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New Study Shows Universe Still Expanding On Schedule

timothy posted about 2 years ago | from the every-time-you-jump-it-screws-things-up dept.

Space 173

The Bad Astronomer writes "A century ago, astronomers (including Edwin Hubble) discovered the Universe was expanding. Using the same methods — but this time with observations from an orbiting infrared space telescope — a new study confirms this expansion, and nails the rate with higher precision than done before. If you're curious, the expansion rate found was 74.3 +/- 2.1 kilometers per second per megaparsec — almost precisely in line with previous measurements."

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173 comments

Obligatory Spelling Comment (5, Funny)

ixnaay (662250) | about 2 years ago | (#41553813)

Not to be pedantic, but that is an impressive way to misspell 'messureents'.

Re:Obligatory Spelling Comment (2)

maroberts (15852) | about 2 years ago | (#41553851)

Not to be pedantic, but that is an impressive way to misspell 'messureents'.

The part of the universe covering that word hasn't fully expanded yet..

Re:Obligatory Spelling Comment (3, Insightful)

Anonymous Coward | about 2 years ago | (#41553861)

that is an impressive way to misspell 'messureents'

Wrong. 'messureents' is how you spell 'messureents'.

Re:Obligatory Spelling Comment (1)

dudpixel (1429789) | about 2 years ago | (#41555331)

that is an impressive way to misspell 'messureents'

Wrong. 'messureents' is how you spell 'messureents'.

The summary now says "measurements", so I guess the above is correct now?

Re:Obligatory Spelling Comment (3, Insightful)

wonkey_monkey (2592601) | about 2 years ago | (#41554079)

Not to be pedantic

Sorry to be pedantic, but you are being pedantic.

Re:Obligatory Spelling Comment (0)

Anonymous Coward | about 2 years ago | (#41554365)

dito ad infinitum

Re:Obligatory Spelling Comment (2)

dudpixel (1429789) | about 2 years ago | (#41555341)

sory to be pedantic but it's "ditto".

Re:Obligatory Spelling Comment (1)

slashmydots (2189826) | about 2 years ago | (#41555223)

Not to be pedantic, but that is an impressive way to misspell 'messureents'.

And yet they calculated the speed of light modified by the expansion of available space to travel through at a potentially non-static rate. I'm sure they didn't make a mistake there either, lol. Okay, here's my amateur astronomer opposition theory: the rest of the universe is gone! IT'S JUST GONE! But we're still receiving light from when it was there. Prove me wrong, lol. See, anyone can make anything up that's unprovable with modern technology.

8 year old's question (4, Insightful)

RichardDeVries (961583) | about 2 years ago | (#41553819)

It expands into what?

Re:8 year old's question (3, Informative)

hutsell (1228828) | about 2 years ago | (#41553839)

Hilbert Space [wikipedia.org]

Re:8 year old's question (4, Funny)

RichardDeVries (961583) | about 2 years ago | (#41553909)

On behalf of all 8 year olds: thank you, that was very informative. As for myself: I'm supposed to have an IQ well above 130, but it would probably take me months to make sense of that page.

Re:8 year old's question (5, Informative)

Anonymous Coward | about 2 years ago | (#41554209)

Unless you have a generic curiosity, don't try to hard to read that, as it is not related to the universe's expansion. The grandparent was just being random or joking. A Hilbert space is just what you get when you treat the set of all continuous functions as a vector space. It has several different possible basis sets of functions you can add up to make any other function, e.g. sine waves via Fourier analysis. Instead of having unit vectors like x, y, and z, you would have unit vectors like sin(x), sin(2x), sin(3x), etc. (which makes it infinite dimensional). The concept is really important to physics, especially quantum mechanics and any where else things like Fourier analysis would be done with some mathematical rigor. But it is not what the universe is expanding into.

The typical analogy used for what the universe is expanding into is like a balloon being inflated, with that being a 2D universe on the surface of the balloon. You could ask about the third dimension it is expanding into, but that is not really relevant (at the moment at least). The only thing that really matters is the curvature of local space (how non-flat any given spot on the balloon is). Short of discovering some new theories unlike what we've seen before or something like brane theory, the equivalent of the 3D dimension in the balloon analogy would be unreachable and meaningless, as it would not be able to affect things in anyway beyond the curvature of the surface.

Re:8 year old's question (3, Informative)

UnknownSoldier (67820) | about 2 years ago | (#41553901)

Nothingness. There is no space & time outside the physical universe. If that doesn't bake your noodle, I don't know what will.

The nice thing about Religion^H^H^^H^H^ science is that it advances one funeral at a time. (With apologies to Max Planck :)

Re:8 year old's question (1)

RichardDeVries (961583) | about 2 years ago | (#41553961)

Question 2

There is no space & time outside the physical universe.

Are you sure? How do you know?

Etc. etc. ad infinitum. It's a good answer though, even I can understand it and it's helpful. Thanks!

Re:8 year old's question (4, Informative)

turbidostato (878842) | about 2 years ago | (#41554405)

"There is no space & time outside the physical universe.
Are you sure? How do you know?"

He doesn't need to know: that's a per-definition fact.

A different question would be if the physical universe is composed of four dimensions or there are more.

Re:8 year old's question (5, Insightful)

kheldan (1460303) | about 2 years ago | (#41553969)

Correction: There is no space and time that we can determine with any certainty outside our physical universe.

Re:8 year old's question (3, Insightful)

arth1 (260657) | about 2 years ago | (#41554207)

Correction: There is no space and time that we can determine with any certainty outside our physical universe.

This is imprecise at best. There is no "outside our physical universe", because dimensions becomes meaningless at the border of the universe, so there is nowhere "outside" for other universes to be. If they exist, they don't exist "outside" our universe, at least not in a dimensional sense.

As for time, that is a purely local phenomenon, and we can not determine it even inside our universe, except right here. Every "here" will have its own rate of time.

Re:8 year old's question (4, Funny)

Nostromo21 (1947840) | about 2 years ago | (#41554771)

"In the beginning, God created the heavens and the earth. The earth was without form and void, and darkness was over the face of the deep. And the Spirit of God was hovering over the face of the waters."

Flame away. <BFG>

Re:8 year old's question (1)

Anonymous Coward | about 2 years ago | (#41554975)

This is imprecise at best. There is no "outside our physical universe", because dimensions becomes meaningless at the border of the universe, so there is nowhere "outside" for other universes to be. If they exist, they don't exist "outside" our universe, at least not in a dimensional sense.

As for time, that is a purely local phenomenon, and we can not determine it even inside our universe, except right here. Every "here" will have its own rate of time.

Not necessarily. At the formation of the universe and perhaps in times and places thereafter, it's possible that our universe became disjoint from other universes even though they intersected in the distant past. These universes would, if they existed, be very real and would necessarily be part of completely understanding the universe we live in. Anything in those now-separate space-times could reasonably be called "outside" the universe. Also, if there are wormholes that join places in our past with places in our future, the part of them that doesn't directly connect with now would be reasonably called "outside" the universe.

I'm also disturbed by your use of the phrase "rate of time." What does that mean, if anything?

Re:8 year old's question (1)

arth1 (260657) | about 2 years ago | (#41555373)

I'm also disturbed by your use of the phrase "rate of time." What does that mean, if anything?

For a local observer observing itself, nothing.
Time itself bends in the presence of gravity or velocity.

If you sit at A, which is equidistant from B and C, and observe a spaceship close to the speed of light going from B to C, you may observe that the trip took five years. However, the spacefarers aboard the vessel will swear up and down that it only took two years. And you're both right.
The travelers who are in a different time frame has a different "rate of time" -- by your clock. Just like you have by theirs.

And consider photons. Through vacuum, they move at c, by definition. That means that no time passes for a photon. This seems like a paradox, because if an electron moves a distance of fifteen thousand million light years, surely it takes fifteen thousand million years? Nope. That is the time an outside observer would measure, not the time for the photon. From its viewpoint, movement is always instantaneous[*].
So from our point of view, a photon's "rate of time" is, for lack of a better phrase, "infinitely slow".
Of course, the Bohr legacy has other ways of describing it, but not in plain ole English in four dimensions.

[*]: This also means that the lifetime of a photon is zero. That's more of a paradox. Taken to its extreme conclusion, it could lead to photonic solipsism and string theories.

Re:8 year old's question (3, Interesting)

MightyMartian (840721) | about 2 years ago | (#41553965)

The universe could be a compact manifold, in which case it isn't expanding into anything. That would fit with the essential notion that it is space itself that is expanding.

Re:8 year old's question (0)

Anonymous Coward | about 2 years ago | (#41554263)

"The universe could be a compact manifold, in which case it isn't expanding into anything. That would fit with the essential notion that it is space itself that is expanding."

Just as easy to say that it is expanding into nothing.

Re:8 year old's question (3, Insightful)

MightyMartian (840721) | about 2 years ago | (#41554349)

The problem with what you're saying is the word "into". It still suggests that there is some medium into which the universe expands. It's another form of the famous Hawking problem "What's north of the north pole?" If there is nothing, then the universe is not expanding into it. It is simply expanding.

As much as anything, it is a problem that while expressable mathematically, is, at least to most peoples' brains (mine included) something impossible to imagine. It is just another way in which our common every day perceptions of the world around us don't model every aspect of reality well.

Your problem... (0)

Anonymous Coward | about 2 years ago | (#41554715)

is thinking that "our common every day perceptions of the world" are somehow not reality. Model, indeed.

--

Re:Your problem... (1)

MightyMartian (840721) | about 2 years ago | (#41554959)

There is a large amount of neurological heavy lifting that goes into interpreting sensory input.

Re:8 year old's question (1)

Shavano (2541114) | about 2 years ago | (#41555013)

"The universe could be a compact manifold, in which case it isn't expanding into anything. That would fit with the essential notion that it is space itself that is expanding."

Just as easy to say that it is expanding into nothing.

It's even easier to say the universe is self-contained, which bypasses the need to explain that the "nothing" you're using in your expression is not the same thing as empty space.

Re:8 year old's question (4, Funny)

multiben (1916126) | about 2 years ago | (#41554015)

Milk. The universe is surrounded by milk.

Re:8 year old's question (2)

Sponge Bath (413667) | about 2 years ago | (#41554515)

I guess God must be a woman... with astronomical tits.

Re:8 year old's question (2)

Shavano (2541114) | about 2 years ago | (#41555025)

Milk. The universe is surrounded by milk.

Unlikely. Turtles don't have milk.

Turtles. Duh! (1)

Anonymous Coward | about 2 years ago | (#41554051)

Turtles. All the way out. Duh! Don't they teach kids anything these days?

Re:8 year old's question (1)

R3d M3rcury (871886) | about 2 years ago | (#41554233)

Other universes. It's that whole 'obesity' thing, which is why the kid should be outside running around and getting exercise rather than sitting inside and asking questions.

Re:8 year old's question (0)

Anonymous Coward | about 2 years ago | (#41554445)

Wise/daughters (oh, iPhone dictation...), please help me understand:

If two objects are separated by distance X and not moving relative to each other does the expansion of the universe mean that at some time in the future the objects will be separated by a distance greater than X? If so, is the change measurable if one were to use a physical object like a ruler to measure the distance or is the change only detectable if the measurement relies on the speed of light?

Re:8 year old's question (1)

gestalt_n_pepper (991155) | about 2 years ago | (#41554491)

Hey man, I just work here, OK?

Re:8 year old's question (0)

Anonymous Coward | about 2 years ago | (#41554685)

Beyond his years, wise, that one is. Checked his midichlorian count, have you?

Re:8 year old's question (1)

Shavano (2541114) | about 2 years ago | (#41554999)

Wrong question. The rate of expansion is the rate at which objects in the universe are moving away from each other, in a massively averaged way.

Re:8 year old's question (1)

dudpixel (1429789) | about 2 years ago | (#41555353)

Good point, are we measuring distance, or the speed of light?

South Park (0)

Anonymous Coward | about 2 years ago | (#41553865)

They should work this into an Eric Cartman quote...

"I'm not fat, the universe is just expanding at 74.3 +/- 2.1 kilometers per second per megaparsec!"

Re:South Park (1)

hazah (807503) | about 2 years ago | (#41554509)

It just rolls off the tongue.

Units (1)

Anonymous Coward | about 2 years ago | (#41553871)

So, I'm probably laying out my lack of knowledge on this one, but can someone who knows about that which they speak explain kilometres per second per megaparsec?

Re:Units (4, Informative)

amRadioHed (463061) | about 2 years ago | (#41553975)

Due to expansion, the speed of objects accelerating away from us is proportional to the distance from us. So according to this, an object at 1 megaparsec from us will be receding at 74.3 km/s, while an object at twice the distance will be moving twice as fast.

Re:Units (4, Interesting)

ImprovOmega (744717) | about 2 years ago | (#41554289)

That can't be right. The universe is about 14,000 megaparsecs in radius, even if we were at the exact center that would have things traveling outward at 1.04E9 m/s or 3.46c. I'm reasonably certain they're not claiming FTL on this one so... Is it actually 74.3 m/s instead of 74.3 km/s? Or is there something else going on here?

Re:Units (4, Informative)

j00r0m4nc3r (959816) | about 2 years ago | (#41554397)

Space itself can expand FTL, but anything inside that space is limited to c. This also means that at any given point in the universe, there is a boundary where you can never reach beyond, because the space itself is expanding away FTL, so you can never catch up to observe anything beyond that boundary...

Re:Units Space FTL, but information thru space? (3, Interesting)

shoor (33382) | about 2 years ago | (#41554569)

Something I've been wondering about, but never knew quite where to ask. (Maybe this isn't the place either, but I'll give it a shot.)

i understand (or at least parse the semantic meaning) that the speed of light through space is fixed, and space can expand fasterthan that. Normally, it seems that the speed of information transmission is also tied to the speed of light, mainly I presume, because paradoxes would arise if it weren't. But can information travel across space at an effective speed uninfluenced by the expansion of space without causing paradoxes? Is it possible that information could still reach us even if light could not?

Re:Units Space FTL, but information thru space? (1)

Andreas Mayer (1486091) | about 2 years ago | (#41555321)

But can information travel across space at an effective speed uninfluenced by the expansion of space without causing paradoxes? Is it possible that information could still reach us even if light could not?

No.

Nothing can travel faster than light and information has to be carried by *something*.

Re:Units (1)

LordLimecat (1103839) | about 2 years ago | (#41554993)

Hold on there.

If I recall, one of the principles around c is that two things may not move apart faster than c, either. So if you have an observer with a lantern on a train moving 60mph, the light moves away from the observer at c. But! It also moves away from the train platform at c, not c + 60mph

Now as I see it, what is being described is that the universe (spacetime) is the train in my scenario. How could you then account for the rate of expansion from the perspective of two individuals, one at each "end" of spacetime?

Re:Units (4, Informative)

thrich81 (1357561) | about 2 years ago | (#41555151)

Space itself can expand such that the objects (events?) within it are moving apart at faster than c. Any two objects separating faster than c can't measure that -- they cannot pass any signal between them. Any light (or other signal) which leaves one will be redshifted away to nothing before it gets to the other. They are outside each other's observable universe. I'm pretty sure this has to handled using General Relativity, I don't think Special Relativity has any concept of expanding or contracting space-time. Space-time described by Special Relativity is flat and static.

Re:Units (2)

RegTooLate (1135209) | about 2 years ago | (#41555011)

whatever my ship can make the Kessel Run in less than twelve parsecs.

The Universe has no center (2)

seibai (1805884) | about 2 years ago | (#41554695)

Just to clarify something that bothers me because so many people seem to believe it despite relativity expressly making it impossible: the universe has no center. Really, look it up. Similarly, the "big bang" does denote an explosion from a specific point.

"exact center"? even if earth was near the center (0)

Anonymous Coward | about 2 years ago | (#41554805)

that makes me wonder. The earth is the center of the universe! Too much like pre-Copernican church doctrine, to my eyes.

I await the day they say where the center of the expanding universe is.

Re:Units (0)

Anonymous Coward | about 2 years ago | (#41555193)

Ahh that is the interesting point about general relativity. c is the speed of light through space, and nothing can travel faster through space. But the space itself can be moving arbitrarily fast. In principle you can use this to travel from one point to another faster than c, by bending the space to such a point that the distance is smaller, then travel that shorter distance, then 'unbend' the space again and you suddenly find you're on the other side of the universe ;-) Of course the energy required to do this is probably too big to ever be practical.

The bottom line though is that the regions of space that are moving away from us faster than c are causally disconnected from our region of space.

Re:Units (2)

Nostromo21 (1947840) | about 2 years ago | (#41554737)

So at around 4000 megaparsecs (13 billion light years) the outer rim hits the speed of light...? Hey, isn't that about the age of the Universe anyway....could I be onto something here...? ;)

Re:Units (1)

olsmeister (1488789) | about 2 years ago | (#41553977)

You use this constant and multiply it by the distance of an object to obtain the speed that it is receding from us. So, for instance, if a particular point in space is 1 megaparsec away from us, it is receding at 1 megaparsec * 74.3 (km/s)/megaparsec ... the megaparsecs cancel and you get 74.3 km/s. Which doesn't tell you how fast the expansion is accelerating, but does tell you how fast it's happening at this moment in time. An point 100 megaparsecs away would be receding 100 times faster or 7430 km/s. Kind of an awkward combination of units but then again it's just a factor that let's you estimate relative speed from distance.

Re:Units (1)

Archangel Michael (180766) | about 2 years ago | (#41554033)

From my understanding, speed is relative, so the terms the relation of the two objects, the one being measured from and the one being measured to. As those speeds (relative) approach Light, that is when we can start seeing other interesting effects, like space curving. Space curving is what really boggles the mind, because it is, and isn't curving, depending on what you are looking at, because the "speed" is what bends our perception.

Re:Units (4, Interesting)

sconeu (64226) | about 2 years ago | (#41554117)

Interestingly, some back of the envelope calculations (using rough numbers ... 300000km/s for c, 75km/s/mpc for Hubble's Constant, and 3.25 ly/pc) gives a value of roughly 13 billion light years for the recession velocity to approach c. 13 billion years is also *ROUGHLY* the age of the visible universe.

Re:Units (1)

sconeu (64226) | about 2 years ago | (#41554139)

Oops... that' 75km/s/Mpc, not mpc.

Re:Units (1)

Nostromo21 (1947840) | about 2 years ago | (#41554787)

Yeah, I just made that 'independent' observation further up. Coincidence or inevitability...? Believe it or not!

Re:Units (1)

gewalker (57809) | about 2 years ago | (#41554085)

Yes, you appear to be slow thinking today (It happens to everybody).

kilometers per second how fast 2 galaxies recede from each other.
mega parsec is a really long distance (3.26 light years / 19 trillion miles / 31 trillion kilometers)

The further away the galaxies, the faster they recede.

E.g., if 2 galaxies are 100 MegaParsecs apart, then they should be separating from each other at about 100 * 74.3 = 7430 kilometers per second.

Re:Units (3, Informative)

sconeu (64226) | about 2 years ago | (#41554161)

No, a *parsec* is 3.26 light years. A Megaparsec is 3.26 MILLION light years.

Re:Units (3, Interesting)

Relic of the Future (118669) | about 2 years ago | (#41554135)

In the vein of xkcd-what-if #11 [xkcd.com] , I wonder about the physical meaning of kilometers per second per megaparsec. Kilometer and megaparsec are both lengths, so you can divide them out by the conversion factor (1 megaparsec = 3.08567758 × 10^19 kilometers) and then you are left with "per second", i.e., a frequency. A frequency of about 240 billion gigahertz. What, if anything, does that mean?

Re:Units (0)

Anonymous Coward | about 2 years ago | (#41554247)

Some times when you take important values from a system, like say the dominant size, and some dominant velocity, you can combine them to get something else, like value with units of time. Sometimes this can be really significant, since it could be comparable to the time for the example system, it could be related to the time it takes processes to cover the whole system and there may be various instabilities or oscillations that are related to that time scale. Or sometimes it is just a hint about what time scales matter, so that if you use a time scale much shorter than that time, you know not much is going to be able to cross the system in the time you are looking at.

Other times, it is completely meaningless. You could end up with similar units like torque and energy, in which case one doesn't provide any insight into the other.

Re:Units (3, Insightful)

Anonymous Coward | about 2 years ago | (#41554501)

I think you got your final result messed up:

(74.3 km / s / mparsec) * (1 / 3x10^19 mparsec / km) = 74.3 ? / s * 3.3x10^-20 ~ 2.4 x 10^-18 cycles per second ~ 403768506056527590 seconds per cycle ~ 12.7 billion years per cycle.

It helps to actually include the units in your math as "unsolvable variables" that cancel each other out in your conversions. It's a fairly easy way to make sure the math comes out correct. Granted, this extremely rough number is kinda interesting because it is less than 10% off from the age of the universe. May mean absolutely nothing though.

Spelling? (0)

Anonymous Coward | about 2 years ago | (#41553875)

Seriously, does someone proof read the articles before posting them?

Gem Secretes as Superman (4, Funny)

badford (874035) | about 2 years ago | (#41553881)

is an anagram of 'megaparsec messureents' thought you'd like to know.

Ok. Now what is it in hogsheads per fortnight? (1)

Nadaka (224565) | about 2 years ago | (#41553887)

ha

Re:Ok. Now what is it in hogsheads per fortnight? (1)

flaming error (1041742) | about 2 years ago | (#41554003)

You're units are incompatible. I think the units you wanted were football field lengths per fortnight per furlong.

Re:Ok. Now what is it in hogsheads per fortnight? (2)

Nadaka (224565) | about 2 years ago | (#41554061)

hmm...

Partially right. but the universe expands in 3d, not just linearly.

What is the answer for hogsheads per fortnight per displacement of Archimedes in a bathtub.

Re:Ok. Now what is it in hogsheads per fortnight? (0)

Anonymous Coward | about 2 years ago | (#41554493)

What is the answer for hogsheads per fortnight per displacement of Archimedes in a bathtub.

1/s. How dull.

Re:Ok. Now what is it in hogsheads per fortnight? (1)

ThreeKelvin (2024342) | about 2 years ago | (#41554155)

Hogshead per fortnight (equivalent to m^3/s) is the wrong unit of measurement for expressing the expansion of the universe. I'd go with 2.4 +/- 0.068 exaHz for a whimsical and opaque way of expressing it.

Re:Ok. Now what is it in hogsheads per fortnight? (0)

Anonymous Coward | about 2 years ago | (#41554187)

I thought the universe was a 3-D thing.so m^3/s sounds plausible.

Re:Ok. Now what is it in hogsheads per fortnight? (1)

ThreeKelvin (2024342) | about 2 years ago | (#41554435)

If you want the expansion as a volume you could use m^3/(s*m^3), i.e., rate of volumetric expansion per volume of space. m^3/s just gives you a rate of volumetric expansion, it doesn't say anything about the volumetric expansion being faster if you look at a larger volume, or equivalently, things move faster away from you the further away from you they are, i.e., m/(s*m), which is what Hubble's Law is all about.

You can of course calculate the expansion of af known volume of space e.g. the entire universe* or just our galaxy in m^3/s, using the newly reported observation.

*As far as I know, we don't know how big the universe is, or even if the universe is finite, so we couldn't actually calculate this.

It's on schedule (0)

Anonymous Coward | about 2 years ago | (#41553979)

but, I understand that The Most Interesting Man in the World's reputation is still slightly ahead. Ah, the suave and dapper Jonathon Goldsmith of Dos Equis fame.

Not to be pedantic (2, Insightful)

ubergeek65536 (862868) | about 2 years ago | (#41554009)

The visible part of the universe is expanding. We have no clue what's happening to the infinitely large part we can't see.

Re:Not to be pedantic (4, Insightful)

countach (534280) | about 2 years ago | (#41554055)

Well, to be pedantic, its a stretch to say "we have no clue". We can make some pretty damned good guesses.

Re:Not to be pedantic (0)

Anonymous Coward | about 2 years ago | (#41554115)

42?

Re:Not to be pedantic (1)

cain amofni (2745583) | about 2 years ago | (#41554977)

yes. the prevailing conjecture seems to be at odds with a little einsteinian problem: no absolute rest, no absolute velocity. so what is expanding at that rate with respect to what? if they said the 'edge of the observable universe' then it would have meaning, but since there is a limit of observable range due to the fact that beyond a certain distance from the observer (us), a galaxy or quasar would be receding at a cumulative rate greater than the speed of light, and hence, exits the observable universe relative to our vantage point. thus, unless we are at the center of the universe - highly unlikely - then the observable universe is a subset of the total universe. so we really have no way of knowing the actual size of the universe, or whether it's infinite, in which case, saying it's expanding at a certain rate has no meaning at all.

Re:Not to be pedantic (0)

Anonymous Coward | about 2 years ago | (#41554217)

Yes we do, because the visible photons are moving through it. The photons we observe here have travelled through everything inbetween the source and us.

Re:Not to be pedantic (1)

Anonymous Coward | about 2 years ago | (#41554333)

I believe the original is talking about rest of the universe that is outside the 13.7 billion light year radius sphere that we can see.

Re:Not to be pedantic (1)

dido (9125) | about 2 years ago | (#41554663)

Well, there is the dark [slashdot.org] flow [wikipedia.org] , a mysterious influence on the motion of distant galaxies whose cause can no longer be observed because it has presumably passed beyond the visible universe. However, we can still see the results of its effect on stuff that is still in the visible universe.

Re:Not to be pedantic (1)

Ironhandx (1762146) | about 2 years ago | (#41555031)

Its things like this that we've confirmed as accurate as much as we can that makes me think the universe isn't expanding at all, we're just able to see more of it all the time. The current size of the universe closely correlates with the speed of light and the time it would have taken that light to reach us... coincidence?

Space itself is supposedly able to expand faster than the speed of light, however I'd like someone to point me to the evidence that this is happening at all.

what's in a name? (2)

X10 (186866) | about 2 years ago | (#41554013)

It's not called "expansion rate". It's called "the Hubble constant".

Sorry for sounding stupid... (1)

Longjmp (632577) | about 2 years ago | (#41554097)

... but shouldn't the universe expand at the speed of roughly 300,000 km/s (i.e. speed of light - and information) from any given point of the universe?
Someone enlighten me please.

Re:Sorry for sounding stupid... (0)

Anonymous Coward | about 2 years ago | (#41554277)

Why?

Re:Sorry for sounding stupid... (1)

Shavano (2541114) | about 2 years ago | (#41555037)

If that were the case, we wouldn't see anything when we look up at night.

unit: kilometers per second per megaparsec ? (1)

AbhiTheOne (2717543) | about 2 years ago | (#41554101)

astronomy noob here. Parsec is unit of length= 3.26 light-years per http://en.wikipedia.org/wiki/Parsec [wikipedia.org] . so what's the measuing unit for expantion rate of unit? 74.3 +/- 2.1 kilometers per second per megaparsec correspounds to "length per time per length" so is it 1. Cancelling lengths all it remains is "per time"? which seems wrong. or 2. length * length / time?

Re:unit: kilometers per second per megaparsec ? (1)

under_score (65824) | about 2 years ago | (#41554199)

I just means that over a given distance (a megaparsec) if you measure that distance every second, it will seem to have grown larger (by 47.3 +/- 2.1 kilometers). In other words, expanding space means that distance itself is growing.

Now, being a cosmology noob myself, I still can't quite wrap my head around this idea: if we look at a much smaller scale, say one meter, what are we actually observing? In our own frame of reference, does this mean that if you removed a one meter ruler from the universe for a second and then brought it back it would be measured to be slightly less than one meter? Or does it mean that the fundamental fabric of the universe that reflects relationships and fundamental constants in physics are changing so that when you bring the meter ruler back into the universe it would "pop" out to the new length of a meter?

I know that it relates to red shift... gack.

Re:unit: kilometers per second per megaparsec ? (1)

Dan East (318230) | about 2 years ago | (#41554709)

In terms of only km, each second the distance 415,299,808,882,907,133 km expands by 1 more km.

Better than ahead of schedule (1)

Dyne09 (1305257) | about 2 years ago | (#41554141)

Because, that would just be a problem.

Sure, but ... (1)

fahrbot-bot (874524) | about 2 years ago | (#41554165)

the expansion rate found was 74.3 +/- 2.1 kilometers per second per megaparsec

... what is that in something useful, like Library of Congresses?

Interesting info (0)

Anonymous Coward | about 2 years ago | (#41554221)

I've heard that the rate of expansion is currently increasing with time. A PBS show mentioned that, and it kinda screws up the big bang theories a bii.

Actually, it shows the Universe WAS expanding (1)

WillAffleckUW (858324) | about 2 years ago | (#41554281)

What most of you don't realize is it started to collapse a few millenia ago, but the light and gravity waves from that haven't arrived yet.

Put on your tinfoil hats!

On what schedule? (0)

Anonymous Coward | about 2 years ago | (#41554399)

The only schedule is the one man came up with. You know the race of animals that still believe in a god, will kill eachother for an ipad, and worry more about some celeberties new boyfriend than they would of anything else? Not to mention the race of beings that has only sought scientific knowledge and discovery in earnest in the past say 75 years, with only about 50 of them with any technology to do so even halfway decently?

Man is incredibly vain, self centered and egotistical to assume to know anything. Let alone something as infinitely huge as the universe and the way we assume it expands according to some schedule we give it.

Megaparsec? (1)

tpstigers (1075021) | about 2 years ago | (#41554411)

Never heard of them. How many in the Kessel Run?

I'm still 'spanding... (0)

grouchomarxist (127479) | about 2 years ago | (#41554547)

yeah, yeah, yeah...

Excelllent (0)

Anonymous Coward | about 2 years ago | (#41554593)

I hate it when the universe is late!

Expansion not accelerating? (0)

Anonymous Coward | about 2 years ago | (#41554599)

Weren't we told that the expansion of the universe was accelerating, hence the need for dark energy?

Is it possibly just contracting *away* from us? (0)

Anonymous Coward | about 2 years ago | (#41554793)

Maybe everything is just squirreling away from Earth, contracting in the other direction.

small rate on human time scales (0)

Anonymous Coward | about 2 years ago | (#41554827)

If you convert that into % per year, it is minuscule. Even converting to % per million years it is 0.0076%. It takes a billion years to reach 7.6%. That means it will take 9.5 billion years for the universe to double in size at a constant rate of expansion.

However the current theory is that the rate of expansion is accelerating so it would actually take less time.

This calculation prompted me to look at and correct the wikipedia page on the rate of expansion, and find a glaring inconsistency! That page claims even with accelerating rate of expansion the universe will take 11.4 billion years to double in size. Which is nonsense, if there is acceleration it MUST be less than 9.5 billion years. So I edited it to add that :) See slashdot has positive effects on wikipedia!

Re:small rate on human time scales (0)

Anonymous Coward | about 2 years ago | (#41554837)

wiki on rate of acceleration, including my paragraph calling out inconsistency in 11.4 billion years to double including acceleration claim.

http://en.wikipedia.org/wiki/Accelerating_universe#Theories_for_the_consequences_to_the_universe

However the 11.4 billion years including acceleration appears to be wrong, because this Nasa study confirms the current [13] rate of expansion at 74.3 km/s per megaparsec. Simple math shows that if that rate of expansion were constant it would take the universe 9.5billion years to double in size without expansion. So unless the rate of acceleration of expansion is negative (ie we would be call it deceleration) 11.4 billion years appears to be in error.

Re:small rate on human time scales (0)

Anonymous Coward | about 2 years ago | (#41555319)

retraction: one of the other wiki authors undid the calc. He appears correct, my calculation had a mistake and the constant hubble rate doubling time would be 13.2 billion years, which makes 11.4 billion years doubling a positive acceleration.

dimensional analysis resolves to frequency (1)

cain amofni (2745583) | about 2 years ago | (#41554923)

I find it fascinating that dimensional analysis of the expansion of space resolves to a frequency: 74.3 ((kilometers / second) / megaParsec) = 2.40789901 × 10-18 hertz http://www.google.com/#q=74.3+km/s+/+megaparsec [google.com] http://www.ardeshirmehta.com/Relativity.html [ardeshirmehta.com]
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