New Study Shows Universe Still Expanding On Schedule

Obligatory Spelling Comment by ixnaay · 2012-10-04 10:43 · Score: 5, Funny

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

Re:Obligatory Spelling Comment by maroberts · 2012-10-04 10:47 · Score: 2

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..

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Re:Obligatory Spelling Comment by Anonymous Coward · 2012-10-04 10:48 · Score: 3, Insightful

that is an impressive way to misspell 'messureents'
Wrong. 'messureents' is how you spell 'messureents'.
Re:Obligatory Spelling Comment by wonkey_monkey · 2012-10-04 11:23 · Score: 3, Insightful

Not to be pedantic
Sorry to be pedantic, but you are being pedantic.

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Re:Obligatory Spelling Comment by Anonymous Coward · 2012-10-04 12:06 · Score: 0

dito ad infinitum
Re:Obligatory Spelling Comment by slashmydots · 2012-10-04 14:57 · Score: 1

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.
Re:Obligatory Spelling Comment by dudpixel · 2012-10-04 15:15 · Score: 1

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?

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Re:Obligatory Spelling Comment by dudpixel · 2012-10-04 15:16 · Score: 2

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

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Re:Obligatory Spelling Comment by Anonymous Coward · 2012-10-04 15:28 · Score: 0

asking for it?
its "sorry"
Re:Obligatory Spelling Comment by elementik · 2012-10-04 18:51 · Score: 1

It's

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Re:Obligatory Spelling Comment by saveferrousoxide · 2012-10-05 04:52 · Score: 1

What I find really funny is that googling 'messureent' comes up with:
"Showing results for measurements"
Re:Obligatory Spelling Comment by mfnickster · 2012-10-05 06:46 · Score: 1

Shirley, it should be Messierments ?

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8 year old's question by RichardDeVries · 2012-10-04 10:43 · Score: 4, Insightful

It expands into what?

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Re:8 year old's question by hutsell · 2012-10-04 10:46 · Score: 3, Informative

Hilbert Space

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Re:8 year old's question by UnknownSoldier · 2012-10-04 10:51 · Score: 3, Informative

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 by RichardDeVries · 2012-10-04 10:53 · Score: 4, Funny

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.

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Re:8 year old's question by RichardDeVries · 2012-10-04 11:01 · Score: 1

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!

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Re:8 year old's question by MightyMartian · 2012-10-04 11:02 · Score: 3, Interesting

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.

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Re:8 year old's question by kheldan · 2012-10-04 11:03 · Score: 5, Insightful

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

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Re:8 year old's question by multiben · 2012-10-04 11:10 · Score: 4, Funny

Milk. The universe is surrounded by milk.
Re:8 year old's question by arth1 · 2012-10-04 11:40 · Score: 3, Insightful

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 by Anonymous Coward · 2012-10-04 11:40 · Score: 5, Informative

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 by R3d+M3rcury · 2012-10-04 11:45 · Score: 1

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 by Anonymous Coward · 2012-10-04 11:50 · Score: 0

"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 by MightyMartian · 2012-10-04 12:01 · Score: 3, Insightful

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.

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Re:8 year old's question by turbidostato · 2012-10-04 12:14 · Score: 4, Informative

"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 by Anonymous Coward · 2012-10-04 12:21 · Score: 0

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 by gestalt_n_pepper · 2012-10-04 12:28 · Score: 1

Hey man, I just work here, OK?

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Re:8 year old's question by Sponge+Bath · 2012-10-04 12:32 · Score: 2

I guess God must be a woman... with astronomical tits.
Re:8 year old's question by Anonymous Coward · 2012-10-04 13:04 · Score: 0

Beyond his years, wise, that one is. Checked his midichlorian count, have you?
Re:8 year old's question by Nostromo21 · 2012-10-04 13:17 · Score: 3, Funny

"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 by Anonymous Coward · 2012-10-04 14:00 · Score: 1

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 by __aaltlg1547 · 2012-10-04 14:05 · Score: 1

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 by __aaltlg1547 · 2012-10-04 14:07 · Score: 1

"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 by __aaltlg1547 · 2012-10-04 14:08 · Score: 2

Milk. The universe is surrounded by milk.
Unlikely. Turtles don't have milk.
Re:8 year old's question by dudpixel · 2012-10-04 15:18 · Score: 1

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

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Re:8 year old's question by arth1 · 2012-10-04 15:21 · Score: 1

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 by Bengie · 2012-10-04 15:30 · Score: 1

"This also means that the lifetime of a photon is zero. That's more of a paradox." - I think it just means our concept of time is wrong.
Re:8 year old's question by Pseudonym+Authority · 2012-10-04 16:14 · Score: 1

For it to not be true, relativity would have to be completely wrong. Since it's back up by math, and you assertion is backed up by an unwillingness to understand, I'm going to have to side with relativity until you show some evidence other than `It's just no common sense!'.
Re:8 year old's question by kheldan · 2012-10-04 17:38 · Score: 1

This is imprecise at best.
Really, you have to admit that for something purely theoretical with a high likelyhood of never being proven at all, "imprecise at best" is a moot statement -- at best. :-)

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Re:8 year old's question by Anonymous Coward · 2012-10-04 18:40 · Score: 0

The universe expands into a lower state of energy.
Re:8 year old's question by Anonymous Coward · 2012-10-04 19:00 · Score: 0

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.
Until we can test our models experimentally (highly unlikely for this particular case), I'd say that "uncertain" is a very precise way to describe it. We used to be certain that the Earth was the center of the universe. We also used to be certain that all matter could be modeled with Newtonian physics.
Re:8 year old's question by RichardDeVries · 2012-10-04 19:56 · Score: 1

Thanks! I've read about the balloon analogy, but it's hard for me to grasp. I'm not made for this, I guess.

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Re:8 year old's question by wonkey_monkey · 2012-10-04 21:17 · Score: 2

But elephants do.

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Re:8 year old's question by Neil+Boekend · 2012-10-04 21:19 · Score: 1

The flame wasn't there in the beginning. Lucifer stole it from the heavens and brought it here. That was why he was kicked out of the heaven.

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Re:8 year old's question by arth1 · 2012-10-05 00:17 · Score: 2

Until we can test our models experimentally (highly unlikely for this particular case), I'd say that "uncertain" is a very precise way to describe it.
being an outside to be uncertain about.
You can't go five feet past the edge of the universe, because there is no space to measure five feet in. There isn't a void outside the universe where other universes can be, because that presupposes that there is a void with spatial coordinates, while those are attributes that belong to our universe.
Yes, we want to think of what's beyond, and our intuitive thinking doesn't deal well with models that doesn't represent space as we think of it.
The background radiation of the universe is uniform in all directions, and is believed to be so everywhere in the universe. I.e. there is no "edge" that expands. Everywhere expands.
If there isn't an "outside" anywhere or -when for a galaxy to be, degrees of uncertainty becomes a moot point. You could as well look at whether there are universes "inside" point particles like gluons and photons, or "before" time existed.
Or inside god's navel, for that matter.
If we are to determine other universes, it's going to be through mathematics, not physics, which are limited to this universe.
Re:8 year old's question by BaronAaron · 2012-10-05 00:57 · Score: 1

I like the loaf of raisin bread analogy better.
The rest of the this wikipedia article explains things in more understandable terms.
Re:8 year old's question by bunratty · 2012-10-05 01:52 · Score: 1

No, no, no. It's pasta sauce created from His noodly appendage.

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Re:8 year old's question by Anonymous Coward · 2012-10-05 02:36 · Score: 0

more correct than you know? etymology of galactic
Re:8 year old's question by Anonymous Coward · 2012-10-05 03:25 · Score: 0

Your opinion is not necessarily wrong... after all, the ability to accept things are incorrect and change our theories/models is part of the advancement of scientific theories and the scientific method. However, in this case, I think a better response would be our concept of time is incomplete. While we could be wrong, that would mean there is a completely different theory that still fits all of our examples and mathematical models. Our current theory fits what we have observed in numerous places... some of which are used in our everyday lives. For example, GPS satellites must account for a slightly different rate of time to remain accurate. Atomic clock that have been shown to go at different rates of time under different conditions (they did this by syncing them, then they took one up in the space shuttle). For our concept of time to be completely wrong, there would have to be a model that still fit all of our observed data and experiments. It is plausible, but unlikely.
However if you say our concept of time is incomplete, then your claim would still fit our current understanding.... after all we still do not have a working "theory of everything" that accounts for discrepancies between quantum physics and general relatively/'normal physics'
Re:8 year old's question by Anonymous Coward · 2012-10-05 03:31 · Score: 0

I suppose this is better than the old theories with ether.... at least with the Milk Theory, I can eat all the Thin Mints I want.
Re:8 year old's question by Anonymous Coward · 2012-10-05 06:38 · Score: 1

You're thinking Prometheus. Who gets to have his liver eaten from his chest while chained to a rock every day for eternity.
Luci was the Celestial Bin Laden, all insurgent up in God's face afore God went GTFO. He just gets to roam around being bad until the Apocalypse, where he gets thrown into a pit for a millenia, then gets out for a bit, presumably to stretch his legs.
Meanwhile, Prometheus is still chained to his rock, gettin' nibbled on. For giving up a bit of fire. Old school myths punished hard.
Re:8 year old's question by Lucas123 · 2012-10-05 07:02 · Score: 1

Another good question is if a galaxy one megaparsec away (that is, 3.26 million light years) is be moving away from us at 74.3 km/sec.How is it that a galaxy two megaparsecs away is moving at twice that speed, or 148.6 km/sec. That doesn't seem to make sense. Is the theory that the universe is expanding more quickly at the edge than at the center or are we at further out looking in?
Re:8 year old's question by Bengie · 2012-10-05 10:34 · Score: 1

If from the photon's perspective, it lasted exactly 0 time, then it never existed as all things that have never existed also have existed a time of 0. In one frame of reference, the photon exist, but it does not exist in the other frame of reference.
Re:8 year old's question by RichardDeVries · 2012-10-05 16:21 · Score: 1

Thanks! The article even has a heading called "What space is the universe expanding into?".

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South Park by Anonymous Coward · 2012-10-04 10:49 · Score: 0

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 by hazah · 2012-10-04 12:30 · Score: 1

It just rolls off the tongue.

Units by Anonymous Coward · 2012-10-04 10:49 · Score: 1

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 by amRadioHed · 2012-10-04 11:04 · Score: 4, Informative

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.

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Re:Units by olsmeister · 2012-10-04 11:04 · Score: 1

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 by Archangel+Michael · 2012-10-04 11:13 · Score: 1

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.

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Re:Units by gewalker · 2012-10-04 11:23 · Score: 1

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 by sconeu · 2012-10-04 11:28 · Score: 4, Interesting

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.

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Re:Units by Relic+of+the+Future · 2012-10-04 11:30 · Score: 3, Interesting

In the vein of xkcd-what-if #11, 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?

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Re:Units by sconeu · 2012-10-04 11:30 · Score: 1

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

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Re:Units by sconeu · 2012-10-04 11:32 · Score: 3, Informative

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

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Re:Units by Anonymous Coward · 2012-10-04 11:47 · Score: 0

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 by ImprovOmega · 2012-10-04 11:53 · Score: 4, Interesting

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 by j00r0m4nc3r · 2012-10-04 12:12 · Score: 4, Informative

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 by Anonymous Coward · 2012-10-04 12:29 · Score: 3, Insightful

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.
Re:Units by Nostromo21 · 2012-10-04 13:13 · Score: 1

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 by Nostromo21 · 2012-10-04 13:19 · Score: 0

Yeah, I just made that 'independent' observation further up. Coincidence or inevitability...? Believe it or not!
Re:Units by LordLimecat · 2012-10-04 14:03 · Score: 1

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 by RegTooLate · 2012-10-04 14:07 · Score: 2

whatever my ship can make the Kessel Run in less than twelve parsecs.
Re:Units by thrich81 · 2012-10-04 14:38 · Score: 4, Informative

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 by Anonymous Coward · 2012-10-04 14:44 · Score: 0

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 by Anonymous Coward · 2012-10-04 16:41 · Score: 0

If space is expanding FTL, wouldn't that mean that the observable universe is actually shrinking? Wouldn't a photon emitted from the edge of the observable universe be unable to make it to Earth?
Re:Units by sadyoshi · 2012-10-04 19:12 · Score: 1

It's the ratio that space itself expands per second. Each second, space expands by a multiple of 1 + (74 km / 1 megaparsec).
Re:Units by f()rK()_Bomb · 2012-10-04 21:10 · Score: 1

Posting to fix Accidental mod

--
"The space elevator will be built about 50 years after everyone stops laughing." - Arthur C. Clarke ~1980
Re:Units by Ginger+Unicorn · 2012-10-05 00:09 · Score: 1

Yes. Eventually each object in the universe will be in it's own lonely little bubble, out of range of everything else

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(1.21 gigawatts) / (88 miles per hour) = 30 757 874 newtons
Re:Units by Sqr(twg) · 2012-10-05 01:38 · Score: 1

You did the math wrong. 74.3 / 3.08567758e19 is approximately 2.4e-18 Hz.
This is how frequently the universe doubles it current size at the current rate of growth.
Re:Units by Quirkz · 2012-10-05 02:40 · Score: 1

Except I don't think the expansion applies at the galactic level, so anything in a galaxy will still have the whole galaxy with it. Now if you're talking about galaxies themselves as the objects of the universe, then that's likely true.

--
The Quirkz Handbook of Self-Improvement for People Who Are Already Pretty Okay
Re:Units by cashdot · 2012-10-05 02:44 · Score: 1

Space itself can expand such that the objects (events?) within it are moving apart at faster than c.
correct

Any two objects separating faster than c can't measure that -- they cannot pass any signal between them.
not correct
Let me explain: Suppose there are two points in space, A and B, which are in rest relative to eachother. The distance between A and B grows FTL as space expands.
It is paradoxical, but nevertheless true, that travelling from A to B takes only a finite amount of time, no matter how slow the travel is. This is because the distance already traveled is expanded as well.
Re:Units by thrich81 · 2012-10-05 03:36 · Score: 1

I'm open to discussion, but I'd say there is a flaw in your example -- if points A and B are truly 'at rest' relative to each other then by definition the distance between them is not growing (no velocity induced redshift). I think you are trying to use the definition of 'rest' as meaning no "peculiar motion" (astronomical term) on top of the motion imparted up on them by the expansion of space between them. A concrete example would be galaxies observed at a large distance -- they all have a redshift due to the expansion of space between us, on top of whatever random peculiar motions they may have, but the true measure of the velocity between us and them is the observed redshift no matter how it comes about (neglecting gravitational redshifts). If the separation velocity is greater than c then the redshift becomes infinite = no signals.
Re:Units by dinfinity · 2012-10-05 04:42 · Score: 1

Yes, the paradox more commonly known as:
http://en.wikipedia.org/wiki/Ant_on_a_rubber_rope (the expansion of space is explicitly referenced at the end of the article).
It has to be said however, that the 'finite amount of time' can easily be ridiculously large.
Re:Units by cashdot · 2012-10-05 05:48 · Score: 1

If the separation velocity is greater than c then the redshift becomes infinite = no signals
I do not understand which theorie/formulae you indicate here
You should not confuse redshift caused by Relativistic Doppler, which is not even defined for FTL, with Cosmological redshift
Re:Units by thrich81 · 2012-10-05 07:00 · Score: 1

Dang, now I have to go review some GR stuff to go any further. When you get deep into GR, either on cosmological distances or strong gravity fields things get badly non-intuitive. In this particular case I think we will run into the problem of what exactly is meant by "areas of space receding from each other at faster than c". I'll leave with this one question -- if you postulate two objects separating from each other at faster than c due to the cosmological distance between them, and further assert that they will be able to "observe" each other (send a light or other signal), what is the observed doppler shift of that signal when received? Appreciated the discussion.
Re:Units by Anonymous Coward · 2012-10-05 07:20 · Score: 0

Depends on if the expansion is accelerating, and if that acceleration is unbounded. If it keeps accelerating, at some point the stretching of space will over power gravity between stars, and eventually chemical bonds, and so on.
Re:Units by Anonymous Coward · 2012-10-05 08:05 · Score: 0

not correct
Let me explain: Suppose there are two points in space, A and B, which are in rest relative to eachother. The distance between A and B grows FTL as space expands.
It is paradoxical, but nevertheless true, that travelling from A to B takes only a finite amount of time, no matter how slow the travel is. This is because the distance already traveled is expanded as well.
You are actually incorrect, if speaking about our universe. What you write above is correct if the rate of expansion is constant.
But it isn't. The rate of expansion of our universe has been shown to be accelerating.

Spelling? by Anonymous Coward · 2012-10-04 10:49 · Score: 0

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

Gem Secretes as Superman by badford · 2012-10-04 10:50 · Score: 3, Funny

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

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-badford

Ok. Now what is it in hogsheads per fortnight? by Nadaka · 2012-10-04 10:50 · Score: 1

ha

Re:Ok. Now what is it in hogsheads per fortnight? by flaming+error · 2012-10-04 11:08 · Score: 1

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? by Nadaka · 2012-10-04 11:19 · Score: 2

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? by ThreeKelvin · 2012-10-04 11:31 · Score: 1

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? by Anonymous Coward · 2012-10-04 11:38 · Score: 0

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? by ThreeKelvin · 2012-10-04 12:19 · Score: 1

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.
Re:Ok. Now what is it in hogsheads per fortnight? by Anonymous Coward · 2012-10-04 12:28 · Score: 0

What is the answer for hogsheads per fortnight per displacement of Archimedes in a bathtub.
1/s. How dull.

It's on schedule by Anonymous Coward · 2012-10-04 11:04 · Score: 0

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 by ubergeek65536 · 2012-10-04 11:09 · Score: 2, Insightful

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 by countach · 2012-10-04 11:18 · Score: 4, Insightful

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 by Anonymous Coward · 2012-10-04 11:28 · Score: 0

42?
Re:Not to be pedantic by Anonymous Coward · 2012-10-04 11:41 · Score: 0

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 by Anonymous Coward · 2012-10-04 12:00 · Score: 1

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 by dido · 2012-10-04 12:58 · Score: 1

Well, there is the dark flow, 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.

--
Qu'on me donne six lignes écrites de la main du plus honnête homme, j'y trouverai de quoi le faire pendre.
Re:Not to be pedantic by cain+amofni · 2012-10-04 14:01 · Score: 1

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 by Ironhandx · 2012-10-04 14:09 · Score: 1

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.
Re:Not to be pedantic by Anonymous Coward · 2012-10-04 16:23 · Score: 2, Informative

Doppler shift. Seriously.
Light can experience doppler shift like sound can (well, really any wave can see a doppler shift). So if two objects are moving away from each other, light from one to the other will be red shifted. If two objects are moving closer together, the light will be blue shifted.
Since chemicals have known spectral emission/absorption lines, you use that data compared with your observational data of distant objects to figure out the actual shift. Add in some math and you can even figure out how fast they are going. Hubble was one of the first to do the observations and noticed that *everything* outside the local group was red shifted. Andromeda and other members of the local group are gravitationally bound, including our galaxy, so you get other interesting values, including a blue-shifted Andromeda which gives us the idea that it will eventually collide with our galaxy as we more accurately measure that.
But if the universe wasn't expanding, you'd expect that you wouldn't see such consistent and uniform redshifts in EVERY direction. And this concept has been backed up with data using a specific type of supernovae as a "standard candle" to figure out distances and confirm that the redshifts are telling us what we think they are telling us. Everything with bigger redshifts we've been able to also measure with a standard candle has been further away from things with smaller redshifts.
The thing is, this red shift is also what allows us to measure the size of the observable universe, because this measured expansion is so uniform. And the constant used to describe this expansion is the Hubble constant. This particular bit of science isn't exactly new either. Hubble did the work almost a century ago now.
Re:Not to be pedantic by Anonymous Coward · 2012-10-04 18:03 · Score: 0

All of which are utterly useless with no way to observe or interact to confirm it.
Re:Not to be pedantic by Anonymous Coward · 2012-10-05 07:25 · Score: 0

The expansion would not be at odds with general relativity and in fact gets along with it quite well. With the metric expansion of space, you would see everything (beyond the short distance that is bound by gravity) receding from you, no matter where you are in the universe. Everything is expanding away from everything else, and to everyone, it looks like further things are expanding faster.
Re:Not to be pedantic by cain+amofni · 2012-10-05 12:09 · Score: 1

I hear what you're saying but my point is that the Hubble constant is relative, not absolute. Relative to the observer in a non-absolute location. The expansion is an exponential scalar motion without any center. Even the edge of the observable universe is relative to the observer. So it's fine to talk about the universe expanding, but expanding relative to what? By definition, the size (radius) of the universe is that of only the observable universe - relative to us. Someone way over at the edge (according to us) is likely to see a different observable universe that extends 13 billion light years in all directions from their center of observation, beyond which the expansion rate is > c (again relative to us only), so quite a bit of that is invisible to us and always will be. So the limit of observability is 13 billion light years. Is it a coincidence that the calculated age of the universe (from only observables) is also 13 billion years? Of course not. Neither is the fact that the dimension of the Hubble constant is a frequency that resolves to 1/13 billion years. What is the probability of all those emerging without a common first principle? And what is the likelihood that we would happen to be at the center of the observable universe? About zero, to say nothing of the "total" universe. There is no reason at all to assume that we know the size or age of the "universe" and to throw that into the discussion of the Hubble constant (as many are on this thread) is meaningless.
Re:Not to be pedantic by Anonymous Coward · 2012-10-05 14:51 · Score: 0

The radius of the observable universe is estimated to be about 46 billion light years while the age is estimated to be about 13.7 billion years. The numbers don't match up because of the expansion. As space expands, the distance between the light and its origin would grow faster than c.
The age of the universe is still fundamentally linked to measurements of the expansion. Because that expansion rate would be observable everywhere, even if just everywhere in the observable universe, indicates expansion from a single, small point. It is not about what the edge of the observable universe is doing, it is about what every point in the observable universe is doing. Even if the total universe was much larger than the observable universe (which has been suggested by various tests of the CMB that however require some assumptions) current models still give the same age from the expansion rates measured, they don't assume the universe stops at the edge of the observable universe.
I'm not sure what you are getting at about some of the numbers being coincidence or not. The inverse of the Hubble constant would be the age of the universe in a flat, non-accelerating universe. Current measurements and models of the accelerating expansion give that the inverse and age should be about the same, and would be about the same for the last 10 billion and for the next 5 billion or so years. That part might be a little coincidental, that we didn't evolve 5-10 billion years later when it would have been more obviously different assuming that model is correct.

what's in a name? by X10 · 2012-10-04 11:10 · Score: 2

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

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no, I don't have a sig

Turtles. Duh! by Anonymous Coward · 2012-10-04 11:18 · Score: 1

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

Sorry for sounding stupid... by Longjmp · 2012-10-04 11:26 · Score: 1

... 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.

--
There are fewer illiterates than people who can't read.

Re:Sorry for sounding stupid... by Anonymous Coward · 2012-10-04 11:52 · Score: 0

Why?
Re:Sorry for sounding stupid... by __aaltlg1547 · 2012-10-04 14:09 · Score: 1

If that were the case, we wouldn't see anything when we look up at night.
Re:Sorry for sounding stupid... by Prof.Phreak · 2012-10-05 00:25 · Score: 1

If you shine a laser pointer at the sky (not airplane), the beam leaves earth, and about 14 billion years the beam will reach the farthest galaxies we can see. What happens after another 1000 billion years? Will the beam curve back on itself? Will it slow down and go only at the rate of expansion? But, if the beam just keeps on going at c---it would be beyond the ``visible edge'' of the universe, no? Wouldn't that imply that the `non-visible' real edge of the universe has to expand at least at 'c' or else you'd have light leaving the universe, which it shouldn't :-/

--
"If anything can go wrong, it will." - Murphy
Re:Sorry for sounding stupid... by Anonymous Coward · 2012-10-05 02:09 · Score: 0

The expansion is non-localized. For example, a galaxy that's 13billion light years away is moving away from us much much faster than one only 1billion light years away, this is true for all galaxies (except the very nearest, gravity holds us together better than the expansion of the universe tears us apart) in all directions. Since the farther away a galaxy is, the faster it's moving away from us this can only mean two things. Either the expansion occurs everywhere (even between you and the floor, but gravity holds you together) or we're the center of the entire universe.

There's also a misconception that the universe is only 14billion light years in radius because of the age, when in fact the visible universe is about 50ish(forget the actual number)billion light years in radius, the reason we can "see" things farther than 14billion light years is due to the expansion of the universe, light from the first galaxies travel over expanding space, it does NOT travel faster than the speed of light but it does get vastly red shifted. What this means is that as far as angular distance is concerned the object is 14 billion light years away, but if you take a photon emitted by hydrogen it will be so red shifted it would indicate the object's "true" distance

So what ends up happening is this, if I shine a beam of light right into an object at the very edge of our observable universe, the light will travel torwards it, but at the same time due to expansion that object will get further and further away. If it was within our exact border of visibility, according to the beam of light, the object would never move. It would race towards it for infinity but never arrive, if it's only slightly closer the beam will eventually reach it, though it take a quadrillion years. (Due to the Planck distance you could probably calculate the exact maximum amount of time it'd take light to reach an object that wouldn't be infinity)

These descriptions are from a beam of light's point of view. From someone on earth, the galaxies will get redder and redder until they vanish from our visible universe, then nearer ones, then nearer ones, until only the gravity bound galaxies remain in our universe, but since matter decays and emits energy, that energy will leave our visible universe too, until eventually the entire visible universe consists of one elementary undecayable thingy (energy or matter).

P.S. I am not a physicist, everything I've said is liable to be wrong!

unit: kilometers per second per megaparsec ? by AbhiTheOne · 2012-10-04 11:27 · Score: 0

astronomy noob here. Parsec is unit of length= 3.26 light-years per http://en.wikipedia.org/wiki/Parsec. 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 ? by under_score · 2012-10-04 11:39 · Score: 1

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.

--
Helping with organizational effectiveness is our job.
Re:unit: kilometers per second per megaparsec ? by Dan+East · 2012-10-04 13:09 · Score: 1

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

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Better known as 318230.

Better than ahead of schedule by Dyne09 · 2012-10-04 11:30 · Score: 1

Because, that would just be a problem.

Sure, but ... by fahrbot-bot · 2012-10-04 11:34 · Score: 1

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

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

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It must have been something you assimilated. . . .

Interesting info by Anonymous Coward · 2012-10-04 11:42 · Score: 0

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 by WillAffleckUW · 2012-10-04 11:52 · Score: 1

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!

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-- Tigger warning: This post may contain tiggers! --

On what schedule? by Anonymous Coward · 2012-10-04 12:12 · Score: 0

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.

Re:On what schedule? by Anonymous Coward · 2012-10-05 07:36 · Score: 0

Yes, when they said it is on schedule, they were implying that astronomers believe they control the whole universe. It started when one day some years ago, when an astronomer sat down and came up with a schedule for the expansion of the universe. After those years, we've checked on the expansion, and the universe is doing exactly what that astronomer said it would. Now all astronomers believe the universe does exactly what they tell it to. Others may interpret the headline to mean the schedule was correctly following what the universe was doing, but you've seen past that false hood and understand the truth, that astronomers think the universe follows whatever schedule they come up. Everyone else who think the causality goes from universe doing stuff -> develop schedule has it backward. The human knowledge doesn't reflect the universe, the universe reflects human knowledge is the fundamental principle all scientist follow.

Megaparsec? by tpstigers · 2012-10-04 12:16 · Score: 1

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

Re:Megaparsec? by Neil+Boekend · 2012-10-05 00:11 · Score: 1

Well, the kessel run is 18 parsecs, so that'll be 18/1,000,000=0,000018 Megaparsecs

--
Well, I might have a way, but it only works on a semi spherical planet in a vacuum.

I'm still 'spanding... by grouchomarxist · 2012-10-04 12:38 · Score: 0

yeah, yeah, yeah...

Re:Units Space FTL, but information thru space? by shoor · 2012-10-04 12:42 · Score: 3, Interesting

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?

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In theory, theory and practice are the same; in practice they're different. (Yogi Berra & A. Einstein)

Excelllent by Anonymous Coward · 2012-10-04 12:45 · Score: 0

I hate it when the universe is late!

Expansion not accelerating? by Anonymous Coward · 2012-10-04 12:47 · Score: 0

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

The Universe has no center by seibai · 2012-10-04 13:05 · Score: 2

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.

Re:The Universe has no center by Anonymous Coward · 2012-10-04 17:29 · Score: 3, Insightful

The center of the observable universe is exactly where I am at this moment. Beyond the observable universe, we have no idea, so we might as well assume that the center of the universe is the same as the observable universe. Me.
Re:The Universe has no center by Kaptain+Kruton · 2012-10-05 03:39 · Score: 1

You're the center of the universe? And people say that I have a big head...

Your problem... by Anonymous Coward · 2012-10-04 13:10 · Score: 0

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

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Re:Your problem... by MightyMartian · 2012-10-04 13:57 · Score: 1

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

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The world's burning. Moped Jesus spotted on I50. Details at 11.
Re:Your problem... by kilfarsnar · 2012-10-05 03:15 · Score: 1

is thinking that "our common every day perceptions of the world" are somehow not reality. Model, indeed.
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That really depends on how you define reality.

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"What the American public doesn't know is what makes them the American public." -Ray Zalinsky (Tommy Boy)

Is it possibly just contracting *away* from us? by Anonymous Coward · 2012-10-04 13:20 · Score: 0

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

"exact center"? even if earth was near the center by Anonymous Coward · 2012-10-04 13:23 · Score: 0

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.

small rate on human time scales by Anonymous Coward · 2012-10-04 13:26 · Score: 0

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 by Anonymous Coward · 2012-10-04 13:27 · Score: 0

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 by Anonymous Coward · 2012-10-04 15:13 · Score: 0

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 by cain+amofni · 2012-10-04 13:48 · Score: 1

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 http://www.ardeshirmehta.com/Relativity.html

Re:dimensional analysis resolves to frequency by sconeu · 2012-10-04 16:08 · Score: 1

That frequency is 1/13billion years.

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General Relativity: Space-time tells matter where to go; Matter tells space-time what shape to be.
Re:dimensional analysis resolves to frequency by wonkey_monkey · 2012-10-04 21:53 · Score: 1

Is that a coincidence?

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systemd is Roko's Basilisk.
Re:dimensional analysis resolves to frequency by sconeu · 2012-10-05 06:22 · Score: 1

I don't know. It corresponds roughly with the age of the universe, and also with the limit at which the recession velocity approaches c.
I'm just a dilletante. You'd have to ask an astrophysicist what the significance of that value is, if any.

--
General Relativity: Space-time tells matter where to go; Matter tells space-time what shape to be.
Re:dimensional analysis resolves to frequency by cain+amofni · 2012-10-05 11:33 · Score: 1

If any astrophysicist knows I'd be surprised.
Re:dimensional analysis resolves to frequency by Anonymous Coward · 2012-10-05 14:59 · Score: 0

If the universe's expansion was not accelerating or decelerating, you would expect the age of the universe and one over the Hubble constant to be the same at all time. There is observed acceleration, but because it is quite slow and not far from the decelerating effects of gravity pulling things together, the 1/H is still about the age of the universe, and would look that way until much closer to the Big Bang, or until several billion years in the future where the acceleration has accumulated.

Re:Units Space FTL, but information thru space? by Andreas+Mayer · 2012-10-04 15:14 · Score: 1

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*.

1.02269 mm / year / Gm by Anonymous Coward · 2012-10-04 15:58 · Score: 0

less-crazy units

even better: it grows by one trillionth per year

It is a factor of 1.00000000000102269 each year.

If you are willing to wait, you don't need pills for enlargement. :-)

Light years please by rossdee · 2012-10-04 17:44 · Score: 1

"The universe is about 14,000 megaparsecs in radius"

A parsec is about 3.26 light years therefore a MegaParsec is 3.26 million light years

Say if you have velocity per distance thats distance per distance per time, the distances cancel out so the value would be a per time in other words a frequency

a very small frequency of course, but still could be expressed in hertz

I think I'm in heaven by Anonymous Coward · 2012-10-04 18:11 · Score: 0

A large collection of intelligent people trying to understand, or help others understand the nature of time, space, and the known universe. All without religious violence or petty arguments over the unknowable.

It's a beautiful scene of cooperation and curiosity. It's a refreshing sight during a time that two douchebags are igniting partisan bickering with their political ambitions. It really puts in to perspective the importance of a turd sandwhich's tax plan(which they will never get past congress).

Free your mind! by Anonymous Coward · 2012-10-04 18:48 · Score: 0

You think that's air you're breathing?
Hm!

Nope. Edwin Hubble didn't believed in Big Bang by Zdzicho00 · 2012-10-04 21:23 · Score: 1

Edwin Hubble was very sceptical about, so called "Big Bang" theory and claimed that there might be different explanation of redshift effect which he observed.

``Astronomer Edwin P. Hubble says that after a six-year study, evidence does not support what we now call the Big Bang theory, according to the Associated Press. “The universe probably is not exploding but is a quiet, peaceful place and possibly just about infinite in size.''''

Check this paper too:
http://arxiv.org/PS_cache/arxiv/pdf/1107/1107.2485v2.pdf

Re:Nope. Edwin Hubble didn't believed in Big Bang by negablade · 2012-10-04 22:10 · Score: 2

That doesn't mean he was right. The prevailing opinion at the time was for a static, unchanging universe. And the discovery that it was expanding would have been difficult to reconcile with our understanding at the time. Prevailing opinions do change, albeit sometimes slowly, in the face of mounting evidence.

Amazing Speed by Anonymous Coward · 2012-10-04 21:49 · Score: 0

Beware! Each day each kilometer gets a bit longer.

That is exactly (74300 m/s / 3.08567758 × 10^22 m ) * 1000 m * 3600 * 24 s = 2,08 x 10^10 m

About the Size of two hydrogen atoms.

Re:Units Space FTL, but information thru space? by Anonymous Coward · 2012-10-05 00:34 · Score: 0

Shadows can travel faster than light.

Naive question by tchi.keufte · 2012-10-05 01:08 · Score: 1

And why wouldn't we consider that the content of the Universe (including us) is shrinking, instead ?

Re:Naive question by Anonymous Coward · 2012-10-05 02:35 · Score: 0

If it was shrinking, then we would observe blueshift in the light from faraway objects. Instead, we observe roughly equal redshift among faraway objects in all directions. This means the universe is expanding. This other comment in this thread goes into greater detail.
http://science.slashdot.org/comments.pl?sid=3164219&cid=41555613

It's... by bunratty · 2012-10-05 01:49 · Score: 2

Monty Python's Flying Circus!

--
What a fool believes, he sees, no wise man has the power to reason away.

Limits of the human mind by microbox · 2012-10-05 02:31 · Score: 1

I think it just means our concept of time is wrong.

Black and white thinking meets the limits of conception. *every* concept is wrong. It is a trivial statement. Both the concept, and its black & white categorization as right/wrong, are artefacts of the human brain. And the GP is wrong. From a photons point of view, it has zero lifetime only if it travels through a perfect vacuum. Light travels more slowly otherwise, and then observes "time" and "distance".

Another way of saying is, if a photon was generated in a distance star, and it intersected with your eye (i.e., you saw it), then from the photons point of view, this would have been instantaneous if it only travelled through a perfect vacuum.

Stated this way, it does not violate quotidian conceptions of time.

--

Like all pain, suffering is a signal that something isn't right

Re:Limits of the human mind by Anonymous Coward · 2012-10-06 00:09 · Score: 0

But if it didn't travel through vacuum, couldn't we argue that it was another photon? An obstacle electron absorbed the original photon, got excited, and after a while emitted another photon of the same wavelength. So each individual photon still has zero lifetime.

Hera by microbox · 2012-10-05 02:33 · Score: 1

Hera (Zeus' wife) sprayed milk across the sky -- creating a luminous strip that we still call the "Milky Way"

--

Like all pain, suffering is a signal that something isn't right

Re:Units Space FTL, but information thru space? by painandgreed · 2012-10-05 05:40 · Score: 1

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?

FIrst off, don't worry about paradoxes, because physics doesn't. As much as it may hurt our brains, according to Tippler's solution for an infinitely long cylinder, Feynman diagrams and other solutions for Einstein's equations for general relativity, it seems that the physics doesn't bear out paradoxes. However, many of these cases are so extreme that we doubt we'll ever see them and its a safe bet to even say they are not actually possible (although nothing prohibits them according to the physics I have seen the math for).

One of those extremes would be a tachyon, a particle moving faster than light. Einstein's equations prohibit anything accelerating to or beyond the speed of light, but have no prohibitions about a particle being created moving at a speed greater than light. However, unless a positron is actually an electron moving backwards in time, we haven't seen any and might not even know what to look for. Last I heard that wasn't pure wishful speculation or unsubstantiated denial, tachyons might have been possible in the early universe but if they could exist, it would be evidence that the universe was at a false vacuum and they would quickly create instability and drop the universe to a more stable energy state. Let's hope we don't create one because that might be the end of the universe as we know it.

Other solutions for FTL travel involve semi-hard science fiction such as warping space, wormholes, or hyperspace. While light and everything else in space must obey the c speed limit, that is the max speed of things travelling through space, whereas space can do whatever it damn well pleases. Once again, they can come up with equations for space warping to the point that such things can happen, but those seem to be so extreme that we're not even sure if they are possible even thought the math works out. Wormholes are a related idea but you really aren't traveling faster than light, but rather taking a short cut where light has a shorter distance to travel. Imagine you are looking at a mountain and to get to the other side, you need to drive around it. Then somebody builds a tunnel through the mountain and you can instead just drive straight across. The speed limits are the same for both routes, but the tunnel (ie wormhole) is a shorter distance. Again, warping space is hard and requires a lot of energy. So much that such wormholes that might actually allow information to travel through might be impossible. There there is hyperspace which stipulates that all of our (3D) space is connected to another space and the physical laws such as c do not apply to that space, or the distances are simply shorter. Imagine the Flatlander being lifted off of Flatland and blown by a wind in 3D space faster than anything can travel in 2D space and then dropped again into Flatland.

TIME FOR SOME REALITY, I THINK! by Anonymous Coward · 2012-10-05 07:25 · Score: 0

Space is INFINITE. It cannot be anything BUT infinite! And I mean LITERALLY infinite. Space has no limit, nor boundary or shape. Our universe is expanding into SPACE. The experts refusal to accept this fact is quite odd.

Seeing as.... by hesaigo999ca · 2012-10-05 09:04 · Score: 1

Seeing as we can not see the edge of the universe from where we are....
how can we really tell if yesterday the edge was 1.2 km less then it is today?

Are we saying that all objects are moving away from each other at that rate?
Of course not, they have gravity and orbits and all that....
so what are they using to gauge the edge of the universe has extended from yesterday?

Seriously! I want to know

Re:Seeing as.... by pantaril · 2012-10-08 00:03 · Score: 1

Seeing as we can not see the edge of the universe from where we are....
how can we really tell if yesterday the edge was 1.2 km less then it is today?
Are we saying that all objects are moving away from each other at that rate?
Of course not, they have gravity and orbits and all that....
so what are they using to gauge the edge of the universe has extended from yesterday?
Our universe has probably no edge, at least not in our three dimensional space. Some studies sugest it looks like four dimensional expanding dodecahedron. What that menas is if you travel in one direction for a very long distance, you will return to the point where you started. You can imagine that quite easily if you take away one dimension and imagine three dimensional curved and expanding space i.e. inflanting air baloon. If you draw black dots on the surface of the baloon (representing galaxies), you will find out that each galaxy is traveling away from each other galaxy as the baloon inflates. Also if you walk on the surface of the balloon for a long time, you will arive to the point where you started.
We are not measuring the expansion rate by observing the border of the universe (we cannot see any border and there is probably no border as i explained above). Instead, we look at distant galaxies. We measure the distance to far away galaxies using supernovae explosions (i.e. standart candles) and the red-shift effect which influence the light as it travels from the distant galaxy to us.
I don't know the details here (astrophysics is just my hobby) but we know somehow that the more distant a galaxy is, the faster it travels from us. Very far galaxies are traveling faster than light from us.
Re:Seeing as.... by hesaigo999ca · 2012-10-09 01:25 · Score: 1

I am not sure about that, who is to say how much further out the edge of the universe is from the very first galaxy that we may record, or maybe we still have yet to actually be able to see the first galaxy seeing as it is so far away, so we could be way off if we just use the distances between us and the galaxies, vs. the actual measurement of the edge to us...no?
I am no mathematician, but it seems that everything is theoretical at this point in terms of what we THINK we know and what is fact, hence my original comment
we do not really know...who knows, maybe the universe started to expand 1 billion years before the first galaxy showed up, would that not affect how much size the universe had already grown, and thereby give us false calculations being off by 1 billion years of expanding/speed?
Re:Seeing as.... by MacColossus · 2012-10-12 09:05 · Score: 1

Doppler Effect on light waves http://archive.ncsa.illinois.edu/Cyberia/Bima/doppler.html
Re:Seeing as.... by hesaigo999ca · 2012-10-18 07:17 · Score: 1

I know about this, and am very aware that this practice is used, however, I also know they estimate that the distance betwen the earth and say star 1 is at xx km per second, but 2 things pop into question.... can we use the same formula for something that does not behave the same as stars, we are not talking about an actual object moving in space, but we are talking about a virtual(is it really?) edge of the universe, from which we assume on the other is nothingness, therefor could we really say this object would be subject to the same formulas used to calculate distances for stars.
Also the premise that the stars are moving away from the Earth at a perticular rate is a false assumption...can we say the big bang exactly started on the Earth's position...I know we think we are the center of the universe on this small rock, but it could also be we are right on the edge of the universe and not even know it,
as we do not know the full size of the universe at this point.
Use this same point of view to understand that all planets orbit stars (most anyways), and stars do solar systems, and solar systems do galaxies, we have a multitude of combinations of orbits that propel objects in such patterns that it would be unpredictable to know at which point one star is coming closer to us because it is coming back on its revolving orbit....have u seen 2 galaxies merge, the actual gravitational pull sends them spiraling together smashing solar systems and planets together from the sheer force of it all....would they not appear differently using this same formula to explain why one day they were further out, and the next closer to use even though their orbit was understood as pulling them away from us.....
All in all, I know we know nothing when it comes to space, and yet we declare so many things as if fact. My point remains, you can only be absolute when you have fact in hand.and unless we have God's 2 dimensional game board or map of the universe showing exact distances of all there is in this universe from each other that we can look down at from a bird's point of view, all we have are these speculations on our part.....

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