Does Light Fade, or Just Spread Out?
In short: Light from a distant source looks weaker mainly because the same light is spread over ever-larger spheres, not because each photon fades, while cosmological redshift is a separate effect of expanding space.
A 1:48 short film in the series “Journey of Light”, narrated by intellect_voice_01.
Sources used in this film: University of Southampton (Physics Skills Workshops), “Microsoft Word - Inverse Square Laws.doc - pdfMachine from Broadgun Software, http://pdfmachine.com, a great PDF writer utility!”; NASA (lesson developed for the WISE mission's education program at the Center for Science Education, Space Sciences Laboratory, University of California, Berkeley), “583137main_inverse_square_law_of_light.pdf”; NASA Goddard Space Flight Center, Imagine the Universe! (High Energy Astrophysics Science Archive Research Center, HEASARC), “Imagine the Universe!”; National Radio Astronomy Observatory (NRAO) – lecture notes by Steven T. Myers, ASTR001, “Lecture 23 - Stars (3/6/96)”; University of Rochester, Department of Physics and Astronomy (Astronomy 142 lecture notes), “02_lecture.pdf”; Fermi National Accelerator Laboratory (Fermilab), Office of Public Affairs; answer by Leila Belkora, Ph.D., Astrophysics, “Fermilab | Science | Inquiring Minds”; Physics Van, Department of Physics, The Grainger College of Engineering, University of Illinois Urbana-Champaign, “Does Light Lose Energy as it Travels?”; Encyclopaedia Britannica (archived via the Internet Archive Wayback Machine), “electromagnetic radiation | physics”; Encyclopaedia Britannica, “Light - Photons, Wavelengths, Quanta | Britannica”; University of Maryland, Department of Astronomy (ASTR120 course supplement), “suppl04.pdf”; Department of Computer Science, University of Massachusetts Amherst (course notes by Erik G. Learned-Miller), “lightAndMotion.dvi”; NASA Science, “Hubble Cosmological Redshift - NASA Science”; NASA Science (James Webb Space Telescope), “What Is Cosmological Redshift? - NASA Science”.
Sources used in this film
- University of Southampton (Physics Skills Workshops) — Microsoft Word - Inverse Square Laws.doc - pdfMachine from Broadgun Software, http://pdfmachine.com, a great PDF writer utility! · View →
- NASA (lesson developed for the WISE mission's education program at the Center for Science Education, Space Sciences Laboratory, University of California, Berkeley) — 583137main_inverse_square_law_of_light.pdf · View →
- NASA Goddard Space Flight Center, Imagine the Universe! (High Energy Astrophysics Science Archive Research Center, HEASARC) — Imagine the Universe! · View →
- National Radio Astronomy Observatory (NRAO) – lecture notes by Steven T. Myers, ASTR001 — Lecture 23 - Stars (3/6/96) · View →
- University of Rochester, Department of Physics and Astronomy (Astronomy 142 lecture notes) — 02_lecture.pdf · View →
- Fermi National Accelerator Laboratory (Fermilab), Office of Public Affairs; answer by Leila Belkora, Ph.D., Astrophysics — Fermilab | Science | Inquiring Minds · View →
- Physics Van, Department of Physics, The Grainger College of Engineering, University of Illinois Urbana-Champaign — Does Light Lose Energy as it Travels? · View →
- Encyclopaedia Britannica (archived via the Internet Archive Wayback Machine) — electromagnetic radiation | physics · View →
- Encyclopaedia Britannica — Light - Photons, Wavelengths, Quanta | Britannica · View →
- University of Maryland, Department of Astronomy (ASTR120 course supplement) — suppl04.pdf · View →
- Department of Computer Science, University of Massachusetts Amherst (course notes by Erik G. Learned-Miller) — lightAndMotion.dvi · View →
- NASA Science — Hubble Cosmological Redshift - NASA Science · View →
- NASA Science (James Webb Space Telescope) — What Is Cosmological Redshift? - NASA Science · View →
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Sources
- Summary by Intellect · source: University of Southampton (Physics Skills Workshops): Microsoft Word - Inverse Square Laws.doc - pdfMachine from Broadgun Software, http://pdfmachine.com, a great PDF writer utility!
- Also: NASA (lesson developed for the WISE mission's education program at the Center for Science Education, Space Sciences Labo: 583137main_inverse_square_law_of_light.pdf
- Also: NASA Goddard Space Flight Center, Imagine the Universe! (High Energy Astrophysics Science Archive Research Center, HEASA: Imagine the Universe!
- Also: National Radio Astronomy Observatory (NRAO) – lecture notes by Steven T. Myers, ASTR001: Lecture 23 - Stars (3/6/96)
- Also: University of Rochester, Department of Physics and Astronomy (Astronomy 142 lecture notes): 02_lecture.pdf
- Also: Fermi National Accelerator Laboratory (Fermilab), Office of Public Affairs; answer by Leila Belkora, Ph.D., Astrophysics: Fermilab | Science | Inquiring Minds
- Also: Physics Van, Department of Physics, The Grainger College of Engineering, University of Illinois Urbana-Champaign: Does Light Lose Energy as it Travels?
- Also: Encyclopaedia Britannica (archived via the Internet Archive Wayback Machine): electromagnetic radiation | physics
- Also: Encyclopaedia Britannica: Light - Photons, Wavelengths, Quanta | Britannica
- Also: University of Maryland, Department of Astronomy (ASTR120 course supplement): suppl04.pdf
- Also: Department of Computer Science, University of Massachusetts Amherst (course notes by Erik G. Learned-Miller): lightAndMotion.dvi
- Also: NASA Science: Hubble Cosmological Redshift - NASA Science
- Also: NASA Science (James Webb Space Telescope): What Is Cosmological Redshift? - NASA Science
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