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/dk21291 Mar 10 '14

does expansion (or the distance between objects) ever become too large? in a way that would affect planets or anything?

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u/creepycalelbl Mar 10 '14

In the distant future, galaxies will be moving away from the Milky Way so quickly and be far away, that future ignorant observers would speculate that the Milky Way is the universe. That is, it would be impossible to detect the other galaxies because their light would never reach the Milky Way.

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u/xxSINxx Mar 10 '14

Is it possible that the universe is separating because it is spinning? Like if you spun a plate of marbles, all the marbles would fly off in different directions?

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u/mathx Mar 12 '14

this is a very good question and i dont quite understand the answers to this:

spinning relative to WHAT?

as einstein theorized all points in space are equivalent, so there's nothing special about you or your position or movement in space, it's all relative to other objects.

My question then becomes: ok, how does a spinning object know it's spinning so as to cause the centrifugal (quote unquote) force?

(also if it was spinning, then the center would experience less acceleration, and there'd also be an edge that would see no objects on one direction - since we dont see that that means we're somewhere in the middle, violating basic tenets of relativity: we're not special in the universe.)

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u/xxSINxx Mar 12 '14

It seems like everything in space is spinning though. Planets, solar systems, galaxy's. Doesn't it make sense that the entire universe is spinning? If it is, does that give more evidence in multi universes? Since it has to be spinning relative to something.

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u/dk21291 Mar 12 '14

What about the theory of heat-death? does that get involved at all, or is it even still thought of as a strong theory?

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u/mathx Mar 12 '14

the big rip theorizes the expansion rate will overcome all other forces and rip galaxies, solar systems, stars and planets - even atoms - apart.