“Eddington number”的意思、由来-开放百科全书

In astrophysics, the Eddington number, N_Edd, is the number of protons in the observable universe. The term is named for British astrophysicist Arthur Eddington, who in 1938 was the first to propose a value of N_Edd and to explain why this number might be important for physical cosmology and the foundations of physics.

History

Eddington argued that the value of the fine-structure constant, α, could be obtained by pure deduction. He related α to the Eddington number, which was his estimate of the number of protons in the universe.^[1] This led him in 1929 to conjecture that α was exactly 1/137. Other physicists did not adopt this conjecture and did not accept his argument.

In the late 1930s, the best experimental value of the fine-structure constant, α, was approximately 1/136. Eddington then argued, from aesthetic and numerological considerations, that α should be exactly 1/136. He devised a "proof" that {{nowrap|1=N_Edd = 136 × 2²⁵⁶}}, or about {{val|1.57|e=79}}. Some estimates of N_Edd point to a value of about {{val|e=80}}.^[2] These estimates assume that all matter can be taken to be hydrogen and require assumed values for the number and size of galaxies and stars in the universe.^[3]

Attempts to find a mathematical basis for this dimensionless constant have continued up to the present time.

In the 1938 Tarner Lecture at Trinity College, Cambridge, Eddington averred that:

Shortly thereafter, improved measurements of α yielded values closer to 1/137, whereupon Eddington changed his "proof" to show that α had to be exactly 1/137.^[5]

Recent theory

Consequently, no one maintains any longer that α is the reciprocal of an integer. Nor does anyone take seriously a mathematical relationship between α and N_Edd.

On possible roles for N_Edd in contemporary cosmology, especially its connection with large number coincidences, see Barrow (2002) (easier) and Barrow and Tipler (1986: 224–31) (harder).

See also

References

1. ^{{Cite book |author=A. S. Eddington |year=1956 |chapter=The Constants of Nature |editor=J. R. Newman |title=The World of Mathematics |volume=2 |pages=1074–1093 |publisher=Simon & Schuster |isbn= |oclc= |lccn=}}
2. ^{{Cite web | url=http://mrob.com/pub/math/numbers-19.html | title=Notable Properties of Specific Numbers (page 19) at MROB}}
3. ^{{Cite journal |author=H. Kragh |year=2003 |title=Magic Number: A Partial History of the Fine-Structure Constant |journal=Archive for History of Exact Sciences |volume=57 |issue=5 |pages=395 |doi=10.1007/s00407-002-0065-7}}
4. ^Eddington (1939), lecture titled "The Philosophy of Physical Science".
5. ^Eddington (1946)
6. ^{{Cite journal |author1=Tatsumi Aoyama |author2=Masashi Hayakawa |author3=Toichiro Kinoshita |author4=Makiko Nio |year=2012 |title=Tenth-Order QED Contribution to the Electron g-2 and an Improved Value of the Fine Structure Constant |journal=Physical Review Letters |volume=109 |issue=11 |page=111807 |doi=10.1103/PhysRevLett.109.111807 |arxiv = 1205.5368 |bibcode = 2012PhRvL.109k1807A |pmid=23005618}}

Bibliography

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{{cite book | author=John D. Barrow & Frank J. Tipler | title=The Anthropic Cosmological Principle | year=1986 | location=London | publisher=Oxford University Press| title-link=Anthropic Principle }}

{{cite book | author=Dingle, H. | year=1954 | title=The Sources of Eddington's Philosophy | location=London | publisher=Cambridge University Press }}

{{cite book | author=Arthur Eddington | title=The Nature of the Physical World | year=1928 | location=London | publisher=Cambridge University Press }}

{{cite book | author=-------- | title=New Pathways in Science | year=1935 | location=London | publisher=Cambridge University Press }}

{{cite book | author=-------- | title=The Philosophy of Physical Science | year=1939 | location=London | publisher=Cambridge University Press }}

{{cite book | author=-------- | title=Fundamental Theory | year=1946 | location=London | publisher=Cambridge University Press }}

{{cite book | author=Kilmister, C.W. & Tupper, B.O.J. | year=1962 | title=Eddington's Statistical Theory | location=London | publisher=Oxford University Press }}

{{cite journal |author1=Mohr, P.J. |author2=Taylor, B.N. | title=CODATA recommended values of the fundamental phh | pages=1–107 | doi=10.1103/RevModPhys.77.1 | year=2005 | journal=Reviews of Modern Physics | volume=77 |issue=1 | bibcode=2005RvMP...77....1M|citeseerx=10.1.1.245.4554 }}

{{cite book | author=Slater, N.B. | year=1957 | title=Development and Meaning in Eddington's Fundamental Theory | location=London | publisher=Cambridge University Press }}

{{cite book | author=Whittaker, E.T. | year=1951 | title=Eddington's Principle in the Philosophy of Science | publisher=Cambridge University Press | location=London }}

{{cite book | author=-------- | year=1958 | title=From Euclid to Eddington | publisher=Dover | location=New York }}

3 : Numerology|Astrophysics|Physical cosmology