The Ether of Space

nner, but it is now time to deal with it more generally. And to do this compactly I

statements concerning

e motion of the medium, unless eddies exist; in other wor

ay will not be the true ray, and his line of vision

oving ether the ray and wave-normal enclose an aberration angle ε,

that alone. If the observer is stationary, his line of vision is a ray. If

er, so long as it has a velocity-potential. Hence if this con

nt as to Negati

bj

r and matter. If there is complete connexion, the ether near the earth is relatively stagnant, and negative terrestrial results are natural. If there is complete independence, the ether is either absolutely stationary or has a velocity-po

tion o

x. In other words, it may be considered as the path of a labelled disturbance; for it is some special featu

ve at B in the same phase; hence the path by which a disturbance travels must satisfy this condition from point to point.

ined in the statement that the time take

/ V =

o the ray, we must substitute for V the modified velocity V cos ε + v cos θ; and so the f

= ∫AB ds / V(c

v cos θ) / V2(1 ?

is the r

nd Time of Jou

nally Mov

al φ in the above equation

θ = δφ

the minute correction factor 1?α2 be

/ (1 ? α2) · ds / V ? (φB

y the second power of aberration magnitude; and hence it has much the same value as if everything were stationar

any effect on path; and effects so produced

α2si

irrotational motion, but not a first-order effect. A similar sta

on's Ex

y to and fro, or round a complete contour, to any important extent. But that taking second-order quantities into accoun

/ 1?α2 = √(1?α2sin2

y time of the double jo

drift would seem to be possible; since the time of a to-and-fro li

f the earth's motion; and is, in fact, a theory of it. There ought to be an effect due to the difference between θ = 0 and θ = 90°. But none ca

ive Expl

idea of a velocity-potential must be abandoned. This would complicate the theory of aberration

ies are a function of their motion through the ether. And such an effect it is reasonable to expect; since, if cohesion forces are electrical, they must

ion; its dimensions across and along the line of ether drift being affected differently. And the amount of the change will be such as prec

al bodies,-that renders any positive result in experiments on ether-drift so difficult or impossible to obtain; so that, in spite of the speed with which we are rus

the Theory of th

f Motion on

sm or

e course of each ray is deflected-refracted or diffracted-by an

uency nor wave-length, and accordingly is without influence on the

e. An observer therefore whom the source is approaching receives shorter waves, and one from whom the source is rec

n observer may change the frequency with which they are received, in an obvious way; they ar

d in Chapter III, but there are some minor and rather

ng Th

hing kinetic; it must be regulated by the merely geometric width of the ruled spac

show a true Doppler effect. But in the case of a moving observer, when all the waves received are of normal length, though swept

so there will be a spurious or apparent Doppler effect due to common aberration. That is to say a spectrum line will not be seen in its true place, but will appear to be shifted by an amount almost exactly imitative of a real Dopp

work out the diffraction observed by a grating advancing towards

ch require attention,-with the inclinatio

ray if all were

ed ray when grati

ived, allowing f

f all were stationary and the w

erration angle ε, such that s

owing relations hold; so that, g

=

= (1?α)

= (1?α

rved by an instrument depending primarily on frequency, like a prism; θ is the

m Th

to depend directly upon frequency-i.e. upon a time relation between the period of a light

annot depend upon wave-length, for the wave-length inside different substances is d

; for in both cases the frequency with which the waves are received will be altered,-either because they are r

matic

se dispersion is corrected and neutralised. Such achromatic prisms, if perfectly achromatic, will treat waves of all sizes alike; and, accordingly, the shortening of the waves from a moving source

ho applied an achromatic prism to a star which the earth was approaching, without observing any effect. A Doppler effect should have been obs

d, since it depends in simple geometrical fashion on retarded velocit

however, is (rashly spe

Transpar

h transparent matter, will not moti

ment with running water, most certainly it will; to the full effect of the load

the velocity of light, for the waves will be conveyed in the sense of the mat

eral planetary motion, i.e. being subject to the opposite all-pervading ether drift,-then no influence due to the drift can be experienced; for

of Ether Drif

nary B

s z, which would naturally be traversed with the velocity V/μ, is traversed with the velocity (V/μ) cos ε + (v/μ2)

α/μ cos θ), ins

r thickness, instead

? z = (μ cos ε ? α co

first order

)z ? α

ween ray and ether dr

e to the motion is approximately ±α

use of dense stationary substances; their extra ether, being stationary, does not affect th

fect of introducing tubes of water into the path of half-beams

by changes in direction, or in frequency, or in phase; for on none of them has i

y that the behaviour of ether inside matter

v co

space, so far as motion of ether a

he presence of dense matter (such as water-filled telescopes) or otherwise. Whatever may be the path of a ray by reason of reflexion or refraction in a s

it still, or to carry it with it. The general ether stream must remain unaffected, not only near, b

e said against aberration effects being producible or modifiable by motion of parts of the medium, or by the artificial motion of transparent bodies and other partitioned-off regions. Artificial motion

ce of the ether of space. Fresnel's law, in fact, definitely means that moving transparent matter does not appreciably disturb the ethe

e of the ether of space by

MM

efficient of 1012 grammes per c.c.; that matter is composed of modified and electrified specks, or minute structures of ether, which are amenable to mechanical as well as to electrical force and add to the optical or

END

AND ETHER

t force, but rather a certain condition or state of the medium, to variations in which, from place to place, the force is due. This Newtonian tension is a much gr

the radius be R and the gravitational intensity is g, the tension at the su

ows at on

′ / r2, the meaning here adopted for ethe

E / r2 dr

dinary intensi

R = γE / R2

net the tension is T0 = gR, or for dif

velocity of free fall from circumference to centre, assuming uniform dis

all this i

. The tension near the sun is 2500 times as great (p. 103). With different spheres in general, it is proportional to the density and to th

have seen is 1033 dynes per square centimetre (or ergs per c.c.) or 1022 tons weight per square millimetre,-it se

t in bodies falling towards it from a great distance; and it may be doubted

ave a radius of eight light years. In order to generate a velocity of free fall under gravity equal to the velocity of light, a globe of the earth's density would have to be equal in radius to t

, would be quite incompetent to raise etherial tension to the critical point 1033 c.g.s. unless it were concentrated to an a

a disruptive tension of the ether would be reached when the radius was comparable to 1013 light years; and the velocity of light

led an electric charge comes into existence; the tension being directly proportional to the square of the charge and inversely as its linear dimensions. Cohesion is quite

END

NS IN CONN

R DE

is likewise of an electromagnetic character, and again is not felt mechanically, because it cannot be moved by mechanical means. It is by far the most stat

Matter loads the ether optically, in accordance with the recognised fraction μ2?1 / μ2; and this loading, bei

eing really that of ether affected by the intrinsic or constitutional electricity of matter-is not so small. The relative optical virtu

charges can load the ether optically, quite appreciably; but as regards mechanical loading, the den

he Ether deduced

nci

as a certain mass associated with it; dependent on its

iquid, its behaviour is exactly as if its mass were increased by half

is half as great again as that of the volume of fluid corresponding to the electron: that is to say the effective mass is 2πρα3, where ρ is the uniform density. If

nal property of the ether, and if we attribute all the magnetic inertia to the magnetic whirl thus caused round its path,-

flying at moderate speed u, so that the ma

u sin

r unit volume eve

s as a circulation of fluid along the lines of magnetic induct

olume anywhere: it can be represe

π = μ / 8π · e

ref

/ 4πρ) · e

must be a maximum at the equator of the sph

√(μ / 4πρ

n

= a2 si

ation is limited to a region not far r

y of this

2 · 2π r sin

ve value of w, the energy co

with a mass mov

3)πρa3(

w0 = ? √3·u; that is to say, if the whirl in contact with the equator of t

u, then the mass of the effectively disturbed fluid is less even than the bulk of an electron; and in that case the estimate of the fluid-density ρ must be exaggerated in order to supply the required energy.

2 √(4

ce the sphe

at of a mass of ether equal to the electron in bulk. But the linear dimension of an electron is 10-13 centimetre diameter, and i

trons move sometimes at a speed not far below that of light, we cannot be accused of under-estimating the probable velocity of magnetic spin by treating it as

nces of this

where its energy amounts to 2 ergs per c.c., comes out only about 10-17 of the wave-lengt

accordance with Poynting's investigation, comes out 10-22 cm. per sec. These calculation

r other magnetic field, if it exist, is comparable to ·003 centim. p

e to the locomotion-velocity of the electron itself, and may therefore rise to something near the speed of light; say 1/30th of that speed: bu

of the speed of the supposed magnetic circulation along the axis-no

ron is 10-9 metre = 10-7 centimetr

s effect in accelerating or retarding the speed of light sent along the lines of magnetic force,-would need a solenoid of great length, r

or the energy of a magnetic field, must be comparable, in centimetres per second, to

END

AW A SPECIA

POTENTIA

f Fresnel's Law m

tia, due to the magnetic field surrounding each of them. And by reason of this property, and as a consequence of their discontinuity, they virtually increase the optical density of the ether of space, acting in analogy

without these discontinuous loads-it had a density μ2 times that which it has in space outside matter.

normal density 1 is absolutely stationary as regards locomotion, whether it be inside or outside a region occupied by ordinary matter, for it is not amenable to either mechanical or e

of a magnetic field; along the lines of which it has, in several theories

a stream of water, according as it travelled with or against the stream. And he found the magnitude of the effect precisely in accordance with the ratio of the locomotive portio

be adopted, the result to be anticipate

ocity of the body while the rest is stationary, it is permissible for some purposes to

and, as it were, evaporating behind; while, inside, it is streaming through the body in its condensed condition at a pace such that what is equivalent to the normal quantity of

forward with this velocity. Then consider two imaginary parallel planes moving with the slab, one in advance of it and the other inside it, and express the fact that the amount of ether between those two planes must continue constant. The amount streaming relatively backwa

equal (u

Fresnel's incontrovertible law for the convective e

more generally, and for every direction o

ether, which outside drifts at velocity v, making an angle θ wit

on to a ray insi

/μ) cos ε′ + v′

/ sin θ′ = v′

ay be

(1 ? α′2) ? ∫ v′ cos

ming that μ2v′ cos θ′ = dφ′/ds, and treating α′ as a quantity too smal

1 ? α′2) ? (φ′B ?

between two points A and B should be the same whether the space between is filled with dense matter or not (or, say, whether the ray-path is taken through or outside a portion of dense medium). In other words (calling φ the outside and φ′ the inside potential function), in order to secure that T′ shall no

atter is to say that to the

2 v′ cos θ′ ? v

nd or disturbing

valent to the assumption that a potential function, ∫ μ2 v cos θ ds , exists

nding rays round any kind of closed contour; nor can the path of a ray be altered by etherial drift through any st

ith velocity u in a direction φ, and subject to an i

v/μ2 cos θ + u[1 ? (

RENDON AN

RS, PL

r the Gene

IN TH

nte Arrhenius, of the Nobel Instit

distribution of life, the conservation of energy, etc., and shows how all ma

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cal Magazine for July, 1889. See als

187, and chap. xvi., of my

omson to a unit angle of circular measure, an

use "stagnant," as meaning stationary with respect

igh, Nature, M

ok, Newton seems to throw out a curious hint in this same direction,-though he immediately abandons it a

cessary concentration absurdly great, showing that

ical Magazine, April, 19

A of British Associat

hical Magazin

, Vol. IV, p. 443, or Nature, Vol

riber'

ng errors and inconsistent hyp

nd pages consisting entirely of

entheses were added to

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