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ESA ACT

FQXi: Foundational Questions in Physics & Cosmology - 0 views

www.fqxi.org

science Research physics astronomy cosmology PHY

shared by ESA ACT on 24 Apr 09 - Cached
  • ESA ACT on 24 Apr 09
     
    To catalyze, support, and disseminate research on questions at the foundations of physics and cosmology, particularly new frontiers and innovative ideas integral to a deep understanding of reality but unlikely to be supported by conventional funding sourc
jaihobah

The Network Behind the Cosmic Web - 1 views

cosmicweb.barabasilab.com

PHY

shared by jaihobah on 18 Apr 16 - No Cached
  • jaihobah on 18 Apr 16
     
    "The concept of the cosmic web-viewing the universe as a set of discrete galaxies held together by gravity-is deeply ingrained in cosmology. Yet, little is known about architecture of this network or its characteristics. Our research used data from 24,000 galaxies to construct multiple models of the cosmic web, offering complex blueprints for how galaxies fit together. These three interactive visualizations help us imagine the cosmic web, show us differences between the models, and give us insight into the fundamental structure of the universe."
johannessimon81

Cosmological model without accelerated expansion proposed - 1 views

www.nature.com/...e-may-not-be-expanding-1.13379

science cosmology

shared by johannessimon81 on 07 Aug 13 - No Cached
  • johannessimon81 on 07 Aug 13
     
    Redshift in this model is partially produced by a change in the masses of elementary particles (and atoms)
  • ...3 more comments...
  • Thijs Versloot on 25 Aug 13
     
    It seems to solve the problem of infinite energy density at the singularity in any case. I would love to see a way of experimentally verifying this, although most people seem to believe it is wrong. I read the following quote though by Dirac to Pauli "we all agree your idea is crazy, but the real question is it crazy enough to be correct?"
  • H H on 25 Aug 13
     
    As far as I can see, this is not untestable per se, rather an explanation to the redshift that is equivalent to accelerating expansion. It is not that the theory is untestable, rather just another way of looking at it. Kind of like that its sometimes convenient to consider light a particle, sometimes a wave. In the same way it could sometime convenient to view the universe as static with increasing mass instead.
  • Thijs Versloot on 26 Aug 13
     
    Well the premiss "matter getting heavier" may be up to falsification in some way or another. Currently, there is no absolute method to determine mass so it might even be plausible that this is actually the case. I don't think it is related but there is a problem with the 1kg-standards (1 official and 6 copies) where the masses seem to deviate.
  • johannessimon81 on 26 Aug 13
     
    It should not be impossible to verify a change in mass(es) over time. For example the electron cyclotron frequency scales ~e/m while the Hydrogen emission frequencies scale with ~m*e^4. Using multiple relationships like that which can be easily and accurately measured an increase in the mass of fundamental particles should - in principle - be detectable (even if the mass of the earth increases at the same time changing the relativistic reference frame).
  • Thijs Versloot on 26 Aug 13
     
    The Watt balance and a definition using the Planck's constant seems to do the trick and is currently being discussed. Would the electron charge not be problematic as it is related to Coulombs which depends on Amperes which is defined by Newtons which hence depends back on the mass again?
Luzi Bergamin

Prof. Markrams Hirnmaschine (Startseite, NZZ Online) - 2 views

www.nzz.ch/...s_hirnmaschine_1.10736223.html

AI neuroscience SciFi

shared by Luzi Bergamin on 29 May 11 - No Cached
  • Luzi Bergamin on 29 May 11
     
    A critical view on Prof. Markram's Blue Brain project (in German).
  • ...4 more comments...
  • Luzi Bergamin on 29 May 11
     
    A critical view on Prof. Markram's Blue Brain project (in German).
  • LeopoldS on 30 May 11
     
    so critical that the comment needed to be posted twice :-) ?
  • Luzi Bergamin on 30 May 11
     
    Yes, I know; I still don't know how to deal with this f.... Diigo Toolbar! Shame on me!!!
  • dejanpetkow on 30 May 11
     
    Would be nice to read something about the modelling, but it appears that there is nothing published in detail. Following the article, the main approach is to model each(!) neuron taking into account the spatial structure of the neurons positions. Once achieved they expect intelligent behaviour. And they need a (type of) supercomputer which does not exist yet.
  • Ma Ru on 31 May 11
     
    As far as I know it's sort of like "Let's construct an enormous dynamical system and see what happens"... i.e. a waste of taxpayer's money... Able to heal Alzheimer... Yeah... Actually I was on the conference the author is mentioning (FET 2011) and I have seen the presentations of all 6 flagship proposals. Following that I had a discussion with one of my colleagues about the existence of limits of the amount of bullshit politicians are willing to buy from scientists. Will there be a point at which politicians, despite their total ignorance, will realise that scientists simply don't deliver anything they promise? How long will we (scientists) be stuck in the viscous circle of have-to-promise-more-than-predecessors in order to get money? Will we face a situation when we'll be forced to revert to promises which are realistic? To be honest none of the 6 presentations convinced me of their scientific merit (apart from the one on graphene where I have absolutely no expertise to tell). Apparently a huge amount of money is about to be wasted.
  • Luzi Bergamin on 01 Jun 11
     
    It's not just "Let's construct an enormous dynamical system and see what happens", it's worse! Also the simulation of the cosmological evolution is/was a little bit of this type, still the results are very interesting and useful. Why? Neither the whole cosmos nor the human brain at the level of single neurons can be modelled on a computer, that would last aeons on a "yet-to-be-invented-extra-super-computer". Thus one has to make assumptions and simplifications. In cosmology we have working theories of gravitation, thermodynamics, electrodynamics etc. at hand; starting from these theories we can make reasonable assumptions and (more or less) justified simplifications. The result is valuable since it provides insight into a complex system under given, explicit and understood assumptions. Nothing similar seems to exist in neuroscience. There is no theory of the human brain and apparently nobody has the slightest idea which simplifications can be made without harm. Of course, Mr. Markram remains completely unaffected of ''details'' like this. Finally, Marek, money is not wasted, we ''build networks of excellence'' and ''select the brightest of the brightest'' to make them study and work at our ''elite institutions'' :-). I lively remember the stage of one of these "bestofthebest" from Ivy League at the ACT...
jaihobah

A Radically Conservative Solution for Cosmology's Biggest Mystery - 2 views

www.quantamagazine.org/logys-biggest-mystery-20180501

PHY space Cosmology

shared by jaihobah on 02 May 18 - No Cached
  • jaihobah on 02 May 18
     
    Two ways of measuring the universe's expansion rate yield two conflicting answers. Many point to the possibility of new physics at work, but a new analysis argues that unseen errors could be to blame. See also this work based on GAIA data that, on the other hand, reinforces the discrepancy: Milky Way Cepheid Standards for Measuring Cosmic Distances and Application to Gaia DR2: Implications for the Hubble Constant https://arxiv.org/abs/1804.10655
LeopoldS

A Population of Fast Radio Bursts at Cosmological Distances - 1 views

www.sciencemag.org/...53.abstract

astrophysics

shared by LeopoldS on 05 Jul 13 - No Cached
santecarloni

Was a metamaterial lurking in the primordial universe? - physicsworld.com - 1 views

physicsworld.com/...48238

CMB Universe PHY cosmology

shared by santecarloni on 05 Jan 12 - No Cached
  • santecarloni on 05 Jan 12
     
    A scientist in the US is arguing that the vacuum should behave as a metamaterial at high magnetic fields. Such magnetic fields were probably present in the early universe, and therefore he suggests that it may be possible to test the prediction by observing the cosmic microwave background (CMB) radiation - a relic of the early universe that can be observed today.
santecarloni

Artificial Braneworlds Made to Collide In Lab - Technology Review - 4 views

www.technologyreview.com/...27537

metamaterials cosmology PHY

shared by santecarloni on 31 Jan 12 - No Cached
pacome delva liked it
  • santecarloni on 31 Jan 12
     
    Physicists have simulated two universes colliding inside a metamaterial--  Now, this is cool (if it is true...)
  • ...1 more comment...
  • LeopoldS on 01 Feb 12
     
    we... the article is a bit overblown in my view ... except maybe the last paragraphs: "The collision between universe's is a variation on this theme. "The "colliding universe" scenario can be realized as a simple extension of our earlier experiments simulating the spacetime geometry in the vicinity of big bang," he says. He simulates an expanding universe using concetric rings of gold separated by a dielectric. "When the two concentric ring ("universe") patterns touch each other ("collide"), a Minkowski domain wall is created, in which the metallic stripes touch each other at a small angle," he says. Being able to recreate these exotic events in the lab is certainly interesting but it is beginning to lose its novelty. The problem is that this work is not telling us anything we didn't know--the universe behaves the same way inside a metamaterial as it does outside. What Smolyaninov needs is a way of using his exotic materials to do something interesting. In other words, he needs a killer app. Any ideas? "
  • Luzi Bergamin on 05 Feb 12
     
    Hm, they use more or less everything I don't especially like. They are nonmagnetic, so the relation materialGR is already rather weak. Usually, experimentalists prefer nonmagnetic media, since they are cheaper and broadband. At least the broadband is no argument here, since the frequency defines the "mass", which I find a rather strange point of view. And finally, they use strong anisotropy as a model of "time", which is rather problematic. Of course, the spatial direction with eps<0 appears in the wave equation with the same sign as time. But this does not mean that it behaves like time. But to teach material physicists that time is more than just a different sign in the wave equation seems to be as hopeless as to teach them that a black hole is more than something that absorbs all light... SIGHHH
  • LeopoldS on 10 Feb 12
     
    Luzi I miss you ...
Nicholas Lan

The Conspiracy Theorist Who Duped The World's Biggest Physicists - 5 views

www.popsci.com/...uped-worlds-biggest-physicists

PHY cosmology hoax

shared by Nicholas Lan on 08 May 14 - No Cached
  • Nicholas Lan on 08 May 14
     
    Weird geocentric universe hoax story
Thijs Versloot

Dwarf planet could illuminate the dark sector - 1 views

physicsworld.com/...uld-illuminate-the-dark-sector

science gravity dark energy matter einstein

shared by Thijs Versloot on 17 Jul 14 - No Cached
  • Thijs Versloot on 17 Jul 14
     
    A dwarf-planet candidate called UX25 and its tiny satellite could provide the first evidence of a new cosmological model that includes antigravity, say Alberto Vecchiato and Mario Gai of the Astrophysical Observatory of Turin in Italy.
pacome delva

Planck captures the universe coming to life - 1 views

physicsworld.com/...43110

phy cosmology planck

shared by pacome delva on 06 Jul 10 - Cached
  • ESA's Planck mission has released its first full-sky map. The image shows the cosmic microwave background (CMB) in higher resolution than ever before and it may help cosmologists to develop a much clearer picture of the early universe. "This is the moment that Planck was conceived for," says David Southwood, who is ESA's director of science and robotic exploration. "We are opening the door to an Eldorado where scientists can seek the nuggets that will lead to deeper understanding of how our universe came to be and how it works now."
  • pacome delva on 06 Jul 10
     
    coooool !
pacome delva

Metamaterials Probe Changes in Spacetime Structure | Physical Review Focus - 0 views

focus.aps.org/st6

phy metamaterials cosmology

shared by pacome delva on 24 Aug 10 - Cached
  • At the time of the big bang, our universe may not have had exactly three dimensions of space and one of time, according to some theorists. In the 6&nbsp;August Physical Review Letters, a team proposes a way to observe the postulated transition to our current universe using so-called metamaterials, structures in which the propagation of light can be precisely controlled. Experiments on such structures, they say, could test predictions that a "big flash" of radiation would accompany changes in the structure of spacetime that may have occurred in the early universe.
pacome delva

Penrose claims to have glimpsed universe before Big Bang - 0 views

physicsworld.com/...44388

phy cosmology

shared by pacome delva on 22 Nov 10 - No Cached
LeopoldS liked it
  • According to Penrose and Gurzadyan, these circles allow us to "see through" the Big Bang into the aeon that would have existed beforehand. The circles, they say, are the marks left in our aeon by the spherical ripples of gravitational waves that were generated when black holes collided in the previous aeon.
  • Julian Barbour, a visiting professor of physics at the University of Oxford, says that these circles would be "remarkable if real and sensational if they confirm Penrose's theory". They would, he says, "overthrow the standard inflationary picture", which, he adds, has become widely accepted as scientific fact by many cosmologists. But he believes that the result will be "very controversial" and that other researchers will look at the data very critically. He says there are many disputable aspects to the theory
  • pacome delva on 22 Nov 10
     
    hehe, a nice controversy? or completely overinterpreted results...?
  • LeopoldS on 23 Nov 10
     
    what the heck is this? sounds strange to me ... would I understand the original paper?
pacome delva

RHIC nets strange antimatter - 0 views

physicsworld.com/...41917

strange_antimatter collider

shared by pacome delva on 08 Mar 10 - Cached
  • The antihypertriton – consisting of an antiproton, an antineutron and an antilambda particle – is the heaviest antinucleus yet produced and opens up a new realm of strange antinucluei. It could also shed light on a number of problems in astrophysics and cosmology, including the dominance of matter over antimatter in the universe.
pacome delva

Mysterious 'dark flow' at the edge of the universe - 1 views

physicsworld.com/...41984

cosmology dark_flow

shared by pacome delva on 16 Mar 10 - Cached
  • Cosmologists have already observed two distinct effects caused by invisible entities in the universe: dark matter is known to affect the rotation of galaxies and dark energy seems to be causing the expansion of the universe to accelerate. Dark flow is the latest addition to this shadowy family.
  • pacome delva on 16 Mar 10
     
    I think Lucas didn't know he would have such an impact in science with Star Wars...!
  • nikolas smyrlakis on 16 Mar 10
     
    do you think it could be the dark side of The Force?
  • pacome delva on 16 Mar 10
     
    what else...?
Luís F. Simões

Stepping Away From the Trees For a Look at the Forest | Science/AAAS - 1 views

www.sciencemag.org/...1612.full

science technology cosmology astronomy exoplanets mars metamaterials climate_change BIO dna microbes cell

shared by Luís F. Simões on 22 Dec 10 - No Cached
  • An ingenious new tool triggers a cascade of new insights. In this special section, Science's news reporters and editors mark the end of the current decade by stepping back from weekly reporting to take a broader look at 10 insights that have changed science since the dawn of the new millennium.
  • Luís F. Simões on 22 Dec 10
     
    For a direct link to the 10 articles, showing their abstracts, go here.
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