Astronomy Cast - Ep. 117: Time

Ep. 117: Time

Ancient Chinese sundial and observatory.

Today, time rules our lives. We live each day with the moments broken up into hours, minutes and seconds. We never seem to have enough time. But can you imagine not being able to tell time at all, where the movements of the Sun and the stars was the only way to know what time it was? Let's learn about the history of time, methods of telling time, and Einstein's historic discovery that time isn't as fixed as we thought it was.

Ep. 117: Time
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Questions Show – light speed, Andromeda galaxy, dark matter and black holes

Another week, another roundup of your questions. This week listeners asked: will reaching light speed destroy the Universe? When is Andromeda going to look really, really cool with the unaided eye? Why didn't dark matter all turn into black holes? 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.

Show – light speed, Andromeda galaxy, dark matter and black holes (17.07MB)
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Ep. 72: Cosmic Rays

We're going to return back to a long series of episodes we like to call: Radiation that Will Turn You Into a Superhero. This time we're going to look at cosmic rays, which everyone knows made the Fantastic Four. These high-energy particles are streaming from the Sun and even intergalactic space, and do a wonderful job of destroying our DNA, giving us radiation sickness, and maybe (hopefully!) turning us into superheroes.

Episode 72: Cosmic Rays (13.3MB)
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Ep. 58: Inflation

$A fraction of a second after the big bang, the universe underwent inflation - but what does that mean?$
We interrupt this tour through the solar system to bring you a special show to deal with one of our most complicated subjects: the big bang. Specifically, how it's possible that the universe could have expanded faster than the speed of light. The theory is called the inflationary theory, and the evidence is mounting to support it. Einstein said that nothing can move faster than the speed of light, and yet astronomers think the universe expanded from a microscopic spec to become larger than the solar system, in a fraction of a second.

Episode 58: Inflation (17.0MB)

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Ep. 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.

Episode 44: Einstein's Theory of General Relativity (15.3MB)

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Ep. 9: Einstein's Theory of Special Relativity

It's all relative. How many times have you heard that? Well, when you're traveling close to the speed of light, everything really is relative; especially the passage of time. This week, Fraser and Pamela give you the skinny on Einstein's Special Theory of Relativity. After listening to a few thought experiments, you too should be able to wrap your head around this amazing theory.

Download Episode 9: Einstein's Theory of Special Relativity (14.6 MB)
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Ep. 117: Time

Questions Show – light speed, Andromeda galaxy, dark matter and black holes

Ep. 72: Cosmic Rays

Ep. 58: Inflation

Ep. 44: Einstein's Theory of General Relativity

Ep. 9: Einstein's Theory of Special Relativity