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The Universe is Pretty Big
Psiolent writes "According to a recent article on Space.com, the universe is pretty big (156 billion light years across, to be more precise). Some recent research examining 'primordial radiation imprinted on the cosmos' has led to this conclusion, as well as a few others. This finding is particularly interesting considering the universe is only 13.7 billion years old (which would mean the universe has been expanding faster than light travels), but the article does a good job addressing this seeming paradox."
Um, not quite. If you had RTA, you would understand that the reason the radius of the universe is so large (relative to it's age) is the hubble expansion of the universe. According to current theory, the universe has been expanding since the big bag at an increasing rate. This expansion is not governed by special relativity, and a result of this expansion is that if something travelled 1 light-year in the early universe, it has now travelled something on the order of 1000 light-years. And yes, IAATP (I am a theoretical physicist (in training, at least))
There's no sig like SIGSEG
Somehow this seems like something that should be in the scientific equivalent of the Weekly World News, or the National Enquirer....
Read this quote.... (which seems to provide a basis for other comments)
"The universe is about 13.7 billion years old. Light reaching us from the earliest known galaxies has been travelling, therefore, for more than 13 billion years. So one might assume that the radius of the universe is 13.7 billion light-years and that the whole shebang is double that, or 27.4 billion light-years wide."
What is our frame of reference here.... Are we still assuming we are the center of the universe, even after all the progress we've made in a variety of sciences???
Doesn't this seem to rule out the possibility of light which simply hasn't reached us yet (i.e. if we were NOT located in the middle of the Universe and it was in fact still expanding)?
Of blankness, I know nothing.
As the previous answer noted, you're a little confused about the Carbon-Nitrogen-Oxygen (CNO) cycle. In these set of reactions, the carbon is only used as a catalyst for making helium (so you're still turning H -> He, but you're doing it by repeatedly capturing protons (H) and then beta-decaying). See this article for more information on CNO.
Now the argument that the referenced article is using is that less massive stars will stay on the main sequence longer, due to the reduction in CNO efficiency. Thus older globular clusters will have a bluer turnoff than previously expected.
While this will cause a systematic underestimation of the age of globulars by ~0.7-1.0 Gyr, the uncertainties are so large (+/- 1-1.5 Gyr or so), that they are still consistent with the age of the universe derived from CMB observations.
Doug
Venn ist das nurnstuck git und Slotermeyer? Ya! Beigerhund das oder die Flipperwaldt gersput!
I am no scientist, so please forgive. How come the distances between objects seem to be increasing ( space time expansion or so they say) but not their size? What makes matter so special that the space time between molecules is not expanding as well? What makes our perception so special that only the distances between objects we like to observe ( galaxies, stars) increases but not the distances within them?
___
No power in the 'verse can stop me
I'm surprised no one has brought this up yet, and I apologize if this seems out of context for me to be commenting, since I'm a musician and a composer, but has anyone read the article and felt that all of this information "makes sense" only if Earth is the center of the creation of universe?
We can measure the distances to far off galaxies to get a "radius", but a "radius" implies a center, primarily the Earth. I have some serious problems with us, because it implies that the "Big Bang" occurred right here, where we are now in the universe. Absolute and utter bull.
Cornish's "explanation" does not make up for the idea that we are not at the center of the creation of the universe. 156 billion light years is not a good number to go by, then, because it doesn't take into account for how far we are from the creation site.
Unless Cornish or anyone else can pinpoint exactly where the Big Bang (or Big Burp or whatever else it's been called over the years) has occurred, this article is completely and utterly pointless.
Please prove me wrong. I study Debussy and Schoenberg, so I may have no right commenting, but this seems like common sense to me.
- wafwot
First off, IANAQP. Most of my modern cosmology and quantum physics comes from SciAm, Brian Greene books, and conversations with Tripoli Rocketry Association member #004. The last time I did tensor calculus was when I looked up Frank Tipler's paper "Rotating Cylinders and the Possibility of Global Causality Violation" twenty years ago. Yes, that is the paper Larry Niven used as the name for a story.
So, based on my rather crude understanding of the whole mess, the answer to your question is "yes." We don't see the extra dimensions in our universe because they are curled up and small. If you look out your window at a telephone wire, the wire appears to be 1 dimensional - it only has length. A closer look shows that the second dimension is "wrapped" around and meets itself.
These dimensions are thought to be exceedingly small, although some string theories allow for the possibility that they could be as big as a millimeter in diameter. The last experiment I remember reading about indicated that, while a millimeter might be too big, they couldn't rule out dimensions on the order of .1 mm. If one of the dimensions is that large, we should soon be able to measure the failure of the inverse square law at very small distances, where gravity leaking into the other dimensions can be seen.
If the four macroscopic dimensions (3 spatial, one time) form closed loops, we might indeed have a strange geometry in space, such as a "horn of plenty."
It's comforting to think that the 4 large dimensions curl up like the small ones. The universe can be "infinite but bounded." There's no messy questions about what happens when you reach the edge of the universe or the universe being infinite in size, although I'd still wonder what's "outside" our universe. There's a symmetry - the big dimensions are simply blown up versions of the small ones and (in some ways) the big dimensions might actually be the same size as the small ones! Measuring the diameter of a dimension can be tricky, since in string theory large and small dimensions are indistinguishable mathematically.
Alas, there's no guarantee that the 4 macroscopic dimensions have their "ends" meet. String theory can handle infinite dimensions and non-loop strings with end points as well. If you could travel far, far faster than light, you might simply keep going in one direction, never returning to your point of origin.
We may never know the answer. If the universe is far bigger than the 156 billion lyrs minimum, then we'll never see edge effects on the cosmic microwave background. The macroscopic universe might go on forever or loop back around or come to a dead stop at a giant brick wall - and we'll never know.
There are two major problems with current quantum cosmologies. One is that they're exceedingly and increasingly difficult to calculate. What good is an equation that is the "answer to everything" if there's no possible way to solve it or even come up with a decent approximation to an answer? The other problem is that there are probably an infinite number of possible theories, and even if they can be solved, the vast majority predict the same answer at any level we could ever hope to explore in any conceivable experiment.
Think of it as job security for physicists.
I wish I could find a link to George Carlin's riff on the Catholic Church's answer "It's a mystery!" It would be oddly appropriate.
This sig seemed like a good idea at the time....
One of the important points about the Picard geometry discussed in the "horn of plenty" theory is that the universe would look different depending on where you are.
As we look around, the universe appears to be pretty much the same in any direction we look. The fine structure constant and other important physical numbers appear to be same here on earth and in the farthest galaxy we see. There is some question if these constants might have changed over time, but the change is thought to be far, far less than the change one would expect being in the strange part of a Picard universe.
The diameters of the "rolled-up" dimensions are thought to affect the properties of the forces and sub-atomic particles we observe. Why those properties are what they are is one of the great mysteries of Quantum Mechanics and Cosmology. An argument can be made that, if the numbers were different, we wouldn't be here to observe that difference. Some have argued that the numbers are deliberate - that God (or some researcher) caused those numbers to be what they are so that either a) life would exist or b) the universe would be "interesting" (like choosing which rules to use for the game of Life.
Would the diameter of the the rolled-up dimensions be affected in an extreme section of a Picard universe? That's a good question. I'd be tempted to say "no." There are places near a black hole where light orbits - in other words, if you look forward, you can see the back of your head! This is similar to the way the Picard universe behaves at an extreme point. Atoms being torn apart in the accretion disk of a black hole seem to have the same physical constants as atoms on Earth. So that would indicate that no, it doesn't change the smaller dimensions. But who knows? Perhaps a Picard extreme region behaves differently from a black hole region in our section of the universe. Our understanding of why the universe "is the way it is" is primative. My understanding, of course, is far more primative than Hawking, Greene, or Thorne.
I have a crude vision in my mind of a universe where, depending on where you are, you see different dimensions rolled up. Properties would change as you moved from one region of the universe to another - each region being far in excess of 156 billion light years in diameter. My topological intuition begins to fail me, though, and I'm getting a major migrane as a result! I should check to see if my brains are being squeezed out my ears.
I really would suggest that you read Greene's books. In the first one, you might find yourself skipping some of the math. I read through it and humored myself by thinking that I understood the math. I do find that Greene has a wonderful way of tying what you already know into what he's trying to explain.
This sig seemed like a good idea at the time....