Questions Show - Black Hole Surfaces, Magnetic Field Strengths, and the Speed of Gravitons

As you know, we wanted to answer listener questions regularly, but we found it was taking away from the regular weekly episodes of Astronomy Cast. So we've decided to just split it up and run the question shows separately from the regular Astronomy Cast episodes. If this works out, you might be able to enjoy twice the number of Astronomy Cast episodes. So if you've got a question on a topic we cover in a recent show, or you just have a general astronomy question, send it in to info@astronomycast.com. Either by email, or record your question and email in the audio file.

Questions Show - Black Hole Surfaces, Magnetic Field Strengths, and the Speed of Gravitons

Does a black hole have a definite surface?

• The Anatomy of a Black Hole – from University of Illinois
• Falling to the Singularity of the black hole – from University of Colorado
• Virtual Trips to Black Holes and Neutron Stars — from Goddard Space Flight Center
• Maximizing Survival Time Inside the Event Horizon of a Black Hole — from Universe Today
• Black Hole Eating Habits – from Eberly College of Science
• Accretion disk – from Internet Encyclopedia of Science

How does the size of a magnetic field come into play for astronomical object vs. bar magnets

• Earth's magnetic field – from Georgia State University
• Tesla – Wiki
• The Force Between Two Magnets as a Function of Distance — from Exploratorium
• "Magnetic Fields Go the the Maximum" — from Physicsworld
• Paper:  On the Magnetism of Stars and Planets

Could dark energy be the uncurving of space?

• Dark Energy –from Beyond Einstein
• Direct signal of dark energy? — from Physicsworld
• Paper:  Does Space Curve?
• Gravity Probe B site with info about gravity and an interactive bowling-ball-rubber-sheet discussion
• Discussion of the bowling-ball-rubber-sheet model — from BAUT Forum
• Image of ball on rubber sheet

Do gravitons travel at twice the speed of light?

• Gravitons – from Cornell University
• What is the speed of gravity? from Cornell University

Is the amount of gravity that comes from an object come from every molecule in the object?

• Everything you need to know about Earth's Geoid — from NOAA
• GRACE Mission – studying Earth's gravity field

Is there a balance between the pull of gravity and the repulsion of magnetism?

• Donut shaped magnet
• Does gravity pull or push?
• Force and its representation — from Physics Classroom
• Anti-gravity — Wiki
• Fundamental Forces

1. Empyre Says:
   September 20th, 2008 at 7:15 am

   In the above-linked Discussion of the bowling-ball-rubber-sheet model, the author concludes that Einstein was wrong and that Newtonian physics still prevails. I doubt that this is what you meant to tell us.

   He is taking the analogy too literally, as if the fabric of space-time was a physical medium being curved by gravity. There are other logical fallacies as well, but I haven't the space here to address them.

2. Hunt McConnel Says:
   September 21st, 2008 at 12:56 am

   After watch I think a Nova show and heard that dark energy is 73%, dark matter 23% and 4%the rest known matter…why am I the only one to notice that the Sun is 73% Hydrogen 23% helium 4% metals….happy oddity?

   Also would all orbit energy of all orbiting mass add up in some math way to the 220,000 m/s the sun orbits the milky way thus showing a way to know when all orbiting mass is known or % known….so it dont collide with earth…

3. Nancy Says:
   September 22nd, 2008 at 7:24 pm

   Empyre-
   That was obviously the wrong link! I've put in a better one and added a link to the Gravity Probe B site that has an interactive bowling-ball-rubber-sheet model.

   Thanks,
   Nancy

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