Dark Energy's Demise? New Theory Doesn't Use the Force, page
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Topic started on 22-8-2009 @ 06:36 PM by kiwifoot

Dark Energy's Demise? New Theory Doesn't Use the Force


news.nationalgeographic.co.uk
Dark energy, a mysterious force proposed more than a decade ago to explain why the universe is flying apart at an increasingly faster clip, is no longer necessary.

That's the conclusion of a controversial new theory that shows how the accelerated expansion of the universe could be just an illusion.

n a new study, two mathematicians present their solutions to Einstein's field equations of general relativity, which describe the relationship between gravity and matter.
(visit the link for the full news article)


reply posted on 22-8-2009 @ 06:36 PM by kiwifoot
I'd imagine, if your anything like me, the specifics of their theory may be a bit too complicated.

But a theory that potentially disproves Dark Energy is quite a big deal.

Here is a interesting article on Dark Matter and Energy:

Dark Matter and Dark Energy: One and the Same?

Dark matter and dark energy are two of the most vexing problems in science today. Together they dominate the universe, comprising some 96 percent of all mass and energy.

But nobody knows what either is. It's tempting to consider them products of the same unknown phenomenon, something theorist Robert Scherrer suggests. The professor of physics at Vanderbilt University says "k-essence" is behind it all.


The theory in a nutshell:

To find a dark-energy alternative, other scientists have proposed versions of the newly supported theory that our galaxy sits inside an expansion wave, a ripple of space with low density.


And from Wikipedia

In physical cosmology and astronomy, dark energy is a hypothetical form of energy that permeates all of space and tends to increase the rate of expansion of the universe. Dark energy is the most popular way to explain recent observations that the universe appears to be expanding at an accelerating rate. In the standard model of cosmology, dark energy currently accounts for 74% of the total mass-energy of the universe.


Even if they are right, I feel it will just create more questions than provide answers!


news.nationalgeographic.co.uk
(visit the link for the full news article)

[edit on 22-8-2009 by kiwifoot]


reply posted on 22-8-2009 @ 07:40 PM by phi1618
reply to post by MrVertigo


thats assuming the galaxy is not only observable from the point of the observer ( us )


reply posted on 22-8-2009 @ 07:48 PM by chiron613
I've always had trouble with the concept of dark energy. It seems like they invented it to explain something that sounded a bit vague to begin with. Of course, I'm not a physicist, don't know the first thing about all this, so my opinion means nothing.

The violation of the Copernican principle simply means that there is something about our local space that is unusual. The basic principle is that, on the large scale, any given point in the Universe would look roughly like any other point. There would not be any special points where things were very different. In other words, what we see from Earth would not be special.

The violation is that we're in some sort of rarefied area of space that doesn't exist throughout the whole Universe. It doesn't mean that we're unique; it just means that we're in a sort of bump or void that, in general, other observers wouldn't see. That could easiiy happen, just like someone could be living on a mountain, even though most of the Earth isn't a mountain. But using such an explanation to explain something makes scientists uncomfortable.

As for the statement that somehow we'd be at the center of the Observable Universe - we *are* at the center of the Observable Universe. Every observer is. Our view of the Universe is about the same distance in every direction, putting us smack in the middle of it. But someone way on the edge, right at the limit of what we could see, would also be at the center of the Observable Universe - the Universe he could observe. However, some of the Universe he could observe would be beyond what we could observe.


reply posted on 9-10-2009 @ 03:47 PM by Arbitrageur
I think this is the same topic but it was posted online on Sept 25, well after this thread was created:

Mathematicians' Alternate Model of the Universe Explains Away the Need For Dark Energy

The basic concepts of the mathematicians' theory are more or less in English in that article (as opposed to the "Greek" used by physicists and mathematicians). One interesting precept of the theory is that it would put Earth near the center of the universe which is a violation of

the Copernican principle that Earth does not have a unique place in the universe.


But it always occurred to me that if the universe has a center, all we can say is the probability of any given mass being near the center is relatively low, but a given cluster of galaxies could be at or near the center, and it could be our local group. the most you could say is that it's not probable, you can't say it's not possible. So I don't think the Copernican principle is a very solid argument against the mathematicians' theory.

Regarding the other arguments against this theory:

But cosmologists say that the new expansion theory has problems. First, observations of the Big Bang's afterglow also indicate the existence of dark energy. Simulations also fit rather well with the observed universe expansion when dark energy becomes a factor.


I'll have to research those further.


reply posted on 9-10-2009 @ 06:36 PM by Sacrosanct
Originally posted by chiron613
I've always had trouble with the concept of dark energy. It seems like they invented it to explain something that sounded a bit vague to begin with. Of course, I'm not a physicist, don't know the first thing about all this, so my opinion means nothing.


While this theory sounds like complete bologna.... this part of your post means little in the field of theoretical physics... It really wasn't too long ago when black holes were nothing but a 'theory'.... and for the most part still are. They have been observed (partly) by gravitational lensing, but much of what happens past an event horizon is still very much nothing but concept, as it is 'imagined' that nothing past the so-called event horizon can be envisioned... thus came the existence of superstring theory etc... a lot of these things are nothing but theoretical works based mostly off previous physicists works... it is in many ways exactly like religion in that there is absolutely no way to test these theories, short of being sucked into a black hole itself (which is, according to current laws of physics inescapable) and even that would prove quite futile as you'd most likely be condensed into nothingness or something very close to it. Or maybe you'd get sucked into another universe or... or... who knows. Nobody knows, but to regard any of these new 'breakthroughs' in physics is much like taking something out of the bible and analyzing it until you came up with some mind-shattering conclusion about something that (probably) wasn't real in the first place.

All these simply accept the General Theory of Relativity at face value. It is just that, a theory, but so much of modern physics is directly related to Einsteins work that if it ever is disproved, a good 20 years of astrophysics has been ruined or must be re-worked to fit in with whatever new theory takes its place.

Sorry for the long rant.


reply posted on 11-10-2009 @ 10:28 AM by Arbitrageur
reply to post by Sacrosanct

Einstein had no proof for his theory of relativity either when it was first published, and it took years for observations to be made during eclipses that would prove his theory true or false. We can't really say Einstein's theory was accepted until it was confirmed by those real world observations (and many since).

But string theorists don't yet have their theories backed up by real world observations, like Einstein did. And until they do have some real world proof, the string theories (or membrane theories) are certainly unproven at best and complete fantasy at worst.

However this new explanation of the observations pointing to a need for "dark energy" show that dark energy is not needed to explain the observations. At least here we are dealing with real world observations (unlike string theory). Now more evidence and research is needed to assess the viability of this interpretation. It's an interesting explanation if only because it makes the universe seem less wacky like the dark energy does.



reply posted on 11-10-2009 @ 11:13 AM by micpsi
11-d space-time consists of two 10-d space-time sheets separated by a small distance whose size determines the strength of the Newtonian gravitational constant G. Ordinary matter governed by the first factor E8 in the unified gauge symmetry group E8xE8' of heterotic superstrings is confined to one sheet and shadow matter governed by the second factor E8' is confined to the other sheet. Dark energy is the bosonic and fermionic fields of E8'. It is invisible and interacts only gravitationally with ordinary matter. Originally, the two sheets were just one sheet in which the gauge symmetry group O(32) governed superstring forces. When they split apart, creating two universes, each invisible to the other, the repulsive gravitational force of dark energy on ordinary matter caused the rate of expansion of the universe to increase - that's why galaxies are moving slightly faster apart than what Hubble's law predicts.

Because of the Uncertainty Principle, the dimensional gap between the two space-time sheets is not sharply defined but fuzzy, allowing matter in the shadow universe sometimes to exist temporarily in the ordinary universe. Its dark energy then becomes detectable physically and can be exploited, providing a huge source of energy in principle. The problem has been to increase the induced leakage in a controllable way.

Another universe of matter (and - yes - beings) interpenetrates ours. As we are partly composed of dark energy, we live in that universe as well, though we rarely experience it. When we do, we say we have seen a ghost or a UFO.


reply posted on 13-10-2009 @ 02:37 PM by Devino
reply to post by Sacrosanct

No, I do follow your Copernican logic and I also understand the Newtonian version of the Universe but I prefer the relative perspective. Relativity is not easy to follow because it deals with test particles and other observers beside our self. Keep in mind that every observer (like you and me) have their own unique inertial frame of reference. With relativity came the understanding that everything is in motion, there is no point that is "at rest' as Newton describes. Objects that appear to be at rest are those that, from our inertial frame of reference, appear to have very similar motions (nearly the same velocities in the same directions).

Another point to make is that we can only observe the Universe through our sensory perceptions and these, along with our inertial frame of reference, are our limitations. Relativity is a way of describing the Universe outside of these limitations and this is where the idea of infinity comes from. The problem is that Einstein's description of relativity also has limitations and it is because of these limitations that we experience a finite Universe.

If infinity has no ending is it true that it also has no beginning? I would imagine that infinite has neither a beginning nor an end. My philosophical understanding of infinity is that it has no bounds from which to measure. Every measurement that we know of have a beginning and an end, they are all subject to motions and our observations. So the infinite has no bounds and is beyond measure, we could imagine that it is a place of absolute nothingness and yet contains everything all at the same time. It is the inconceivable, impossible "nothing" that is absolute.

Finite has a beginning and an end and there are bounds with which to measure from. It is the conceivable, possible "something" that have limitations. So think of yourself as a vessel and your eyes are windows, what do you see? The Universe unfolding around you. Everything that you can see, measure and ever imagine are all within limitations or bounds, this is the center of the Universe for you as an active observer.
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