Questions Show: Galactic Dust, the Speed of Photons, and the Big Bang Calculations

Another week, another roundup of your questions. This week listeners asked: what is galactic dust anyway, and where does it come from? Why can photons move at the speed of light? And how can astronomers know what happened right after the Big Bang? And there's even more. If you've got a question for the Astronomy Cast team, please email it in to info@astronomycast.com and we'll try to tackle it for a future show. Please include your location and a way to pronounce your name.

Galactic Dust, the Speed of Photons, and the Big Bang Calculations

What is galactic dust and where does it come from?

• Dust in Galaxies – Bill Keel/U of Alabama
• The Interstellar Medium
• Nitrous Oxide – Just Say N2O
• Chlorofluorocarbons — NOAA
• Acetylene — Wiki

Why can photons move at the speed of light?

• Do photons move slower in a solid medium? – Physics Forum discussion
• Is the speed of light constant? – Astronomical Society of South Africa

How can astronomers know what happened right after the Big Bang?

• The Big Bang – CERN
• Common Misconceptions About the Big Bang – The Angry Astronomer
• WMAP – NASA

Is there an upper limit to the size of black holes?

• Pamela's Star Stryder post on the size of black holes
• Black Holes Can Only Get So Big – Universe Today
• Paper:  Is There an Upper Limit to Black Hole Masses? — arXiv
• How big can black holes get? — Virginia Tech

What is vacuum?

• Paper:  What is Vacuum? – arXiv
• Vacuum – Wiki
• Vacuum Energy — UCLA

Is dark matter antimatter, and is there dark antimatter?

• Dark matter – Goddard Space Flight Center
• Primer on Dark Matter -- UTK
• Antimatter – CERN
• Astronomy Cast Episode 106:  The Search for the Theory of Everything
• Lightest Super symmetric particle – Wiki
• Intro to Super Symmetry – Berkeley

How are gravitational waves detected?

• Episode 83:  Wave Particle Duality
• History of gravitational wave detection

Isn't it impossible for black holes to merge?

• What Happens When Black Holes Collide? – Universe Today
• What Happens When Three Black Holes Collide? — Universe Today
• Watching something go into a black hole -- Berkeley

Does time dilation come from speed or distance?

• Time dilation and length contraction in Special Relativity – U of New South Wales
• Relativity tutorial

Are there areas of astronomy in which persons with limited sight could participate?

• Retinitis Pigmentosa
• Contact by Carl Sagan
• Fourier Analysis
• Astronomy for the Blind and Visually Impaired — Astronomy Education Review
• Hands On Astronomy book:  Touch the Universe -- HubbleSite

Will the sun release a huge solar flare and kill us all?

• Coronal Mass Ejections – Marshall Space Flight Center
• Solar Maximum – Wiki
• 2012:  No Killer Solar Flare – Universe Today
• Phil Plait's book:  Death From the Skies

1. Jerry Says:
   October 20th, 2008 at 10:55 am

   Show notes?

2. Eugene Says:
   October 20th, 2008 at 10:16 pm

   looking forward for more information about this. thanks for sharing. Eugene

3. Jerry Says:
   October 21st, 2008 at 6:19 am

   ah… there they are!

4. Huntley Woods Says:
   October 23rd, 2008 at 1:16 am

   I'm sure you're probably aware by now, but when you try to donwload this episode from itunes, it gives you the nebula episode instead!!

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