## is ether needed as a medium to propagate light?

Feb 24, 2002 11:10 AM
by Eldon B Tucker

```I did a quick search on the Internet for a good
explanation of why there is no need for physical
ether to explain how electromagnetic waves are propagated. I
found the following message online at:

<http://www.lns.cornell.edu/spr/2001-06/msg0033705.html>

```
```For ocean waves, the "particles" of water move in "orbits"
(circular in deep water, ellipses in shallow water), in an
organized fashion. By that I mean that in one place the water
may be moving up, at another place, farther along, the water
moves down, and at locations in between the water moves in other
directions around the orbits. The wave is the combination of all
that, and can be thought of as a disturbance moving through the
water.

Waves in a string are simpler. At one instant some parts of the
string are moving up (assuming the plane of the motion is
vertical) some parts are moving down, and a few points are
motionless. At another instant this pattern will have moved
along the string. Sound waves in air (or water or some other
fluid) involve the motion of the air (or whatever) molecules.

But there are other types of waves that don't involve the motion
of a substance. Electromagnetic waves (light, radio and
television, X-rays, etc.) are variations in the STRENGTH of
electric and magnetic fields in space. When they were first
discovered, in the 19th century, scientists had no experience
with any kind of waves except those moving through a medium. So
they invented one, "ether" (not the stuff that doctors used to
use as an anesthetic), to carry the waves. It had to have some
really strange properties, but more to the point no experiment
could detect it, or its effects (except for the purely
hypothetical effect of being there to carry the electromagnetic
waves). Now people understand that there is no experimental
justification to assume that ether exists, and it isn't needed to
explain how (for instance) light gets from the Sun to the Earth.

You could think of waves as an abstract way of describing a
certain type of organized motion, where you interpret "motion"
loosely.
```
```This does not mean that there might not be nonphysical
matter that extends beyond the earth, and perhaps at some
levels embraces all of space. It just means that there is
no need for a physical version of ether to exist in order
to explain how something like magnetism is propagated across
space.

In the quoted explanation above, it's interesting to note
the two kinds of waves. One is an influence upon a material
body such as water. The other is an influence upon the
strength of fields in space.

For something like light, it could be considered as either
a wave or a stream of particles (photons). As particles, it
could go shooting across space without needing any medium
to propagate it. As a wave, though, a form of vibration,
I'd expect that there would need to be something vibrating,
something whose movement carries that wave. If you picture
light as the variation in the strength of a field in space,
that's saying that there's a field of something in space
that's there and can be varied. That universal field may not
be composed of matter as we know it, but it exists and is
there to "create" light by it's being able to be varied.

If we picture a beam of light shooting through space, with
it riding on a variation in intensity of universal light
energy, I'd see an analogy here to picture a wave moving
across the ocean. In one case, it's a moving disturbance of
the intensity of a universal light field, and somewhat
immaterial. In the other case, it's a moving disturbance
of water, something very material. But in either case, that
disturbance moves across *something* as it traverses space.

Perhaps if we dwell on this idea, it may yield some new
insights? (The philosophers among us could offer some
philosophical insight. The historians could quote 100-year-old
opinions on the subject. The scientists could tell us additional
information on what modern science holds true. And the mystics
could explain things in a way that leads us into deeper
inner reflection.)

-- Eldon

```