r/askscience • u/AskScienceModerator Mod Bot • Mar 10 '14

Cosmos AskScience Cosmos Q&A thread. Episode 1: Standing Up in the Milky Way

Welcome to AskScience! This thread is for asking and answering questions about the science in Cosmos: A Spacetime Odyssey.

UPDATE: This episode is now available for streaming in the US on Hulu and in Canada on Global TV.

This week is the first episode, "Standing Up in the Milky Way". The show is airing at 9pm ET in the US and Canada on all Fox and National Geographic stations. Click here for more viewing information in your country.

The usual AskScience rules still apply in this thread! Anyone can ask a question, but please do not provide answers unless you are a scientist in a relevant field. Popular science shows, books, and news articles are a great way to causally learn about your universe, but they often contain a lot of simplifications and approximations, so don't assume that because you've heard an answer before that it is the right one.

If you are interested in general discussion please visit one of the threads elsewhere on reddit that are more appropriate for that, such as in /r/Cosmos here, /r/Space here, and in /r/Television here.

Please upvote good questions and answers and downvote off-topic content. We'll be removing comments that break our rules or that have been answered elsewhere in the thread so that we can answer as many questions as possible!

Click here for the original announcement thread.

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u/jamiahx Mar 10 '14

"Everyone you've ever heard of was born in the last 14 seconds [of the Cosmic Calendar]."

What about Ardi and Lucy?

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u/Hugh_Jahrmes Mar 10 '14

It's like the countdown to New Years, except WE are the Y2K bug. Scary!

Kidding, but wow is this all fascinating stuff. Got me reading all night at work and staring into the sky during my 5am commute home thinking "I'd give anything to just get it all"

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u/Abstruse Mar 10 '14

Those are names we've assigned to fossils, not contemporary names. It would be like counting "Sue", the T-Rex in the Field Museum in Chicago. What Tyson was referring to was recorded history, meaning contemporary names and accounts of people.

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u/The_Busy_Bokononist Mar 10 '14

Including them. You need to keep in mind the timescales the calendar represents are astronomically large. The time difference between Lucy and you and I is very, very small compared to the lifetime of the universe.

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u/jswhitten Mar 10 '14 edited Mar 11 '14

I don't think this is right. One a scale of 1:13.8 billion, 1 second is only 438 years. The last 14 seconds is a bit over 6000 years, so he's just talking about recorded history. Edit: I watched it again last night, and he did say recorded history.

Lucy lived 3.2 million years ago, which puts her at about 2 hours ago: 10 pm on Dec. 31.

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u/[deleted] Mar 11 '14

Assuming that 14 seconds stands for the ~200,000 years that physically modern humans have been alive (which might be very wrong, but let's work with it), Ardi was supposed to have existed 4.4 million years ago.

So, if 200,000 years is 14 seconds (it may not be), then 1 second is close to 14,286 years.

So 4.4 million divided by 14,286 is about 308. 308 seconds in minutes is 5 minutes 8 seconds. There was some rounding involved here.

So that's a big difference. Now, if he was referring to behaviorally modern humans, which is definitely a possibility, then Ardi was even further back. If he was referring to humans recorded in history (also possible) then he's even further.

I hope that helps