Mar 05 2008
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The Universe is 13.73 +/- .12 billion years old!
Happy birthday, Universe!
Kinda. It’s not really the Universe’s birthday, but now we do know to high accuracy just how old it is.
How?
NASA’s WMAP is the Wilkinson Microwave Anisotropy Probe (which is a mouthful, and why we just call it WMAP). It was designed to map the Universe with exquisite precision, detecting microwaves coming from the most distant source there is: the cooling fireball of the Big Bang itself.
New results just released from WMAP have nailed down lots of cool stuff — literally — about the Universe.
I am about to explain the early Universe to you. I’ll be brief, but if you want to skip to the results, then go ahead.
Here’s the quick version: the Big Bang was hot. The Universe itself expanded outward from a single point — actually, it’s space itself that expands, not the objects in it — and like any expanding gas it cooled. After about a microsecond, it had cooled enough for protons and neutrons to form. Three minutes later (yes, just three minutes) it had cooled enough for protons and neutrons to stick together. Hydrogen, helium, and just a dash of lithium were created, and these would be the only elements for some time (hundreds of millions of years, in fact). The Universe was a thick soup of matter and energy.
It kept expanding and cooling. At this point, it was opaque to light. A photon couldn’t travel an inch without smacking into an electron and then getting sent off in some other random direction. However, after a few hundred thousand years, an amazing thing happened: neutral hydrogen could form. Before this point, the Universe was still too hot; as soon as an electron bonded with a proton, some ultraviolet photon would come along and whack it off. But at that golden moment the cosmos had cooled off enough that a lasting atomic relationship was in the offing. Neutral hydrogen was born. At that moment — astronomers call it recombination, which is a misnomer, since it was the first time electrons and protons could combine — the Universe became transparent; without all those pesky electrons floating around, photons found themselves free to travel long distances.
It’s those photons WMAP sees. After 13.7 billion years, the expansion of the Universe has cooled the light, stretched its wavelength from ultraviolet to microwave. Another way to think about it is that the temperature associated with each photon went from thousands of Kelvins down to just a few, less than 3, in fact. That’s -270 Celsius, and -454 Fahrenheit.
Brrrr.
That light emitted just after recombination tells us a vast amount about the Universe at that time. By carefully mapping the exact wavelength of the light and the direction from where it came, we can tell the density and temperature of the matter at that time. Incredibly we can also tell how much dark energy there was, and even the geometry of the Universe: whether it is flat, open, or closed.
All this, from the dying glow of the Big Bang itself.
A lot of this information was determined a while back, just a couple of years after WMAP launched. But now they have released the Five Year Data, a comprehensive analysis of what all that data means. Here’s a quick rundown:
1) The age of the Universe is 13.73 billion years, plus or minus 120 million years. Some people might say it doesn’t look a day over 6000 years. They’re wrong.
2) The image above shows the temperature difference between different parts of the sky. Red is hotter, blue is cooler. However, the difference is incredibly small: the entire temperature range from cold to hot is only 0.0002 degrees Celsius. The average temperature is 2.725 Kelvin, so you’re seeing temperatures from 2.7248 to 2.7252 Kelvins.
3) The age of the Universe when recombination occurred was 375,938 years, +/- about 3100 years. Wow.
5) The energy budget of the Universe is the total amount of energy and matter in the whole cosmos added up. Together with some other observations, WMAP has been able to determine just how much of that budget is occupied by dark energy, dark matter, and normal matter. What they got was: the Universe is 72.1% dark energy, 23.3% dark matter, and 4.62% normal matter. You read that right: everything you can see, taste, hear, touch, just sense in any way… is less than 5% of the whole Universe.
We occupy a razor thin slice of reality.
There are other important things that have come from the WMAP data, and if you’re interested, you can read all about them on the WMAP site and in the professional journal papers.
But if you only want to peruse the results I’ve highlighted here, that’s fine too. But remember this, and remember it well: you are living in a unique time. For the first time in all of human history, we can look up at the sky, and when it looks back down on us it reveals its secrets. We are the very first humans to be able to do this… and we have the entire future of the Universe ahead of us.
Does WMAP data go any of the way to hypothesising just what dark energy and dark matter are? I mean does it firm up any particular theory or does it just quantify just how much of this stuff there is?
Great post BA. Thanks.
Wow. I am in awe. This is probably one of the biggest days in the history of science, up there with the confirmation of heliocentricism and the moon landings.
And yet, few people will even hear about it. More’s the pity.
Phil, this is a well-written entry.
I llllllllike it
Phil, this is a well-written entry.
<Tom Brokaw>I llllllllike it</Tom Brokaw>
(I wanted to see if this would parse correctly the second time)
I was just listening to Fraiser Cane and Dr. Pamela Gay discussing WMAP in the Astronomy Cast. Their explanation is excellent and it’s definitely worth linking to:
http://www.astronomycast.com/astronomy/ep-78-what-is-the-shape-of-the-universe/
However, I was also reading Scientific American’s article on the end of cosmology as we know it, and it makes me wonder what pieces of the puzzle we’re still missing. Still, all of this is very exciting.
I have yet to get a straight answer to these two questions:
1. How long did the big bang take for expansion?
2. Are there any scientific experiments with results which prove the assumptions about expansion?
FYI, I am not a right-wing christian fundamentalist or anything of the sort.
I just want to know what we think we know, versus what we know by proof.
Thanks!
It’s good to be alive. I don’t understand how people can think that science takes away the magic, so to speak. Stuff like this just makes me more in awe of it all.
I find it amazing that we can pinpoint the age of the universe with that much accuracy! It is a pity this would at best be a footnote in the mainstream news.
Wow. This is amazing and awe-inspiring.
“The Universe itself expanded outward from a single point, and like any expanding gas it cooled”
wouldent that make our universe a bubble, but every time i hear physisits talking about the cosmos they say its flat or curved, or wrinkled. whatever. how can bubble expanding evenly in all direction be flat?!? then they go into the whole “4th dimention” thing which makes my head want to pop from an overload
finite an unbounded or infinite and closed. admit it our universe is a bubble, like a baloon, exapanding in all direction evenly. would that not make it a sphere?
“The age of the Universe when recombination occurred was 375,938 years, +/- about 3100 years.” Sig fig error, anyone?
Other than that…coooool.
shame on me for not readin the article thourghly,
“The Universe is flat”, huh, like a piece of paper!?!
again i cant wrap (haha) my head around that idea, no matter how much i read about it. its a bit counterintuitive considering i can look out into the sky at all possible direstion in 3 dimensions. never mind. ill go back to playing freecell
I’m a bit baffled by the choice of words in stating that the ‘universe is flat’. Clearly it is not, so what exactly is the cosmological definition of ‘flat’. I read the NASA article and I think they are saying that the universe is well-approximated by Euclidean space in its behavior, but I’m not certain that is what they are trying to tell me.
My favorite result is that the universe is flat (to within +/- 2%). A flat universe is consistent with an infinite universe. That really is something to think about.
The world really is flat! Say it with pride.
(Another Digg and Reddit worthy blog entry.)
[…] to this fascinating piece over at the Bad Astronomy Blog, that’s the age of the Universe. And furthermore… The […]
[…] blog reports on a five-year analysis of the cooling remnants of the Big Bang from NASA’s Wilkinson Microwave Anisotropy Probe (WMAP). Posted in […]
[…] Bad Astronomy Blog » The Universe is 13.73 +/- .12 billion years old! […]
Blu-Ray-Ven: Here is a link that explains what a “flat” universe means.
http://www.newton.dep.anl.gov/askasci/ast99/ast99517.htm
You’ll have to scroll down to the bottom of the page to get to it. Basically it says in a “flat” universe 2 parallel lines will always remain the same distance apart. In an elliptical universe, straight lines would eventually meet; in a hyperbolic universe, parallel lines would have one region of closest approach, and diverge in both directions from there.
Hopefully that will end this 2008 crap…when can we all start writing 12,000,002,008?
Alright, so the universe is flat, but that leaves me with one question:
The universe being flat means that space literally goes on forever, and doesn’t curve in on itself like it does with a closed universe. So there’s an infinite amount of space. Is that infinite amount of space populated by a finite or infinite amount of matter?
If there is a finite amount of matter, would that mean that there would actually be some “center” of the universe, approximately at the center of all of that matter, and at the point at which the big band originated? I’m aware that it’s space itself that is expanding and not that matter itself is expanding away from any particular point, but either way if you reverse time, any finite amount of matter should eventually collapse into a point somewhere in space.
And if the amount of matter is infinite, does that mean that the big bang actually occured everywhere at once, and the universe didn’t start out as a point but rather an infinitely large singularity which then expanded and simply became less dense?
I also had another, slighly unrelated question: Any light which is emitted by an object that is more than about 13 billion light years away from us will never reach us due to the expansion of space. (Yes I know we can see objects which are further away because they were close enough when they actually emitted the light, but I’m talking about anything emitting light right now). I’m not sure of the exact number, but it was very close to 13Gly and was calculated from the Hubble constant which had a fairly large error anyway. My question is, is it merely coincidence that this number happens to be so close to the age of the universe (albeit in different units)?
The universe is flat within a 2% margin of error. But “flat” is such a special term that that margin of error makes for radically different cosmology and physics. To state that it’s flat without the margin of error caveat is incredibly misleading.
BB wrote: Alright, so the universe is flat, but that leaves me with one question:
The universe being flat means that space literally goes on forever, and doesn’t curve in on itself like it does with a closed universe. So there’s an infinite amount of space. Is that infinite amount of space populated by a finite or infinite amount of matter?
Please correct me if I’m off base but it may be that space and matter, ie. the universe, is finite but is expanding infinitely.
To infinity and beyond…
Phil wrote: “The Universe itself expanded outward from a single point”
I’m not a cosmologist, but this sounds like a schoolboy howler to me. Space itself is doing the expanding, so it’s nothing like an ordinary explosion. See
http://en.wikipedia.org/wiki/Metric_expansion_of_space
Oops, I meant to say in particular that there is no center point of the expansion.
BB: There are several possibilities for a universe which has a finite amount of space in it but no center point and no edge.
It’s easiest to start with a 2-dimensional example– take the surface of a sphere, which has finite area, but no center point (remember, we’re only considering the surface of the sphere) and no edge.
This is a bit abstract: mathematicians like to think of these things (they call them manifolds) without requiring them to be embedded in a larger space. (I know, it seems impossible to imagine the surface of a sphere without thinking of it as embedded in 3-dimensional space.)
Another 2D example is the torus (the surface of a doughnut). This one is interesting because it can be flat (unlike the sphere), but unfortunately a flat torus can’t be embedded in 3D Euclidean space. However, the flat torus is actually quite easy to imagine: think of the video game Asteroids, where your ship wraps around to other side of the screen whenever it hits the edge of the screen.
There’s also a 3D version of the torus, which you can think of as the interior of a cube, where whenever you pass through one of the walls of the cube you reappear at the opposite wall.
And there are many other 3D manifolds, most of which are a lot harder to explain…
I’ve always been curious about what the exact meaning of the 13.73 billion years is or whatever other number you’d care to choose. Is that the elapsed time on some hypothetical clock that existed from the beginning? Of course, such a thing is impossible, but if some type of clock could have been created at the same instant as the Big Bang what would its reading be now?
Consider what happens if we drop an object which emits a radio pulse every one second into a black hole. At the beginning our radio receiver picks up the pulse every second but as the object gets closer and closer to the event horizon the pulses get more and more spread out - once every minute, once every hour, once every day, etc., etc. From the point of view of the outside observer the object takes an infinite amount of time to fall through the event horizon.
Doesn’t the same thing apply here with the universe as a whole? The early universe had severe space-time warpage which would have caused time to slow down. Doesn’t that mean from the perspective of general relativity the elapsed time back to the original singularity of the Big Bang is infinity? Or does it all change since we are inside the universe and there is no outside observer? Can someone clarify this paradox for me.
Oh, and this wikipedia article looks pretty good:
http://en.wikipedia.org/wiki/Shape_of_the_Universe
“So there’s an infinite amount of space. Is that infinite amount of space populated by a finite or infinite amount of matter? ”
If it’s truly a perfect Euclidean space with no overall curvature then a finite amount of matter would have to have a particular center of mass. So in such a universe you actually could have a point that was the real center of mass. Now, whether you could deduce where it was only from data from the observable part of your universe is a different story.
And unless the matter in the universe is moving quickly enough it will eventually tend to accumulate at that center. That’s what Newton feared and that’s why he speculated that we live in an infinite universe with an infinite number of more-or-less evenly spaced stars.
Sorry for the newb question:
So if the universe is “flat,” meaning it’s angular measurements have lines that stay parallel to each other, (assumedly in all 3 dimensions) wouldn’t that make our universe more like an expanding box (or quadrilateral maybe), except with invisible edges?
If not, is it possible to interpret our flat universe as a 3D representation? Showing it as a simple plane just seems to confuse (at least) me.
Tom Marking wrote: “If it’s truly a perfect Euclidean space with no overall curvature then a finite amount of matter would have to have a particular center of mass.”
Not true. The flat 3D torus which I described earlier has no center, and every point is the same as every other point. (The center point of the cube model is not special, because the walls of cube aren’t boundaries; opposite walls are “glued” together.)
This stuff is too hard to understand. God did it, case closed.
Just kidding, great post. All kinds of good information I need to get up to speed with.
Ivan, yeah, you have a point. I should have left off the word “outwards”. It’s not really wrong; the Universe is expanding outwards, as every point in the Universe measures it. But in that context and phrased that way, it could easily be interpreted as outwards from a point. I’ll fix it now.
jmil: Unfortunately it’s difficult to describe the flatness of space without resorting to 2D analogies. The easiest to understand compact flat 3D manifold is the flat 3-torus, which you can imagine as the interior of a cube with each pair of opposite walls glued together. I’ve been trying to find a good picture of this, but no luck so far…
Thanks for changing that, Phil. I just tend to worry a lot about misconceptions that are suggested unintentionally.
If you really want to tie your brain into knots… Once you think you get a grasp on what a “flat” universe is, throw in the Einsteinian warping of space/time due to gravity. I once heard of a way to imagine the expansion of the universe as compared to raisin bread. As the bread cooks it expands. The raisins move farther away from each other but don’t actually move.
Answering drew terry:
1. How long did the big bang take for expansion?
The big bang was the beginning of the expansion of the universe, but the expansion is still going today. That’s as straight an answer as you can get.
2. Are there any scientific experiments with results which prove the assumptions about expansion?
Several, but there is one big one. Back when most astronomers mocked the big bang supporters, they realized that the big bang would have created 3 Kelvin radiation filling the sky. Nobody knew that radiation actually *existed* back then, because they couldn’t detect it. It was eventually discovered by accident, pretty much proving the big bang people right. If it *hadn’t* been there, they would have been proven wrong. There have been other experiments that support the expansion, but that was the best. (There are no experiments that refute it either. That’s important, too.)
Now I remember where I’ve seen good pictures of the 3-torus. Google “Jeffrey Weeks” and/or “The Shape of Space”. He’s got some great stuff, including a book, videos, and even software to let you fly through the models.
Wow…this is a freakin’ cool blog entry. How in the world can anyone oppose science so strongly when we discover things like this. It is truly a great time to be alive.
Great postin Phil!
I’m just pleased the results have been published in time for me to include them in my final submission for my cosmology course!
It’s at time like this that science just makes your jaw drop!
Happy Birthday Universe and well done us for working out how many candles to light and what size and shape of sweater to knit!
Awesome!
Wow. Just…Wow.
This one really impacted me. I guess I had grown comfortable with the inflating balloon analogy. Now that’s not it at all.
That’s the inspiring part of science, always challenging your view of everything around you.
Thanks Phil
Great stuff Phil!
I’m having slight difficulty deciding how “WMAP” should be pronounced; for some unexplainable reason I think of it as [We-map], and Double-You-map sounds a bit clumsy in comparison :S
Can someone refer to this?
(Please, forgive my English)
I like your post, but there is one thing I can’t understand:
If the dark energy is forcing space to expand, doesn’t that mean that the Universe is open and not flat?
I hope you get what I mean. Thanks.
Sorry Phil - But space is not a thing and it does not expand. While you can talk about expansion of space in a metric sense, saying “space expanding” moves galaxies apart is incorrect.
[ps - the wmap result is great]
So, is it true to say that all the basic atomic building blocks that I’m made from, and my desk and laptop and everything around, are all 13.7 billion years old?
It would be amazing to know the ‘life story’ of a proton or electron, they’ve been on a wild trip.
Truly mind blowing.
I don’t think of space as being ‘nothing’. It is clearly something which makes it a ‘thing’. True nothingness has no dimension, and cannot be imagined in any form; as it is nothing.
Space however has dimension. If I take a 1 meter cube of space, I can’t have a cube of nothing, due to the fact I can measure it. If you want nothing, you must remove its dimensions. Doing so shrinks it right down to; not even a pinpoint, but nothing. You can’t even imagine nothing, due to your trying to imagine it, making nothing, something.
Sure, its not an aether, but it seems to warp under gravitational influence. For something to warp, it has to be a ‘thing’. ( this assumes Quantum Gravity is not the cause)
the entire temperature range from cold to hot is only 0.0002 degrees Celsius. … so you’re seeing temperatures from 2.7248 to 2.7252 Kelvins.
I’m either confused by this statement (entirely possible due to lack of coffee) or the numbers above are slightly wrong. Cool article though.
>Sure, its not an aether, but it seems to warp under gravitational influence. For something to warp, it has to be a ‘thing’. ( this assumes Quantum Gravity is not the cause)
This is incorrect. If you don’t believe me (who has written several papers on the issue) how about Steve Wienberg?
‘Good question,’ says Weinberg. ‘The answer is: space does not expand. Cosmologists sometimes talk about expanding space - but they should know better.’
Rees agrees wholeheartedly. ‘Expanding space is a very unhelpful concept,’ he says. ‘Think of the Universe in a Newtonian way - that is simply, in terms of galaxies exploding away from each other.’
From: http://www.newscientist.com/article/mg13818693.600-all-you-ever-wanted-to-know-about-the-big-bang—-everyweek-questions-about-the-big-bang-flood-into-the-new-scientist-officesowe-thought-it-was-about-time-to-let-some-experts-loose-on-the-subject-.html
@Overstroming, no, only Hydrogen, Helium and some lithium were initially formed from what was available after the big bang. All other elements are formed from one aspect or another of a star’s ‘life’ cycle. Which elements are formed is mainly dependent on the size and type of star and thus are still being formed today.
[i]Ivan: BB: There are several possibilities for a universe which has a finite amount of space in it but no center point and no edge…[/i]
Yes, I’m aware of that. But that only applies to a universe with a closed geometry. According to WMAP, space is flat which means it extends infinitely. In a closed universe if you travel in one direction long enough you’ll end up right back where you started just as you would on the earth or in Asteroids. In a flat universe if you travel in one direction, you just keep going forever. It’s like a piece of paper that just extends infinitely in every direction. It has no curvature, therefore there’s no way by travelling in a single direction you could ever return to your starting point. My point is that a flat universe is infinite, not finite as you talked about in your post.
However, within this infinite amount of space there could be either a finite or infinite amount of matter, and I’m asking which, because it makes a big difference to how we look at the universe.
@BolingbrookPete
The balloon idea isn’t entirely wrong. As I understand it, something akin to pennies on the surface of a balloon can be considered a model of the universe (for expansion, not shape) because it is finite, yet unbounded and the farther away something is the faster it moves away.
Someone correct me, as I’ve undoubtedly made a mistake.
“as soon as an electron bonded with a proton, some ultraviolet photon would come along and whack it off”
Man, and you tell us to keep the comments clean …
@John Phillips, FCD, thanks but I meant that all matter that’s around today is made from the same matter, reconfigured or otherwise, that was created then. Electrons, protons etc can be arranged into various atoms but they themselves are as old as the universe.
That’s my pretty inexpert understanding anyhow -
Martijn.
Sorry for the lame question, but can someone tell me the basic method by which measuring these microwaves can tell us when the big bang happened?
I skimmed the article looking for a layman’s explanation but didn’t notice one. Sorry if I just missed it.
“What they got was: the Universe is 72.1% dark energy, 23.3% dark matter, and 4.62% normal matter.”
Shouldn’t that 4.62% be referred to as “unusual matter” or “rare matter”, since it’s clearly in the minority?
“Not true. The flat 3D torus which I described earlier has no center, and every point is the same as every other point. (The center point of the cube model is not special, because the walls of cube aren’t boundaries; opposite walls are “glued” together.)”
The universe you’re describing is not globally flat. It has space-time warpage, actually rather severe space-time warpage connecting the opposite walls of the cube together. It is only “flat” in between the walls. Usually the terms “flat”, “open”, “closed” are used to refer to the overall amount of space-time warpage in the universe and not to some particular region within the universe.
I guess that means Kent Hovind is only wrong by 13.729994 billion years. Somehow I didn’t expect him to get so close.
To all you people who work in the field of astronomy, I’ve been dying to ask:
Did you ever in your wildest dreams think you would know the answers to questions like this, (the age/geometry/nature of the universe, etc..)? I mean before you knew these experiments were on the drawing board, and even though we’ve known for a long time some of the possibilities.
Or did you think these answers were unlikely to be answered within your lifetime, or perhaps were intrinsically unknowable?
@David
I’m really confused here, and I thought I understood all the “geometric” concepts of cosmology.
How can a flat space be both finite and unbounded? If the universe is flat, then won’t there be an edge to it somewhere?
Maybe it really is spherical, but the mass of the universe occupies only a small portion, and the curvature is too small for us to observe (somewhere in that odd 2% margin of error).
Just thought of something weird.
If the universe is finite and flat, and shaped like a raisin, then the wrinkles might explain the strange distribution of the background radiation. The bright and dim points are where the wrinkle is farther from or closer to us (or maybe the other way around).
I’m still envisioning something like a Star Trek episode where the ship reaches the edge of the universe …
You’re confusing intrinsic and extrinsic curvature. The torus is intrinsically flat, but to embed it in a 3D euclidean space introduces extrinsic curvature. No measurements made completely within the surface of the torus will produce any evidence of curvature, such as triangles whose angles don’t sum to 180 degrees.
Think ‘Pacman.’
drew terry writes:
[[How long did the big bang take for expansion?]]
It’s still expanding.
That being said, thanks, Phil, for posting this. This is very, very cool stuff. Is there a single article which summarizes all these findings?
I hope, for philosophical reasons, that the amount of matter in the universe turns out to be finite. But I don’t see how we could even test the question.
Lots of really cool information here, I’m definitely gonna have to spend some more time studying this flat geometry of space. While it’s nice to be able to put a “timestamp” on the Universe, is it not a rather trivial one? Why are we putting the age of the entire Universe in terms of Earth years? Is there no better standard? I understand that by using Earth years it makes it easier to comprehend in the sense of time that we use everyday, but the rest of the Universe hardly cares if the Earth goes around Sol in 365.25 days.
“but now we do know to high accuracy just how old it is.”
That’s funny. High accuracy is actually 120 000 000 years
Oh, the relativity of things…
2.7252-2.7248=0.0004. You mean it ranges from 2.7249 to 2.7251, yes?
I know it’s picky but this IS science. Shouldn’t it be the Universe is 13.73 billion CE years old? CE standing for current earth. From our frame of reference (time, space) it may seem obvious we are talking about Current Earth Years but change trhe reference point and the number becomes meaningless. It’s meaningless without a stated reference point anyway.
zer0,
“Why are we putting the age of the entire Universe in terms of Earth years?”
Because it’s a convenient unit? If we measured it in galactic rotations or used the Mesoamerican Long Count then we’d still have to convert it to some other unit to make sense out of it.
I suppose we could define the Schlomowitz Unit as being equal to the current age of the universe. Then we could say that the universe was exactly 1 Schlomowitz Unit old. This would have the benefit of being infinitely precise, but it wouldn’t be very useful.
Greg,
I believe that CE stands for “Common Era”, not “Current Earth” (unless there’s a new astronomy term I wasn’t previously aware of).
@ drew terry:
The answers to your questions is right in the post! The current age (of the still expanding universe - big bang is the still ongoing expansion) and the very best experiments behind the age estimate. (Several experiments are combined, see the linked references.)
@ BB:
I’m not a cosmologist, but coincidence I think not. AFAIU the cosmological clock discussed is measured by following the expansion as a comoving observer (comoving coordinates). The size of the observable universe and its cosmological age are intimately related. As the universe expands and ages we can see further back and further out.
@ Tom Marking
See my comment on the cosmological clock above. This clock is correlated with the temperature of the CMB radiation that WMAP measures. So it is a very real clock.
Relative to what? We can only measure time by observing clock and comparing them. If all clocks are slowed we don’t measure any difference.
As you suggest, that we live inside the universe makes a difference. There is no outside to compare with.
Hey Phil,
Another great post! I’ve always thrilled at the precision of these numbers ever since they were first published. I mean, it doesn’t get much cooler than having such an exact estimate of the universe’s vital stats!
One thing though; I think your calculator may need new batteries. If the entire temperature range from cold to hot in the CMB is 0.0002 K, than we’re actually talking about a range from 2.7249 K to 2.7251 K rather than from 2.7248 K to 2.7252 K.
But whose quibbling
After all, it was only the most precisely measured black body spectrum in nature, ever.
Keep up the good work, bro!
[…] indrukwekkend lijstje van resultaten die de WMAP geboekt heeft. Wordt vast en zeker vervolgd! Bron: Bad Astronomy Blog + […]
The question of space being flat confuses many people. First, locally, general relativity teaches that space is curved by mass - (mass tells space what to do, space tells mass how to move) - but on a cosmic scale the universe is spatially - note, spatially - flat. However, space-time is curved: flat space expands in the time direction making space-time curved. Think of space as a “slice” through space-time.
Hope this helps explain, not increase confusion!
Note that the “big bang” explains how the universe behaves (its a consequence of general relativity): it does not tell up anything about its origin. The fact that, when we extrapolate (always risky) “big bang” behavior far enough backward in time we get a singularity tells us that our familiar physics breaks down there: Hence, there is something incomplete about our knowledge of physics. This incompleteness is what M-theory, loop quantum gravity, etc. is all about!
@ Cusp:
Not if you are comparing different comoving frames, I think. You refer later to “Steve Wienberg” [sic], but in that article Steven Weinberg is discussing the universe as seen from a local comoving frame.
That is why they call it relativity theory - physics looks different in different frames, precisely because there are universal laws and symmetries. It’s only if we use comparable frames it will be comparable results.
He is also discussing the fact that reasonable GR solutions (i.e. low massenergy density) are locally flat, so there is no observable local expansion of space that rips small objects apart. Especially with local gravitation from masses warping space slightly to prevent that.
So in the local comoving frame it makes much sense to use Weinberg’s model. Over proper distances - not so much.
Btw, this article seems to suggest Weinberg uses non-conventional terms. And that “The issue of how to best describe and popularize the apparent superluminal expansion of the universe has caused a minor amount of controversy.”
So I would give this description some leeway.
Don’t get me started on pesky historical accidents in science. Why should the SI mass unit be “kilogram” instead of “gram”? [Because of a political decision, that’s why. Don’t get me started on politics in science … :-P] Why does a theoretical current still, by historical definition, flow from a positive potential to a negative, when the later observation is that in the most usual physical current, electrons, particle flow goes in the reverse direction? Why is everyday “normal” matter suddenly rare?
And so on and so pesky forth…
“Hope this helps explain, not increase confusion!”
Nope. Didn’t help.
BA’s post said that the *universe* is flat - not local space. I assume that he meant that on a cosmic scale, the universe is not curved.
I understand the balloon analogy (I read “Flatland” when I was very young), and I can understand a 3 dimensional space could seem to be flat to its inhabitants (”internally flat”) and still be warped around in higher dimensions as to have no edges (”externally curved” - note that in such a situation, the sum of the angles of a triangle would have more than 180 degrees, but no one would notice because the measuring sticks are also bent).
What boggles me is the statement that the universe is flat (taken to meaning “externally flat”) and has no boundries. That does not compute. If the universe is warped around itself in higher dimensions then it’s not really flat - it’s spherical (or saddle-shaped, or whatever). If it’s really flat, then it must have edges - you can’t flatten a basketball without making an edge unless you warp space.
Very interesting, It is nice to know the age of the universe.
Couldn’t the universe be far older than this? This is only the light we can actually see and measure. What about the stuff that has already expanded out of our sight, over the universal horizon so to speak?
The flatness of the universe has NOTHING to do with its 3d shape. Its just a concept that means two parallel lines will never meet, ever.
Another concept to realize is that not only is everything IN the universe expanding, the actual universe itself is expanding but this expansion is not something we can measure since we are inside the frame of reference. Only someone outside of our universe could measure that expansion.
“The universe is flat” 1000 years ago, our best scientific guess was the world was flat. That should be changed to “our percieved universe is flat” as “the universe is flat” excludes a lot of quantum theories
Wow. Judging by the votes, it looks like Digg users are significantly more interested in astronomy than Reddit users.
All my Reddit submission managed to generate was a few sarcastic comments.
Pity, because I much prefer the Reddit interface. It’s far superior to Digg.
Although I readily admit that I’m VERY unsophisticated about this stuff, I’d be willing to bet that much of what we’ve concluded in recent years will be proven wrong in the future as science “marches on.” I say this based on history which seems to indicate that a great deal of scientific consensus is proven wrong by future generations of scientists. Still, it’s pretty exciting to read about these “discoveries.” And who knows, maybe they’re right!!!
[…] Find out more here… This entry was posted on Thursday, March 6th, 2008 at 10:06 am and is filed under le Chat Marchet. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site. […]
What about sweet baby Jesus? The universe is 2008 years old +/- 34 years(the age of Christ). What is wrong with you people? Have you forgotten why we are here? It’s not to measure the temperature of the sky! It’s to live the best life possible to return to sweet baby Jesus. I’m not saying that beleiving in science is a one-way ticket to H-E-Double Hockeystick, I’m just saying remember what life is about!
this exciting stuff …
nice article … great info …
so 12 billion years … not 6000 eh …?
thats kewl …
Recombination is only a misnomer IF
1) this was the first time the universe “expanded”. If it wasn’t, then this round was certainly a “re”combination.
2) we fully understand the dynamics of the universe before the universe. How the matter existed in the moments/eons before the universe expanded isn’t clear to anyone so stating categorically that it’s a misnomer is highly debatable and not a position I’d want to be debating from.
I believe in the “Big Bang Theory”, but have one question that anyone has yet to answer.
If the universe expanded out from a single point of origin, what is the “space” called that the universe and big Bang occured in and what space does that space occupy and so on and so forth?
Best Regards,
ScienceGeek
No way, the bible doesn’t say it’s that old. If you don’t believe the bible, just consult the bible! It says right in there that it’s right.
Please use the word “literally” correctly. Nothing is being nailed down literally. In fact, things are being nailed down figuratively!
“We are the very first humans to be able to do this…”
Really? I somehow doubt that, seriously.
Theoretically…if the universe is flat and it is called infinite, then how can we believe it to be infinite when we assign it a rudimentary shape that takes form under a finite perspective? Imagine a sheet of paper under a microscope. When you see the fibers the space is larger and filled with gaps. On a small enough scale you could pass through the paper. If our universe is flat like the paper, from a far enough perspective you could see the whole. If the universe is defined by the clusters of matter that form individual galaxies, then the shape would mimic the elemental binding of particles like a drop of water on a flat surface. With each dying star more water is added to the drop.
when we assign it a rudimentary shape that takes form under a finite perspective? Imagine a sheet of paper under a microscope. When you see the fibers the space is larger and filled with gaps. On a small enough scale you could pass through the paper. If our universe is flat like the paper, from a far enough perspective you could see the whole. If the universe is defined by the clusters of matter that form individual galaxies, then the shape would mimic the elemental binding of particles like a drop of water on a flat surface. With each dying star more water is added to the drop.
This data assumes there was a big bang in the first place. Use the data outside of the big bang model and WOW holy crap batman, interesting revelations.
DrewTerry, Er… why would it matter if someone was a “right-wing Christian fundamentalist”?
Sigh - Space is not a thing. Space does not expand - no matter what frame you look at it in. There is no physical manifestation of expanding space. It is a useful mathematical picture, but it is not physical.
Expanding Space: the Root of all Evil?
Francis, Matthew J.; Barnes, Luke A.; James, J. Berian; Lewis, Geraint F.
Publications of the Astronomical Society of Australia, Volume 24, Issue 2, pp. 95-102. (PASA Homepage)
Abstract
While it remains the staple of virtually all cosmological teaching, the concept of expanding space in explaining the increasing separation of galaxies has recently come under fire as a dangerous idea whose application leads to the development of confusion and the establishment of misconceptions. In this paper we develop a notion of expanding space that is completely valid as a framework for the description of the evolution of the universe and whose application allows an intuitive understanding of the influence of universal expansion. We also demonstrate how arguments against the concept in general have failed thus far, as they imbue expanding space with physical properties not consistent with the expectations of general relativity.
Question… if the universive was too dense and photons couldn’t pass through and microwave spectrum hadn’t yet “expanded” then what data are they reading prior to the expansion? Seems a little off to me…
I think “recombination” is not a misnomer.
The ultraviolet photons were knocking electrons off the protons as fast as they were combining. Each time an electron and proton combined, an ultraviolet photon was emitted, knocking an electron off some other proton.
“Recombination” is a good term for the timeframe when things were sufficiently spread out that the electrons weren’t immediately knocked off again. This last gasp of photonic radiation is what we’re measuring. The last recombination started the modern period where neutral hydrogen existed for more than nanoseconds.
so if recombination was 375,938 years ago, is that the furthest back we can look, experimentally? is there something we can look at (other than photons/EM radiation) to peer back within the first few (hundred thousand) years?
@ josh
I think you misread… or maybe mis-spoke… recombination was not 375,938 years ago… it occurred 300,000 + years after the big bang.
@Tom Marking: what MartinM said. If you’re inside the flat 3-torus, it looks like a hall of mirrors, except without reflections. When you look straight ahead, you see your own back, and another copy of yourself in front on that one, etc. So there appears to be a whole 3D grid of copies of “you”, except there’s still really only one “you”.
@BB: I understand better what you were getting at, now. However, “flat” does not imply “infinite”: the universe may be both flat and finite, just like the Asteroids universe or the 3-torus described above.
I recommend Jeff Weeks’ flight simulator for the 3-torus and other flat/nonflat finite universes: http://www.geometrygames.org/CurvedSpaces/
Yes, it reveals that you ought to be using a big bang model.
A very good article, i like it and i’m conscient to be lucky to know all theses facts, thank you !
Space itself is not a nothing, it is ’spacetime’ which is a thing that can warp, ripple, and carry waves. This is part of relativity. Its actually (per mathematics) full of something called a Higgs field which gives things mass. Per quantum, the Higgs field is both waves and particles, or can be thought of as probability waves.
Actually space can look both flat and be curved. It could be the outside of a baloon, or the inside of one, or it could be part of some other indeterminate shape so big that just our part of it looks flat. According to Expansion theorey (refined big bang math taking quantum into the calculations) the universe is at least so big and is expanding so fast that just the part of it that we can see is like rhode island on the surface of the globe. Everything else is beyond our event horizon. Although the globe is round, rhode island looks flat, becasue the globe which it is on is so large.
These theoreys are tested which is the closest thing we can do to proving them by checking if #1 they can mathematically explain *everything* we see, and then #2 using the math to make predictions about things we havnt looked at yet and then looking and see if they matched up. If the math is so accurate it can predict reality that it is considered sound, as all math *is* is a description of reality.
Quantum and Expansion theorey have been tested in this way multiple times and they have held up to be accurate prediction of reality. One of my favorites is how well they predict the irregularities in the distribution of the stars across the sky.
I wish that they would provide the error bounds more often in the press. It is a very important part of experimental science and the concept isn’t too hard to grasp for a high school student.
And on top of that it makes us scientists seem more . . . human. “Here look we know we aren’t exact, see we even worked out how inexact we are!”.
(hmm I think of myself as a scientist, yay!)
You said: “It was designed to map the Universe with exquisite precision, detecting microwaves coming from the most distant source there is: the cooling fireball of the Big Bang itself.”
Wouldn’t the most distant point be PAST the point of the Big Bang to the other side of the expanding universe?
P.S. Ow.
josh: Gravitational waves, in principle, should be able to probe past recombination. Unfortunately, I don’t think we’ll ever detect any individual sources out that far, but there are predictions of the background fluctuations that we’d expect due to all of the sloshing around that happened in the early universe, and as an aggregate those might be detectable.
Personally, I’m happy that the new value of sigma_8 (the overall amplitude of matter fluctuations on scales of 8 Mpc) is up to 0.8… the WMAP3 value was a little low compared to all other measurements, but 0.8 makes a lot of people happy.
[TMB]
[…] 72.1% is dark energy, 23.3% is dark matter, and 4.62% is normal matter. Phil Plait over at the Bad Astronomy blog puts it best: “We occupy a razor thin slice of […]
It’s stuff like this - thinking about how much stuff is happening quadrillionths of a second after the big bang that really confuses me :S
> Space itself is not a nothing, it is ’spacetime’ which is a thing that can warp, ripple, and carry waves. This is part of relativity. Its actually (per mathematics) full of something called a Higgs field which gives things mass. Per quantum, the Higgs field is both waves and particles, or can be thought of as probability waves.
Space is not a thing - and space-time is not a thing. I suggest you read the paper I pointed to.,
G’day Science Geeks!
Now before you take that to offence… I wish I was one, I wish I could understand more about astronomy and science and how it all works!
I have a question for those who do understand: We know so much about the universe, minute details, temperatures, what colour something was when it was a few degrees colder 50 million years ago etc, what I want to know is… What is beyond the walls of the universe? What is the universe expanding into? Where is it going? Where does it end and what is beyond that?
Cheers!
Mathew in Asutralia
> What is beyond the walls of the universe? What is the universe expanding into? Where is it going? Where does it end and what is beyond that?
There are no walls in the universe, so no beyond to worry about
Cusp in Australia (wonder if its the same bit as Matthew)
The total of percentage of dark matter, dark energy, and normal energy is 100.02%. So, my question is, why does the sum of all things equal more than what can be possible by the current laws of physics and mathematics?
In the capital north of the monolith!
Ok.. I understand the Universe is a complete different dimension, but how could i explain to my 7 year old (me inclusive) the answer to where does the universe end… and then he asks what is behind that, then what is behind that etc?
Is there a physical example that makes understanding it easier?
Cheers Cusp
As a creationist… anytime I hear the terms “millions” and “billions” of years… It reminds me of another fairy tale I heard that begins with …
” a long time ago, in a galaxy far far away ”
Basically when any “scientist” says such absurd things, and rounds off to the hundreds of millions (and then claims their numbers are accurate) you must be skeptical.
I would like to ask *since its not on the study page, or on this one* what is the dating method they used… in other words… isn’t this whole dating thing based upon the obviously MADE UP and clearly flawed geologic column timetables?
The interconnectedness of the branches of your socalled science will be its downfall… since you can prove the geologic column dating is totally wrong, then the dating that the astronomers use to calculate the age of the universe is ALSO totally wrong.
HAHA
rotflmao!
Back to the darwin board boys!.. whoops I mean DRAWING board
We are along way apart - I’m in the place with the pretty bridge and opera house
Given the current cosmological model - the universe is infinite in extent - it just goes on and on and on and on. This means if you head off, you can fly for an infinite amount of time and just keep going - no walls or boundaries, no outside.
Although, funnily enough, you can’t explore an infinite amount of the universe in infinite time.
[…] from the WMAP probe have nailed down lots of cool stuff — literally — about the Universe.read more | digg […]
Well I hope you’re a Swans supporter… Thanks for your help!
This is all lies, see the Scientology timeline of the universe. We don’t need proof, just lies.
that’s nice..
but what put me in awe here is how creative this article is made..
great post! more power!
–
btw, does anyone know how long WMAP has been detecting these kind of things? you can’t just send a detector 10 minutes in open space and receive results already, so I was wondering how long was it reading these waves..
I couldn’t focus on the article thanks to the ad-picture of the chick on the right.
Phil started out his post with:
“Happy birthday, Universe!
Kinda. It’s not really the Universe’s birthday,”
which reminded me of a story originally published in one of those science-fiction comic books back in the 50s or early 60s (which I came across some years later, probably sometime in the 80s). In the story, one day strange objects appeared on Earth, and as usual in such stories scientists were baffled. At the end it turned out that the objects were gifts from the other planets in the solar system because that day was the Earth’s four billionth birthday . . .
(When the story was written you could still find mention of the hypothesis that the planets formed as the nebular disk around the Sun shrank, and periodically threw off a ring from the outside edge which condensed into a planet, hence the planets formed at different times, with Pluto — still considered a planet in those long-ago days
— therefore being the oldest planet and Mercury being the youngest . . .)
Cusp
“Expanding Space: the Root of all Evil?” An excellent paper.
However, from the experience of trying to explain the ‘big bang’ to a variety of students for the last forty years or so I still find it difficult to do so without resorting to mathematics that only a few understand. I keep looking for metaphors other than the balloon; which is misleading and always leads to the ‘Expanding into what?’ question. As but one more attempt, I offer the following; please tell me if it helps:
Suppose there is an elastic band; a very long one. The band has very small dots on it; one dot for each and every integer that exists beginning with 1. So we have dots for 1,2,3,4,…. (keep counting for as long as time is!) … one dot for each count! The dots are very small and close together - touching even - but distinct. This situation is the universe (if you look in one particular direction) at the moment of the ‘big bang’. No matter how small you make the dots for each integer: How long is the elastic band?
For some reason - (the reason is another story) - the elastic band begins to stretch (’the big bang’). Think what any one of the integers ’sees’ looking either in the direction of either the larger, or the smaller integers as the band stretches.
Now suppose that, no matter what direction you look, you see another elastic band that is identical to the one above.
If you consider any instant in time and you look about you in the universe of integer dots described above, you can use plane old Euclidean geometry for everything - the universe if ‘flat’. If you have to include time, then things are different - things aren’t where they where so the universe of space-time isn’t flat.
Was this any less confusing???
Is there anything here that demands that the understanding of our ‘universe’ is truly a Universe, and not a local system amid a really True Universe? There are threads which speak of a universal existence of time and space, without beginning or end, within which such a universe as we exist in sparks into existence. I know, we are only aware of things that begin and end, so can’t reasonably grasp things that have no beginning or end. But, I’m asking, is our known universe reasonably known to be the only existance?
WHERES YOUR GOD NOW?!
Another question I had was this. In the image the red spots are condensations of matter that will someday evolve into galaxies and the blue spots are voids where there is less matter, is that correct? Then can we pinpoint the red spot that will someday evolve into our Milky Way galaxy or our Local Group of galaxies or our part of the universe? Is that possible to do?
O.K. I’m getting more and more confused by the term “flat”. It was my prior understanding that in a flat or open universe if a traveller travels in a straight line (defined by a beam of light) then he or she will never come back to the same point. In a closed universe the traveller returns to the same point after travelling in a straight line. Clearly in the toroidal universe being described as “flat” a traveller travelling in a straight line returns to the same point. So there seems to be a different definition of what “flat” means in this case. I’m using the definition contained in this posting when I speak of a flat universe.
I’m rather impressed, btw, at everyone’s ability to ignore the ‘trolls’ in the comments above and attempting to make things clearer to those who want to get it, but haven’t quite gotten it yet (like myself).
You all show an incredible level of maturity.
As for the article, for something science related, it was a fresh breath of fun to read. Good job.
Tom, Its more like a disk, if that helps. Plus the outside link said 2% varitation. All gravity tends to form a disk shape over time, like our solar system, so this isnt anything new.
Mike J said : The interconnectedness of the branches of your socalled science will be its downfall…
Totally agree. What has science done for us?
The intertube.
Ok, except for the intertube what has science done for us?
Modern medicine.
Except for the intertube and modern medicine what has science done for us?
Industrialisation has allowed a good chunk of humanity to devote free time to art and sport and the pursuit of happiness instead of the daily drudge of attending to essential needs.
Except for the intertube, modern medicine and industrialisation what has… ah fudge.
Quote: What they got was: the Universe is 72.1% dark energy, 23.3% dark matter, and 4.62% normal matter.
Not really…
WMAP mainly measures the difference between the incident microwave radiation from two foci. It does not measure dark energy or anything of the sort.
When the WMAP data are used to constrain the parameters of the theoretical Lambda-CDM model of the universe, the given values are predicted with some level of confidence. Whether they turn out to be correct depends entirely upon the validity of the model.
The putative dark energy is a derived quantity in the model. It has not been measured directly by WMAP or anything else. It is a numerical parameter that is necessary to make the model fit the observed data.
Tossing off a value for the fraction of the universe that is dark energy without context is fanciful, to say the least.
Mathematical models predict all sorts of things that might or might not be confirmed, such as gravitational waves and particular real values for the vacuum energy and so on. We should be aware that modeling is new and interesting, but not necessarily predictive.
Science is the process of deriving generalizations from the iterative testing of hypotheses through experimentation. WMAP is not, strictly speaking, an experiment and Astronomy is not, strictly speaking, a science. To forget this is to make fools of ourselves.
Oops. Sorry Chris. Engaged keyboard before engaging brain.
Otherwise this blog post and nearly all comments above have been really elucidating. Thanks.
@Tom Marking
Flatness is a local property, not a global one. The question of whether space is curved on average (locally) is independent of the question of whether it has a finite or infinite global geometry. I really recommend the wikipedia article on the shape of the universe if you want more details.
Apparently there’s also some potential confusion stemming from the fact that cosmologists use “open” and “closed” to describe the curvature, whereas mathematicians use those terms to talk about the global geometry.
If we’re at critical density now, how long have we been there, and how long before it begins some sort of Einsteinian curve and everything collapses?
Could we use this data to predict the end of the universe just as accurately?
Odds are, our galaxy will have merged with another by then and everything will be atomized anyway, but it would be nice to know in a Death Clock sort of way.
I am scientific sceptic, only to the point where I the type of person who doesnt just read something and believe and argue for it without corroborating evidence/proof/research. That said, I have a couple of questions:
What exactly do you mean in this point -
1) The age of the Universe is 13.73 billion years, plus or minus 120 million years. Some people might say it doesn’t look a day over 6000 years. They’re wrong.
Can you back up the ‘They’re wrong” bit? I understand creationists beleive the universe is only about 6000-10,000 years old, but scientific positions on this point out that many scientists are abandoning the Big Bang theory (yes, it is just a theory). And, if the universe was created, would it not be created “mature”? When a watchmaker creates a watch, he makes it so its all working from the start, not as an infant watch with half a band, a couple of gears and a small winder, in the hope that it will grow into a mature watch. This perhaps explains why there is the possibility of a universe which is physically mature but only 6000-10,000 actual years old.
—————-
My second question is where the rules for the Big Bang (if we consider it to have occurred) came from. Everything in the universe has a set of rules it follows, so the Big Bang must have had rules for it to have occurred yes? I mean, something had to have been there to bang, and those things must have banged for a reason…stuff doesnt just bang without a cause. So who or what made the rules the Big Bang had to follow?
[…] The Universe is 13.73 +/- .12 billion years old! […]
[…] to the Wilkinson Microwave Anisotropy Prob (WMAP), we now know, the universe is Flat (within a 2% margin of error) and 13.73 Billion Years old (+/-120 million years). How can something be “flat” within a two-percent margin of […]
David, assuming you’re not trolling and you genuinely interested you may not be aware you’re propagating a couple old canards, and I don’t mean ducks, that might make a few around here suspicious that you’re a troll. Specifically the watch thing, the it’s just a theory thing and the first cause thing.
So maybe you could clarify a couple of thing first.
1. Can you provide evidence that many scientists are abandoning the Big Bang theory?
2. Can you define theory?
3. Who is maker of the rules?
4. Who/what made the maker of the rules?
Of course you realize this is only an estimate of how long it has been since the big bang, and not the age of the existing matter of the universe, there’s nothing to say there was no universe before the big bang. Should have been made with a proper title.
In response to david, if he believes in creationism of any sort then things to bang all the time without reason.
Not trolling at all. They are genuine questions. I read an article in New Scientist about the scientists questioning the validity of the Big Bang and trying to find another more plausible explanation. I cant remember the issue number or I would provide it. So perhaps we disregard that statement.
A theory is a set of ideas/hypotheses which attempt to explain something. Why did you need a definition for this?
My very question was, although perhaps hidden in the statement, exactly what you have asked Shane; “Who[/what] is the maker of the rules?” They cant have just existed…nothing ‘just existed’…at least, it doesnt makes sense to me that stuff could just exist.
The last question is one of perpetual mystery…who created the rules, who created that entity, and who created them and so on…it could go on forever. So for the sake of simplicity, lets keep it at one entity creating the rules…if that is indeed what happened. Or is the universe simply one of the marbles in the pocket of a being - as it was so portrayed in ‘Men In Black’
I am a layman and not very well acquainted with the upper levels of astronomy and physics, but what I have learned so far from this discussion is the universe is infinite with a finite amount of matter, it is shaped like a disc sort of like a cd without the hole, and no matter how fast you go in a straight line you will never reach the edge. Things that are still confusing and seem rather pesky are whether space is expanding which I take to mean something like the volume of space inside the universe is expanding or whether space is not a thing and can’t expand.
Anyways this was an excellent article that makes me feel awed by what science has the possibility to show to us with a reasonable margin of error. I love it when reason and sense help humanity grow and change in such interesting ways.
No. The CMBR originates at every point in space, but anything local is long since gone; what we observe is coming from a great distance.
Imagine you’re standing in the middle of a pond in a hail-storm. When the hail stops, all that’s left is circular ripples from the last impacts, expanding outwards from every point in the water. The ripples from impacts nearest you will pass your position early, never to be seen again. As time passes, ripples from further and further away will reach you. If all ripples are travelling at the same speed, at any given time the ripples arriving at your location originated on a circle centered on you.
The CMB is like this; it permeates the Universe, travelling in all directions. But we can only see those CMB photons which originated on a spherical shell centered on our location.
No, you’re conflating two separate concepts, curvature and topology. The simplest cosmological models all have trivial topology - they are simply connected. A flat, simply connected manifold has the property you describe. The torus is a flat, multiply connected manifold.
That’s true of everything. You can’t tell me what colour your socks are without assuming the validity of some model or other.
There’s a difference between appearance of age and appearance of history. A watchmaker would certainly make a complete product, but he wouldn’t crack the face, tarnish the metal, and fray the strap to make the watch appear older than it really is, unless he wanted to deceive us.
Similarly, a creator might want to make a Universe complete with stars and galaxies, but if this Universe is that Universe, then what are we to make of distant supernova? Apparently, the creator saw fit to create streams of light carrying images of stars which never existed in the first place. This isn’t maturity, it’s history. Same for the Earth; a mature planet doesn’t need a history showing billions of years of continental drift, for example.
Of course, it’s always possible that a vastly powerful being is trying to deceive us as to the true nature of the Universe, but that’s hardly a useful hypothesis.
And the reason you were asked to define ‘theory’ is because you pulled out the ‘just a theory’ canard. You seem to be under the impression that theories are uncertain, shaky models which could be thrown out tomorrow. On the contrary, theory is the pinnacle of scientific method. We have atomic theory, germ theory, the special and general theories of relativity, quantum theory, the theory of evolution. In none of these does ‘theory’ denote uncertainty. Everything on that list is as close to certainty as science can ever come. These are some of the greatest achievements of science.
No. The map is not the territory. Everything in the Universe can be described by a set of rules. There’s a difference.
Why is one simpler than none? Do rules always need rule-makers?
Oops, missed that one. If stuff can’t ‘just exist,’ then where does that leave us? If the Universe doesn’t ‘just exist,’ and the creator doesn’t ‘just exist,’ then we’re stuck with either an infinite regress or a causal loop. In either case, the creator doesn’t seem to add anything.
No. The finite speed of light allows us to see only a finite section of the Universe, which contains a finite amount of matter. The simplest models consistent with observation are spatially infinite, and contain an infinite amount of matter, evenly spread (to a reasonable approximation) throughout.
Sayeth the BA :
“We occupy a razor thin slice of reality.”
Reality - whats that?
Some would say 5 % is about my grip on sanity too!
Not me though! Naturally!
Of course, what;s relauty does depend on how much you’ve drunk …
How Coopers pales is that now … ?
*!@!!@!!##@!##!@ cosmology! Give me stellar stellar astrosphysics anyday! That I can get my head around ..almost .. !
“How Coopers pales is that now … ? ”
Shouldn’t that be :
“How *many* Coopers pales is that now … ? ” [Best beer in Oz!]
I’m guessing it should be! & I’m guessing quite a few!
“# Mentionableon 07 Mar 2008 at 4:33 am
“How Coopers pales is that now … ? ”
Shouldn’t that be :
“How *many* Coopers pales is that now … ? ” [Best beer in Oz!]
I’m guessing it should be! & I’m guessing quite a few!”
Da