Middlebury register. (Middlebury, Vt.) 1886-1937, 1908-09-18
NEWEST THEORY OF
LIGHT.
WHICH MAKES 1T A STREAM
OF MINUTE BODIES.
Old Ideas Upset by the Arrhenius
Theory of Light Pressure-Com =
cts, the ZodiacaI Light and Other
PerpIexins Problems Explained
by Swedish Professor.

PerpIexing Problems Explained
by Swedish Professor.
Cambridge, Mass, Aug. 29.-The the
DRY of light PRESSURE the subject of dis
cussion for some time past among astron
omers, physicists and chemists, has be-
gun to impinge itself upon popular con-
seriousness. n
But light, so well behaved, so definite
and so positive in the laboratory, has
been creating scandals among the makers
of textbooks. New sections have had to
be added to explain the ultra violet mi
croscope, and now the books apparently
must be revised to include a theory
which makes of the pressure of light
force co-equal in importance with CRAWL
tation.
Just whether Arrhenius, Lebedeff,
Hull and Nichols, whose names are asso-
ciated with the recent discoveries of the
cosmical significance of light pressure,
have hit upon something as fundamental
in the history of science as Newton's
discovery of the law of gravitation it
would be out of place to attempt to argue
now. Enough that their theories have
proved to be immensely suggestive; that
conservative astronomers like Prof Ed
ward G. Pickering at Harvard, whose
work has lain in other than electro
chemical directions, are expressing them
selves as intensely interested in the gen.
civilizations from the light pressure doc
trine, and that to most people the con-
ception of light as a propulsive agent is
still new and even startling.
That beam of light theoretically
ought to exert pressure upon whatever
| object it falls was evident in the DAYS
when the Newtonian theory of emission
of luminous corpuscles was held by
scientists. If a candle flame or a sun in
burning threw off minute particles of
material light, clearly the impact of these
travelling at 1915, 900 miles second should
be considerable.
| The Russian, Lebedeff, first proved
experimentally that light exerts pressure.
Prof. Nichols and Hull, working at Dart
mouth College. confirmed his expert
ments and improved his methods.
Meantime Svante Arrhenius of the
University of Stockholm began drawing
up statements of changes of cosmic
theory that must take place now that a
new factor in the framework has been
demonstrated. A few of the conse-
quences of the acceptance OF the light
pressure theory as seen by this Swedish
scientist may be set forth.
The sunlight perpetually beating upon
this planet exerts. according to the
measurements of Arrhenius, a pres
sure of abouts $4,000 tons. That is
merely negligible force as compared with
the pull of gravitation, many times as
great.
Out in the solar system, however,
where there exists no one knows how
tenuous condition of the material fill
ing in. the propulsive force exerted by
the light upon any little particle of mat
ter that is flying about may be quite as
potent as the power of gravitation that
tends to draw all things together. Light
pressure, in other words, appears to be
a foil to the universal get together ten
dency.
Just why this force is relatively more
important when acting upon minute
than upon large masses will be evident
| nn "a pnnpnapf's consideration
ton acts upon masses as a whole. Light
pressure is exerted only on surfaces.
And now comes the Arrhenius theory
to interpret in terms of the light pres
sure discovery a list of perplexing prob
lens, such as the aurora borealis, the
zodiacal light. the turning of the comets
tail away from the sun, the drainage of
the silicious matter composing Saturn's
rings and the glow of distant nebuae.
Discussion of light pressure is mex.
tricably bound up, of course, with the
doctrine of the suns bombardment of
space with corpuscles negatively charg-
ed. According to the theory these off
shoots from every luminous body in the
universe collide in the intersolar spaces
and there form the matter that, hurried
now hither now hence. under impact of
the forces of gravitation and light pres
sure may make up the lonely wandering
meteors or the myriad swarms that con-
stitute the comets.
There exists, in other words, in Arr
henius's thought complete circulation
of matter in the universe. The meteoric
dust falling today through our atmos-
phere is compound projected not from
our sun alone but from many other suns
many light years ago. A portion at least
of the soil beneath our feet has come