Mapping The Universe

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A new map of our complex universe is out. We’ll look at our “chunky” cosmos.

We look up at the night sky and marvel at its depth and beauty. Its constellations and its stupendous scale.

And then on a curious night we wonder, what is all that? What shape, what age, what stuff? And where are we in it?

It turns out this is a very good moment to ask. Last month, the European Space Agency’s Planck satellite mission unveiled the results of scan after scan of radio and microwaves pouring out of the universe. Cosmic baby pictures from the dawn of time.

We know more than we have ever known. We know a lot. Up next On Point: Knowing the universe.
--Tom Ashbrook


Charles Lawrence, lead U.S. scientist for Planck mission at NASA’s Jet Propulsion Laboratory and co-chair of the Planck editorial board

Sean Carroll, theoretical physicist at the California Institute of Technology, writer for Discover's Cosmic Variance blog, and author of "The Particle at the End of the Universe: How the Higgs Boson Leads Us to the Edge of the World" (@seanmcarroll)

Collected Show Highlights

You can listen to all the clips here, or see them individually further below:

Individual Show Highlights

Carroll and Lawrence mused about big question of whether the universe is finite or infinite. Carroll admitted that's not so easy to determine:

Well, I think both this question "Is the universe finite or infinite?" and this question "Why did the universe come into existence in the first place?" have the same answer — namely, we don't know! And that's okay to admit that we don't know. We don't see any edge or any finitude to the universe, but because we only see part of it, it might be finite or it might not be. It might have come into existence for a reason or it might be random. This is not something we're allowed to impose on the universe. We have to look at it and keep an open mind and wait until we figure out what those answers are.

And Lawrence agreed, adding that it really doesn't matter if the universe is finite or infinite:

I don't distinguish between those. It's so big compared to the Earth. It's so big compared to the solar system. It's so big compared to the Milky Way. And so big compared to the part that we can observe — that light has had time to get to us from — that for practical purposes it might as well be infinite. But there is a difference, I agree, and Sean [Carroll] has fun thinking about that difference in his professional life.

What is dark matter anyway? How different is it from normal matter? Lawrence explained:

We have normal matter — the kind of stuff that we're made out of: electrons, protons. And then we have something called dark matter. We call it dark matter because it doesn't interact with light. It doesn't emit light; it doesn't absorb light. In fact, if we had a blob of it in front of us, we couldn't see that it was there at all. Light would just be going through it, wouldn't make any difference. But it has gravity. And so here we have two kinds of matter. One that has gravity and is affected by light (normal matter) and we got another kind (dark matter) that has gravity and isn't affected by light.

Carroll said dark matter is all around us, even in us:

Most of our theories right now say that dark matter is not only in your front yard but in your body right now. There are dark matter particles passing through, but because they're dark — which is a fancy physicist way of saying they don't interact very noticeably with the particles that we're made of — you don't know. They just go right through us, they go right through the Earth, we're passing through a wind of dark matter. And physicists are working very hard to build very sensitive experiments deep underground, shielded from radiation and noise and so forth that will detect the occasional, very rare dark matter particle bumping into them. So we think that we are swimming in a sea of dark matter. It's not perfectly smooth — there's more of it in the middle of the galaxy than in the outskirts — but it's definitely all around us.

Ever wonder about parallel universes? Or multiverses? Carroll offered up some answers:

So there's many different kinds of multiverse scenarios. And there some that are multiverses of possibility, suggested by quantum mechanics, or multiverses that are literally parallel and the next universe is less than a millimeter away from you but in a direction in which you can't move. But there's also the idea that there is a multiverse in a sense of just different regions of space where conditions are very very very different. Then it's really just like a map of the Earth where you have oceans some places, plains other places, mountains other places and we're looking at one square acre in the middle of Nebraska and it looks pretty normal and uniform to us, but far away things could look dramatically different.

Galaxies are like teenagers, they stick together in groups but move apart from other groups. Lawrence explained further:

The Andromeda galaxy and the Milky Way are part of a gravitationally bound system and we see many examples of this — clusters of galaxies could be hundreds, even thousands, of galaxies that are gravitationally bound. They're not moving away from each other, and they won't. Gravity is holding them together. But on the large scale, from one cluster of galaxies to another cluster of galaxies far away, from one galaxy to another galaxy far away, they are moving away from each other in the general expansion of the universe. But where gravity controls, where you have enough concentration of mass to hold things together doesn't move apart.

Here's an image of the mapped universe, and Lawrence guided us through how to interpret it:

Two Cosmic Microwave Background anomalous features hinted at by Planck's predecessor, NASA's Wilkinson Microwave Anisotropy Probe (WMAP), are confirmed in the new high precision data from Planck. (ESA and the Planck Collaboration, March 21 2013)
Two Cosmic Microwave Background anomalous features hinted at by Planck's predecessor, NASA's Wilkinson Microwave Anisotropy Probe (WMAP), are confirmed in the new high precision data from Planck. (ESA and the Planck Collaboration, March 21 2013)

If you take a look at that image, the upper left part and the lower right part are the ones that are different. If you draw not a straight line, but divide the sphere in half with a line that cuts diagonally from upper right to lower left, the large-scale variations in the upper left part are smaller than the large-scale variations in the lower right part. If you're looking at that now, you can kinda see that. But the difference is small.

Carroll explained how the big bang may — or may not — explain the lopsidedness of our universe:

It's really hard to come up with a good theory that accounts for this kind of lopsidedness. It might be something absolutely world changing. It might be a hint as to what happened before the big bang. It might be something absolutely boring, just a statistical fluctuation. So that's what we need to figure out. We cosmologists, my colleagues and I, will sometimes tell you that nothing happened before the big bang. But the truth is that we don't know. The big bang is not the beginning of the universe; it's the end of our understanding of the universe. It might have been the very very beginning. It might have been just a phase the universe went through. So if there was something that came before the big bang and that something had some asymmetry, some difference from one part to another, then that might be reflected in the way that our universe came into being. So, like I said, it could be really tremendously big news — or it could just be, "Eh, we could lucky."

Tweets From During The Show

From Tom's Reading List

Slate: The Universe Is 13.82 Billion Years Old "Some of this light comes from stars, some from cold clumps of dust, some from exploding stars and galaxies. But a portion of it comes from farther away…much farther away. Billions of light years, in fact, all the way from the edge of the observable Universe. This light was first emitted when the Universe was very young, about 380,000 years old. It was blindingly bright, but in its eons-long travel to us has dimmed and reddened. Fighting the expansion of the Universe itself, the light has had its wavelength stretched out until it gets to us in the form of microwaves."

Science: Best Image of Big Bang Afterglow Ever Confirms Standard Cosmology "If the universe were ice cream, it would be vanilla. That's the take-home message from researchers working with the European Space Agency's orbiting Planck observatory, who today released the most precise measurements yet of the afterglow of the big bang—the so-called cosmic microwave background (CMB) radiation. The new data from Planck confirm cosmologists' standard model of how the universe sprang into existence and what it's made of. That may disappoint scientists who were hoping for new puzzles that would lead to a deeper understanding."

New York Times: Universe As An Infant: Fatter Than Expected And Kind Of Lumpy "Astronomers released the latest and most exquisite baby picture yet of the universe on Thursday, one that showed it to be 80 million to 100 million years older and a little fatter than previously thought, with more matter in it and perhaps ever so slightly lopsided."


You can listen to these songs and more on the Ultimate On Point Playlist on Spotify.

  • "The Big Bang Theme Song" (2007) by The Barenaked Ladies
  • "The Galaxy Song" (1983) by Monty Python

This program aired on April 16, 2013.


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