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Thread: Episode 44: Einstein's Theory of General Relativity

  1. #1
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    Post Episode 44: Einstein's Theory of General Relativity

    If you remember way back to Episode 9, we covered Einstein's Theory of Special Relativity. Well, that's only half of the relativity picture. The great scientist made an even more profound impact on physics with his theory of general relativity, replacing Newton with a better model for gravity.

    <strong><a href="http://media.libsyn.com/media/astronomycast/AstroCast-070709.mp3">Episode 44: Einstein's Theory of General Relativity (15.3MB)</a></strong><br />&nbsp;<br />

    Read the full blog entry

  2. #2
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    It is nice that Astrocast has picked up a sponsor like the Discovery Channel.

    I have been trying to figure out how and where to start my five sigma grandson to universal concepts...listening to, and discussing astrocasts just might work!

    The cast sounds better than ever, buy the way, is it my new speakers, or is there a wider bandwidth?
    “It is a capital mistake to theorize before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts.” ― Arthur Conan Doyle, Sherlock Holmes

  3. #3
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    I can't play this weeks episode either. Both this weeks and last weeks episode cut out after a short while. Whats changed? Bit rate? Server? Please can you post future episodes in the old format.

  4. #4
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    I don't think we've changed anything.

  5. #5
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    Thank you for putting out a podcast that makes perfect sense to us under-laymen.

    This is a show my 13 year old son will be able to understand perfectly. (He's already gotten college credits in science and math)


    Simple language can make very smart people.

  6. #6
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    Great show as usual, and easily my favorite podcast with The Skeptics Guide to the Universe coming a close second.

    It would have been nice if when you was explaining gravity waves you could have mentioned the BOINC einstein@home project. This is a practical way that people can become involved in astronomy and the search for gravity waves by donating spare computer cycles.

  7. #7
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    Quote Originally Posted by Stygiangloom View Post
    Great show as usual, and easily my favorite podcast with The Skeptics Guide to the Universe coming a close second.

    It would have been nice if when you was explaining gravity waves you could have mentioned the BOINC einstein@home project. This is a practical way that people can become involved in astronomy and the search for gravity waves by donating spare computer cycles.
    Been on it for almost a year. And Seti@home.

  8. #8
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    As I mentioned in the show, gravity waves are going to be a whole other show.

  9. #9
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    The show notes for this episode don't appear to be working.

  10. #10
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    In this episode there is a mention of the corrections that the GPS satellites have to make to their time because of gravitational interaction.

    I was just curious what order of magnitude are these correction were? How much of the correction is due to GR effects, vs plain old SR effects (accelerating around in a circle is going to cause local time to be percieved slower as well). The SR time correction part of that correction I can try to calculate myself (I'm guessing I can lookup the orbital height of a GPS satellite somewhere), but I need a few years of study before I could tackle the GR half of the question.

  11. #11
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    According to GPS and Relativity, the effects of SR and GR combined lead to the clock on the GPS satellite gaining 38 microseconds a day.

    SR describes how the relative motion of satellite means its clock runs slow by 7 microseconds a day when compared to a clock on Earth. GR describes how the difference in gravity means the satellites clock runs faster by 45 microseconds a day.

    From the article:

    If these effects were not properly taken into account, a navigational fix based on the GPS constellation would be false after only 2 minutes, and errors in global positions would continue to accumulate at a rate of about 10 kilometers each day!

  12. #12
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    great little article. Thanks!

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