25

I doubt that organisms have electromagnetic (EM) fields. If we did have such a field, then we would certainly be susceptible to having electric currents induced in us by stronger EM fields. Or worse, being affected by magnetic fields like a scrap of iron.

Do any organisms actually have such a field? Where does this claim come from?

Edit:

This question arose because of this question.

  • Context? Origin of the claim? – Borror0 Mar 2 '11 at 17:02
  • Don't most smartphone touch screens work by sensing the body's natural EM field? – ESultanik Sep 28 '11 at 14:05
  • 1
    @ESultanik: No; the screens contain oscillators to generate EM fields; your body affects that field because it's salty water (i.e. conductive). – MSalters Sep 29 '11 at 14:04
  • 2
    Google "ampullae of lorenzini". There are whole families of animals that have evolved to hunt by detecting the electric fields of other animals. – slebetman Apr 21 '16 at 4:22
  • 1
    "If we did have such a field, then we would certainly be susceptible to having electric currents induced in us by stronger EM fields" i.e, electrocution? – ApproachingDarknessFish Apr 25 '16 at 0:38
35

They have plenty of EM fields!

  1. Atoms are held together by the electromagnetic field
  2. Chemistry is based on electromagnetism
  3. The body emits heat through electromagnetic radiation
  4. There are currents which flow around muscles and the nervous system.

We are affected by the EM field:

  1. Through light
  2. Through radiative heat
  3. Through radiation in general
20

Wherever electric current exists, magnetic field is also induced. (see Maxwell's equations) This means that all living organisms, which utilise electric current in their biology (like nerve impulses) emit weak electromagnetic fields.

Some animals (sharks for example) are even capable of sensing these fields.

Now, being a source of such emission does NOT necessarily mean, we are also susceptible to interference by external sources.

  • 3
    On the other hand, since our functioning does depend partly on electric currents, they can be messed with by external sources. – David Thornley Mar 7 '11 at 3:29
14

Yes, humans and other organisms do have electromagnetic fields. Current western medicine often uses machines to measure the electromagnetic waves of various parts of the body in order to determine the health of a patient.

  • Electrocardiograms (EKG) are used to measure a patient's heart. The animation shows how the ECG wave in the heart is plotted on a strip chart.

beating heart and strip chart animation

  • An electroencephalogram (EEG) is used to measure the electromagnetic fields produced by the neurons in your brain. Epileptic seizures, for instance, can be measured and plotted. A sample is provided:

EEG plot of a patient experiencing an epileptic seizure

Follow the three links to see a whole host of other similar instruments/procedures used in verified scientific ways.

  • 1
    +1 Nice, especially the EKG animation. It shows the central AV node very well. I have WPW, which is a bypass around that. I had to get educated that signals are passed in the heart not by nerves, but by excitable muscle tissue. I've also had an EMG, an "exciting" experience :) – Mike Dunlavey Oct 3 '11 at 12:51
6

Humans, animals and other diamagnetic objects are affected by magnetic fields. The effect is just so weak that it is usually not noticable. But you can e.g. levitate a frog using an extremely strong magnet (see this video on YouTube).

EM fields also induce currents in humans, but they are usually so small as to be unnoticeable. But you don't want to stand directly in front of, e.g. a military radar or other sources with extremely high power.

  • 4
    My understanding of the radar example is that it is a source of RF and the energy output has less to do with EM field interaction and more with bombarding molecules with energy, exciting them to cause heat, damage (i.e. mutations leading to cancer), etc. – JYelton Mar 2 '11 at 17:30
  • 2
    @JYelton It's bombarding us with energy in form of an EMF causing an interaction with that EMF, there is really no difference in what you wrote and what I wrote. – Mad Scientist Mar 2 '11 at 18:01
  • The health risks associated with EMF fields are not well understood. – blueberryfields Mar 2 '11 at 20:29
  • 2
    @blueberryfields that depends on the type of EMF. Cellphones, for instance have been studied extensively, and no detrimental effects have been found. Same from living under power-lines and wi-fi. That said, there are forms of EM radiation that CAN affect health, as noted by Sklivvs, such as visible light (blindness if too bright), infrared (heat causes burns), ultraviolet light (skin and DNA damage), xray (possible cancer risk), microwave (can excite water molecules causing burns), etc. People get scared at the word "radiation," but typical dose stuff is known to be safe. – Ustice Mar 4 '11 at 14:18
  • 1
    @JYelton: RF is just EM radiation with the frequency of between a few kHz to several hundred GHz. Visible light is EM radiation in the THz range while magnets are EM fields that have frequencies below a few hundred Hz or zero Hz for permanent magnets. – slebetman Apr 21 '16 at 4:19
2

If we did have such a field, then we would certainly be susceptible to having electric currents induced in us by stronger EM fields.

How do you figure? A lump of iron or pith doesn't have its own fields, but is still affected by external fields.

Yes, humans generate small electric and magnetic fields, as well as emitting a few hundred watts of thermal electromagnetic radiation.

We are also affected by external fields, but we have evolved to not be affected by things like static magnetic fields or electrostatic shocks. It generally takes a lot of energy/power to affect us. See Transcranial magnetic stimulation for an example.

1

Lots of good answers here already but nobody seems to have mentioned the interesting case of Transcranial Magnetic Simulation (TMS) which provides a direct answer to the original questions.

Since nerve signals are partially transmitted by electrical currents, they both create and can be manipulated by the right electromagnetic fields. As the summary of the Encyclopedia of Neuroscience entry says:

TMS represents a noninvasive method to induce electrical currents within the brain that in turn can be used to transiently disrupt the function of a targeted brain area, functionally map cortical areas, assess cortical excitability, and modulate cortical activity. TMS is being widely used to investigate complex facets of the human brain, including sensory and motor function as well as cognition.

So the answer to the question is yes organisms do have EM fields and, yes, they can be influenced by external fields (though it takes a very focussed and specific field to cause anything of note). The idea that crystal healing might make a difference is not rendered more plausible by this observation.

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .