Dark Energy May Be Changing 346
SpaceAdmiral writes "Nature is reporting that Dark energy, the hypothetical energy driving the universe's expansion, may not be as constant as previously thought. According to new research the strength of dark energy may be very different now than it was when the universe was young."
well no kidding (Score:5, Funny)
Indeed. Begun, this clone war has.
Re:well no kidding (Score:2, Funny)
Re:well no kidding (Score:2)
Lets hope.. (Score:5, Funny)
"I too, sense a disturbance in the Force"
And in Related News... (Score:2, Funny)
It is changing, but we don't know which way (Score:3, Interesting)
wtf
Re:It is changing, but we don't know which way (Score:2)
Re:It is changing, but we don't know which way (Score:3, Insightful)
Re:It is changing, but we don't know which way (Score:5, Informative)
An analysis: http://cosmicvariance.com/2006/01/11/evolving-dar
That's a pretty bold statement... (Score:5, Insightful)
Re:That's a pretty bold statement... (Score:2, Funny)
How else would the other theories be consistent without dark matter to accoount for any discreptancies?
Ergo: dark matter exists, since without it the theories would fail.
Re:That's a pretty bold statement... (Score:2)
It's like saying that 1 + 1 = 1 and there must be some magical "Dark 1" that is subtraction from the equation.
It may just be that the equation is actually 1 * 1 = 1 or 0 + 1 = 1 and the theory isn't quite right.
Usually if a theory relies on the existence of something which cannot be proven, it's the theory at fault. Not saying this is the case here since there is considerable evidence supporting the ideas of dark matter and energy, but to simply state that it must exis
Re:That's a pretty bold statement... (Score:3, Informative)
Physics is a science. Physics is not really a hard science in the same way as Math is a hard science. Physics is way harder science than Biology and Chemistry but still a lot softer than Math, which is the Queen of Science.
Since Physics is a "soft" science, they have "theories". Some of these theories are either incomplete, not fully understood or maybe incorrect. These theories are still very useful for Physicists, too useful too just discard just because they are not c
Math != Science (Score:5, Informative)
Mathematics is not a science. It is a tool (an important tool, but a tool nonetheless) that is used in science. Science (from Latin scientia - knowledge) refers to a system of acquiring knowledge - based on empiricism, experimentation, and methodological naturalism [wikipedia.org]. Mathematics is not based on experimentation or empiricism, it is based on deduction and logic.
Also, I don't know how you could argue that physics is not a "hard" science. As the sciences go, one can argue that physics is the "hardest" science of them all, because at a fundamental level, all the other "hard" sciences (chemistry, biology, geology, etc) derrive from physics in one form or another.
Re:That's a pretty bold statement... (Score:2)
I tend to see math as a language of patterns, with many dialects for different situations but so ubiquitously used that its become inconceivable that there would be any other way to communicate fundemental ideas. This really struck me back when I was translating evolutionary ecology ideas into equations and simulations - the biologists knew exactly what they were talking about and had very sophisticated concepts, but they didn't speak their ideas in equations and so to other scientists, it looked like they
Re:That's a pretty bold statement... (Score:2)
Re:That's a pretty bold statement... (Score:5, Insightful)
Sigh. Ok, let's try this.
Mathematics is not science. It is a very complex formal system. You could desribe it as the science of understanding that system, I guess. But I wouldn't. Although you are right, mathematics is somewhat purer, that does not invalidate physics. For example: Let assume we have a theory of space, time and gravity, that seems to be tremendously correct for all observations we made as of now (note that this is just an example, we do not have such a theory, but please bear with me). Now we observe some new event or something that was out of reach previously, which cannot be described with current theory, and seems to need not a small fix, but a complete rework of current theory. So, does this observation suddenly invalidate the usefulness of the existing body of theory? Does an apple on earth suddenly not fall with the same speed as before and does it not release the same amount of kinetic energy in impact?
What physics is about is one belief: That the world can be described in terms of a formal system (mathematics). That is the only 'faith' physicists have. We don't know (and probably never will) if that is true or not. All we know is that everything in nature that follows rules can be described with a formal system and if there is something that does not follow a set of rules, it cannot be predicted anyways.
Besides that, physics is just trying to find new insights and new systems to describe rule-abiding reality as accurate as possible, using mathematics as a tool. Physics does acknowledge, that it may never be complete. But the knowlege we have gained so far is correct and works, albeit only for the cases in which it has been tested. And no new insight will invalidate that. No machines will stop working, no buildings collapse, because of a new observation that cannot be described within the current body of theory. We may find a better, simpler or more complex theory, which gives for tested known and understood cases the same results as the old one AND describes previously unexplainable observations.
And if you want to start with "formally proveable", may I give you Gödel? Any system complex enough to reference itself (like mathematics) is by definition incomplete AND contains provably unprovable sentences which are nonetheless valid within this system.
Re:That's a pretty bold statement... (Score:2)
So you have the only theoretical science, only it has no theories hmmm sounds to me like you are trying to have it both ways. You should really join the rest of us who think that math is extremely useful, but not a science.
Re:That's a pretty bold statement... (Score:2)
Additionally most people don't know what theory means, hence the Intelligent Design debacle.
Re:That's a pretty bold statement... (Score:3, Informative)
Re:That's a pretty bold statement... (Score:2)
Re:That's a pretty bold statement... (Score:2)
Re:That's a pretty bold statement... (Score:2, Interesting)
Re:That's a pretty bold statement... (Score:3, Insightful)
I always cringe when I hear physicists talk about dark {matter|energy}. Finding new data on dark matter is like claiming that the invisible pink unicorn is actually purple.
Re:That's a pretty bold statement... (Score:5, Informative)
Dark matter [wikipedia.org] is required by looking at galaxy rotation curves. Essentially, the rotation speed of galaxies is too fast given the mass that can be seen, so there must be some mass that doesn't emit light as conventional, baryonic matter does. Dark matter was first hypothesized by Zwicky in 1933 and has been well accepted throughout the astronomical community for decades.
Dark energy [wikipedia.org] is required by looking at Type 1a supernovae from the early universe. Astronomers and cosmologists use Type 1a supernovae [wikipedia.org], which have a well known intrinsic brightness (they are called a "standard candle"), to establish a cosmological distance scale and measure the expansion rate of the universe. If the universe is composed of ordinary matter and dark matter, the self-gravity of all the matter in the universe would cause the expansion rate to slow over time. A goal of these observations was to determine whether there is enough matter in the universe to stop it from expanding forever and ultimately cause it to collapse back on itself in a "big crunch."
In about 1998, the supernova observations were pinned down well enough to show that the expansion rate is actually increasing with time. Therefore, there must be some "antigravity" force that causes the expansion of the universe to accelerate. This is dubbed "dark energy."
The "cosmic energy budget" says that about 4% of the mass/energy in the universe is ordinary matter, 23% is dark matter, and 73% is dark energy. The matter and dark matter total mass is measured from observations of the cosmic microwave background [wikipedia.org].
All of this is pretty well supported by the best current observational evidence, although the physical nature of dark matter and dark energy are both poorly understood (and new observations can always change things, of course).
The new claim in the current article is that the effect of dark energy has changed over time. The fundamental problem is that the new evidence relies on gamma-ray bursts, which are not nearly as well established a standard candle as the Type 1a supernovae, so it's much harder to say with certainty what distance they are at. Note that the new claim was presented at the American Astronomical Society meeting in DC last week; it has not yet appeared in a refereed journal. (Nature news is merely reporting on the AAS presentation.) The author himself has an appropriate degree of skepticism of his claim.
(Yes, I am an astronomy grad student, although I don't do any work on cosmology.)
Re:That's a pretty bold statement... (Score:2)
Why couldn't it be that our understanding of how gravity scales over interstellar distances is completely offbase? When we see things like the Pioneer anomaly [wikipedia.org] giving slight indications that our understanding of gravity over large non-interstellar distances may be flawed, then why wouldn't we assume that gravity simply doesn't scale over extremely long distances? I don't know enough to intelligently debate this with an astronomy student, but from here dark matter and dark ener
Re:That's a pretty bold statement... (Score:4, Insightful)
It is even so obvious that in order to make the measures stick to the theory, we need to introduce 'patches' that have well known properties, but unknown 'physical' representation like the dark matter and dark energy.
That the way science works. Before having an absolute correct theory we still need any theory to start with, demontrates and experiment and maybe change it or even replace it later. It is easier to start with a theory we are more or less confident with ( by experimentation ) and patch it to make some progress than throw everything away and start from scratch.
Maybe in x years some guy(s) will find that 3 stars in a line of 100 lightyears produce the same effect as if there was an amount y of dark matter. And this guy will be able to demonstrate his theory because thanks to a patched theory during the previous x years, scientists have been able to measure very precisely the characteristic of this dark matter and are able to validate his results!
Now of course, I said 'start with a theory we are more or less confident with' and that's where people starts disagreeing...
the fundamental flaw (Score:3, Interesting)
Scientists in the persuasion of Materialism believe that the universe is fundamentally composed of matter.
Vitalists maintain that the physical universe is just a very tiny subset of "all that is". Conciousness is primary, the physical universe is the playground that we all are currently occupying.
Matrix terminology: Conciousness is "the real world", whereas the physical universe is "the matrix". The movie was based on buddhist philosophy, so it is an apt a
Re:That's a pretty bold statement... (Score:5, Insightful)
Kind of like aether was "required." And phlogistion. And igneous fluid.
I'm not saying that dark matter and dark energy don't exist - I don't know, and neither does anyone else - but I am saying that they're not necessarily "required."
Re:That's a pretty bold statement... (Score:3, Insightful)
Aether was a perfectly reasonable hypothesis that made certain predictions that turned out not to be true and so was replaced when something better came along. This story is showing the
Re:That's a pretty bold statement... (Score:2, Insightful)
Physicists were once certain that "ether" existed. It was a construct that was necessary in order to make sense of many observations that were being made.
It turns out they were wrong. Ether does not exist. Ether was a construct that had nothing to do with reality even though it had some explanitory power.
That the construct of Dark Ene
Re:That's a pretty bold statement... (Score:2)
To me this sounds like the amount, location and mass of the black holes in each galaxy may simply not be accurate. As black holes donot emi
Re:That's a pretty bold statement... (Score:2)
Re:That's a pretty bold statement... (Score:2, Informative)
Re:That's a pretty bold statement... (Score:2)
> galaxy rotation curves.
Which, in every case, suggests a number about 10 times visible mass. I point this out for reasons that will become clear later.
> Dark matter was first hypothesized by Zwicky in 1933
After examining galactic _clusters_. In his analisys, the number was 400 times.
And then you don't note the other argument: that the large-scale structure of the universe cannot be explained without adding lots of mass. The filamental structur
Re:That's a pretty bold statement... (Score:2)
More importantly--Do not cite to the Wikipedia as a source of genuine authority when trying to prove somebody else he's wrong.
IIRC, the whole beauty behind Dark Matter is it is supposed to be some constant that solves the problems we have with understanding how the universe operates. If that constant is not constant, then doesn
Re:That's a pretty bold statement... (Score:3, Interesting)
You're confusing dark matter and dark energy, and no, a non-constant dark energy doesn't ruin anything. The point of dark energy, like any theory, is to explain our observations. If our observations indicate that the universe is expanding in a weird way, we may need a weird e
Re:That's a pretty bold statement... (Score:2)
What you are basically stating is that when we observe galaxies they don't seet to follow the Newton's theory of gravity (or general relativity). So how to solve this contradiction? Well, according to cosmoligist, we just add an error correction term generally known as da
Re:That's a pretty bold statement... (Score:2)
Re:That's a pretty bold statement... (Score:2, Insightful)
I find it disturbing that the Physics community allow these sub fields to still call themself "science" when they have nothing at all to do with real science and only results in dilluting the value of real/hard science. I say this as a mathematician, the only remaining hard science.
I mean where is the scientific methods, where are the scient
Re:That's a pretty bold statement... (Score:4, Informative)
For starters mathematics isn't a science - it tells us nothing about the physical world, mathematics is a tool, nothing more, nothing less. I have the highest esteem for mathematics, but it's not science.
Secondly science has never proved anything. The requirement of the scientific method is that hypothesis be falsifiable. If its predicted results turn out to be reproducably observed you have the makings of a good theory.
I don't know what your gripe about "stub fields" is, but unfortunately kinematics and Newtonian ballistics have been pretty well explained, so physicists have been compelled to move into more arcane fields. Too bad they've never produced anything of value like the computer chip or GPS.
Anyhow this rant reminds me of a joke I heard once whose punchline was something like "When I went to college I learned that all sociologists are really psycologists, who are really biologists, who are really chemists, who are really physicist, who use mathematics - The mathematicians just think they're god."
Re:That's a pretty bold statement... (Score:5, Informative)
The problem is that using theories, that are just theories and not provably correct
No theory is provably correct. All you can do is fail to disprove them. All you can ever say is that a theory explains the observable results as we can measure them, and that we have been unable to make any observations that run contrary to the theory.
In time, it may be that we improve our measurement-making capacity and find that the theory is *not* correct - this is essentially what happened to Newtonian mechanics. At very small scales and/or very high velocities Newtonian mechanics is wrong, and we need quantum mechanics (for the small) and relativistic mechanics (for the fast).
At no point, however, do we get to sit back, relax, and say "that's that - this one is proven to be correct". Science just doesn't work like that. The closest we get is "this one has survived many attempts to disprove it, so we can be pretty confident in it, but who knows what the future may bring?"
Damn right (Score:2)
To affirm this principle, BTW, is why the Intelligent Design crazies have to be defeated.
Re:That's a pretty bold statement... (Score:2)
Like the continuum hypothesis?
Re:That's a pretty bold statement... (Score:5, Insightful)
Later on, pretty much anybody dealing with sailing ships noticed that the mast came over the horizon before the rest of the ship did. It was the church, with its insistence on the literal veracity of biblical statements about the world, and its stranglehold on political power throughout Europe, that made the Earth's shape a dangerous topic to shout from the rooftops.
For a modern analogue, biology, rather than cosmology, would seem to be the place to look.
Re:That's a pretty bold statement... (Score:2)
Dark matter is needed to locally provide additional gravitation.
Dark energy is needed to globally provide anti-gravitation.
Gravitons, if they exist (which we will not know for sure until we have a successful theory of quantum gravitation) don't have mass (if they had mass, gravitation would only act on a limited distance, just like the weak force). OTOH this is not really a counter-argument since gravitation isn't really generated by mass, but by energy and momentum (generation by mass is jsut a go
Gravitrons (Score:2)
First, matter conservation. Yes, I know about entropy, but these particles would have to exist somewhere and, like parent post said, would change the gravity of whatever they were pushing toward. Second, Newton wouldn't all
An extraordinary Claim requires... (Score:5, Interesting)
topic (will hear more about it from local experts for sure), but
it doesn't sound a statistically significant claim to me.
For the life of me I can't recall a false study about something...
I think it's about pulsars / neutron star. Astronomers found the
first few pulsars and found them to be aligned in a similar
orientation. This provoked a few new thoughs and fresh ideas
among the community...but later only to realize that the first few
detections happened to be a freak series of coincidence; further
observations revealed that other pulsars orient in many different ways.
Choosing random samples is important here. I'm not sure how carefully
that thought process has been applied here by this author (i.g., that
is what Adam Rees alludes to, I think).
We have to be careful since some people tend to see what they want
to believe in.
He does not really believe in Dark Energy (Score:5, Informative)
He actually believes in Dr. Mannheims Conformal Gravity. An attempt to define
gravity in terms of Conformal Symmetry, which the other three forces observe.
In the theory Dark Energy is just a manifestation of the repulsive component of
gravity. And this force changes with the evolution of the universe. He has just
found proof of this. This would mean that they have discovered something that has
not yet been predicted by the standard model. They have been hard at work to come
up with something that they can predict something that can be proved based on the
observation. The only other significant difference from the standard model is that
in the theory universe is always expanding, and there was no contraction phase.
The observations are not yet conclusive enough on this point.
more information (Score:5, Informative)
http://www.phys.lsu.edu/GRBHD/pressrelease/ [lsu.edu]
It seems that the results are very damning to cosmological
constants.
Unfortunately there are no good web sites talking about
Mannheim's theory the only paper that explains a lot of
it is "Alternatives to Dark Matter and Dark Energy" which
can be accessed at http://arxiv.org/abs/astro-ph/0505266 [arxiv.org]
Re: more information (Score:3, Interesting)
http://www.phys.lsu.edu/GRBHD/pressrelease/ [lsu.edu] It seems that the results are very damning to cosmological constants.
It seems that even if he's right it would only require one cosmological constant to be non-constant.
Or maybe not even that. Maybe the effect he's observing is dependent on something that changes with times, such as the temperature or density of the universe. Most cosmologists already believe the universe underwent a sort of "phase change" du
Re:Don't Use Line Breaks (Score:2)
Re:What do extraordinary claims require? (Score:2)
The underlying implication leads to the potential changes in the gravity theory (yes, theory, not just an idea) and other branches of physics. It opens up a door, possibly, that the physics as we know may not be the same in the past.
A number of researches do tackle this question from time to time, i.e., the studies of fine structure constant are the famous example. As you may or may not know, researchers a
A stretch (Score:2, Insightful)
Re:A stretch (Score:2)
Re: (Score:2)
Re:A push (Score:2)
Gravity is not a force at all. That's where pretty much all amateur theorists fall down.
Re: A stretch (Score:2)
Perhaps you should write your favorite physicist or science journal about it. I'm sure they'd love to hear your views on it.
> is this really any better than the Greeks accounting for oddities in terms of gods and goddesses?
Yes, because even the most far-out cosmology doesn't invoke the unpredictable whims of powerful beings.
> It seems to me that we are
Re: A stretch (Score:2)
Of course, often it also turns out that the complexity of the description isn't due to the complexity of the system, but due to the description not fitting the system well. The classical example for that are the epicycles. All that complexity vanished as soon as Kepler found his three laws. Now, of course looking clos
article wasn't very clear, but... (Score:4, Insightful)
http://en.wikipedia.org/wiki/Big_Rip [wikipedia.org]Big Rip.
clarification (Score:2)
I realized that I wasn't very clear when I said this - our current theory of dark energy came about because of a type Ia supernova explosion that was about half of the age of the universe. If the older xray sources are brighter than expected, then this means that the acceleration is accelerat
Not THAT again... (Score:4, Interesting)
Re:Not THAT again... (Score:4, Insightful)
Well, in this particular term that is.
I'm sure some nerds will bring in on Einstein reference that is E = mc^2.
Death of dark matter greatly exaggerated (Score:2)
http://cosmicvariance.com/2005/10/17/escape-from-t he-clutches-of-the-dark-sector/ [cosmicvariance.com]
Quoted from the article there....
Let's turn first to the attempt by Cooperstock and Tieu to do awa
We Prefer That You Call It... (Score:2, Funny)
Energy destroyed or converted to matter? (Score:2)
At the end of the day, do we have enough data to be able to say anything about "dark energy" that is anything other than wild speculation?
Re:Energy destroyed or converted to matter? (Score:2)
IANAP but... (Score:5, Insightful)
Maybe its just the engineer in me, but isn't it possible that we're just observing some other unknown effect. Something so complicated and exotic doesn't feel right. When it comes down to the math we juggle equations around, fit curves, and re-evaluate until the math yields a good approximation. Math juggling is one thing but I don't think there's a strong case for creating a physical entity for it.
Re:IANAP but... (Score:3, Interesting)
MOND [wikipedia.org]
Re:IANAP but... (Score:5, Informative)
In the theory repulsive component decays with the evolution of Gravity, and hence the Dark Energy which is what the repulsive component amounts to.
Re:IANAP but... (Score:2)
In the theory the repulsive component increases with the increase of the size of the universe, and hence the dark energy should increase with time.
Re:IANAP but... (Score:2)
Ha! Shows what you know! Clearly this is an interaction between the Phlogiston and Ether, not some engineers h
Re:IANAP but... (Score:2)
String Theory Fallout (Score:5, Interesting)
It's looking more and more like String Theorists are on the wrong track. I think this may have bred a new skeptisism in people with regard to the more "out there" physics theories.
The whole debate about Intelligent Design may also be playing a part. There's been a very public question about "what is science". String Theory has already come under fire from this, and it's understandable that some other theories such as Dark Energy might also be brought under the spotlight of a new skeptisism.
This might be stifling for scientists, paticularly those with more outlandish sounding, but still reasonable hypotheses. But ultimately I think it will be good for science. No one should blindly accept any scientific theory without sufficient evidence. And supplying that evidence can only further validate the theory. In this sense, skeptics are good for science.
Re:String Theory Fallout (Score:3, Insightful)
Face it, we dont't what makes the universe expand/contract. We really don't know shite. All we can do is attempt to observe, and propose theories on those observations and try to falsify them. As we learn more, invent/discover better methods and devices for measurements, our understanding will evolve. I know this is basic stuff, but it seems many folks are forgetting this. We are mear children in our understanding of our universe.
Re: String Theory Fallout (Score:2)
Fall from grace among scientists, or just among Slashdotters?
> The whole debate about Intelligent Design may also be playing a part. There's been a very public question about "what is science".
No, there have just been some high profile attempts to redefine science to include ID, never mind the fact that the new defini
Re:String Theory Fallout (Score:2)
Ummm, science is formalised skepticism.
Re:String Theory Fallout (Score:2)
Re:String Theory Fallout (Score:2)
In fact, to keep it simple, I'd say that some of these findings actually support the membrane theory. Additionally, part of the string theory equations that actually hold water support dark matter and dark ene
Been there, seen that (Score:2, Interesting)
Up till today I haven't seen another team confirming this.
Ob blackadder quote (Score:4, Funny)
OMFG, COSMIC WARMING (Score:4, Funny)
if you'd care to understand.... (Score:2, Informative)
it has been reasonably established from several independent observations (cosmic microwave background, supernovae 1a, large scale structure) that the expansion of the universe is accelerating; the universe today is expanding
War in heaven (Score:2)
dark energy linked to hubble constant (Score:2, Interesting)
Dark Matter/Dark Energy is a kludge (Score:2, Insightful)
It's almost as if the people who are proposing these explanations aren't willing to toss out the current explanations they have for things and essentially start from scratch. But when you start to kludge explanations together as they have with dark matter/energy, that's exactly what you should do: go back to the drawing board. Having to kludge something is a huge hint that you got somethin
alternative: warped geometry (Score:2)
(This astrophysicist keynoted the 2004 SIGGRAPH because his mathematics is widely used in computer graphics.)
Hypothetical energy is always changing (Score:2)
"Could Einstein's theory of gravity, which has proved to be correct in all cases so far, be somehow wrong?"
(from http://chandra.harvard.edu/xray_astro/dark_matter 2
Sure, it could be wrong...something as theoretical can always be wrong. I think the observations that man can make from Earth most likely are bent or distorted by the massive size of the galaxy and the distances between them. Something so huge is hard to measure or calculate definitively.
Cant resist... (Score:2, Funny)
Warlock Science. (Score:3, Funny)
Speak for yourself. I'm keeping my talent points at 31/00/21 for nightfall and shadow burn.
...Eh, nevermind. You would have had to have been there.
Some astronomers doubt this result (Score:3, Interesting)
Obligatory Douglas Adams quote (Score:3, Interesting)
There is another theory which states that this has already happened."
Science Slashdot slogan. (Score:2, Funny)
The Unknowable (Score:2)
Occam is rolling in his grave.
Re:The Unknowable (Score:2)
Good. You're beginning to understand how science in the real world works.
And people make fun of creationism and intelligent design.
Re:The Unknowable (Score:2)
I am a scientist. I understand how science works in both the real world and in theory. This is an example of science not working. Creationism and its weasel word alternative name Intelligent Design are not connected to science in any way; they are politics and religion.
Of course it keeps changing... (Score:2)
And why shouldnt it (Score:2)
Just my two cents...I guess that I am of the mindset that you can't get something from nothing?
Kludge. (Score:2)
I love physics, but beware any time a physicist says "I've found something that changes/that I can change to fit in my otherwise not-completely-working theories."
This isn't to say it's not true. The universe is peculiar. But beware.
Re:The Light vs The Dark (Score:2)