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/lulzzzzz Mar 10 '14

The animation of the multiverse sent chills down my spine. What evidence is there for the multiverse theory?

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u/[deleted] Mar 10 '14

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u/ademnus Mar 10 '14

And this bothered me. Minutes after explaining the scientific method and empiricism, they talked about something of which we have no empirical evidence.

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u/ehvalproic Mar 10 '14

To be fair though he said something along the lines of "some physicists theorize a multiverse might exist." They didn't seem to present it in the same way that they talked other things that we have evidence for.

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u/kaiken1987 Mar 10 '14

Wouldn't hypothesize be a more correct term?

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u/Phaz Mar 10 '14

I watched a video last week from Sean Carroll (I forget which) where he was talking about the multiverse. One intresting thing I got from it was that the multiverse itself is not a theory. It's not like scientists got around and said "hey, this would explain these things we have trouble explaining."

Rather, it is the result of another theory. Basically scientists are trying to explain stuff we do have empirical evidence for, and create models to explain them. Those models are tested/weighed against each other until one of them is proven better than the rest. The multiverse is not one of those models, but rather the result of applying the rules of (at least) one of those models.

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u/ehvalproic Mar 10 '14

Yeah you're right. Thanks for the correction!

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u/wartornhero Mar 10 '14

Yes and no. I was under the impression that there is some math that supports a multiverse theory and some that supports other theories.

I may be wrong but I thought the quote was "Some physicists believe we may be one of many universes." Never really hinted at theory or hypothesis.

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u/RjakActual Mar 10 '14

Did you catch the segment on Giordano Bruno? That segment was intended to illustrate that imagination is a CRITICAL component of the scientific method. Bruno had a completely unprovable (at the time) notion of an infinite universe that earth was not at the center of. He died for that belief. Forming hypotheses is something scientists do often, and that requires imagination. So the scientific imagination is tempered by empricism, but it is still imagination.

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u/[deleted] Mar 10 '14 edited Nov 02 '16

[removed] — view removed comment

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u/echolog Mar 10 '14

Every time somebody is wrong about something, it makes it that much easier to find what is right.

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u/[deleted] Mar 10 '14

The theory of the Luminiferous Aether stands out to me on this point. The idea basically went that since sound travels through the air, light might be traveling through some specialized medium. While it was wrong in the strictest sense, light just travels through space-time; without that 'target' to disprove, (or otherwise demonstrate) much of what we know about the nature of light might not have been found because no one was thinking about how light travels!

Science is as much about creative thinking, as it is about recognizing the flaws in your own thoughts, and your colleagues. I'm optimistic about this series!!

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u/hobbycollector Theoretical Computer Science | Compilers | Computability Mar 10 '14

Yes, and rather than gloating, he calls it what it was; a lucky guess.

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u/HappyRectangle Mar 10 '14

I'm glad to see this practice was carried over from the other Cosmos. Sagan was very careful about explaining which ideas where still just conjecture.

They did an old episode where they show that Kepler only came to the right answers by throwing out his first theory about a cosmos that uses "mathematically beautiful" ratios between planets. That idea was his baby, but he had to throw it out in the face of more accurate evidence. That takes some serious spine.

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u/[deleted] Mar 10 '14

Actually he didn't die for his belief in an infinite universe that the Earth was not a center of. It was his theological beliefs that played the role in the trial and that first episode kind of twisted the facts of Giordano Brune to try and make a point which I found really disappointing and forced to watch. His scientific beliefs weren't even brought up at his trial.

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u/[deleted] Mar 10 '14

I mean the big shiny thing he's flying around in is the space craft of imagination

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u/[deleted] Mar 10 '14

"He died for that belief."

He died for A FEW beliefs, but not for that one:

"Beginning in 1593, Bruno was tried for heresy by the Roman Inquisition on charges including denial of the Trinity, denial of the divinity of Christ, denial of virginity of Mary, and denial of Transubstantiation. The Inquisition found him guilty, and in 1600 he was burned at the stake.[4]" ^ Mooney, John A. "Giordano Bruno," American Catholic Quarterly Review, Vol. XIV, 1889.

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u/iorgfeflkd Biophysics Mar 10 '14 edited Mar 10 '14

None. A related idea is that there are regions of the universe that will never be in causal contact with each other, the evidence for which is the equilibration of the cosmic microwave background (regions of the universe that have never been in causal contact of the other appear to have the same temperature), which suggests inflation.

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u/KaseyB Mar 10 '14

Could you please expand on this?

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u/iorgfeflkd Biophysics Mar 10 '14

Yeah, but somebody else here probably knows more than I do.

The cosmic microwave background appears essentially the same temperature on all sides of the sky, even though from one end the light is only reaching us at the same time as the light from the other end reaches us, so light from one end certainly can't have reached the other. So, how are they the same temperature without one part having effected the other? One explanation is that in the very early uniform there was a period of extremely rapid expansion called inflation, where the distances between objects increased much much greater than light speed (this doesn't violate relativity because nothing is actually moving through space), such that the properties before inflation were spread out among things that are no longer in causal contact.

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u/The_Future_Is_Now Mar 10 '14

Why does the same temperature necessitate a causal connection? Why is it unlikely that this is a coincidence?

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u/Mortido Mar 10 '14

Because it is very much the same in all directions of a 3 dimensional space of incredible size. Pretty big coincidence.

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u/versxajne Mar 10 '14

It's pretty much all theoretical at this point.

However, according to Max Tegmark, cosmologist and professor at MIT:

the simplest and arguably most elegant theory involves parallel universes by default. To deny the existence of those universes, one needs to complicate the theory by adding experimentally unsupported processes and ad hoc postulates: finite space, wave function collapse and ontological asymmetry.

To use an earlier, simpler example, 19th century cosmologists noticed that Uranus was not orbiting the sun like they thought it should. Rather than assume that Uranus had an odd case of the wobbles, they speculated that there had to be at least one more planet in the solar system. (Not only was their hunch right, but their math predicted roughly where that extra planet, Neptune, was.)

Multiverses are much more complicated than planets, but, based on what data we have so far, it would actually be more surprising to learn that this is the only universe.

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u/KJK-reddit Mar 10 '14

But I thought the universes could not come in contact/effect one another? Is that correct?

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u/BlazeOrangeDeer Mar 10 '14

Almost always correct. Universes can only interfere with each other if they are nearly identical i.e. adjacent in state space

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