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Who said: “Truth is ever to be found in simplicity, and not in the multiplicity and confusion of things.”
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Home > Category Index for Science Quotations > Category Index R > Category: Radius

Radius Quotes (4 quotes)

I am afraid all we can do is to accept the paradox and try to accommodate ourselves to it, as we have done to so many paradoxes lately in modern physical theories. We shall have to get accustomed to the idea that the change of the quantity R, commonly called the 'radius of the universe', and the evolutionary changes of stars and stellar systems are two different processes, going on side by side without any apparent connection between them. After all the 'universe' is an hypothesis, like the atom, and must be allowed the freedom to have properties and to do things which would be contradictory and impossible for a finite material structure.
Kosmos (1932), 133.
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In the discussion of the. energies involved in the deformation of nuclei, the concept of surface tension of nuclear matter has been used and its value had been estimated from simple considerations regarding nuclear forces. It must be remembered, however, that the surface tension of a charged droplet is diminished by its charge, and a rough estimate shows that the surface tension of nuclei, decreasing with increasing nuclear charge, may become zero for atomic numbers of the order of 100. It seems therefore possible that the uranium nucleus has only small stability of form, and may, after neutron capture, divide itself into two nuclei of roughly equal size (the precise ratio of sizes depending on liner structural features and perhaps partly on chance). These two nuclei will repel each other and should gain a total kinetic energy of c. 200 Mev., as calculated from nuclear radius and charge. This amount of energy may actually be expected to be available from the difference in packing fraction between uranium and the elements in the middle of the periodic system. The whole 'fission' process can thus be described in an essentially classical way, without having to consider quantum-mechanical 'tunnel effects', which would actually be extremely small, on account of the large masses involved.
[Co-author with Otto Robert Frisch]
Lise Meitner and O. R. Frisch, 'Disintegration of Uranium by Neutrons: a New Type of Nuclear Reaction', Nature (1939), 143, 239.
Science quotes on:  |  Atomic Number (3)  |  Charge (29)  |  Deformation (3)  |  Estimate (19)  |  Fission (7)  |  Kinetic Energy (2)  |  Nucleus (30)  |  Quantum Theory (55)  |  Repulsion (4)  |  Surface Tension (2)  |  Uranium (16)

Neutrinos ... win the minimalist contest: zero charge, zero radius, and very possibly zero mass.
In Leon Lederman and Dick Teresi, The God Particle: If the Universe is the Answer, What is the Question (1993, 2006), xiii.
Science quotes on:  |  Charge (29)  |  Contest (5)  |  Mass (61)  |  Neutrino (8)  |  Zero (15)

The unprecedented identification of the spectrum of an apparently stellar object in terms of a large red-shift suggests either of the two following explanations.
The stellar object is a star with a large gravitational red-shift. Its radius would then be of the order of 10km. Preliminary considerations show that it would be extremely difficult, if not impossible, to account for the occurrence of permitted lines and a forbidden line with the same red-shift, and with widths of only 1 or 2 per cent of the wavelength.
The stellar object is the nuclear region of a galaxy with a cosmological red-shift of 0.158, corresponding to an apparent velocity of 47,400 km/sec. The distance would be around 500 megaparsecs, and the diameter of the nuclear region would have to be less than 1 kiloparsec. This nuclear region would be about 100 times brighter optically than the luminous galaxies which have been identified with radio sources thus far. If the optical jet and component A of the radio source are associated with the galaxy, they would be at a distance of 50 kiloparsecs implying a time-scale in excess of 105 years. The total energy radiated in the optical range at constant luminosity would be of the order of 1059 ergs.
Only the detection of irrefutable proper motion or parallax would definitively establish 3C 273 as an object within our Galaxy. At the present time, however, the explanation in terms of an extragalactic origin seems more direct and less objectionable.
'3C 273: A Star-like Object with Large Red-Shift', Nature (1963), 197, 1040.
Science quotes on:  |  Account (45)  |  Difficulty (113)  |  Energy (185)  |  Forbidden (8)  |  Galaxy (38)  |  Identification (11)  |  Impossibility (50)  |  Line (44)  |  Luminosity (4)  |  Occurrence (30)  |  Red-Shift (4)  |  Spectrum (23)  |  Star (251)  |  Unprecedented (7)  |  Velocity (14)  |  Wavelength (5)


Carl Sagan Thumbnail In science it often happens that scientists say, 'You know that's a really good argument; my position is mistaken,' and then they would actually change their minds and you never hear that old view from them again. They really do it. It doesn't happen as often as it should, because scientists are human and change is sometimes painful. But it happens every day. I cannot recall the last time something like that happened in politics or religion. (1987) -- Carl Sagan
Quotations by: Albert Einstein Isaac Newton Lord Kelvin Charles Darwin Srinivasa Ramanujan Carl Sagan Florence Nightingale Thomas Edison Aristotle Marie Curie Benjamin Franklin Winston Churchill Galileo Galilei Sigmund Freud Robert Bunsen Louis Pasteur Theodore Roosevelt Abraham Lincoln Ronald Reagan Leonardo DaVinci Michio Kaku Karl Popper Johann Goethe Robert Oppenheimer Charles Kettering  ... (more people)

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