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Hints of structure beyond the visible universe
by New Scientist
Thanks to GP for the link.
http://space.newscientist.com/article/dn14098-hints-of-structure-beyond-the-visible-universe.html?feedId=online-news_rss20
Hints of structure beyond the visible universe
Colossal structures larger than the visible universe – forged during the period of cosmic inflation nearly 14 billion years ago – may be responsible for a strange pattern seen in the big bang's afterglow, says a team of cosmologists. If confirmed, the structures could provide precious information about the universe's earliest moments.
In the first instant after its birth, the universe is thought to have experienced a rapid growth spurt called inflation. During this period, space itself expanded faster than the speed of light.
Inflation solves some cosmological puzzles, such as why relic radiation from the big bang, released when the universe was less than 400,000 years old, is relatively uniform.
Called the cosmic microwave background (CMB), the radiation can be observed in all directions in the sky. It has a slightly mottled appearance due to small differences in temperature from place to place in the early universe. The temperature differences are thought to be caused by variations in the density of matter, with denser regions being warmer than emptier regions.
But the theory of inflation predicts that the mottling should be equally prominent in all directions. Curiously, it is 10% more pronounced on one side of the sky than the other, an asymmetry that was reported in 2004 by Hans Eriksen of the University of Oslo in Norway, based on a map made by the Wilkinson Microwave Anisotropy Probe (WMAP) satellite.
Now, cosmologists led by Adrienne Erickcek of Caltech in Pasadena, US, think they may have found the reason for this pattern. They suggest the universe has been skewed by the imprint of primordial structures that date back to the period of inflation.
Extra field
The structures stretch beyond the edge of the observable universe, which is essentially confined to a region with a radius of 14 billion light years, since only light from within that distance has had time to reach us since the big bang. The entire "global" universe is about 10100 times as large as the universe we can see.
In the inflation scenario, the expansion is driven by an energy field of still-mysterious origin. Erickcek and her colleagues argue that the asymmetry could be the remnant of fluctuations in an additional energy field, which started out very tiny, but were blown up by inflation until they were larger than the observable universe.
As a result, the value of this energy field varied from one side of the universe to the other at early times, enhancing the variations in temperature – and matter density – on one side of the sky relative to the other.
The conclusion, if correct, would shatter a cherished assumption about the universe. "One of the basic tenets of cosmology is that the universe is the same in all directions, and the standard model of inflation is built on that foundation," Erickcek told New Scientist. "If the asymmetry is real, then it tells us that one side of our universe is somehow different than the other side."
Few and far between
The asymmetry could theoretically be explained by the standard, single-field inflation scenario, though researchers say that is unlikely. That's because the standard theory allows for a few large-scale differences across vast regions of space. But these asymmetrical spots are expected to be few and far between, meaning that there is only a 1% chance that our observable universe would happen to occupy one.
Charles Bennett of Johns Hopkins University in Baltimore, Maryland, US, the chief scientist for the WMAP mission, notes that Erickcek's team has predicted additional subtle differences in the CMB compared to the standard inflation picture.
These predictions could be tested when more sensitive CMB maps are available. "It might be within reach of WMAP, and it will be within reach of Planck," he told New Scientist, referring to the European Space Agency satellite scheduled to launch later in 2008 to scrutinise the CMB.
Mysterious era
If further observations bear out the scenario, it would provide some precious new information about the universe's earliest moments, about which little is known. "It was a period of extremely rapid expansion, but what drove that expansion and how long it lasted is an open question," Erickcek says.
Alan Guth of MIT in Cambridge, Massachusetts, US, one of the scientists who pioneered the inflation idea in the 1980s, says inflation is only the framework of a theory, with many details remaining to be filled in.
He says the team's "well thought-out" analysis is just the kind of thing needed to help do that. "Although the hint [from asymmetry] may very well turn out to be a fluke, it is only by pursuing such hints that new ideas will be generated, and that ultimately we will have a chance to find the right theory," he told New Scientist.
The asymmetry is distinct from another curious pattern in the CMB called the axis of evil, which some scientists have proposed is also a remnant of exotic physics during inflation.
Cosmology - Keep up with the latest ideas in our special report.
http://space.newscientist.com/article/dn14098-hints-of-structure-beyond-the-visible-universe.html?feedId=online-news_rss20
Hints of structure beyond the visible universe
Colossal structures larger than the visible universe – forged during the period of cosmic inflation nearly 14 billion years ago – may be responsible for a strange pattern seen in the big bang's afterglow, says a team of cosmologists. If confirmed, the structures could provide precious information about the universe's earliest moments.
In the first instant after its birth, the universe is thought to have experienced a rapid growth spurt called inflation. During this period, space itself expanded faster than the speed of light.
Inflation solves some cosmological puzzles, such as why relic radiation from the big bang, released when the universe was less than 400,000 years old, is relatively uniform.
Called the cosmic microwave background (CMB), the radiation can be observed in all directions in the sky. It has a slightly mottled appearance due to small differences in temperature from place to place in the early universe. The temperature differences are thought to be caused by variations in the density of matter, with denser regions being warmer than emptier regions.
But the theory of inflation predicts that the mottling should be equally prominent in all directions. Curiously, it is 10% more pronounced on one side of the sky than the other, an asymmetry that was reported in 2004 by Hans Eriksen of the University of Oslo in Norway, based on a map made by the Wilkinson Microwave Anisotropy Probe (WMAP) satellite.
Now, cosmologists led by Adrienne Erickcek of Caltech in Pasadena, US, think they may have found the reason for this pattern. They suggest the universe has been skewed by the imprint of primordial structures that date back to the period of inflation.
Extra field
The structures stretch beyond the edge of the observable universe, which is essentially confined to a region with a radius of 14 billion light years, since only light from within that distance has had time to reach us since the big bang. The entire "global" universe is about 10100 times as large as the universe we can see.
In the inflation scenario, the expansion is driven by an energy field of still-mysterious origin. Erickcek and her colleagues argue that the asymmetry could be the remnant of fluctuations in an additional energy field, which started out very tiny, but were blown up by inflation until they were larger than the observable universe.
As a result, the value of this energy field varied from one side of the universe to the other at early times, enhancing the variations in temperature – and matter density – on one side of the sky relative to the other.
The conclusion, if correct, would shatter a cherished assumption about the universe. "One of the basic tenets of cosmology is that the universe is the same in all directions, and the standard model of inflation is built on that foundation," Erickcek told New Scientist. "If the asymmetry is real, then it tells us that one side of our universe is somehow different than the other side."
Few and far between
The asymmetry could theoretically be explained by the standard, single-field inflation scenario, though researchers say that is unlikely. That's because the standard theory allows for a few large-scale differences across vast regions of space. But these asymmetrical spots are expected to be few and far between, meaning that there is only a 1% chance that our observable universe would happen to occupy one.
Charles Bennett of Johns Hopkins University in Baltimore, Maryland, US, the chief scientist for the WMAP mission, notes that Erickcek's team has predicted additional subtle differences in the CMB compared to the standard inflation picture.
These predictions could be tested when more sensitive CMB maps are available. "It might be within reach of WMAP, and it will be within reach of Planck," he told New Scientist, referring to the European Space Agency satellite scheduled to launch later in 2008 to scrutinise the CMB.
Mysterious era
If further observations bear out the scenario, it would provide some precious new information about the universe's earliest moments, about which little is known. "It was a period of extremely rapid expansion, but what drove that expansion and how long it lasted is an open question," Erickcek says.
Alan Guth of MIT in Cambridge, Massachusetts, US, one of the scientists who pioneered the inflation idea in the 1980s, says inflation is only the framework of a theory, with many details remaining to be filled in.
He says the team's "well thought-out" analysis is just the kind of thing needed to help do that. "Although the hint [from asymmetry] may very well turn out to be a fluke, it is only by pursuing such hints that new ideas will be generated, and that ultimately we will have a chance to find the right theory," he told New Scientist.
The asymmetry is distinct from another curious pattern in the CMB called the axis of evil, which some scientists have proposed is also a remnant of exotic physics during inflation.
Cosmology - Keep up with the latest ideas in our special report.
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Posted: Tuesday, June 10, 2008 | PermalinkComments 1 - 50 of 56 |
Reload Comments | Back to Top | Page Numbers2. Comment #191062 by mmurray on June 10, 2008 at 6:57 am
The entire "global" universe is about 10100 times as large as the universe we can see.
What is that 10100 ? Wikipedia gives 14x 10^9 light years for the radius of the visible universe and 78 x 10^9 light years as a lower bound on the radius on the whole universe based on the sphere occupied by the cosmic background radiation.
Michael
Other Comments by mmurray
3. Comment #191070 by GBile on June 10, 2008 at 7:07 am
mmurray,10100 might be a typo for 10-100, somewhere between 10 times or 100 times. Does that make sense ?
Other Comments by GBile
4. Comment #191081 by Geraint on June 10, 2008 at 7:33 am
If you look at the original article, it's 10^100 (ten to the power of one hundred). Sub- and superscript formatting often seems to get killed.Other Comments by Geraint
5. Comment #191097 by GBile on June 10, 2008 at 7:56 am
Geraint,If 10^100 is true ... wow !
You might get lost in such a place.
Other Comments by GBile
6. Comment #191111 by rod-the-farmer on June 10, 2008 at 8:25 am
"Seems like an awful waste of space", he said, origin-ally. Other Comments by rod-the-farmer
7. Comment #191123 by mordacious1 on June 10, 2008 at 9:00 am
I like the caveat, that this is only the "framework of a theory". This area of cosmology is getting a lot of interesting info lately, but it's going to be awhile before solid theories can be put forth.Does anyone know if this asymmetry was predicted by anyone? or was a complete suprise? I would expect the big bang to have been symmetrical, maybe because everyone else did. Interesting stuff.
"A rapid growth spurt called inflation". Well, that part I can argue with, inflation continues today, and hopefully for awhile still. Big crunches are hard to deal with.
Other Comments by mordacious1
8. Comment #191125 by 7Fred7 on June 10, 2008 at 9:04 am
Cor! Big init!Well, the predictions will be tested pretty soon, thanks to the accelerating expansion of science and technology.
"A rapid growth spurt called inflation". Well, that part I can argue with, inflation continues today, and hopefully for awhile still. Big crunches are hard to deal with.The (theorised) inflation was something a special. Like an almost instantaneous change in dimensions from the microscopic to the astronomical. Different to the expansion we see now.
Other Comments by 7Fred7
9. Comment #191141 by Synchronium on June 10, 2008 at 9:34 am
If you look at the original article, it's 10^100 (ten to the power of one hundred). Sub- and superscript formatting often seems to get killed.
Formatting aside, I'd still rather read the articles on here without getting about 3 popups trying to sell me something.
Other Comments by Synchronium
10. Comment #191147 by Double Bass Atheist on June 10, 2008 at 9:43 am
Interesting article.
Unfortunately, it will simply become just another item for creationists to misquote and/or mischaracterize. All the creotards are going to hear is "structure beyond the universe".
...another example of "god's perfect plan."
...or, See, science has shown that there was always order in the universe, immediately after creation."
Now we all know that this precisely NOT what the cosmologists are saying, but that certainly won't stop the creotards.
Other Comments by Double Bass Atheist
11. Comment #191165 by ridelo on June 10, 2008 at 10:06 am
"Seems like an awful waste of space", he said, originally.Or: "Seems like an awful waste of real estate", he said, still more originally.
Other Comments by ridelo
12. Comment #191169 by mordacious1 on June 10, 2008 at 10:08 am
7Fred7Yes, I realize your point. But the word "inflation", can be used either way. For example, Some suggest that we have: inflation, crunch, inflation, crunch...These guys use inflation to mean expansion, including the rapid inflation immediately after the BB. I know it's just semantics, but I prefer: rapid inflation, or rapid expansion for right after the BB. Then inflation or expansion there after, though you're right when you suggest that most cosmologists use expansion for the later time, it gets confusing for people who don't understand the diff.
Other Comments by mordacious1
13. Comment #191191 by kaiserkriss on June 10, 2008 at 11:02 am
" Hints of structure beyond the visible universe"
Don't they get it, that's obviously HEAVEN. (sarcasm) jcw
Other Comments by kaiserkriss
14. Comment #191199 by Scep on June 10, 2008 at 11:13 am
It is good to see comments like this on other blogs. This one is from the Huffington Post, written by a man who knows all about (un)reality:Dr Chopra writes, "The second reason for today's bad news is an addiction to unreality".
There is another addiction to unreality, it is bad news too. It is when seemingly normal people are threatened and intimidated by logic, reason and critical thinking. On your own blog, intentblog.com, comments promoting these traits are often removed.
The latest removal is a report that a team of physicists has claimed that our view of the early Universe may contain the signature of a time before the Big Bang.
http://news.bbc.co.uk/2/hi/science/nature/7440217.stm
So on one hand you, or whoever looks after IB, remove scientific opinions but go on telling us that you "know" that there is "Life after Death". Or you cite that bizarre University of Virginia study that to date has found over 2,000 children who vividly remember their past lives . . . Even more astonishing, over 200 of these children exhibit birthmarks that resemble the way they remember dying in their most recent lifetime. http://dangerousintersection.org/2007/02/28/the-great-afterlife-debate-michael-shermer-v-deepak-chopra/
In "Peace is the Way" you even tell us that mental spoon bending is a fact our culture is trying to deny us. You tell us how you and your wife have been part of many spoon-bending get-togethers.
Thank goodness for Arianna's blog, here everyone is welcome no matter how addicted one is to unreality or reason.
Note: Dr Chopra once called Richard Dawkins a bigot because of a disagreement about consciousness.
Other Comments by Scep
15. Comment #191203 by A.Lex on June 10, 2008 at 11:20 am
10^100 = googol!Other Comments by A.Lex
16. Comment #191205 by Drool on June 10, 2008 at 11:22 am
Synchronium, use Firefox.But these asymmetrical spots are expected to be few and far between, meaning that there is only a 1% chance that our observable universe would happen to occupy one.When I read that, I immediate thought of the anthropic principle.
If our "observable universe" lies within asymmetrical (hot?)spots, would it not be difficult to determine if even the laws of physics in other regions are the same as ours (i.e. no 'boundary condition'). Was it Stephen Hawking who said that if one element of the laws of physics were ever-so-slightly 'off', conditions probably wouldn't support a life-sustaining universe?
If the structure and physical laws vary across the unseen global universe, might we be fortunate enough to be placed [edit: sic] in a spot that is "just right"? Or maybe I've completely misunderstood the article, my scientific knowledge of the field is at best, poor. :)
Other Comments by Drool
17. Comment #191209 by Scep on June 10, 2008 at 11:40 am
Ref 16. Comment #191205 by Drool'If the structure and physical laws vary across the unseen global universe, might we be fortunate enough to be placed in a spot that is "just right"?'
This must be the case. Even in a "Multiverse Universe" we are in the one that permits complexity to arise from simplicity.
The anthropic principle: cosmological version.
Richard Dawkins says that we can now apply these principles to the existence of the universe. He says that physicists have calculated that if the laws of nature that govern this universe were just slightly different, then the evolution of life would not have been possible.
Other Comments by Scep
18. Comment #191212 by Barry Pearson on June 10, 2008 at 11:48 am
mordacious1 said: I like the caveat, that this is only the "framework of a theory". This area of cosmology is getting a lot of interesting info lately, but it's going to be awhile before solid theories can be put forth.
Last week's New Scientist had an article about problems with "Inflation". The complete article isn't available free online:
http://www.newscientist.com/channel/fundamentals/mg19826591.500-inflation-deflated-the-big-bangs-toughest-test.html
http://arxiv.org/abs/0712.1148
Evidence one way or another will be arriving over the next year or two!
Other Comments by Barry Pearson
19. Comment #191215 by huzonfurst on June 10, 2008 at 11:53 am
I have a Bachelor's degree in astronomy and physics and still think the concept of faster-than-light inflation of space is absurdly ad hoc, considering the leap of 'faith' it takes that such a thing is even possible. Apparently it's the only way to get from the early Big Bang to the present universe, but what the theorists really mean is "it's the only way we can think of so far." It was still called the inflationary *hypothesis* the last time I looked.Einstein never fully accepted quantum physics and I've never fully accepted inflation. Another example of the essential similarity of our thought processes ;>).
PS: Deepak Chopra is a frickin' idiot!
Other Comments by huzonfurst
20. Comment #191222 by eclampusvitus on June 10, 2008 at 12:11 pm
And now for something completely different.Huzon, my Los Angeles Dodgers have a player named Hu.
I've been waiting for the announcers to say it.
PS: You're right about Chopra.
ECV
Other Comments by eclampusvitus
21. Comment #191223 by gcarrison on June 10, 2008 at 12:17 pm
Unfortunately, it will simply become just another item for creationists to misquote and/or mischaracterize. All the creotards are going to hear is "structure beyond the universe".
...another example of "god's perfect plan."
...or, See, science has shown that there was always order in the universe, immediately after creation."
Now we all know that this precisely NOT what the cosmologists are saying, but that certainly won't stop the creotards.
I think we all understand that due to the nature of creationist that they will always find some kind of argument even if its to argue that an apple is not really an apple. Just be glad that you and alot of other folk are rational enough and have enough common sense to be able to argue our point well enough to put them in their place and show them up to be intelectual idiots.
Other Comments by gcarrison
22. Comment #191227 by hoops mccann on June 10, 2008 at 12:21 pm
"...another curious pattern in the CMB called the axis of evil, which some scientists have..."
Who says that scientists are humorless?
Other Comments by hoops mccann
23. Comment #191229 by oskorei on June 10, 2008 at 12:27 pm
#1: QM has little to do with stellar structure. It is mostly rather standard thermodynamics and nuclear physics, but I see your point...;)In any case, the Universe is usually taken to be our spacetime continuum, and that is most likely finite. We use the word "multiverse" for everything else, and that is, just as likely, infinite, although such terms may not even be applicable to it.
#7: The era of inflation is defined as that time within which the universe, in a fraction of a second, inflated 10^30 times its size...or so. It is certainly over, although normal expansion is still ongoing and is, perhaps, accelerating (there are other solutions to the supernovae problem that do not involve accelerating expansion, but it is the most likely one).
Other Comments by oskorei
24. Comment #191291 by William1w1 on June 10, 2008 at 2:04 pm
King of NH:What you have suggested is possible. The thing to remember about science is that it does not make assumptions without evidence. We assume that the universe is similar to what we can currently see and that it is relatively uniform. In fact, one of the principles that you must accept in order to give credence to any version of the Big Bang theory is that the universe is uniform. Frankly, you might as well jump to the conclusion that some supernatural being created everything we can see if you're going to assume that there was something before the universe that we have no evidence for.
Other Comments by William1w1
25. Comment #191348 by perkyjay on June 10, 2008 at 4:22 pm
Synchronium: You do not have to suffer through pop-ups. There are a number of pop-up preventers available for download free. I haven't had a pop-up in 4 years - mine is called "No pop-ups".Other Comments by perkyjay
26. Comment #191367 by perkyjay on June 10, 2008 at 5:40 pm
I'm sorry Synchronium - that name should have beenno-pops.com
Other Comments by perkyjay
27. Comment #191374 by utelme on June 10, 2008 at 6:34 pm
A universe so vast that it's been estimated that there are more stars in the current universe than grains of sand on every beach on earth. Now an infinite universe posited that makes that universe seem tiny. Yet, people believe that a finger on the edge of that atom (earth) points down to a bunch of moving, talking quarks on this infinitely small spot in the middle of nowhere and is also interested in what we do. Crazy!Other Comments by utelme
28. Comment #191393 by rebelest on June 10, 2008 at 7:54 pm
huzonfirst wrote:I have a Bachelor's degree in astronomy and physics and still think the concept of faster-than-light inflation of space is absurdly ad hoc, considering the leap of 'faith' it takes that such a thing is even possible.
I don't have a degree in astronomy or physics but what I understand this faster than light expansion of space to mean (and of course I may be wrong) is that if space is expanding from some given point, at or near c then the addition of expansion in opposite directions equals space itself expanding at or near twice c.
It may be easier to think of two space spaceships that are speeding away from each other in opposite directions: each of them is traveling at three-quarters the speed of light (so neither of them is traveling at the theoretical speed limit of light) and the speed which they are moving away from each other is 2 X 3/4c = 1.5 c-the speed that they are moving away from each other is faster than c but neither spaceship is traveling at c.
Other Comments by rebelest
29. Comment #191407 by William1w1 on June 10, 2008 at 9:24 pm
rebelest:Your argument would make sense were it not for Einstein's Theory of Special Relativity. There are no absolute points in space; there is no aether.
Let's imagine galaxies instead of spaceships. Now, let us say that there are 3 galaxies in a row: galaxies A, B and C. Galaxy A is on the left, galaxy B is in the middle, and galaxy C is on the right. From our reference frame, we will claim that galaxy B is "stationary." Galaxy A is moving to the left at 60% the speed of light (c), and galaxy C is moving to the right at 60% c.
A man in galaxy A wants to send a message with radio waves (a form of light) to galaxy C. However, based on your logic, his transmission would never catch up with galaxy C because he would see galaxy C moving at 120% c. Instead, the man decides to send the message first to galaxy B, which in turn can relay it to galaxy C. AHH, but herein lies the flaw in your logic. If the message could go from galaxy A to B at 100% c, and another message could move at the exact same speed from galaxy B to galaxy C, then actually we can take galaxy B out of the entire system and the radio transmission STILL MAKES THE JOURNEY.
The reason this is possible has to do with time dilation and length contraction based on relative velocities of different systems. Read up on the Special Theory of Relativity, specifically the clock paradox. It will blow your mind.
Other Comments by William1w1
30. Comment #191413 by Scep on June 10, 2008 at 10:52 pm
"Read up on the Special Theory of Relativity, specifically the clock paradox. It will blow your mind."Stephen Hawking's "A Briefer History of Time" is a fascinating read.
Other Comments by Scep
31. Comment #191442 by oskorei on June 11, 2008 at 1:26 am
rebelest; speed of light in vacuum is a limiting velocity for travel within spacetime; spacetime itself can stretch much faster than that (there is no limit, really). If inflation is correct, which at the moment sort of hangs in the balance, that is what happened. Nothing actually travelled through space; the universe itself inflated at enormous rate until the scalar field driving that inflation collapsed. Other Comments by oskorei
32. Comment #191508 by LUCASWB on June 11, 2008 at 5:14 am
"Frankly, you might as well jump to the conclusion that some supernatural being created everything we can see if you're going to assume that there was something before the universe that we have no evidence for. "
Do we really need evidence to assume there was something before our universe. I find it easier to beleive there was something that created our universe(not an intellegent being), than to beleive our universe developed from nothing out of no where. that indeed would take some sort of divine magician.
Other Comments by LUCASWB
33. Comment #191518 by Steve Zara on June 11, 2008 at 5:35 am
Do we really need evidence to assume there was something before our universe. I find it easier to beleive there was something that created our universe(not an intellegent being), than to beleive our universe developed from nothing out of no where. that indeed would take some sort of divine magician.
Imagine the universe shrinking back to it's origin. It gets smaller and smaller, eventually much, much smaller than an atom. As it gets down to the Planck length, it is very likely that quantum gravitational effects are present. Gravity is to do with spacetime, so quantum effects mean that space and time themselves become uncertain. When time is uncertain, causality itself makes little sense, and something coming out of nothing is entirely reasonable.
Other Comments by Steve Zara
34. Comment #191558 by huzonfurst on June 11, 2008 at 8:16 am
Rebelest, the relative velocities of those two spaceships can never even equal the speed of light, even if they are flying in opposite directions at 99% of c!But that scenario is about objects moving in space, whereas the inflation of space is thought to have happened at thousands of times light speed (or millions; I don't recall the figure).
Other Comments by huzonfurst
35. Comment #191630 by LUCASWB on June 11, 2008 at 10:33 am
how can you talk about a moment in which time does not exist? if our universe is contracting and expanding then we can talk about the time when time did not exist, and what happend before that. maybe time as we know it is only do to our consciousness,which may or may not have existed before our universe. Other Comments by LUCASWB
36. Comment #191642 by William1w1 on June 11, 2008 at 11:39 am
LUCASWB:It would seem to me that it would be just as difficult to imagine an infinite universe as a universe that came from nothingness. If something caused the universe to commence, then that thing must have had a cause as well if we only use our natural sense of time. In either case, we must drop our common-sense notions of time and space.
Steve Zara's comment seems to be well in league with many quantum mechanical writings that I have read on this subject. I've read something too about how, because of virtual particles and entropy... or something, the net energy of the universe may be less than zero. Because of this, it would make more sense for the universe to exist than for it not to. I'm pretty fuzzy on the details though. Grasping Relativity is child's play when compared with trying to comprehend some of the ramifications of quantum physics.
Other Comments by William1w1
37. Comment #191678 by padster1976 on June 11, 2008 at 12:44 pm
If the visible universe is 13.7 billion years old, then if there is a much bigger section of the universe unseen, doesn't this imply that the universe could be a lot older? Other Comments by padster1976
38. Comment #191770 by LUCASWB on June 11, 2008 at 4:30 pm
william1w1
I know that I don't really know anything about this stuff, but I love to TRY to wrap my head around it. Having said that it seems to me that either scenario is very hard to imagine. Both of them seem impossible, but one of them has to be the case. It is easier for me to imagine an infinite regress than something popping out of complete nothingness. Sometimes I have to remind myself that you can't teach a dog physics.
Other Comments by LUCASWB
39. Comment #191824 by LochRaven on June 11, 2008 at 11:32 pm
I'm wondering if this 10% difference in the density of matter, and hence the 10% increased "mottled" appearance from one side of the observable universe to the other, might make sense in light of theories that our universe "bubbled" off of a larger parent universe. It seems this bubbling would have had to occur in a specific "direction", for lack of a better term, and we are seeing the increased matter density on the part of the bubble that first expanded. Other Comments by LochRaven
40. Comment #191827 by qster on June 11, 2008 at 11:53 pm
fasinating stuff,Steve Zara or others, Im not very well read on the subject but could it not be feasible that the universe is simply in a state of continuous expansion until some point (and i believe there is some evidence of a slow in the rate of expansion) that the universe begins to contract in a scenario as you describe and therefore we exist in one of these infinte cycles thus indicating that 'this' universe is x billion years old but we are simply one of many bfore and many to come. The greatest challenge to Humans is to get our rather feeble brains around the concept of infinity, also that time is relative and not constant and that a million years appears a long time to us but is relative - might be like a day to another more intelligent form of energy?
Other Comments by qster
41. Comment #191865 by Tyler Durden on June 12, 2008 at 3:06 am
Comment #191678 by padster1976
If the visible universe is 13.7 billion years old, then if there is a much bigger section of the universe unseen, doesn't this imply that the universe could be a lot older?No :)
Other Comments by Tyler Durden
42. Comment #191867 by Steve Zara on June 12, 2008 at 3:10 am
Comment #191827 by qsterIt is possible, although the evidence actually points to a speeding up of expansion.
Other Comments by Steve Zara
43. Comment #191874 by the great teapot on June 12, 2008 at 3:25 am
Is there an explanation for a speeding up of the expansion? (that can be understood by an idiot.)Although I suspect the reality of the expansion is itself beyond my comprehension, I live in a strictly 3D world and can't escape.
Other Comments by the great teapot
44. Comment #191875 by Tyler Durden on June 12, 2008 at 3:27 am
Comment #191827 by qster:
and i believe there is some evidence of a slow in the rate of expansionAs Steve points out, latest evidence points to speeding up, not slowing down.
"The discovery of the linear relationship between redshift, interpreted as recessional velocity, and distance yields a straightforward mathematical expression for Hubble's Law as follows:
v = HoD
where
v is the recessional velocity, typically expressed in km/s.
H0 is Hubble's constant and corresponds to the value of H (often termed the Hubble parameter which is a value that is time dependent) in the Friedmann equations taken at the time of observation denoted by the subscript 0. This value is the same throughout the universe for a given comoving time.
D is the comoving proper distance from the galaxy to the observer, measured in megaparsecs (Mpc), in the 3-space defined by given cosmological time. (Recession velocity is just v = dD/dt).
In using Hubble's law to determine distances, only the velocity due to the expansion of the universe can be used. Since gravitationally interacting galaxies move relative to each other independent of the expansion of the universe, these relative velocities, called peculiar velocities, need to be accounted for in the application of Hubble's law."
http://en.wikipedia.org/wiki/Hubble_Law
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45. Comment #191879 by Steve Zara on June 12, 2008 at 3:37 am
Comment #191874 by the great teapotIs there an explanation for a speeding up of the expansion? (that can be understood by an idiot.)
No :)
Not because you are an idiot, but because no definite explanation has been found.
Although I suspect the reality of the expansion is itself beyond my comprehension, I live in a strictly 3D world and can't escape.
I think it is actually pretty simple. Space is stretching. This stretching acts like a force on everything. Your body is being pulled apart right now by it. You don't explode because the force is far, far less than those forces keeping you intact. However, you are just a tiny bit taller (and fatter) than you would be if the universe was static.
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46. Comment #191885 by AtheistJon on June 12, 2008 at 3:50 am
The analogy I always heard (read) is that if you had a sponge with raisins in it and squeezed it real tight, and then let it go. The expansion of the universe is like the expansion of the sponge, with the distance in between the embedded raisins increasing, just as the galaxies which are embedded in the "expanding universe" are all moving away from each other.
But, of course, this is just an analogy.
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47. Comment #191889 by Steve Zara on June 12, 2008 at 4:04 am
Comment #191885 by AtheistJonA good analogy.
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48. Comment #191891 by the great teapot on June 12, 2008 at 4:15 am
Slightly off topic, I have always wanted to "get my head around relativity", particulary the constant nature of the speed of light and the twin paradox (time going slower when traveling close to the speed of sound). Whenever popular TV approaches the subject all I ever learn is light can not escape from a black hole (no, you don't say! another hour wasted)Can anyone recommend any books or sites that explain clearly and correctly the theories.
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49. Comment #191898 by AtheistJon on June 12, 2008 at 4:31 am
There is a pretty good lecture series called the Mechanical Universe which was filmed at Caltech around 1985. Here's one of those lectures that discusses relativity (time and velocity):
http://video.aol.com/video-detail/caltech-the-mechanical-universe-43-velocity-and-time/2625034273
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50. Comment #191899 by Tyler Durden on June 12, 2008 at 4:33 am
great teapot,
A Brief History of Time by Hawking is a classic.
The Universe in a Nutshell also by Hawking deals with relativity in a few chapters.
Atom by Lawrence M. Krauss is on my shelf waiting to be read...
Cosmos by Carl Sagan is superb, and slightly more readable if coming at it from a novice's perspective :)
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1. Comment #191045 by King of NH on June 10, 2008 at 6:40 am
Is there any layman's rebuttal to the less extraordinary claim (in my opinion) that the 'universe' is not expanding, but only the kernel of matter and energy we occupy is. Why is it a wrong hypothesis that the universe is infinite, and that as far as our instruments can see is only a scratch on the surface of that eternal infinity? What evidence is there that there was nothing anywhere before the Big Bang?
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