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Universe 250+ Times Bigger Than What Is Observable
eldavojohn writes "The universe is only fourteen billion years old so we are unable to observe anything more than fourteen billion light years away. This makes it a bit difficult for us to measure how large the universe actually is. A number of methodologies have been devised to estimate the size of the universe including the universe's curvature, baryonic acoustic oscillations and the luminosity of distant type 1A supernovas. Now a team has combined all known methods into Bayesian model averaging to constrain the universe's size and their research is saying with confidence that the universe is at least 250 times larger than the observable universe."
...
As good science as flat earth.
I mean, what's at the outer edge? A wall?
If the universe started with a big bang, with all matter originated in an extremely compact volume, and if it's radius can't expand faster than light, then there should be no points in the universe beyond what we can see (as limited by light speed.) What am I missing?
If I can be modded down for being a troll, can I be modded up for being an orc, or a balrog?
Can we now be done with all these "my universe is bigger" disputes? Or is someone else going to come along now and say it's 500 times larger?
It is, but oddly enough that does not bind the expansion. Space can be expanding faster than c and I believe the inflationary theory says just that.
The world's burning. Moped Jesus spotted on I50. Details at 11.
First, How can you use a bayesian model to average results into a precise number?
Second, Why are you bothering to do this from theories on top of inelegant theories?
Third, if the universe actually is that size What does that mean for the heat death of the universe?
If video games influenced behavior the Pac Man generation would be eating pills and running away from their problems.
I recall reading a Scientific American article that indicated that the Universe had infinite size and mass, meaning that probabilistically, the exact construction and configuration of our observable universe would repeat itself (infinity tends to have nasty implications like that). Or to put it another way, another you is reading this somewhere (actually, an infinite number of you's, to be precise).
But crazy conjecture aside, does this talk of the 'full size' of the universe mean that the article even had its starting premise wrong?
Take that Creationism!
The bigger the fool the more confidence they have.
From what I gather, we're stuck somewhere in the middle-ish of the universe. What if were were located near the "edge" of the expanding universe, and the "edge" was within our observable light cone. What would we see? Nothing? or is the "edge" of the universe expanding faster than the speed of light, therefore one could never see the "edge"?
until the 20th century, reality was everything humans could touch, smell, see, and hear.
since the inital publication of the charged electromagnetic spectrum, humans learned that what they can touch, smell, see, and hear...is less than one millionth of reality.
It's more than a MILLION times bigger, in fact!
What else can happen when an unstoppable force collides with an immovable object?
Space can be expanding faster than c and I believe the inflationary theory says just that.
Damn fed printing money, now see what they've done.
A complete misapplication of Bayesian statistics. There is no viable prior for these quantities (except maybe that they must be some real number?), and therefore Bayesian statistics tells you nothing. The "answer" you get is just a function of the "prior" you made up. Garbage in, garbage out.
if the universe is 15 billion light years and that's only 1/250th of the space. Empty space? parallel universe. Is the universe this big giant godly fart? :)
Never antropomorphize computers, they do not like that
That's why Stargate Universe ends: they figured out they can't reach the edge of the Universe in just a few seasons, to figure out what that mystery is all about.
Correct me if I'm wrong, but wouldn't our observable constrain be 14 billion light years IF we were at the epicenter of the big bang?
Instead, shouldn't there be some area of the sky that we can only find much younger stars, and others that appear further away?
Mod me down with all of your hatred and your journey towards the dark side will be complete!
we can see much smaller than farther? i would have thought both were infinite?
Some physicist is very welcome to fill in here, but I'm not sure it's correct to say that the universe "expands faster" than the speed of light. Locally, the expansion is slow, and objects aren't really "moving away" from each other -- rather more space is added in between them.
Think of it like blowing up a balloon with ants walking around on the surface. The distance between ants could increase faster than they can move, but none of the ants are moving relative to the space they occupy.
As a side note: One theory of the ultimate fate of the universe is that the expansion rate will increase past the point where the observable universe becomes smaller than atoms and other particles (a higher expansion rate means objects must be closer to each other for light travelling between them to overcome the expansion of the distance between them), essentially ripping all matter apart.
That is some interesting numbers but that almost indicates that the radius would be more than ~6 times thus the universe is actually ~88 billion years old... yeah crude math aside... still way more than before.
Why such a strange prior? I understand that they believe that the curvature is 0, but how do they know they should drop it down so quickly? What about the rest of the prior, why does it look so strange? What would happen if they changed the prior. I'm guessing that tweaking the prior would yield greatly different universe sizes.
The question of whether a computer can think is no more interesting than the question of whether a submarine can swim.
Beverly:
If there's nothing wrong with me...maybe there's something wrong with the universe!
Here's one you shouldn't be able to answer...
Computer, what is the nature of the universe?
Computer:
The universe is a spheroid region, 705 meters in diameter.
If telephones are outlawed, then only outlaws will have telephones.
Some physicist is very welcome to fill in here
Really?
Am I eval()? - http://www.monst3r.com.br
In 50yrs we'll find the universe is 500+ times larger. Heisenberg is rolling in his grave.
like my belly button (poke)(sniff)
L'esperienza de questa dolce vita (The experience of this sweet life) - Dante Alighieri, The Divine Comedy
The submitter obviously did not read his own links. While the universe is only 14 billion years old, the _observable_ universe is > 90 billion light years across.
This is due to expansion, which stretched the wavelength of the light coming towards us, so redshifting those galaxies. It also makes those galaxies appear to be moving away from us at many multiples the speed of light, although they're not really moving at all, space is expanding.
An explanation
In the early days people thought the earth was flat..
These days we know that is not true:
'The earth is round.. Like a pancake...' (H. Finkers)
Hmm, I just don't understand this relatively stuff. So if the universe is 3500 billion light year across (14 billion * 250 times larger) and it is 14 billion years old it expanded at 125 time the speed of light (on the average). Sigh.
Which city is closest to the center of the Earth?
Since Earth is an oblate spheroid, it would probably be the most northern or southern coastal city on Earth.
This is probably it (city > 1000 people): http://en.wikipedia.org/wiki/Longyearbyen
the growth in cynicism and rebellion has not been without cause
take offense to this comment. I/We/Gaia have beautifully curved boundaries that I/We/Gaia are proud of. In our assimilation of the galaxy, we will make sure to prioritize your solar system and eradicate this stupidity.
L'esperienza de questa dolce vita (The experience of this sweet life) - Dante Alighieri, The Divine Comedy
Indeed so, and there was a recent report of a galaxy being spotted that was formed when the Universe was only 480 million years old. The report said that this galaxy was red-shifted to the limit of the Hubble telescopes's range, so they don't expect to find any older ones until the James Webb goes up.
The 250 times is in relation to the sphere we can see, about 45 billion light years across.
Consciousness is an illusion caused by an excess of self consciousness.
the truth.
L'esperienza de questa dolce vita (The experience of this sweet life) - Dante Alighieri, The Divine Comedy
Which city is closest to the center of the Earth?
I'm not sure, but there are several settlements on the Dead Sea, and the answer is likely to be one of them (assuming the name "city" can accurately be applied to any of them. :)
(Yes, I understand the point you were trying to make, but this is slashdot, so I'd be falling down on the job if I didn't pick nits with your argument.)
This is why God was invented. ;)
It is, but oddly enough that does not bind the expansion. Space can be expanding faster than c and I believe the inflationary theory says just that.
It did so for a VERY short while following the big bang: a period of superluminal expansion known as the Inflationary Epoch.
Physicists like to separate notable periods in time on a logarithmic scale, referring to each as the "Whatever" Epoch. As novel as the system itself is, what's most novel is how tiny of a portion of it our planet will be around for.
Recommended reading for the curious.
Boot Windows, Linux, and ESX over the network for free.
By far, that is my top favorite ST:TNG episode. Not sure why. (maybe it's my thing for redheads...)
8==8 Bones 8==8
The sphere is almost 14 billion light-years across.
Yes, but c is a measure of absolute velocity, not relative velocity. You ants story is a bad analogy because their "maximum speed" is a relative velocity. It is however possible that the universe is expanding at a rate of 2 * c, as any two given objects could each be moving at c in opposite directions to another.
AccountKiller
Dear Slashdot Readers
This article (and subsequent posts) have demonstrated that the once trusted car analogy is no longer in favour and from now on, complicated subjects should be explained using balloons instead.
Thank you for your co-operation in welcoming our new balloon overloads. Or something.
Relativity says that no particle can go faster than c, but that does not imply the universe can't expand faster than c. Here's why:
The universe is a space, like a blank sheet of paper, which can hold particles. The paper itself is free to expand. If the entire sheet is expanding uniformly (think: anything you draw on the paper just gets bigger), then clearly the "velocity" between two points is proportional to the distance between them. For our universe, v = H*d, where H is the Hubble constant. If d is large enough, the "velocity" might exceed c. But this does not violate relativity because in any little patch of the universe the speed limit remains c.
So based on this new estimate, the Great Galactic Barrier is further, and all of this time we have been afraid to voyage out to far and fall off the edge... Perhaps the final frontier is further out there! Now if we can just get DARPA or NASA to fund the Cochrane or Cubierre drive...
"As for the future, your task is not to foresee it, but to enable it." - Antoine de Saint-Exupery
Einstein taught us there is no such thing as absolute velocity.
For those of you who did not bother to read the whole article, there's a really important nugget that's lost in the 250+ times headline. The results show that the most likely curvature of the universe = 0. This means the universe, as near as our best minds can tell, is infinite. All the same dusting of galaxies in every direction, infinitely. Infinity is not a concept most people grasp easily. People ask things like "what's outside the universe?" but there is no outside, as "directionality" or "position" have no meaning outside the context of the universe. Likewise, there's no "before" the universe, as time has no meaning outside the context of the universe. My instinct says that we'll eventually come up with a nifty model of reality that includes a non-intuitive description of "position" that causes everything to make mathematical sense and has both quantum physics and relativity as predictable consequences.. but that is pure speculation. And it's a sure bet it'll be even harder to wrap our heads around than what we have now.
No. Firstly, it is at least twice that (we can see things 14 bullion years old in bot directions), and secondly space has expanded since the light set out, so it was, as it were, running up the down escalator and had to travel further to get to us. http://en.wikipedia.org/wiki/Observable_universe
Consciousness is an illusion caused by an excess of self consciousness.
Great. Wait until we see our real estate tax bill this year.
Of course, we should be able to get a few more dollars for it when we sell.
That's life!
eleven plus two / twelve plus one
It's possible because nothing prevents it. Matter cannot move faster than the speed of light, but a radius is not made of matter, it's a mathematical abstraction. There's nothing to suggest it can't change in value at any speed it wants. This does not mean the speed of light changes, nor does it mean matter can move faster than it, it merely means space (which is not matter, it's nothing) can expand at whatever rate it likes, causing distances between non-moving objects (and thus, not breaking the cosmic speed limit for matter) can expand and speeds far greater than the objects could possibly move apart if space were not expanding between them. The rate at which the universe expands is dependent on how quickly space expands between the objects, not the speed at which the objects are moving -- they can be perfectly stationary and the distance between them expanding at a rate that causes them to be ten light years further apart in only one year.
The expansion of the universe is not caused by all the matter in the universe moving away from each other, it's caused by the expansion of space itself, with the matter being just "carried along" so to speak.
"Convictions are more dangerous enemies of truth than lies."
Picturing this I imagine the ant doing the splits due to the fact that the balloon beneath it's feet is also stretching. How does this affect matter? If the space that a particle occupies expands does it apply any stretching force on the particle? Or does gravity prevent space from expanding wherever there is mass?
The light has been travelling for 14 billion years. But it might have got half way in the first nanosecond.
If our universe has lower limits on size and duration, so must there be upper limits. You can't call a line infinite if you've found one end of it.
Make it 256 and say the other 255 universes are running on their own shard servers so we can't just walk over to them :)
-- Sig down
Yes, but didn't he also say that regardless of your frame of reference c is always c. (It's very likely I'm wrong, so don't flame please, educate instead)
"This calls for a very special blend of psychology and extreme violence" - Vyvyan "The Young Ones"
No, he was right, or at least closer. It's actually about 90 billion light years across (in diameter), 45 billion light years in radius, at least, measured in terms of comoving or proper distance (what you would think of as roughly the "actual" distance today).
14 billion is roughly the age of the universe, so obviously the light at the boundaries of the observable universe had to be emitted about 14 billion years ago. However, the universe was much smaller back then and has expanded a lot since. So the stuff that was a few billion light years away in the early times of the universe is now much farther away. Thus the counter-intuitive result that we are able to see things that are up to about 45 billion light-years away today (well, the oldest *thing*, i.e. galaxy, we've actually seen is around 30 billion light-years away presently, because there are limitations of present technology as well as issues related to the lack of transparency of the early universe).
Hopefully I got all that right. :)
is there a name for the theory where the extent of the full universe is just so much bigger than our observable universe that there is plenty of room for other locally observable universes (presumably created by other big bangs), but they're just too far away for us to see?
(multiverse seems to be about extra dimensions and quantum effects. omniverse includes fictional items. so pls do not reply with those unless you think I have mischaracterized them.)
As a population, we're not getting fatter, it's the universe expanding that makes us look bigger.
Live forever, or die trying.
No. Such things lie outside of our lightcone past and future, so there's no way they can be part of the observable universe.
Physicists confirm: universe is a TARDIS
Just because you're paranoid doesn't mean there isn't an invisible demon about to eat your face
The inflationary theory says that space expanded faster than c in the first fractions of a second after the big bang. It's important to note it doesn't say space is still expanding faster than c now.
Who is John Cabal?
If the universe is spherical (regardless of whether it might also be hyperbolic, which is widely assumed to be the case), we should be able to see things that are farther than 14B light years merely due to the fact that they're closer along another trajectory, just as the apparently flat surface of the Earth ends up being continuous. This could be a really important discovery; if we can find something 14 billion light years away, we would either see a spectacular creation of space itself, or we would find something that revises our theories, including the possibility of confirming the spherical universe hypothesis (by seeing something disproportionately old). Either way, it would be quite exciting even outside the field of cosmology.
Of course, that's assuming that there is something to see; if the universe's initial expansion was anything but perfectly instantaneous, areas farther from the center would have been created proportionally later. Something 14B light years distant would therefore not be anywhere near as old as more central points, and therefore they wouldn't have had the appropriate time to emanate anything back towards us (or anywhere, for that matter). There is also the matter of the universe's hyperbolic shape, which has already helped scientists theorize that the universe is 78B light years wide (see the Wikipedia article cited in the /. summary) despite the observable 13.7B light year radius which gives a 15.8B light year visibility. It should also be noted that since we aren't in the center of the universe, we should be able to see farther in some directions than in others (though never more than 13.7B light years along its shortest path). Assuming that there are enough dark areas to make enough measurements, we could conceivably use this information to determine where the Big Bang actually began (the true center of the universe).
Use my userscript to add story images to Slashdot. There's no going back.
When our cosmos expands, it's not expanding into some pre-existing bit of volume and taking it over, it's creating volume that didn't exist before.
To be fair, we don't actually know that. Our models tell us something like what you describe might be happening but to say our models of the universe are imperfect would be a gross understatement.
Yes, that's correct, in the sense that c is the highest possible speed anything can have relative to any frame of reference you choose. However, depending on which frame of reference you do choose, the speed of a separate object can be perceived differently.
To give an example: Suppose two space ships A and B leave Earth in opposite directions, both traveling near the speed of light relative to Earth. Standing back on Earth you would see precisely that; from your perspective, the speed of the two ships relative to each other would be roughly two times the speed of light.
If, on the other hand, you were on space ship A, you would not see space ship B traveling away from you faster than the speed of light, because the highest possible speed of anything relative to you is still c. Both Earth and space ship B would be traveling away from you at a speed close to c, the other space ship slightly faster than Earth. Geometrically, this is possible because (or a consequence of this is that) you would perceive time and distance differently on one of the space ships as compared to being back on Earth.
Thus, there is no absolute speed at which any of the two space ships travel. The speed varies depending on which frame of reference you choose.
None of this prevents the universe, at an astronomical scale, from expanding several times faster than light could travel across it, though, which leads to the observable universe being smaller than the "entire universe".
Disclaimer: This isn't my area of expertise, so I may not be able to give the best explanation of special relativity, or even a correct one.
Sadly, I left my explanation of how an infinite universe works in my other pants, which I left at the Hilbert Hotel.
Beverly:
If there's nothing wrong with me...maybe there's something wrong with the universe!
Computer:
The universe is a spheroid region, 705 meters in diameter.
On no! I hope it doesn't crush 'er.
According to new theories universally accepted by at least one crackpot scientist, the observed universe is as it exists in that moment, and so you cannot say anything about what exists beyond what is possible to observe (not counting what is unobservable due to optical resolution, sensitivity, etc). What lies beyond the observable is not a part of reality; essentially it does not exist.
There are absolute velocities in a given inertial frame, i.e. velocities with respect to that inertial frame. Though the relative velocity between two objects moving in a reference frame is relative, and can take a value up to 2c.
GAAH! MY PRINTER IS ON FIRE!!! PUT IT OUT! PUT IT OUT!
This is the part with which I have a fundamental problem. If I measure the distance between myself and an object at two different times, and the distance between us increases by more than c*dt, then how can it be claimed that our relative velocity has remained less than the speed of light?
Is the problem simply one of using incompatible measuring sticks? I cannot conceive of a mechanism by which the instantaneous measured speed of any entity can be less than c and yet the total distance measured over some time period is greater than c times that time period, unless either c is changing or the definition of distance is changing over time in a very silly way.
The only other consistent thing of which I can think is to revise relativity to say that no object can be observed to travel faster than c*k, where k is some function of distance. I admit that I'm not that familiar with the details of expansionary theory. What's the verifiable mathematical explanation that resolves this apparent inconsistency?
"There are a dozen opinions on a matter until you know the truth. Then there is only one." - CS Lewis (paraprhase)
From TFA:
"They say that the curvature of the Universe is tightly constrained around 0. In other words, the most likely model is that the Universe is flat. A flat Universe would also be infinite and their calculations are consistent with this too. These show that the Universe is at least 250 times bigger than the Hubble volume. (The Hubble volume is similar to the size of the observable universe.)"
So...the Hubble volume is roughly 1/250th the size of infinity?
We probably agree on the physics, but personally I wouldn't use that terminology. If we are talking about "velocities with respect to [an] inertial frame", they are by definition relative (to that inertial frame). But sure, an observer can see two objects moving where the sum of their velocities (as seen by the observer) is greater than c.
Nevertheless, as far as I can understand, this does not determine how fast distances between objects can theoretically increase as a result of the expansion of space. Of course, when the distance to an object increases faster than the speed of light, it would forever pass out of your cosmological horizon, so I suppose you could debate to what extent it actually continues to exist.
...should be big enough for anybody!
G.
Astronomers have different conventions they use when talking about distances. When talking about "the size of the universe" in relation to the observable universe, in this context, what they mean is "the size at the present time". That is, you freeze the universe's expansion at the current time, and ask how much bigger the total universe is compared to the bubble which encloses the galaxies we can currently see.
The cosmic background radiation we observe today has taken 13 Gigayears to get here. In all that time, the gas which emitted that radiation has not been running away from us at near lightspeed. Rather it has had random motion relative to it's neighborhood of around 0.001c., and the geometry of space has been expanding about 1000-fold since that time. That expansion of the geometry both stretches the wavelength of light from visible at 3000 Kelvin down to microwave at 3 Kelvin, and also adds to the volume of space both behind and ahead of a traveling photon. No part of space is stretching locally very fast, but the total stretching of space across the universe can exceed apparent lightspeed without violating relativity, because relativity operates locally, not globally across the universe.
Similarly, conservation of energy applies locally, but not to the universe as a whole. If dark energy is constant per volume of space (the theory of how it works), then the total energy of the universe increases as it grows. If that sounds weird, it is. Modern physics is just not intuitive to us humans that mostly deal with non-quantum, non-relativistic stuff on a daily basis.
The easiest, more graphical example I can think of are two trains A and B on the same rail speeding at each other, with an observation point C just close to the rail around the middle. If each train is going at 100km per hour, point C will see both A and B travelling at 100km/h. A will see B moving at 200km/h, and B will see A moving at 200km/h. If instead of 100km/h they where moving at 0.99 c, A would see B moving at almost 2c, but that's just the relative velocity.
WTF am I doing replying to an AC at 5 A.M on a Friday night?
Actually, since neither object can move faster than c, we'll have to calculate the limit of the function, that'll be close to 2c, but never 2c.
Also, most probably there's effectively a minimum space-unit that objects can move (since there must be a minimum subatomic particle, even if we don't know it yet for sure), so that'll surely limit how close to c we can get, and 2x that value will be the max relative velocity.
WTF am I doing replying to an AC at 5 A.M on a Friday night?
I am a physicist. The situation is complex. The speed of light limit applies to the motion of matter and energy as measured in a local inertial reference frame. It doesn't apply to space itself. It can be hard to define "the speed of space"; in general, that doesn't even make any mathematical sense in general relativity.
In the case of a perfectly symmetric expanding universe, though, you can sort of define "the speed of space": a hyperspherical universe, for example, has a well-defined volume. You can convert that to a radius. (This won't work for some arbitrary lumpy geometry.) Likewise, such a universe has a well defined "universal time": it's the time measured by an observer who views the cosmic background radiation as the same in all directions (up to some statistical fluctuations). (This again won't work in an arbitrary lumpy universe, since it will never look symmetric to any observer.) You can then divide the change in "radius" by the change in "universal time" to get a "speed".
Because of these complications, cosmologists don't really lie awake at night trying to work out the speed of the universe's expansion. It's a messy concept that doesn't have much practical use.
But anyway, your analogy with the ants is pretty good.
Your side note about "the Big Rip" refers to "phantom energy", which is a kind of dark energy with particularly extreme properties. I believe it has been observationally ruled out by now.
If instead of 100km/h they where moving at 0.99 c, A would see B moving at almost 2c, but that's just the relative velocity.
Not really. Of both trains where going 0.99c, A would see B moving at about 0.99995c. Special relativity is counter-intuitive in this way, because we live in a world where relativistic effects are not normally visible.
You can read more about adding relativistic velocities on Wikipedia.
The universe will always be larger than we can imagine..
Have you fscked your local propeller head today?
I'll not believe it until I see it!
Fascinating. I only applied logic, it seems I had my concepts all wrong. I must say, IANAP, obviously :)
Thanks for proving me wrong, now I've learned something new. And, damn you, I'm going to be trapped reading about this the rest of the night (It's 1 A.M here). I was supposed to get up early, but fuck it, wikipedia is almost as bad as tvtropes.
WTF am I doing replying to an AC at 5 A.M on a Friday night?
Also from TNG, Episode 4x05 "Remember Me":
Beverly: What is the primary mission of the Starship Enterprise?
Computer: To explore the galaxy.
Beverly: Do I have the necessary skills to complete that mission alone?
Computer: Negative.
Beverly: Then why am I the only crew-member? (the computer takes a moment to process and makes a strange noise) Aha, got you there.
Computer: That information is not available.
My top favorite ST:TNG episode was season 6x05, Schisms. It's too bad they didn't have time to bring back the subspace aliens (the writers were originally going to bring them back again to challenge the crew in a future episode, but apparently they either decided not to or didn't get around to it before the series completed its run).
Because I'm hard-science light.. I thought c was considered an boundary of some sort.. would this imply the ability for matter to travel faster then c?
There's not a perfect consensus on how to describe the trap door here...
The DMZ of first-level handwaving is to call an early phase the "inflationary epoch" where the basic structure of space-time expanded at a significant rate and effectively pushed most parts of the universe past the c-limited visibility limit of most other parts. That was a VERY early period that lasted less time than anything we can time. One way of looking at it (heretical) is that the universe came into existence (POOF!) at a size larger than something travelling at c could cross. By the end of the first milli-micro-nano-nanosecond the "inflation" was done.
Not that this matters.
No one reading this can know with anything like certainty what became of the parts of the universe that inflated past the c horizon in the first 10^-32 second of existence. It is out there. It exists. I think. Maybe. Wanna bet?
Not mattering means that this is a great area for people who really want to know to conjecture about what is in an area that can't ever (as far as they can theorize) ever be known. In that context, it might be ~250x as big as we can see. Or it might not be there at all. I believe in Bayesian analysis and hence believe that it is 250x as big as we can possibly imagine it ever being. Therefore, I (you, they, anyone who could matter...) can't really know
WANNA BET, BEEEEAOOOTCHES?!?!?
I should add: I don't have any formal physics or math credentials beyond A+'s in 5xx level courses, and we all know that 5xx means REJECT.
I'm a sysadmin who reads. Take it for what it is worth. That would be nothing. Read, you stupid fucks.
I'm a physicist.
Some physicist is very welcome to fill in here, but I'm not sure it's correct to say that the universe "expands faster" than the speed of light. Locally, the expansion is slow[...], and objects aren't really "moving away" from each other -- rather more space is added in between them.
The speed of expansion of point A relative to point B depends on how far apart A and B are. If you take A and B to be sufficiently far apart, the speed is greater than c. If you take A and B close rnough together, the speed can be as small as you like.
and objects aren't really "moving away" from each other -- rather more space is added in between them.
Either explanation is OK. General relativity doesn't say that one is right and one is wrong.
As a side note: One theory of the ultimate fate of the universe is that the expansion rate will increase past the point where the observable universe becomes smaller than atoms and other particles (a higher expansion rate means objects must be closer to each other for light travelling between them to overcome the expansion of the distance between them), essentially ripping all matter apart.
This is incorrect. Strongly bound systems like a hydrogen atom, a solar system, or a galaxy are almost completely unaffected by cosmological expansion. More info here: http://www.lightandmatter.com/html_books/genrel/ch08/ch08.html#Section8.2
Find free books.
Luckily we were spared "does not compute", sparks and smoke.
One that hath name thou can not otter
What about the space inside matter? there is huge empty space between particles. Doesn't that space expand?
Does this mean that we need more than 64 bit to address every atom in the universe?
Sorry, but you're wrong. You are thinking of the lightcone based on the current size of the universe. The "observable universe" *is* essentially our lightcone, corrected for expansion of the universe.
See http://en.wikipedia.org/wiki/Observable_universe
One of the misconceptions listed under the Misconceptions heading is that the radius of the observable universe should be 13.7 billion light-years - and it notes that that would only be true in a flat, non-expanding Minkowski spacetime. Hubble expansion proves we're not in such a universe.
And the fact that the farthest objects observed are about 30 billion light years away (http://en.wikipedia.org/wiki/UDFy-38135539) should hint to you that things can be farther than 13.7 billion light years away from us currently and still be in our lightcone.
Basic special relativity-style intuition fails on a cosmological scale, unfortunately. :)
And the fact that the farthest objects observed are about 30 billion light years away
There is no misconception here. The farthest objects we observe were 13.7 billion light-years away at the time of observation. If the universe still is expansionary to the degree expected, then those objects are now and forever will be unobservable.
As I pointed out, anything that doesn't lie in our light cone, is outside the observable universe.
The Big Bang is a religious fantasy just like Intelligent Design. It is based on a deeply held religious belief that the universe was created instantly by the command of some supernatural supreme being wrapped in a veil of science. It requires the belief in way to many fantastic unverified processes and concepts like inflation, dark matter and dark energy. A far simpler and verifiable explanation is one of a universe shaped by electromagnetic forces as well as gravitational forces (a misnomer for the perceived effect of time dilation due to volumetric electromagnetic energy density). The microwave background radiation is not a remnant of the big bang it is the logical result of Compton scattering off the ions and atoms present in interstellar space. This scattering is also responsible for the observed Red shift of objects farther away than nearer. A simple calculation based on the density of atoms in space shows that the light from the edge of the visible universe transverses approximately the same number of atoms that light from our own sun crosses when it enters our own atmosphere at sunrise and sunset. It makes the sun look red and it makes distant stars look red. If you look up on a clear day the sky is not dark it is lit by scattering. That is the same effect that creates the microwave background radiation. The vacuum of space is not a total vacuum so scattering takes place. It is a good vacuum so it takes great distances to accumulate scattering. The size of the universe is essentially infinite as is its age. The universe however is not static. Entropy is constantly reduced by black holes that spew out matter streams. The universe never dies it is constantly recycled.
So does this make the age of the universe 3.3 trillion years old?
"On a scale from 1 to 10, people are stupid"
Indeed, it does. However, the expansion rate of a region is proportional to its size, so in absolute terms, the expansion rate at the scale of particles is extremely small, and easily overcome by the forces that attract particles in matter to each other.
Objects like stars or galaxies, on the other hand, can drift apart, because the distance between them is vast (which means two things: 1 - there is more expanding space to keep up with, and 2 - the only attracting force between them, gravity, has very little influence).
The light travel time is obviously a maximum of about 13.7 billion years, so clearly the light travel distance is 13.7 billion light years (well, actually 13.1 billion years is the oldest stuff we've actually seen, but whatever, you get the gist). But that's just the age of the oldest stuff we can possibly see times the speed of light - it doesn't say anything about where those objects presently are relative to us.
In fact, the objects are not currently 13.7 billion light years away in any meaningful sense of the word - they currently are 30 billion light years in terms of comoving or proper distance.
See: http://en.wikipedia.org/wiki/Distance_measures_(cosmology)
On a merely interstellar or even ordinary intergalactic scale the light travel distance and proper distance are going to be very similar.
Obviously, the light travel distance is essentially a coordinate system in which it's really easy to tell whether something is or is not in our light cone, since by definition, our light cone includes stuff with a light travel distance of 13.7 billion light years or less.
If the balloon inflates faster than the ant can walk, the ant can never walk all the way around the balloon. If unable to walk very far around the balloon, the ant could not even estimate its curvature.
In human (non-ant) terms, we would never see the same thing on opposite sides of the sky, or see our own backsides way out there in all directions.
Obviously, the light travel distance is essentially a coordinate system in which it's really easy to tell whether something is or is not in our light cone, since by definition, our light cone includes stuff with a light travel distance of 13.7 billion light years or less.
This is only true in the past. In the future, only stuff that currently is within a billion or two light years will be, even briefly in our future light cone. Speaking of something 30 billion light years away physically makes no sense, since that object is no longer part of our observable universe.
The paper you want to read is Max Tegmark, "Parallel Universes," 2003. Available here: http://arxiv.org/pdf/astro-ph/0302131v1
"Abstract: I survey physics theories involving parallel universes, which form a natural four-level hierarchy of multiverses allowing progressively greater diversity. Level I: A generic prediction of inflation is an infinite ergodic universe, which contains Hubble volumes realizing all initial conditions — including an identical copy of you about 101029 m away. Level II: In chaotic inflation, other thermalized regions may have different physical constants, dimensionality and particle content. Level III: In unitary quantum mechanics, other branches of the wavefunction add nothing qualitatively new, which is ironic given that this level has historically been the most controversial. Level IV: Other mathematical structures give different fundamental equations of physics. The key question is not whether parallel universes exist (Level I is the uncontroversial cosmological concordance model), but how many levels there are. I discuss how multiverse models can be falsified and argue that there is a severe “measure problem” that must be solved to make testable predictions at levels II-IV."
250+ times bigger than the observable universe should be enough space for anyone.
B. Gates
It will be exactly 2c for mass-less particles (like photons). And this is still measurable, by for example having them reflect off two mirrors at equal distances from the observer, measuring the time it takes to do the round-trip. You will find that they both travel at exactly c, in opposite directions, thus, they (from your point of view) travel with a speed exactly 2c relative to each other.
GAAH! MY PRINTER IS ON FIRE!!! PUT IT OUT! PUT IT OUT!