so on.

Our vision registers only a limited part of the EM spectrum. We can augment that with devices, such as spectrometers, infrared cameras, radio receivers, and other detectors. We feel the general degree of thermal frequencies.

Are there life forms that not only see some of the EM spectrum but also feel the texture and shape of a wide range of that spectrum? Or, smell the discrete energies and taste the flavors of EM fields? Might they be able to exceed Feynman’s limited abstractions?

Quantum field theory depicts our immersion in a jumble of all the Standard Model particles’ fields — a constant, complex dance (linear superposition) of vibrations (Feynman’s wiggles) everywhere. Especially all those neutrinos!

What’s amazing is that we exist in a universe which is knowable. A universe which is reliably itself (cosmological principle)  — one with patterns that we can detect and understand. Laws of physics which can be discovered — abstractions which boggle the imagination and nurture our need for wonder.

… the fact that the universe is so gloriously knowable is perhaps its most remarkable feature. It’s one of the aspects of reality that helps make our Sisyphean struggles so ultimately rewarding. — Carroll, Sean. The Big Picture: On the Origins of Life, Meaning, and the Universe Itself (p. 432). Penguin Publishing Group. Kindle Edition.

There are wonders enough out there without our inventing any. — Sagan, Carl. Demon-Haunted World: Science as a Candle in the Dark (Kindle Location 1073). Random House Publishing Group. Kindle Edition.

[1] The quote is preceded by this sentence in the prior paragraph: “Thus the most general solution of the three-dimensional wave equation is a superposition of all sorts of plane waves moving in all sorts of directions.”