# Body wavelength

1. Mar 29, 2009

### Albert George

Hi

We have talked in school about waves and I heard that our bodies have a wave length. What does it mean? I know it's very little.

I do not mean our brain but our entire body. Any good explanation would be appreciated.

2. Mar 29, 2009

### tiny-tim

Welcome to PF!

Hi Albert George! Welcome to PF!

Yes, technically anything has a wave function, and has "wave behaviour" as well as "particle behaviour" … but for a human body the "wave behaviour" is soooo little that it has no noticeable effect whatever.

I think that the largest object for which any effect has ever been noticed is a C60 atom …

chuck C60 atoms through a double-slit, and you get the same "wave behaviour" effects as for light or electrons

3. Mar 29, 2009

### Staff: Mentor

Re: Welcome to PF!

You call it an atom? I call it a molecule

4. Mar 29, 2009

### tiny-tim

oops!

oops!

5. Mar 29, 2009

### Albert George

Okay, but what does it mean that we humans have a wave function? What is causing it and is it always the same (a constant)? Is it on the electromagnetic spectrum or where can you place it?

6. Mar 30, 2009

### alxm

It doesn't really mean as much as it seems to imply. Everything has a wavelength/wave function according to quantum physics. It means that things exhibit wave-like behavior under certain circumstances. But for a big, macroscopic object, the wavelength is too short for this to be measurable.

As they said, the biggest object they've been able to measure 'wave-like' behavior for is C60 - 60 atoms.
That's an object that weighs about as little in comparison to you, as you do in comparison to Jupiter.

The wavelength is h (Planck's constant) divided by p, the momentum of the object. As for why.. that's a fairly open question in physics.

No, because although things have wave-like behavior they're not necessarily electromagnetic waves.

7. Mar 30, 2009

### Andy Resnick

In general, if people are talking about wavelengths of the human body, they usually completely lack any real science. Especially if the subject of 'resonant behavior' or resonance, or something like that in connection with health and disease is also mentioned.

8. Mar 30, 2009

### mgb_phys

You might also be thinking of the wavelength of infrared light our bodies emit because of our temperature - that's around 10um.

9. Mar 30, 2009

### JorgeLobo

It's pure BS - humans have no "wave function."

10. Mar 30, 2009

### mgb_phys

Has someone told Erwin Schrödinger ?

11. Mar 31, 2009

### Staff: Mentor

12. Apr 1, 2009

### Eidos

Human beings are also a 'perfect' antenna for some frequencies of electromagnetic radiation.

Now, everything that is conductive can act as an antenna, but it 'recieves' frequencies better than others. Basically if we were a thin piece of wire that is 1.5 m tall, 100Mhz is the frequency which we could pick up the best.

Say the average human is 1.5m tall. Now the 'perfect' antenna size, $x$ is half a wavelength of the frequency you are using, $x=\frac{\lambda}{2}$.
This implies that the wavelength we are looking for is $\lambda=2\;x=2(1.5)=3\;m$. The frequency that this wavelength corresponds to is,
$f_{\mathrm{MHz}} \approx \frac{300}{\lambda}$

*Note: this is assuming some special geometry (which we don't possess) and that we are purely conductive (which we aren't).

13. Apr 2, 2009

### Andy Resnick

This is what I meant by not having a sound basis in science.

14. Apr 2, 2009

### Eidos

How is that not a sound basis in science? Your body acting as an antenna is an observable, measurable, repeatable fact. Granted my order of magnitude calculation is not 100% accurate since I was assuming a dipole geometry.

If I am in the wrong then we need a volunteer to go stand within a couple of meters to a high power HF transmitter to show that the human body cannot act as an antenna. :P

I was using reciprocity when I used the half-wavelength calculation. Also I had that $c\approx 300\times10^8$m/s which is again a rough approximation.

15. Apr 2, 2009

### alxm

Eidos, so you're saying:
But by the given rationale, you could say the same about any elongated conductor.

So the only thing you're actually saying about humans is that we're significantly taller than we are wide, and that we conduct electricity. Which is news to no-one, really.

16. Apr 2, 2009

### Eidos

The same is true for any elongated conductor ;)

Im convinced this thread was concerning body-wavelength. The antenna interpretation is here simply for the sake of offering an alternative to the other proffered explanation.

Enjoy

\'''\(..^.....^...)/'''/

17. Apr 2, 2009

### mgb_phys

Is that how physicists pick up women now?

18. Apr 2, 2009

### JorgeLobo

What silliness. Let's see the data and not the BS.