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Necessity of Dark Energy Questioned
ttnuagmada points us to an article about scientist David Wiltshire's suggestion that theorized dark energy is not needed to describe the expansion of the universe. His work challenges assumptions made about the distribution of matter in the universe. Early solutions to general relativity were based on a "smooth distribution" of matter. Wiltshire's approach focuses on a "lumpy" dispersal, which more accurately fits data from modern studies. We have discussed other theories about dark energy in the past. Quoting:
"Through observational projects like the Sloan Digital Sky Survey and the 2 Degree Field survey, we now have a much better picture of the large-scale structure of the universe and we know that galaxies are not uniformly distributed. 'Rather, they are in clusters sprinkled thinly in filaments and "bubble walls" surrounding huge voids hundreds of millions of light-years across,' Wiltshire says.
As Zapp Brannigan is in lukewarm discussions with the Neutral Planet president, the planet's scientists are holding a lukewarm debate over the possible existence of Grey Matter.
Knowledge is how to play a game, intelligence is how to win, wisdom is knowing what game to play.
Anybody want my mod points?
Just because you know that something is happening doesn't mean that you account for it correctly or fully appreciate the implications; I'm a biologist, all the systems I deal with are heterogeneous, and it's always a major bitch to deal with. That said, I share your skepticism but this doesn't strike me as implausible - although I know essentially nothing about astrophysics.
The good and new comes from no quarter where it is looked for, and is always something different from what is expected.
From the article, it seems like he believes that this lumpiness was always there, rather than an earlier smooth distribution they've been assuming.
While we might not ever know who is correct in this regard, I tend to prefer theories that don't have the need for dark energies, or matter,even if that really really screws up the equations we use to model the early universe. I think at some point every physicist just stares at a black board somewhere and says to himself " thats fucked up". We really have lost the elegance of the universe being a series of spherical shells rotating around the earth. Since that point we've managed to go through cycles of discovering elegance in the universe on a deeper level (the simple math of kepplar and Newton), and having to reject it for more complexity( Einstien's huge matrix of PDE's ). Let this be a lesson to us all, Don't let what should be prevent you from seeing what is.
Well.. maybe. Or Maybe not. But Definitely not sort of.
... can be accessed here: http://arxiv.org/abs/astro-ph/0510059 . A bit less recent (but even more readable) account is http://xxx.lanl.gov/abs/astro-ph/0310342 . The first linked article also mentions the approaches featured in the slashdot post (this is an ongoing business for a while). For starters the flow diagrams in the front pages describing the options might be particularly useful.
Attitudes make the difference between Space and Time: we want to MAX our temporal, and MIN our spatial extension.
I did some googling and found David Wiltshire's home page which had links to his recent publications. That brought me to this full article which I am guessing is the one that corresponds to what was discussed in the original /. article here.
I had a couple courses in astronomy and cosmology way back in my college days. That said, I can't begin to understand the details. I'm hoping someone with more knowledge and experience could elaborate. Is he really onto something that can dispense with the need for dark energy? And, if he is, am I correct in thinking this would be Nobel-Prize-Candidate-Worthy?
The fact that matter forms bubbles around the voids intuitively make me think that some force is pushing matter away from the center of each void. Perhaps the center of each void is location where mini-inflation events have happened and what we see today is the reslut of these events pushing shells of matter up against each other so that they form filaments and bubbles. Just a though, IANAP though.
Actually, physicists hate complex answers. The overwhelming guiding principle of physics is to describe the universe with as few axioms and rules as possible. Leon Lederman (former director of FermiLab) has a neat little passage in his book about the goal of physics being to produce the ultimate t-shirt: everything that's needed to describe everything written on a shirt. And not one of those XXXL shirts couch potatoes wear.
If this guy is correct then it's a nice advancement of cosmology. From what's described in the article it appears that at least the sign of the effect in his argument is correct. You hear a LOT of these claims though, that explain one or two observations and conveniently omit a hundred or so others.
And the article is terrible. It sets this up somehow as a battle between this guy and Einstein. Einstein postulated a cosmological constant (the equivalent of dark energy) because he wanted a STATIC universe and then retracted it when Hubble came up with experimental evidence that the universe isn't static at all. Einstein's theories have nothing to do with whether matter is smoothly distributed or not.
You do know that the temperature of the corona has been explained by observation of the sun's magnetic field lines right? Your confusion stems from modeling the sun as a light bulb, rather than the physics.
The shortage of detected solar neutrinos was explained by hypothesizing that neutrinos actually have a very small mass. That would imply that they oscillate between types, only one of which we were detecting. That implies that the shortage is made up by neutrinos of the two other types that we couldn't detect. Now, with better equipment, we've discovered that neutrinos do have some very small mass and everything adds up nicely. Sorry, but that's a TRIUMPH of quantum mechanics, nuclear physics and the standard model, not a failing.
But if you don't like all that math, that's no problem. Please sell or recycle your computer, which is only possible due to all that math.
Exactly, even though we don't need to postulate the presence of "Dark Matter" to construct mathematical models of the expanding Universe, Einstein did not need the "ether" theory to construct "relativity" mathematical models that incorporated how light seems to behave.
Still that does not prove that the "ether" either exists or doesn't exist. Just that it is not necessary to incorporate into a mathematical model, that will more or less express what is observed. But we still have the question of "zero point energy", what exactly is it? And what possible connections or similarities might it have with "dark matter" and "ether" theories.
I have my own theory, and it is about the limitations of thought or of comprehension. Thought itself seems to work on a relativistic principle, where the polar opposite is always simultaneously needed as a contrast. Example: Up/Down, In/Out, Near/Far, Good/Bad etc. etc. So Einstein's theory of Relativity does not necessarily explain how the Universe works, it only explains how the limitations of thought work. Thought as a medium of awareness can therefore never grasp the Absolute, or the Non-Relativistic Totality, because that requires a different kind of awareness than thought is capable of.
You confound dark energy with dark matter. They are very, very different concepts. This paper deals with dark energy.
Warning: this article may contain humor, sarcasm, parody, and perhaps even irony. Read at your own risk.
Why have they been wasting our time with this dark energy stuff for the last decade then? Why posit the dark energy if its only needed to fix a model that was derived with what has for a while now known to be a false assumption? It seems stupid. Instead of endless science articles on dark energy, instead there should have been articles on scientists working to solve pde's with really hard constraints that match modern astronomical observations. I don't get it. Is there more to the story?