Astronomers Challenge Idea that Universe is Expanding at an Increasingly Fast Pace A team of astronomers have determined the universe may not be expanding quite as quickly as previously believed, based on observations of young supernovae. The University of Arizona (UA) team reported their findings in two studies published in the Astrophysical Journal. The studies focus on the diversity of supernovae in the universe and their implications on its expansion. "We found that the differences are not random, but lead to separating IA supernovae into two groups, where the group that is in the minority near us are in the majority at large distances - and thus when the universe was younger," Peter A. Milne, an associate astronomer in the UA's Department of Astronomy and Steward Observatory, said in a press release. "There are different populations out there, and they have not been recognized. The big assumption has been that as you go from near to far, type IA supernovae are the same. That doesn't appear to be the case." Supernovae occur when stars explode and often act as magnifying glasses that allow astronomers to see objects deep in space that a telescope may otherwise not be able to spot. The researchers compared the diversity of supernovae to how different light bulbs can vary in brightness. The study also challenges the 2011 Nobel-Prize-winning findings of three astronomers who determined a force called "dark energy" was hastening the expansion of the universe. http://www.universityherald.com/art...is-expanding-at-an-increasingly-fast-pace.htm Dark Matter, yes; Dark Energy, no.
Already done that at...... http://www.sciforums.com/threads/un...e-1a-s-n-chemical-clock-gravity-waves.145676/ Plus your headline, "Astronomers Challenge Idea that Universe is Expanding at an Increasingly Fast Pace" is not correct. From your link itself, it says, "A team of astronomers have determined the universe may not be expanding quite as quickly as previously believed, based on observations of young supernovae". In essence then, this article, and the one I posted, do not in any way invalidate DE. The Universe is still according to the data, accelerating in its expansion rate, just not as fast as we previously thought. All we have is a refinement in tolerances and accuracy, which is happening all the time. eg: We recently thought the BB happened 13.7 billion years ago: Latest data now puts that at 13.83 billion years ago.
Well, excuse me for copying the title exactly from the article: Astronomers Challenge Idea that Universe is Expanding at an Increasingly Fast Pace Please Register or Log in to view the hidden image! (Photo : Reuters) Pictured is an X-ray and infrared image of a supernova explosion, not the one from the latest study. A team of astronomers have determined the universe may not be expanding quite as quickly as previously believed, based on observations of young supernovae. Like Us on Facebook The University of Arizona (UA) team reported their findings in two studies published in the Astrophysical Journal. The studies focus on the diversity of supernovae in the universe and their implications on its expansion. "We found that the differences are not random, but lead to separating Ia supernovae into two groups, where the group that is in the minority near us are in the majority at large distances - and thus when the universe was younger," Peter A. Milne, an associate astronomer in the UA's Department of Astronomy and Steward Observatory, said in a press release. "There are different populations out there, and they have not been recognized. The big assumption has been that as you go from near to far, type Ia supernovae are the same. That doesn't appear to be the case." Supernovae occur when stars explode and often act as magnifying glasses that allow astronomers to see objects deep in space that a telescope may otherwise not be able to spot. The researchers compared the diversity of supernovae to how different light bulbs can vary in brightness. The study also challenges the 2011 Nobel-Prize-winning findings of three astronomers who determined a force called dark energy was hastening the expansion of the universe. EMAIL http://www.universityherald.com/art...t-an-increasingly-fast-pace.htm#ixzz3XVtK5XUl That group of astronomers is, in fact, challenging the validity of "dark energy", believing that the purported faster expansion nearby compared to far away is an artifact of the "big assumption has been that as you go from near to far, type Ia supernovae are the same. That doesn't appear to be the case." Or don't you read?
Please Register or Log in to view the hidden image! Certainly I read......More to the point is the headline you quote saying one thing and the beginning of your link saying another. You don't believe that in itself needs questioning? We had also the sensationalistic headlines a while back re Hawking claiming BHs don't exist. They can challenge all they like, and think what they like, but all they have shown is what I have said...a refinement in measuring and a review or reappraisal of type 1a S/N. In that respect I commend them. What I don't commend is the sensational headlines and others that immediatley jump on the band wagon, in the vain hope that it may in someway support their own hypothesis on cosmology and/or claims of a ToE.
Well, to be frank, they appear to be being quite coy about it. They state they are not willing yet to put numbers to the correction for the purported change in "dark energy" as previously postulated. They have shown two distinct populations of 1A (1A-N and 1A-F; i.e Near and Far) which would require a revision on the purported "dark energy" value for expansion. It appears they are laying the groundwork for further refinement, or possible elimination, of "dark energy", by future observations. "Dark energy" has no theoretical explanation, and many astronomers would likely welcome the chance to challenge it further. Hence the "?" in the title of the thread. http://www.eurekalert.org/pub_releases/2015-04/uoa-aun041015.php
Like I said, the discovery of the type 1a S/N variations has not invalidated the accelerated expansion rate. Time, and further science will tell, will it not? I'll wait for further explanations and new data.
Certainly DE does indeed have an explantion...the observed acceleration in the expansion rate, which has just been refined even further. We just do not yet know exactly what it is.....the CC? most probably, but we'll wait for new data on that. Please Register or Log in to view the hidden image! The title in the thread? Please Register or Log in to view the hidden image! You mean "Accelerating Universe? Not so Fast." I see just a humorous play on words.
I'm sure some group will find something somewhere sometimePlease Register or Log in to view the hidden image!
It's more than one experiment that predicts the universe expansion is accelerating. That's a good reason to be coy about making any claims based specifically on one observation. This is an interesting one http://en.m.wikipedia.org/wiki/Accelerating_universe#Baryon_acoustic_oscillations
The authors make no such absolute claim. The article in question: http://iopscience.iop.org/0004-637X/803/1/20/ Preprint: http://arxiv.org/abs/1408.1706 Focusing on Section 5. In fact, they write: "Without absolute magnitudes determinations that separate NUV-blue from NUV-red SNe Ia, we do not know the exact bias that results from treating both groups as a single sample." and also "given the small sample size presented in this work, there is still considerable uncertainty about the size of the difference between the NUV colors, the physical mechanism that causes it, and the relative ratio of the two groups and it’s evolution with redshift." The authors aren't able to fix the sign of the potential bias in treating the Ia supernovae as a single population rather than two. Moreover, the WMAP people called out the potential because the supernova data analysis didn't make sense in light of other data sources, so in section 2.2.4 of http://lambda.gsfc.nasa.gov/product...year/cosmology/wmap_9yr_cosmology_results.pdf they write: "The 472 Type Ia supernovae used in the SNLS3 analysis are consistent with the ΛCDM model predicted by WMAP (Sullivan et al. 2011), thus we can justify including these data in the present analysis. However, the extensive study presented by the SNLS team shows that a significant level of systematic error still exists in current supernova observations. Hence we restrict our use of supernova data in this paper to the subset of models that examine the dark energy equation of state."
Dark matter doesn't interact with ordinary matter; does it interact with itself? What happens when two dark matter particles collide? What happens when you try to find out the answer using google? The question seems to have different answers: no, dark matter particles don't collide, but yes, they appear to interact via some force other than gravity.
it depends on which particle theory you're speculating with. If you were using the mirror dark matter theory there's an entire dark matter mirror standard model. All the theoretical ideas are theories if they make predictions for dark matter particles. Some cool physics. IE ongoing experiments to directly detect dark matter particles. Science has directly detected the presence of dark matter just not specifically what it is. Even Sheldon was thinking of switching from quantum gravity to dark matter. LOL.
Dark energy and dark matter are both an unproven hypothesis. We simply have some observations that defy explanation.
DM is much more then just hypothesised and we have observational evidence of its existence. See Bullet cluster. http://chandra.harvard.edu/press/06_releases/press_082106.html http://www.astro.cornell.edu/academics/courses/astro201/dm_evidence.htm DE, the true nature of which is a complete mystery at this time, is also evident by indirect observational evidence. http://www.dailygalaxy.com/my_weblo...ys-an-international-team-of-astronomers-.html
It is much more correct to say the totality of human observation is consistent with a universe evolving via the standard model of particle interactions and general relativity with observationally constrained amounts of baryonic normal matter, a cold, clumpy, nearly intangible, nearly invisible material (CDM) and a pervasive effect that acts like either Einstein's cosmological constant or nearly like an energy field (DE). This thread was about newly resolved uncertainties for one class of evidence, that may one day go towards resolving which model of DE is best.
