Planck unveils the Universe

July 5, 2010 5:09 PM

Planck telescope reveals ancient cosmic light. "The picture is the first full-sky image from Europe's Planck telescope which was sent into space last year to survey the oldest light in the cosmos. It took the 600m-euro observatory just over six months to assemble the map. It shows what is visible beyond the Earth to instruments that are sensitive to light at very long wavelengths - much longer than what we can sense with our eyes."

Phil Plait: "The line running horizontally across the image is the Milky Way galaxy itself. The galaxy is a flat disk, and we’re inside it, so it looks like a line. Think of it this way: imagine you are inside a vast fog-filled room, five hundred meters on a side, but only five meters high. When you look across the room you see lots of fog, but when you look up you only see a little bit — the amount of fog depends on how far into the room you look. The Milky Way is the same way; we’re halfway to the edge of a huge, flat disk filled with dust. When we look into the disk we see it edge-on, and we can see all that dust. Look up or down (toward the top and bottom of the image) and we don’t see as much."

posted by homunculus (30 comments total)

I think the technical term for what you see there is "pesky foreground".
posted by edd at 5:14 PM on July 5, 2010

Why is that we believe the local irregularities of the CMB reflect the early physical structure of the universe and not cosmic "noise" in the signal, i.e. noise due to transmitting through the universe, not instrument noise?
posted by ennui.bz at 5:15 PM on July 5, 2010

ennui.bz, it's because in order to form an image of something like a filament on that scale, the thing forming the image has to be creating a unified effect over an area millions of light-years across. If the space-time continuum were displaying flaws on that scale it would be a big problem for physicists, because it would preclude a lot of stuff they've got working in other areas from ever being able to work.
posted by localroger at 5:24 PM on July 5, 2010

So wait, the universe if round?
posted by new brand day at 5:30 PM on July 5, 2010

Round is the shape you get when something expands in all directions from its center, yes.
posted by LogicalDash at 5:41 PM on July 5, 2010

That image is a projection. Undistorted, the image would occupy the interior of a sphere, since the telescope looks in every direction. The universe doesn't have a center, everything is expanding from every possible vantage point.
posted by Humanzee at 5:49 PM on July 5, 2010 [3 favorites]

"Round is the shape you get when something expands in all directions from its center, yes."

This is some pretty sad snark. Round is the shape if everything expands from the center at a uniform rate. If things in different places accelerated differently, you'd end up with something quite different from "round". Besides, the real answer is that the shape of the image is dictated by the fact that we're taking pictures of the inside of an imaginary celestial sphere and doesn't have very much to do with any shape the universe might or might not have.

"The universe doesn't have a center, everything is expanding from every possible vantage point."

This doesn't mean there's no center. The textbook (literally, it's in a lot of textbooks) example is bread baking with raisins in it. As far as any given raisin can tell, all of the others are expanding away from it. Nonetheless, there's still a center to that loaf.

That said, I have no idea if the universe has a center or not.
posted by kavasa at 6:09 PM on July 5, 2010 [7 favorites]

So wait, the universe if round?

The universe WHEN round.
posted by Sys Rq at 6:09 PM on July 5, 2010 [4 favorites]

A picture of the universe without the earth or sun, very cool how this is done, very cool.
posted by hortense at 6:19 PM on July 5, 2010

I'm familiar with that textbook example. I don't like that example for precisely that reason. The universe having an edge like a loaf of bread is inconsistent with relativity and is not featured in any cosmological model I've ever heard of. Anyway, when people talk about the universe expanding from a center, they're imagining the big bang as an explosion, and it's perfectly fine to point out that isn't right without covering every possible other misinterpretation.
posted by Humanzee at 6:25 PM on July 5, 2010

As I understand it, one of several extant theories is that the universe may have a sort-of spherical shape (a hypersphere with a bounded surface), but the reason the question is usually asked generally underestimates how odd the universe actually is compared to our everyday human-scale experience.

A lot of people, when they think of Big Bang theory, imagine the universe as a kind of balloon expanding into empty space. This is incorrect. There is no empty space. The universe *is* the space. It is not "expanding into" anything. The objects inside of it are gradually growing further and further apart.

There is currently still debate as to whether the universe is finite or infinite and whether it is a bounded or unbounded space. The reason the picture in the link is kind of circular, I believe, has more to do with the way instruments collect light than with the actual shape of the universe.
posted by kyrademon at 6:26 PM on July 5, 2010

The observable universe is a constantly expanding sphere with a radius of the speed of light * the age of the universe. The universe is vastly larger than that, but we can't see further than that because the light hasn't had time to reach us.


(well, kind of -- you can't go quite back to the beginning because the universe was opaque for some time, and inflation complicates things, but basically that is why it's spherical)
posted by empath at 6:34 PM on July 5, 2010

I don't get it, but I like it.
posted by doublehappy at 6:38 PM on July 5, 2010 [1 favorite]

BTW, the fact that this image is projected onto a sphere is a much different question than what the 'curvature' of space is, so don't get those confused.

If you take a picture of the furthest thing you can see in every direction (unless the view is blocked by something), you will roughly get a sphere because the speed of light is the same in all directions.

That has nothing to do with discussions of whether the geometry of space is curved, and whether it's spherical, flat, or hyperbolic.
posted by empath at 6:41 PM on July 5, 2010

The Beginning and End of Time: Life, The Universe, Nothing Professor Lawrence M. Krauss.
posted by hortense at 6:59 PM on July 5, 2010

There is currently still debate as to whether the universe is finite or infinite and whether it is a bounded or unbounded space.

I have it on good faith that there IS an end to the universe, and at that end there's a lovely little restaurant.
posted by jimmythefish at 7:28 PM on July 5, 2010

It's not round because it's expanding, it's round because it's tiny. These maps are visions of the past when the universe was young and small. You're looking into the past, the farther away things are, the longer it has taken for the light you see to get here, the smaller the space occupied by the things you see was. As volume approaches 0, shape approaches spherical.

Think about a fat rubber band, it has an outside and an inside, but you can twist it (rotate around the circumference) and make the outside the inside and the inside the outside. Then think about doing the same to a tennis ball, rotate it around it's surface so that the fuzzy side is on the inside and the rubber side is on the outside. Now the hard part, imagine that you have a solid ball, and rotate it so that the outside becomes the center and the center becomes the surface. That's what you see in these pictures of the sky. You're not looking at the edge, you are on the edge looking back to the center.
posted by zengargoyle at 7:36 PM on July 5, 2010

I'm trying not to panic.
posted by Devils Rancher at 7:39 PM on July 5, 2010

BTW, the fact that this image is projected onto a sphere is a much different question than what the 'curvature' of space is, so don't get those confused.

Entirely correct - the image is projected onto a sphere because that is the way we see the cosmos, but that doesn't necessarily map to the actual topology of the universe: which, evidence seems to suggest, is both flat, and closed (i.e. two parallel beams of light projected into the universe will remain parallel; they will also, eventually, come back to where they started from.) The question is what "shape" matches those conditions. Imagine two compass points, held a fixed distance apart, inscribing lines onto a surface. A sphere satisfies the condition that the lines will remain parallel and return to where they started, but so does a dodecahedron, or even (my personal favorite), a doughnut. The actual "shape" remains unknown.

This is another incremental and wonderful succession of satellites, from COBE to WMAP to Chandra, showing our universe in far more instructive ways than the extremely limited gamut afforded to human eyes.
posted by Bora Horza Gobuchul at 7:57 PM on July 5, 2010

hat doesn't necessarily map to the actual topology of the universe: which, evidence seems to suggest, is both flat, and closed (i.e. two parallel beams of light projected into the universe will remain parallel; they will also, eventually, come back to where they started from.)

When I put this question to Dr. Gott (of Logarithmic Maps of the Universe fame, among others) he replied that, while flat and closed is a theory, we don't yet have empirical evidence of this, such as seeing "mirrored" or "shadowed" images of objects when going from one side of the universe to the other — which is what we would expect, topologically speaking. Has this changed since the mid-2000s?
posted by Blazecock Pileon at 9:19 PM on July 5, 2010

Blazecock, according to analysis of WMAP data, the universe is flat (with only a 2% possible margin of error). I did get my topology models mixed up, however: I should have said that the universe is flat, not both flat and closed, the latter being a contradiction.
posted by Bora Horza Gobuchul at 10:13 PM on July 5, 2010

That said, I have no idea if the universe has a center or not.

probably not. from what I've heard, it's apparently some sort of 4-dimentional shape, like a hypersphere (where, when you go out one side, you come in the opposite side, or out the top, in the bottom) but probably not actually a hypersphere...

(i.e. two parallel beams of light projected into the universe will remain parallel; they will also, eventually, come back to where they started from.)

wellll...not really. because of the expansion era, you see, when the space in the universe, for a brief time, expanded faster than the speed of light (the expansion of space is the only thing that can go faster than the speed of light). (FWIW, this era was very very short, lasting from when the universe was about the size of a pea and until it was about the size of a softball) even if you took off at the speed of light, you could never return to where you started, it's just a bit too far away...(plus it would be so very different by the time you got back.)
as for the parallel lines part, i don't know if that's precisely true...from what i've heard, the whole point of this cosmic background mapping was to figure out what the actual topology of the (non-hyperspherical) 4-D shape of the universe is...apparently it's pretty complex. i.e. when you exit at 3 o'clock(direction-wise, not time-wise) you come back in at 5, exit at 2 o'clock, back in at 9...you wouldn't return to your starting point (discounting expansion) by a straight-line route, but only after criss-crossing all over creation...wouldn't this cause parallel lines to eventually diverge? or not necessarily?
posted by sexyrobot at 12:33 AM on July 6, 2010

It's flat, it's round, and it's a hologram. It might be infinite, and it's made of something that might not even exist. Plus there's a restaurant at the end. I think it deserves a capital letter.
posted by doublehappy at 12:36 AM on July 6, 2010

"Why is that we believe the local irregularities of the CMB reflect the early physical structure of the universe and not cosmic "noise" in the signal, i.e. noise due to transmitting through the universe, not instrument noise?"
It reflects both. There are primordial fluctuations, and fluctuations imposed upon that through later effects. They have slightly different effects and operate at different characteristic scales, and you can disentangle them through cunning use of statistics and correlation with where you know the mass is in the universe later (galaxy surveys and so on).
These effects include gravitational lensing, the Sunyaev-Zel'dovich_effect, and the Integrated Sachs-Wolfe effect.
The non-primordial effects are also usually quite small. You can do an awful lot without worrying about them too much.
As for why we think it really can't be more local effects, well for one thing it would be really surprising that it looks so much like what we expect primordial CMB to look like and for it to be so astonishingly uniform. Primordial CMB pictures are scaled to show the tiniest detail. Here's a mildly silly image of how smooth the CMB is. I'm not sure how you'd get that with more local effects alone.
posted by edd at 1:56 AM on July 6, 2010

I don't even understand why anyone is confusing the roundness of the universe with this photograph. It is a photograph of everything, from one vantage point. (Roughly "here".) It is a panoramic view in all directions. Until we get spherical laptop displays that can encircle our heads, this round looking projection is the best we can do to display that information. It's got nothing to do with the center of the universe or anything like that. It's just like taking a 360 panorama picture of a landscape and trying to display it on a flat display. There is a point at which the same thing is at both the far left and the far right. But in reality they are right next to each other. That's not the universe fucking with our heads, it is the realities of how the image is being displayed.
posted by gjc at 2:35 AM on July 6, 2010

A lot of people, when they think of Big Bang theory, imagine the universe as a kind of balloon expanding into empty space. This is incorrect. There is no empty space. The universe *is* the space. It is not "expanding into" anything. The objects inside of it are gradually growing further and further apart.

What is there?
posted by jefficator at 6:48 AM on July 6, 2010

It's just like taking a 360 panorama picture of a landscape and trying to display it on a flat display.

Yes. Has anyone found a version of this image rendered inside a panoramic viewer with a movable camera? Something like this QTVR of Cape Town, only standing at the center of the Planck telescope image? Surprisingly I can't find any cosmic microwave panoramas of any sort.
posted by Nelson at 8:58 AM on July 6, 2010

Uh, I was making a lame joke about the sphere shape of the photo.

Stay literal Metafilter!
posted by new brand day at 10:03 AM on July 6, 2010

In other news: Hayabusa capsule particles may be from asteroid
posted by homunculus at 1:49 PM on July 6, 2010

Hubble sees spectacular star birth and death
posted by homunculus at 7:56 PM on July 8, 2010