Astronomy and Cosmology

3685 topics in this forum

1. Is the sun hollow?

   By calprime21, March 23, 2012
   • 11 replies
   • 8.6k views
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   • Ophiolite
   • October 1, 2012

2. Holding pen for overly argumentative posts

   By Martin, December 9, 2010
   • 9 replies
   • 8.6k views
   • 
   • hypervalent_iodine
   • December 14, 2015

3. Quantum Entanglement Solar Flare Detection and Transmission 1 2 3 4

   By Addictive Science, December 28, 2013
   • 89 replies
   • 8.5k views
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   • Schneibster
   • February 22, 2014

4. Why is a fine-tuned universe a problem? 1 2 3 4

   By 34student, February 11, 2022
   • 83 replies
   • 8.5k views
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   • Mordred
   • December 27, 2022

5. Black Hole: Why do we believe that matter could be such dense? 1 2 3 4

   By MaximT, April 13, 2019
   • 93 replies
   • 8.3k views
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   • Strange
   • April 23, 2019

6. Is a time machine possible? 1 2 3

   By Chap, January 22, 2012
   • 52 replies
   • 8.3k views
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   • zapatos
   • March 1, 2012

7. outside the universe 1 2 3

   By joshuam168, August 20, 2008
   • 73 replies
   • 8.3k views
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   • throng
   • September 16, 2008

8. Big Bang 1 2 3

   By David Levy, June 24, 2012
   • 53 replies
   • 8.3k views
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   • ACG52
   • July 13, 2012

9. Rate and Location of Expansion 1 2 3 4

   By JustinW, January 2, 2012
   • 82 replies
   • 8.2k views
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   • michel123456
   • January 21, 2012

10. What would happen if the universe stopped expanding?

    By astro geek, January 17, 2010
    • 8 replies
    • 8.2k views
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    • Airbrush
    • January 26, 2010

11. Spaceship Drive?

    By minimoman, September 24, 2011
    • 10 replies
    • 8.2k views
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    • Schrödinger's hat
    • September 28, 2011

12. Would crossing the event horizon of a black hole be instantly fatal? 1 2

    By Hypercube, April 10, 2012
    • 43 replies
    • 8.2k views
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    • MigL
    • May 9, 2012

13. Stephen Hawking retracted his paradoxical view 1 2

    By G Anthony, September 8, 2011
    • 38 replies
    • 8.1k views
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    • JohnStu
    • February 29, 2012

14. Why is the Earth electrically neutral?

    By Bluemoon, November 20, 2014
    • 11 replies
    • 8.1k views
    • 
    • John Cuthber
    • August 12, 2019

15. Universe Expansion 1 2 3 4

    By David Levy, January 1, 2016
    • 84 replies
    • 8.1k views
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    • swansont
    • February 13, 2016

16. Expanding space needs surroundings to expand into. T or F. 1 2 3

    By Martin, January 19, 2008
    • 64 replies
    • 8k views
    • 
    • Martin
    • October 5, 2008

17. More Stars than Atoms on Earth?

    By mustang292, April 15, 2005
    • 15 replies
    • 8k views
    • 
    • mustang292
    • April 21, 2005

18. Basic Concepts of modern science 1 2 3

    By David Levy, March 11, 2015
    • 60 replies
    • 8k views
    • 
    • pantheory
    • March 19, 2015

19. Is the universe at least 136 billion years old, is the universe not expanding at all, did the universe begin its expansion when Hubble measured its redshift for the first time or was light twice as fast 13.5 billion years ago than it is today? 1 2 3 4 8

    By tmdarkmatter, August 7, 2023
    • 187 replies
    • 8k views
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    • swansont
    • November 27, 2023

20. What am I observing? 1 2 3 4

    By JohnLesser, March 20, 2017
    • 88 replies
    • 7.9k views
    • 
    • JohnLesser
    • March 26, 2017

21. determining semiminor axis in elliptic orbit

    By h4tt3n, March 2, 2006
    • 17 replies
    • 7.9k views
    • 
    • Smashinbedrock
    • October 28, 2015

22. Why Mars has no Plate Tectonics ?

    By Widdekind, May 14, 2009
    • 22 replies
    • 7.9k views
    • 
    • Widdekind
    • May 20, 2013

23. Methane implies Biology ?? 1 2

    By Widdekind, May 31, 2009
    • 42 replies
    • 7.9k views
    • 
    • John Cuthber
    • July 13, 2009

24. S2 orbit deviates from Keplerian ellipse 1 2 3 4

    By David Levy, April 1, 2017
    • 79 replies
    • 7.9k views
    • 
    • Janus
    • May 10, 2017

25. Why is there something rather than nothing? 1 2 3

    By Vexen, March 16, 2019
    • 50 replies
    • 7.8k views
    • 
    • MigL
    • February 20, 2021