Fermilab Reports Dark Energy Not Needed

An anonymous reader writes "A Fermilab press release reports that the expansion of the universe may be explainable without the need for dark energy or a cosmological constant. Apparently, ripples from inflation in the early universe may account for the observed expansion rate of the universe."

Comments

Nothing for you to see here.

[brilinux]

Nothing for you to see here. Please move along.

Well, apparently the dark matter is still important on Slashdot.

Re:Nothing for you to see here.

[digismack]

It doesn't matter.

Re:Nothing for you to see here.

[erice]

Nothing for you to see here. Please move along.

Wouldn't that be, nothing for you to *not* see here?

But what about the Horizon problem?

[mr100percent]

But what about the Horizon problem?

From an earlier /.-linked article 13 things that do not make sense:

The horizon problem

OUR universe appears to be unfathomably uniform. Look across space from one edge of the visible universe to the other, and you'll see that the microwave background radiation filling the cosmos is at the same temperature everywhere. That may not seem surprising until you consider that the two edges are nearly 28 billion light years apart and our universe is only 14 billion years old.

Nothing can travel faster than the speed of light, so there is no way heat radiation could have travelled between the two horizons to even out the hot and cold spots created in the big bang and leave the thermal equilibrium we see now.

This "horizon problem" is a big headache for cosmologists, so big that they have come up with some pretty wild solutions. "Inflation", for example.

You can solve the horizon problem by having the universe expand ultra-fast for a time, just after the big bang, blowing up by a factor of 1050 in 10-33 seconds. But is that just wishful thinking? "Inflation would be an explanation if it occurred," says University of Cambridge astronomer Martin Rees. The trouble is that no one knows what could have made that happen.

So, in effect, inflation solves one mystery only to invoke another. A variation in the speed of light could also solve the horizon problem - but this too is impotent in the face of the question "why?" In scientific terms, the uniform temperature of the background radiation remains an anomaly.

"A variation in the speed of light could solve the problem, but this too is impotent in the face of the question 'why?'"

Also, in the same article, Dark Energy is discussed:

9 Dark energy

IT IS one of the most famous, and most embarrassing, problems in physics. In 1998, astronomers discovered that the universe is expanding at ever faster speeds. It's an effect still searching for a cause - until then, everyone thought the universe's expansion was slowing down after the big bang. "Theorists are still floundering around, looking for a sensible explanation," says cosmologist Katherine Freese of the University of Michigan, Ann Arbor. "We're all hoping that upcoming observations of supernovae, of clusters of galaxies and so on will give us more clues."

One suggestion is that some property of empty space is responsible - cosmologists call it dark energy. But all attempts to pin it down have fallen woefully short. It's also possible that Einstein's theory of general relativity may need to be tweaked when applied to the very largest scales of the universe. "The field is still wide open," Freese says.

Re:But what about the Horizon problem?

[Anonymous Coward]

If the universe is 14 billion years old, and the edges are nearly 28 billion light years apart, what's the problem? It expands at relativistic speeds 14 billion years one way, 14 billion years the other. 14*2 = 28. So unless they're stating this wrong, shouldn't that be the way that it works?

Re:But what about the Horizon problem?

[PureFiction]

If you read the article you would see they address this issue. The key is to realize that the horizon extends beyond what we can see (our cosmic horizon):

• It is widely believed that during the inflationary expansion early in the history of the universe, very tiny ripples in spacetime were generated, as predicted by Einstein's theory of General Relativity. These ripples were stretched by the expansion of the universe and extend today far beyond our cosmic horizon, that is over a region much bigger than the observable universe, a distance of about 15 billion light years. In their current paper, the authors propose that it is the evolution of these cosmic ripples that increases the observed expansion of the universe and accounts for its acceleration.
• 
  
  "We realized that you simply need to add this new key ingredient, the ripples of spacetime generated during the epoch of inflation, to Einstein's General Relativity to explain why the universe is accelerating today," Riotto says. "It seems that the solution to the puzzle of acceleration involves the universe beyond our cosmic horizon. No mysterious dark energy is required."

Re:But what about the Horizon problem?

[Penguinoflight]

I was going to moderate your comment "interesting", but then I realized all of this is just hypothesis so it doesn't really belong outside the original study group.

two edges are nearly 28 billion light years apart and our universe is only 14 billion years old.

In 1998, astronomers discovered that the universe is expanding at ever faster speeds. It's an effect still searching for a cause - until then, everyone thought the universe's expansion was slowing down after the big bang.

A true scientific perspective would be to look at the evidence of the universe and theorize about the origins from there. Many studies(like this one find that light slows down over time. The idea that the universe must be 14-28 billion years old just to cover for the huge size is unnecessary and sloppy when the speed of light is not considered as a constant.

I beileve in explaining things in the most simple possible way. If a theory is challenged by plain old evidence the theory probably has an error and should be fixed. Making up new theories to explain a dead one is very sloppy and it takes away from the ethical reputation of science.

Re:But what about the Horizon problem?

[bperkins]

But what about the Horizon problem?

The work in this article assumes that inflation is right. People don't like inflation because they don't know how it happend, but something like it had to have happened in the early universe.

Re:But what about the Horizon problem?

[rm999]

According to a recent scientific american article that was written to debunk common myths about the universe, given that the universe is expanding, the visible universe is actually larger than 14 billion ly radius. This is because light from a star that is *now* 30 billion ly away could have reached us by now because for part of its trip it was closer than 30 billion lys from us. This is, of course, assuming that light goes at a constant speed.

The problem with all this highly theoretical physics is that no one really understands it - even the people who study it. I don't study it; I am just repeating what I read in an article, so I am sure that I know even less about all this stuff.

Re:But what about the Horizon problem?

[farquharsoncraig]

IT IS one of the most famous, and most embarrassing, problems in physics.

Obviously a physicist didn't write this article. When something unexpected happens in the field of physics, physicists are not embarassed, there is rather much rejoicing among the people of science. The TOE aside, we in the pursuit of pure research do not concern ourselves with the prerogative of questions or the solving of problems, rather we are in the business of finding new questions and new classes of questions to ask. This is the essential difference between pure and applied research.

Re:But what about the Horizon problem?

[digitalchinky]

This is all theory, but say you could instantly travel 14 billion light years to the horizon (as seen from earth)

What would you see? Another horizon a further 14 billion light years distant? My personal feeling is yes, and that the age of the universe is wrong - I don't subscribe to the big bang theory, relativity, or any other convenient explanations for this 'anomaly'. Nor do I believe in God.

I may be marked as troll, but I suspect there are many others with a similar view.

Re:But what about the Horizon problem?

[niktemadur]

While it is a generally accepted law that nothing WITHIN space can travel faster than light, this law may not apply to SPACE ITSELF, which could inflate at superluminous speeds if the correct conditions are present.

I know this sounds bizarre, and I'm no expert on the subject, but I'll try to give a simple example that even I can understand:

Let's say space is like a balloon.
Matter are the molecules within that balloon.
The matter within may not move faster than light by its' own means.
But the balloon may inflate faster than light, and the matter within goes along for the ride.
At the end of inflation, the matter has kept its' same relative position in space.

The correct condition for inflation to happen is known as supercooling. Here is an example that Alan Guth used to describe it: water that's below 32 degrees farenheit but retains its' liquid state. However, just gently tap the plastic mold and the water will abruptly crystalize into ice before your very eyes. Supercooled water.

Another example would be a beer in the freezer that's liquid, but turns to ice from the top down when you open the lid. Supercooled beer.

Accordingly, the universe would have to inflate at a certain speed (much faster than light) to re-attain its' appropriate state under specific conditions.

According to Alan Guth, most of the universe's matter cancelled itself out instants after the Big Bang, due to matter-antimatter collitions. In a super-excited state, the universe found itself almost empty, and had to readjust by inflation and a spontaneous burst of creation of matter. In fact, Guth said that with 28 pounds of matter under the right conditions, a universe just as massive as ours could be created. This is why Guth said that our universe could be the ultimate "free lunch".

Re:But what about the Horizon problem?

[Y2]

But what about the Horizon problem?

Inflation solves the horizon problem. According to this latest calculation (see TFA), inflation also leaves some UBLW (unimaginably long wavlength) gravitational waves that account for the apparent acceleration of the general expansion, without the shamefully ad-hoc introduction of dark energy.

Re:But what about the Horizon problem?

[John Hasler]

> ...moving at the speed of light away from the
> epicenter.

There is no epicenter.

Re:But what about the Horizon problem?

[Almost-Retired]

You can solve the horizon problem by having the universe expand ultra-fast for a time, just after the big bang, blowing up by a factor of 1050 in 10-33 seconds. But is that just wishful thinking? "Inflation would be an explanation if it occurred," says University of Cambridge astronomer Martin Rees. The trouble is that no one knows what could have made that happen.

Unforch, either the exponent was forgotten, or got lost in an html glitch someplace, What I'm refering to is the 1050 figure used above, which should be 10^50, which is the correct value used in Martin Rees's original release on the subject.

And that is not a trivial difference folks, it is truely astronomical in its own right.

--
Cheers, Gene
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
99.34% setiathome rank, not too shabby for a WV hillbilly

Re:But what about the Horizon problem?

[Planesdragon]

If the universe is 14 billion years old, and the edges are nearly 28 billion light years apart

It's not.

Our perceptable universe is 28 billion light-years apart. We have no way of knowing how much larger the universe is, because no information from beyond our information-cone can get to us.

(Graph space and time on an X-Y axis. Pick a point on Y, time, and draw two 45-degree lines down the page. As time progesses, the distance that we can get light from increases, because light has a finite speed. That "cone" of sense is what I mean by information-cone.)

Re:But what about the Horizon problem?

[WaterBreath]

A few things:

According to "accepted" theories of expansion, there is no epicenter. All space is expanding equally in all directions. So wherever you are standing, everything will appear to expand outward away from you.

Because of that, things farther away from you will be receeding from you faster, because every extra bit of space between you and them means an extra bit of expansion, and so an extra bit of recession speed. As the theory goes, superluminal recession speeds are possible because the distant objects are not actually moving relative to the stationary frame of space in their vivinity. Space itself is changing shape, and the "motion" we see is just a side-effect.

Supposedly, there is a certain distance, which can be measured starting at any given point, beyond which every everything is receeding from the reference point faster than light, and so will never be visible from that point. This is called the Hubble distance. Related is the Hubble constant, which is a measurement of change in velocity of expansion per unit distance from the reference point. (Not the odd way to measure acceleration. Normal acceleration is m/s/s, or m/s^2, but this is m/s/m, or just 1/s, which is 1Hz. Weird, eh?) The Hubble constant is under contention, I think, and the value of the Hubble distance depends on the value of the constant.

Anyway, this stuff is kind of where the idea of Star Trek's "warp drive" comes from (at least in the more recent series). If it were possible to create some sort of device that could cause the space in front of a ship to contract and the space behind to expand proportionally, the ship could move without moving through space. It would be space itself changing shape around the ship that causes it to "move". And hence the speed at which you could move would be limited only by the speed at which you could channel energy into the expansion and contraction of space. Of course, this might just happen to be limited by the speed of light as well, so maybe superluminal speed still wouldn't be possible!

But if these guys' new idea is right, then none of that matters. =)

Re:But what about the Horizon problem?

[Surazal]

The problem with the theory wasn't so much you couldn't move faster than the speed of light (apparently this was a valid way to "cheat" according to the calculations). It was that the amount of energy required to maintain such a bubble would be powerful enough to instantly destroy any event causing this phenomenon in the first place (aka a warp drive). It was akin to being inside a extremely unstable black hole.

Re:But what about the Horizon problem?

[MillionthMonkey]

There is no epicenter like there is in an earthquake, but you can define any position at rest in the frame of the background radiation itself to be as good of an "epicenter" as any other for purposes of this discussion. The Earth doesn't meet this standard, because it's moving at a speed of 365 km/sec relative to the CMBR (hence the Doppler shift), but it probably doesn't matter.

Here is a good FAQ entry regarding the difference between the observable universe and the entire universe.

Re: But what about the Horizon problem?

[digitalchinky]

http://members.aol.com/crebigsol/awards.htm

So basically

[Neil Blender]

They don't need somethings they invented to explain away what they didn't understand.

Re:So basically

[theparanoidcynic]

Go science! Now if only religion could get around to realizing that . . . . . .

Difference?

[Ender_Wiggin]

Can someone tell me, what's the difference between Dark Matter and Dark Energy?

Re:Difference?

[Pfhorrest]

The other responses to this thus far are completely off. Dark matter and dark energy are not (by any current theory at least) related anything like how normal matter and energy relate via e=mc^2.

Dark Matter is a hypothetical unknown "stuff" with normal mass just like regular matter but which we cannot observe with light; it doesn't appear to be emitting or noticably obscuring any kind of radiation. But we see the movement of galaxies in such a way that they appear to be responding to the mass of something that we can't see. Hence "dark matter" - we can't see it, but it seems to be some sort of matter. Think of it like leaves blowing in the wind - we can't see the wind, but we see the motion is causes.

Dark Energy is another hypothetical unknown "stuff" that seems to be adding, somehow, to the velocity of all objects in the universe. It is postulated because the universe appears to be accelerating in its expansion, which does not make sense given an empty, neutral vaccum and a bunch of matter in it. It should be slowing down or at best, expanding at a steady rate. Hence "dark energy" - we can't detect it, but some source of energy which is causing the expansion of the universe to accelerate.

Hope this helps.

Re:Difference?

[Aglassis]

It has been observed that galaxies on the whole do not obey Kepler's Laws of Planetary Motion. In particular, stars along different positions moving outwards from the core have about the same measured period (to do a complete orbit of the core). Kepler's Third Law says that the square of the period of a star is directly proportional to the cube of the stars' semimajor axis. Stars further out should have a much longer period (like Pluto) than those close to the core. Dark matter is an invention that compensates for discrepancy by saying that there is perhaps a large halo of non-detectable mass around the galaxy (about 10 or more times the observed mass). There are reasons to believe (too complex to go into here) that dark matter is not like ordinary matter but still has mass.

The Hubble constant, which was discovered by Edwin Hubble, showed that the universe was expanding. If the universe began at the Big Bang (and there is a significant amount of data to support this assertion) then the speed of expansion should be fairly straightforward to calculate. What is observed at great distances is greater than that value. For this reason scientists have named (very poorly) another potential fundamental force dark energy which accounts for the expansion. Dark energy would be like gravity, but repulsive, and is only significant at extreme distances (so that it wouldn't hurt the formation of galaxies).

Re:Difference?

[GHOST OF THE DEEP]

Hence "dark matter" - we can't see it, but it seems to be some sort of matter. Think of it like leaves blowing in the wind - we can't see the wind, but we see the motion is causes.

maybe more surch dark matter is leaves ,and we can see wind ,but we can`t see leaves (can, but whence if not)

Re:Difference?

[niktemadur]

Here's a bit more about the nature of Dark Matter, what theory thinks it is in a more specific manner. However, we must explain what "Normal" Matter is.

"Normal" Matter is matter that is influenced by the four forces of the universe. The first three are at the atomic and sub-atomic level, the fourth one is on the Relativistic Scale:

1. The Strong Force, keeping the atomic nucleus together, even as it is composed of neutral and positively charged particles.
2. The Weak Force, which makes the orbits of electrons decay over time. We know it also as Radiation.
3. The Electromagnetic Force, which creates attraction between atoms, creating molecules.
4. The Gravitational Force, which creates an attraction between masses.

Dark Matter of the WIMP variety (Weak Interactive Massive Particles) is UNAFFECTED by the first three forces. It is like a mist that congeals under gravity, but is never more than "ghostly", and since it cannot bond at the atomic and subatomic level, it is undetectable except by the gravity it creates.

Dark Matter of the MACHO variety (Massive Compact Halo Objects) consists of would-be stars that never made it, or stray planets and planetoids roaming around the galaxy.

Therefore, we call it Dark Matter because we haven't been able to detect it, but we can perceive the gravitational effect it has, everywhere we look. And I mean everywhere, since the figures say that between 90% and 98% of the universe consists of Dark Matter.

Re:Difference?

[hesiod]

> 5. The Duct Tape Force, which sticks things that are unstuck
> 6. The WD-40 Force, which unsticks things that are stuck

Which brings me to my next point. Never try to remove duct tape with WD-40, or the universe may disappear.

How did the ripples get there?

[Dancin_Santa]

If there was nothing to push against, what would cause something to be held back and "ripple" as if there were some sort of repulsive force?

Let's say we've reached the edge of the universe, what happens when we step beyond that boundary? What is out there that would possibly hold back further expansion of our universe?

Re:How did the ripples get there?

[TrekkieGod]

If there was nothing to push against, what would cause something to be held back and "ripple" as if there were some sort of repulsive force?

Not really related to the ripple they are talking about in the article, but "repulsive force" doesn't require something to push against. When students first learn of Newton's third law, "for every action, there's an opposite and equal reaction", teachers often give as an example that when you push against a wall, the wall pushes against you. That gives the idea to students that there must be something to push back against you (don't feel bad, some early rocket scientists thought the same thing). That is, however, not true. You don't need something to push against, you just need to exert a force in one direction, and there will be a a force in the opposite direction.

Because of this misconception, it was originally thought that rockets wouldn't work in space, because the exhaust they put out wouldn't be able to push against the atmosphere. But hey, they do!

Let's say we've reached the edge of the universe, what happens when we step beyond that boundary? What is out there that would possibly hold back further expansion of our universe?

Gravity. There's an attractive force between every object with mass. When you jump, you move away from the center of the earth, but only for a short time. You accelerate up, but then you start decelerating. You reach a maximum height, then you start accelerating back down. During the big bang, the universe started expending. It was originally thought that there would be a "big crunch", and the universe would stop expanding, than start collapsing towards the center. Then we discovered the universe was not only not slowing down in it's expansion, but actually accelerating. That made no sense, so Dark Energy was used to explain it (a force like gravity, but pushing outwards). Under that scenario, the universe would end not through a big crunch, but would simply become dark as suns die and black holes evaporate. If we don't need Dark Energy, maybe the big crunch theory will come back.

Re:How did the ripples get there?

[pintpusher]

Is this like trying to pick up the soap in the shower?

Re:How did the ripples get there?

[Anonymous Coward]

You still need something to push against in order to create those ripples. Unlike vector thrust which only requires a directed force, a ripple requires a reflection of an energy wave.

Let's take a very simple example of a wave in water. It has a wave front and the energy contained in the wave form continues in a straight line until deflected or it runs out of energy due to friction. The only way to get a ripple is to reflect the energy back upon itself (like hitting a solid barrier). But even then, some energy is transmitted to the solid object because the reflected waves do not contain the same amount of energy as the original waves.

So in space, the huge burst of energy at the time of the Big Bang generated ripples, but what was reflecting the energy such that there were ripples, and how much of that energy was transferred to that "external" universe? If we can measure the intensity of the pre-ripple energy and compare it to the energy of the ripples, we can judge how much energy was lost to that "other" universe. But what is that external universe and how can it absorb that energy?

Ripples in our space mean a breakdown in the conservation of momentum, N's 2nd Law. It means that there is a net loss in energy for our single universe. However if we postulate that there is another universe that was able to absorb that lost energy we can trust that our natural laws are still in effect.

Re:How did the ripples get there?

[Anonymous Coward]

There is not an edge to the universe- note that when the universe expands, it is the universe itself expanding, time and space, and not just the stuff the universe contains. There is no space as we know it outside the universe- what we call the universe is the region where spacetime has unfolded into the dimensions we know and love.

Note that the topology of the universe likely makes it such that you couldn't leave the universe if decided to fly as fast as you can "away"- it's likely that you would curve back on the universe and be pointed back towards home. There are suggestions that our spatial dimensions as we know them arise from the space of the universe being arranged as a gigantic hypersphere. Imagine a two-dimensional universe on the surface of a sphere. Inhabitants could go and go and go, but unless they are somehow able to "pop" into the third dimension and leave the surface, no amount of motion on the sphere's surface will get them out of the universe. Now bump it up another dimension. Just as the two-dimensional inhabitants are stuck on a 2D surface, we are stuck on a 3D surface. Just as if you could pop out of the 2D universe, you'd see the entire universe as a sphere, if you could pop out of our universe, you'd see a hypersphere (technically, a 3-sphere, since the surface of the sphere, which we're on (I know it feels like "in") is three dimensional).

Re:How did the ripples get there?

[gardyloo]

And you know why conservation of momentum holds true? It's because of Newton's Third Law!

After one has studied physics for a while, the reasoning that Newton's Third Law ==> Conservation of Linear Momentum is generally replaced by more of a feeling that momentum conservation is more basic (due to, in part, Noether's Theorem http://en.wikipedia.org/wiki/Noether's_theorem) and that Newton's Laws are simply a consequence of momentum conservation. The advantages of this abstraction are manifold (*cough*), but the "obvious" ones are cases in which forces are very hard to identify (such as in radiation reaction), and systems which may be much more immediately approached through Hamiltonian's or Lagrage's formulations rather than Newton's laws.

Re:How did the ripples get there?

[Almost-Retired]

Uhmm ... rockets work due to conservation of momentum, not because of some mysterious reaction force.

Not a very good explanation. Rockets work in space because the exhaust gases are, in the process of being accelerated out the back of the engine, are pushing equally hard on the walls of the engine thats burning the fuel. Since thats cone shaped, wider at the rear, its the net circular square area of the back flange of the motor that the gasses push against, and its anchor to the rest of the rocket transfers that push to the rocket proper. And don't forget that a little like the e=mc2 of Einsteins famous equation, the net power, minus some losses here and there, is still e=mv2, so the holy chalice/grail of the rocket is the one that moves the gas at the highest velocity at the face of the nozzle, with some of the flame cone actually being a velocity to pressure translation so in the end, the gas velocity, being highest out near the tip of the flame, serves to increase the felt pressure pushing forward on the engine proper.

The ion and plasma drives that use zenon gas, electrostaticly or thermally accelerated to a fraction of C speed, are many times more efficient in terms of the amount of push per pound of expendable than any chemically fired rocket can ever hope to be simply becasue of the 'fraction of C speed' is many times what a chemical fired gas generator can do.

I've heard/read of estimates that a xenon gas rocket, fired by a nuclear light bulb heat source (circa 30,000 degrees C) making a plasma out of the gas, could go to Alpha Centari in just a few years, as it would accelerate at a steady .05G's to the halfway point, then turn around and decelerate at that same rate. THat of course means it would have to be launched into leo by some other means before lighting the torch. If not turned around and slowed down, it would go by Alpha Centari at truely relativistic speeds, near .99 C. I haven't personally ran the math, but the article I read 2 decades back sure did. ISTR the article said it would only take about 20 tons of gas. That was with estimates of about 5 tons for the whole nuclear light bulb reactor so the total vehicle weight wouldn't be near as heavy as a Saturn5 at launch. We played with such a reactor at Rocky Flats for a while, but the natives (thats us people folks) got restless. I don't know if there ever was a true 'accident' involving one of them because basicly if the 'light bulb' envelope fails, the reaction is self quenching. One of the safest reactors ever developed, but the word nuclear was its death knell.

Sometimes I swear we are our own worst enemy.

--
Cheers, Gene
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
99.34% setiathome rank, not too shabby for a WV hillbilly

Inflation...

[ackthpt]

Apparently, ripples from inflation in the early universe may account for the observed expansion rate of the universe."

Hmm. Better check the exchange rates on Altairian Dollars, Flainian Pobble Beads and the Triganic Pu.

Has anyone contacted Alan Greenspan about this?

Comment removed

[account_deleted]

Comment removed based on user account deletion

Eddies in the space time continuum

[starling]

Arthur : Oh, is he?

string theory Nova

[Fox_1]

Nova did a great piece on the all of physics (a lot on the universe and big focus on Quantum Mechanics and String Theory). It's pretty good if you are trying to find commonplace explanations of some of the theories the article just mentions and doesn't explain.

Re:string theory Nova

[OpenSourceOfAllEvil]

FAR more interesting than The Elegant Universe is his subsequent book The Fabric of the Cosmos: Space, Time, and the Texture of Reality. I highly recommend this to anyone that was interested by his earlier work or the various discussions here.

Most posts here seem to be quoting science from decades ago. The errors and misconceptions too numerous. It is clear that many have no idea how far we have come in understanding everything all the way back to and including time zero, including what even caused the Big Bang. It takes a mass of just 10Kg at the Big Bang to explain all known matter and energy in the unverse today. The Inflationary Model today is nothing like the originally proposed Big Bang. It predicts and explains what we currently observe.

Fermilab's proposal is fascinating and if they are correct could have a serious impact on modern research such as the search for the Higgs boson that will be done at the CERN supercollider. The Higgs Field is related to the Inflaton Field responsible for the initial expansion.

The universe is very possibly 2 dimensional, you can think of a Pac-Man screen. If string theory is correct, all known matter is made of open ended strings. Open ended strings must be attached to a d-brane, a one or more dimensional membrane predicted by string theory. It is very likely our entire universe is attached to a 2 diminsional d-brane. This prevents our universe from any of those sci-fi parralel or other universes we love reading about. The only thing that can possibly escape is gravity, hence Gravity Phones for those of you that watched the Elegant Universe.

Re:string theory Nova

[possen]

Scientific American this month has a article called the Misconceptions of the Big Bang this month (March 2005). This article attempts to correct the errors that even experienced scientist make about how the Big Bang theory works. Until I read this article I was somewhat skeptical of BBT because the misinformation out there causes the theory to make little sense.

Roadrunner Cosmology

[Tablizer]

So it is like when Wile E. Coyote yanks the road up and down and the ripple gets bigger and bigger as it moves toward the Roadrunner? (and then bounces off a mountain side, comes back, and smashes Coyote.) Next you know they will find a giant U magnet at the edge of the universe.

Re:Space beyond the edge of Universe

[ari_j]

Yes, there is space beyond the cosmic horizon. The horizon on Earth is just the farthest you can see because of the curvature of the planet's surface. The planet keeps going beyond the horizon - the horizon is a function of the observer. The same applies to the universe, although I am not knowledgeable enough to tell you if the cosmic horizon is the limit of what we can see because of the distance, because of a higher-dimensional curvature of the universe, or because of something else.

WWDVS?

[LokieLizzy]

(What would Darth Vader say?)

"Do not be so proud of this cosmological terror you have created. Its existence pales when compared to the power of the Dark Side."

I'm not an expert...

[chazR]

but Sean Carroll is. And he's not convinced.

Gravity leaks

[Tablizer]

I've read another hypothesis recently: that gravity slowly "leaks" into other dimensions so that over long distances it's attractive force diminishes, and that is why the universe is flying apart. The average distances between the galaxies has now reached a threashold where the leakage makes a big difference, giving the appearence of a relatively sudden expansion speedup.

Re:Gravity leaks

[XanC]

Even if gravity were zero, the universe would then expand at a constant rate. But it appears to be accelerating, implying some kind of negative gravity.

Re:Gravity leaks

[the_2nd_coming]

M-Theory. Gravitons can escape to other branes (other 10 dimensional surfaces that hold universes because they have a closed structure with respect to our brane (complete circle) where as all other elemental particles are open so they are physically connected to our universe and cannot escape.

I like the idea of M-Theory.. the only thing is that we do not have the mathematics to describe it yet..... Personally I think the problem lies with the undefined values of 1/0. if we can define that as u and define u*u^{-1} = 1 then we can show that 0|n because n = 0*un.

Re:Gravity leaks

[Stalyn]

The hypothesis in question was explained here

Also here for the braver souls.

If Dark Energy is not needed

[sharkey]

Then there's no need for Branigan's Law.

Comment removed

[account_deleted]

Comment removed based on user account deletion

The true explanations for the Universal Expansion.

[Timmy D Programmer]

The mystery of why the universe is expanding more rapidly rather that slowing down is explained easily with the following theory:

'Our' Universe actually resides within a red rubber ball that belongs to gigantic beings, and it is currently being inflated

I simply fear they will begin playing dodgeball soon.

Re:Space beyond the edge of Universe

[Anonymous Coward]

although I am not knowledgeable enough to tell you if the cosmic horizon is the limit of what we can see because of the distance, because of a higher-dimensional curvature of the universe, or because of something else.

Because of light speed. Since nothing can travel faster than light, you can't receive a signal from anywhere in the Universe that is farther from you than the distance light could have travelled since the formation of the Universe (14 billion years approx.)

That Einstein...

[Omniscientist]

"Whether Einstein was right when he first introduced the cosmological constant, or whether he was right when he later refuted the idea will soon be tested by a new round of precision cosmological observations," Kolb said.

So either way, Einstein was right. Damn you Einstein!!!

Fermilab Reports Dark Energy Not Needed

[secolactico]

Fermilab Reports Dark Energy Not Needed

Well, thank god! I was going crazy trying to find some.

Wish I understood Alpha

[purduephotog]

Saw this article a few days ago and it talked about Alpha- raised all sorts of questions for me (being a non-enlightened individual) such as

a) What are the implications if Alpha is 'decaying' with time?
b) What are the implications if alpha is variable with graviational mass?
c) If enough photons were gathered in one location, would they have a 'gravitational' effect... and would that affect any known 'constants'?

Tantalizing and interesting, but I know I lack the education to understand all of the ramifications.

I believe in Dark Energy, and...

[LokieLizzy]

I'm not a scientist.

But I did stay at a Holiday Inn last night. And when the lights went out at midnight (power outage), I can assure you that there was more than a little energy going on in the room next door.

Re:Why insist that the universe be "elegant"?

[mcc]

The idea is that if two theories produce and predict the exact same results, the simpler one is to be preferred. If two theories produce and predict slightly different results, but the predictions only differ on matters which cannot be empirically tested, the simpler theory is to be preferred until such time as a way is found to empirically test which is more accurate.

This principle is often referred to as "Occam's Razor", as it is seen to be similar to an argument a 14th-century theologian named William of Ockham employed. His words, as Wikipedia quotes them, were something closer to "If two things are sufficient for the purpose of truth, it is superfluous to suppose another."

While this principle is technically not guaranteed to pick the "correct" theory, this is reasonable; would it be better, given two theories, to pick the one with more arbitrary complexity? Anyway, the only standard we have for "correct" is that it is consistent with evidence. Satisfying all collectable evidence is a worthwhile persuit in itself.

Yeah, but...

[baldass_newbie]

...eddies in the space time continuum.

Enjoy Fermilab's work while you can

[stox]

Their budget has been slashed almost in half. After all, low quality bombs are far more important than high quality science. In fact, spending on basic research is dropping at an alarming rate through all the national laboratories. This does not bode well for our future.

Re:Enjoy Fermilab's work while you can

[stox]

Well, we could get into a very long and detailed discussion into the value of basic research. I'll point out just a few of the benefits we have received from Fermilab, and leave the rest to you.

1) Ever hear of a "computing farm"? I'm sure you have. The concept was pioneered at Fermilab.

2) Ask Bob Young, "Who made the most important confirmation of the value of Linux in the early days?" Couldn't be Fermilab, could it? ( Bob Young was one of the founders of RedHat, BTW. )

3) Who has done more basic research into superconductors? Who pioneered the use of superconductors? Fermilab.

4) How many lives have been saved through the use of radiation for treating cancer? Neutron therapy was pioneered at Fermilab.

5) Do you like American Buffalo? At one time, the only surviving herds were at Fermilab and Yellowstone. Fortunately, they have made a comeback.

6) Enjoy using the web? Fermilab was the third website on the planet, behind CERN and SLAC.

I'm sure I have missed a few, but I hope you get the point. We are lucky that our ancestors didn't take the same outlook as you. Some things need a horizon of lifetimes, not just your own. How long was the electron studied? Quantum theory? Radiation? Thankfully, many did, and have left us with a rich environment to live in. I hope the current generation, and those to follow, are wise enough to invest in the future with basic research.

As for my assertion that money devoted to basic research is dropping at a alarming rate, I will leave this as an exercise for the reader. The results of your studies will be quite enlightening, and quite possibly, terrifying.

Re:energy

[Jerf]

If 10 billion light years worth of protons travelling from a galaxy had a mass, does it's own emitted energy pull it away from the bang? and do other stars' emitted energy push away at the accellerating galaxies?

You're suffering from what I call the Big Number Fallacy; while the number of photons may be large, the amount of matter is so much larger it completely swamps it.

More to the point, conservation of energy and mass<->energy equivalency says that when a star emits a photon, it loses that energy in mass. Obviously, stars are not routinely boiling away due to photon energy losses, or indeed, energy losses at all. Not enough mass-energy is floating around as photons to affect anything.

What was that experiment confirming Earth's 'tearing' effect of gravity the sattelite?

I think you're referring to the "frame dragging" experiment, which is almost completely unrelated, except inasmuch as they are both related to relativity.

I know it's fun to play word games with the shiny Physics and Cosmology terms, but if you really care, you need to learn the real stuff, not merely keywords. I rather liked this; the fact that it's seriously tough shit is a good sign, if you get my drift. If it's easy, you're just playing word games.

Re:Not Funny, Insightful

[wanerious]

Insightful? What would you like to have happen? Publish fewer articles? Not research it so much? Sheesh.

This anti-intellectualism stain in /. responders is saddening. Basically it seems to be, "I don't understand what they're talking about, so I think I'll make fun of them" or "I don't understand the thousands of papers that have been published, so I'm going to shout something superior-sounding from the cheap seats". Dismissing a beautiful and maturing field of physics with "we don't really know anything, so give up" is a sophomoric and pretentious reaction.

Sure, there's a bunch that we don't understand, but please realize that this is the way science works. Nature is too subtle for us to have canned and precise answers for her behavior. Cosmologists are rightly invigorated by the new data, and ought to be encouraged to research and refute each other's ideas.

Interesting?

[MustardMan]

Seriously, how did this get a mod as Interesting? He bitches about the arrogance of humans thinking we are the center of everything, then is INSANELY arrogant in stating his own theory as if it were an indisputable fact, while providing NO evidence to support it.

The whole POINT of the term "dark energy" is to say "there's something funny here and we don't know what it is". I'd say that's one regulation shitload less arrogant than camel pilot's claim.

By the way, I'm far from a cosmologist, but the poster clearly has no grasp on the difference between dark matter and dark energy, and therefore has proven he doesn't have a clue what he's talking about.

In other news...

[sPaKr]

The producers of Startrek Enterprise gave themselves concusions from repeated blows of their heads to their desks. One producer cried "Ripples in space time explain the universe, WHY COULDNT WE GET THESE GUYS AS WRITERS!'

Re:In other news...

[ari_j]

How about

COMES NOW the plaintiffs, who allege:

1. Plaintiffs are producers of the TV show Star Trek: Enterprise.
2. Defendants are the class of all scientists in the world.
3. Defendants stole and used as their own a plot device from the Star Trek: Enterprise finale; namely the idea that ripples in space-time explain the universe.
4. Because of defendants' act of plagiarism as described in paragraph 3, plaintiffs suffered gazillions of dollars of damages.

WHEREFORE plaintiffs demand that the court give them gazillions of dollars from the scientists, and rename the universe "Space: The Final Frontier."

What if Dark Energy Wasn't Required

[nimblebrain]

There's a decent amount of evidence that has been mounting over the past few years that a large component of redshift is in fact intrinsic, i.e. not attributed to the Doppler effect.

In some ways, it seems related to the much-glossed-over "K Effect" of a few decades ago, where it was found that bright, bright blue stars seemed to be systematically redshifted.

Researchers like M. B. Bell are of the opinion that the intrinsic redshifts are superimposed on a Big Bang flow (reducing the actual velocity we should be measuring). Others, like Arp, believe that the Hubble Flow is an illusion, and that the universe is actually relatively static once you take away the intrinsic redshifts.

David Russell's paper that just came out supports either view, and shows that other explanations (like Tully-Fisher Relationship errors or rotational velocities) are far too small to account for the large discrepancies.

(Some more hubbub on the topic.)

In either case, intrinsic redshifts will take a lot of pressure off researchers to find 'dark energy', because the discrepancies of speed/distance are much reduced.

Then, perhaps, we can stop looking for something that isn't there? :)

Re:What if Dark Energy Wasn't Required

[TerrierTribe]

oops, forgot the link: SCIAM.

Re:What if Dark Energy Wasn't Required

[nimblebrain]

That's the summary of the story that's been put together so far :)

The redshift they describe is 'cosmological redshift'. It is true that it would be technically incorrect to call it a Doppler redshift if the currently-held accelerating universe view is actually true.

There are Doppler redshifts on top of this as well - rotations and movement add to or subtract from the cosmological redshift.

What the papers I quote have been finding is that cosmological redshift (whether Doppler or not) isn't enough.

Intrinsic redshifts are statistically important. They do not, however, get rid of the cosmological component.

The current 'accepted' value of the Hubble Constant, which reflects the age of the universe, is 72 km/s/Mpc, giving us an age of about 13 billion years.

Taking the instrinic redshift from that gives us a Hubble Constant of 50-60 km/s/Mpc, which gives us an age of about 18 billion years, so that theorists might have time to deal with the 'vegetable soup' phenomenon, to quote a sound bite.

(Looking back to 1-2 billion years after the Big Bang, the universe still doesn't look very young. Of course, the revised age will also alter back the ages of some of the objects.)

There's some reason to believe that even the remaining cosmological component may not actually represent expansion, and it was presented in one of Edwin Hubble's later lectures, "The Observational Approach to Cosmology".

The premise, basically, is that a redshift would give a corresponding decrease in photon density, if due to expansion, but it doesn't.

We'll see what happens over the next few years, though :)

Thanks for the link!

Re:Can somebody fill me in here...

[Anonymous Coward]

A cosmological constant is like a global variable, only with broader scope and remaining constant.

Here is the original paper

[leoval]

For anyone that can actually understand it click here (in pdf format)

Scientists aren't the only clueless ones here

[foreverdisillusioned]

Can't we just admit we don't have a freakin' clue and move along?

Move along to what? Above all else, science is supposed to try to explain these mysteries. To give up because we don't have a (seemingly) elegant or simple explanation is, well, the anthesis of the scientific method. You've got to come up with a theory. Maybe it sounds good, and maybe it doesn't--the only real question is, does it explain the phenomenon being observed?

If I knew Einstein back in 1905, I would've told him he needed to lay off the crack pipe. "Matter bending space? Relative velocity creating differing timeframes? Dude, what a fantasy, what a KLUDGE! You can't just go ripping apart some of the basic assumptions of science just because you want Maxwell's and Newton's ideas to play nicely together."

...but he was right. He took a stab in the dark, figured out an explanation that worked (even though it sounded insane from a "common sense" point of view), and the evidence proved him right. Time and space are relative--we know this for a fact now, because other scientists set out to prove (or disprove) Einstein's crazy ideas. We're not so sure about Dark Energy/inflation ripples/mystical tomatoes, and hell, we might never know for sure, but it's obvious that SOMETHING is going on here, and I for one am glad that the scientists of today are coming up with these all of these cheesy, crazy explanations.

Re:Physics data and theories - how suspect are the

[Y2]

How can we be sure that the data we receive from galaxies 10 billion light years away has not been diluted or compromised in a way we could not detect?

I don't know what you're thinking when you say "data ... diluted or compromised," but it's a lot more difficult than you may realize to come up with a scheme which has something funky happpening over long distances of space without us being able to detect side-effects.

Summary

[Anonymous Coward]

[1]
When his own Theory of General Relativity clearly showed that the universe should expand or contract, Einstein chose to introduce a new ingredient into his theory.
[2]
His "cosmological constant" represented a mass density of empty space that drove the universe to expand at an ever-increasing rate.
[3]
"We realized that you simply need to add this new key ingredient, the ripples of spacetime generated during the epoch of inflation, to Einstein's General Relativity to explain why the universe is accelerating today," Riotto says

Re:Fermilab employee chiming in

[heyitsme]

Their budget has been slashed almost in half. After all, low quality bombs are far more important than high quality science. In fact, spending on basic research is dropping at an alarming rate through all the national laboratories. This does not bode well for our future.

This isn't quite true. DOE's funding for High Energy Physics Programs (basically, Fermilab and SLAC) is down 3.1%, or $22.5 million, from $736.4 million to $713.9 million. (I couldn't find out exactly how much Fermilab lost from those cuts, but I recall seeing a figure of about a 4% decrease w/inflation, which is pretty consistent over the past 5 years) Furthermore, run times of the accelerators would be increased over FY 2005 levels at the Fermilab Tevatron (6% more operating hours) and SLAC (54% more hours).

Along with the budget cuts, the BTeV project at Fermilab was canceled. With HEP experiments at SLAC and Brookhaven going offline in a couple of years, Fermilab will soon be the only HEP lab in the nation. Currently the CDF/D0 experiments (the two main detectors) on the Tevatron are scheduled to run until 2009 or 2010. And MINOS/NuMI will run at least that long as well.

Fermilab is going through a 5% workforce reduction, voluntary at first... The saving grace for Fermilab right now will come in the form of the International Linear Collider, the Next Big Thing(tm) in HEP. More info at http://www.interactions.org/linearcollider/ and http://ilc.fnal.gov

More insider info upon request, heh.

preprint

[bcrowell]

The preprint is here.

In the words of Rainer Wolfcastle...

[isny]

Einsteiiiinnnnnnnn!!!!!!! (shakes fists in the air)

Re:Why insist that the universe be "elegant"?

[radtea]

It isn't the universe that has to be elegant, but our theory of it. The reason why is that we aren't very smart, and theories with fewer free parameters are a lot easier for us to understand.

--Tom

Would this mean the universe is closed?

[JoeGee]

Or do physicists still think everything is doomed to continue flying apart until the heat death of the universe in the distant future? Is the Big Crunch back in the picture?

-Joe G.

Re:Would this mean the universe is closed?

[MightyMartian]

Current models indicate that there is simply not enough matter to halt the expansion. It appears the Universe is headed for a heat death.

Why is it okay..

[mpn14tech]

for Fermilab to announce some scientific result by press release, but if some other institution does it they get slammed for it.

Shouldn't they at least wait until the paper is peer reviewed and accepted before doing a public announcement like this?

Hear Hear

[theolein]

Very well put! What really shocks me is that the cowboy mentality is even so prevalent here on slashdot, where many people interested in technology seem to believe that science is of no worth, but God and bombs are.

I find it simply frightening, because I think it poses a very significant threat to the future of the USA, which is heading down the road of becoming a military power without the brains needed to steer it in a wise direction.

It's not dark matter...

[Biomechanical]

It's fire.

In the beginning was nothing right? Then a Bang.

I'm thinking about this Bang. Nothing, not absence of something nothing, but Nothing. Nothing exploding.

Fire. An explosion is fire, burning combustible materials and releasing hot gases that expand.

In the middle of Nothing, there was an Explosion.

Is it possible that our universe is bounded, instead of Nothing, by Anti-Energy? The quantum equivalent of reverse-charged light?

Could a single, "mutated" quark, quasar, or thing, become charged the wrong way from subtle interaction with it's surrounding particles?

Matter and Anti-Matter. Touch one to another, and stand well back.

The universe is expanding, and it encompasses all space and time as we know it.

Could it be like a big sheet of paper (paper == anti-energy) and someone (rogue element) "ignites", switches polarity, triggers a "burn"?

When you light the centre of a sheet of paper, it expands, sometimes uniformly.

Are the boundaries of our universe a massive bluish-white of fire? Masses of matter reacting against the inverse Nothing of anti-matter, burning, accelerating like a brush-fire on a hot day.

If the universe is all time and space then it doesn't necessarily have to be planets and stars out there on the boundaries.

It could be the Burn, already moving faster then light from the instant it started, expanding constantly, releasing energy that is recycled back into matter in our own space-time.

Re:And they call me crazy?

[dalyraptor]

No, something that does not appear possible or make sense in nature does not prove that god exists. You cannot put everything that you do not understand down to god, jesus christ!

Re:And they call me crazy?

[Glock27]

Then along comes an argument like this. Gee we science types have data that all our science says doesn't make sense, so to explain it we'll postulate unexplained varying physical sates for the Universe that start for no reason we can nail down and then end for no particular reason we can give (Expansion), invisible energy that no one seems able to find (Dark Matter), or unprovable ripples that just happen to be beyond our ability to find or prove (Cosmic Irregularity Theory?). And our evidence for this? Well it makes our math look good (just as long as you use our equations to do the math with, anyway)

What you're missing is that science has theories that make predictions about observable things in the real world.

General Relativity, for instance, led to predictions of 1) longer particle decay times for moving subatomic particles, 2) different orbital period for Mercury than Newtonian mechanics predicted and 3) bending of starlight due to intervening gravitational fields. There are quite famous observations confirming these predictions.

Similarly, there are quite convincing observations that lend support to the Big Bang theory. Cosmic backround radiation measurements, observed Hubble expansion and observations of galactic evolution as we look further away (further into the past) come to mind as examples.

That is the difference between religion and science. Science attempts to verify its theories with observed phenomena and experiments. Religion accepts its theories based on blind faith.

All that said, there is nothing incompatible between science and religion really, as long as your religion doesn't dogmatically insist its wisdom about the real world subsumes observed scientific knowledge (the big trap into which some Christian sects seem to have fallen). In fact, I would argue that quantum mechanics provides an interesting "out" for religion - quantum randomness versus "Gods will". After all, quantum randomness is neither knowable or predictable for us, but it might be exactly enacting Gods will...

I've often wondered why Einstein said "God would never play dice with the Universe". Perhaps Gods dice are loaded. :-)