08-10-11

Does dark energy accelerate space missions ? ESA has a plan to launch Euclid mission to find more about dark energy.

 

 

October 05, 2011

 

dark energy, ESA, cosmology,

The movie stills pictured above illustrate the formation of clusters and large-scale filaments in the Cold Dark Matter model with dark energy.

 

copyright :

 

http://upload.wikimedia.org/wikipedia/commons/thumb/7/7d/...

 

wikimedia commons

 

Perfect timing: Yesterday, three astronomers received the news every scientist wants: they would be receiving the physics Nobel Prize for their work in discovering dark energy, a repulsive force that is ramping up the expansion of the universe.

 

So it was somehow fitting that, on the very same day, European Space Agency officials were approving a space mission, called Euclid, that would pin down more precisely dark energy’s key parameters.

 

“It was just coincidence, really,” says David Schlegel, principal investigator for BOSS, a ground-based mission that is also trying to get a handle on the stuff that looks a lot like a cosmological constant, the fudge factor that Einstein introduced in his relativity equations when he thought the universe was static, but later regretted.

 

Okay, so the prize has nothing to do with ESA’s decision.

 

But will it bolster the case for other dark energy missions?

 

In the United States, NASA, the Energy Department and the National Science Foundation are all trying to get a piece of the action. NASA’s WFIRST is the most expensive mission and the most sought after (it was ranked tops in the US decadal survey), and it’s probably the most capable.

 

 

But it’s stuck in line behind the James Webb Space Telescope, and so most observers think it doesn’t have a chance of flying at all until the 2020s.

 

The selection of Euclid, a very similar mission that would scoop much of the early science, may put further pressure on NASA to attempt what has failed in the past: a mission merger.

 

 

Ground-based dark energy experiments may get a lot more bang for the buck -- but even there, money is a problem.

 

 

LSST, another community favorite that will make major strides in measuring dark energy, still needs cash.

 

 

In a universe that keeps moving faster and faster, missions like LSST and WFIRST seem to get farther and farther away.

 

“It seems like it’s so far in the future,” says Schlegel.

 

copyright :

 

http://blogs.nature.com/news/2011/10/post_85.htm

l

 

26-06-11

Multiverse From Wikipedia, the free encyclopedia

cosmology,multiverse,

copyright :

http://commons.wikimedia.org/wiki/File:Multiverse.jpg

 

The multiverse (or meta-universe, metaverse) is the hypothetical set of multiple possible universes (including the historical universe we consistently experience) that together comprise everything that exists: the entirety of space, time, matter, and energy as well as the physical laws and constants that describe them.


The term was coined in 1895 by the American philosopher and psychologist William James.


The various universes within the multiverse are sometimes called parallel universes.


The structure of the multiverse, the nature of each universe within it and the relationship between the various constituent universes, depend on the specific multiverse hypothesis considered.


Multiverses have been hypothesized in cosmology, physics, astronomy, religion, philosophy, transpersonal psychology and fiction, particularly in science fiction and fantasy.


In these contexts, parallel universes are also called "alternative universes", "quantum universes", "interpenetrating dimensions", "parallel dimensions", "parallel worlds", "alternative realities", "alternative timelines", and "dimensional planes," among others.

 

copyright :

http://en.wikipedia.org/wiki/Multiverse

 

20-06-11

Observation of Rare Particles May Shed Light On Why the Universe Has More Matter Than Antimatter

 

cosmology, antimatter,cern

copyright :


http://commons.wikimedia.org/wiki/File:3D_image_of_Antihy...


ScienceDaily (June 19, 2011) — Shortly after experiments on the Large Hadron Collider (LHC) at the CERN laboratory near Geneva, Switzerland began yielding scientific data last fall, a group of scientists led by a Syracuse University physicist became the first to observe the decays of a rare particle that was present right after the Big Bang.

 

 

By studying this particle, scientists hope to solve the mystery of why the universe evolved with more matter than antimatter.


copyright :

 

http://www.sciencedaily.com/releases/2011/03/110328101306...

 

11-06-11

New Data Still Have Scientists in Dark Over Dark Matter June, 8th 2011

 

dark matter,dark energy,cosmology,skynetblogs

copyright :

 

http://upload.wikimedia.org/wikipedia/commons/5/59/Mass_d...

 

ESA/Hubble

 

A dark-matter experiment deep in the Soudan mine of Minnesota now has detected a seasonal signal variation similar to one an Italian experiment has been reporting for more than a decade.

 

The new seasonal variation, recorded by the Coherent Germanium Neutrino Technology (CoGeNT) experiment, is exactly what theoreticians had predicted if dark matter turned out to be what physicists call Weakly Interacting Massive Particles (WIMPs).

 


copyright :

 

http://www.sciencedaily.com/releases/2011/06/110607094515...

 

 

20-04-11

Antigravity Could Replace Dark Energy as Cause of Universe’s Expansion

 

 

anti-gravity,dark energy,cosmology

copyright :


http://commons.wikimedia.org/wiki/File:NGC_3021_Hubble.jp...

 

Since the late 20th century, astronomers have been aware of data that suggest the universe is not only expanding, but expanding at an accelerating rate.

 

According to the currently accepted model, this accelerated expansion is due to dark energy, a mysterious repulsive force that makes up about 73% of the energy density of the universe.

 

Now, a new study reveals an alternative theory: that the expansion of the universe is actually due to the relationship between matter and antimatter.

 

According to this study, matter and antimatter gravitationally repel each other and create a kind of “antigravity” that could do away with the need for dark energy in the universe.

 

copyright :


http://www.universetoday.com/84934/antigravity-could-repl...

 

17-03-11

NASA Prepares Antimatter-Hunting Detector for Space Shuttle Launch

 

16 March 2011

 

 

cosmologyn,dark matter,AMS,Space Shuttle,ISS

copyright image :

http://commons.wikimedia.org/wiki/File:AMS-01.jpg?uselang...

 

 

A high-tech astrophysics experiment that will probe the mysteries of our universe is getting ready to fly to the International Space Station aboard the space shuttle Endeavour when it launches on its final mission next month.


The Alpha Magnetic Spectrometer (AMS) is a particle physics detector that will primarily measure high-energy particles in space, called cosmic rays, and search for signs of antimatter and mysterious dark matter in the universe.

 

copyright :


http://www.space.com/11149-nasa-antimatter-detector-shutt...

15-03-11

Bizarre Dark Energy Theory Gets Boost From New Measurements

 

 

15 march 2011

 

cosmology,dark matter,more evidence

 

copyright :


http://commons.wikimedia.org/wiki/File:Abell_1689_(captur...


Credits : NASA and ESA

 


New measurements of the expansion rate of the universe lend new support for the theory of dark energy that suggests a mysterious force is pulling the cosmos apart at ever-increasing speeds.

 

Scientists have few ideas why such a force would exist, but the evidence for dark energy –

which like dark matter has remained elusive to detection attempts – is growing, and a competing hypothesis can apparently be ruled out. [The Strangest Things in Space]

 

copyright :

 

http://www.space.com/11129-dark-energy-theory-universe-ex...

 

 

 

26-02-11

Dark Matter: New Evidence on How Galaxies Are Born

 

By Michael D. Lemonick Wednesday, Feb. 23, 2011

 

dark matter,halo,cosmology

Copyright : http://commons.wikimedia.org/wiki/File:Hs-2007-17-a-full_...

 

If you think it's hard to swallow the concept of dark matter, you're not alone.

 

Decades ago, a few astronomers began to suspect that the universe was swarming with some mysterious, invisible substance that was yanking galaxies around with its own powerful gravity.

 

And for those same decades, most of those astronomers' colleagues dismissed the notion as pretty much nuts.

 

But the evidence kept mounting, and nowadays dark matter is a firmly established concept in modern astrophysics.

 

It pretty much has to exist, in fact, to explain why individual galaxies spin as fast as they do without flying apart, and why groups of galaxies move the way they do in relation to one another.

 

If there weren't 10 times as much dark matter as there are stars and gas clouds and other visible matter, the universe would make no sense.

 

Nature abhors irrationality, and so we live in a universe in which just about every galaxy, including the Milky Way, is held safely inside a huge blob of dark matter like a butterfly floating inside a glass paperweight.

 


Copyright and Read more

 

http://www.time.com/time/health/article/0,8599,2052614,00...

 

 

 

18-02-11

Dark energy is not directly detectable, but scientists can track its footsteps through history.

 

dark matter,the hunt,cosmology

 

copyright

http://upload.wikimedia.org/wikipedia/commons/c/c9/Dark_m...

 

A massive survey of distant galaxies should help unravel a mind-bending cosmic mystery: Why has the expansion of the universe sped up ?


copyright

http://news.discovery.com/space/dark-energy-galaxies-univ...

 

 

17-02-11

Herschel finds less dark matter but more stars

 

dark matter,Herschel

copyright

http://upload.wikimedia.org/wikipedia/commons/9/9d/Struct...


16 February 2011

 

ESA’s Herschel space observatory has discovered a population of dust-enshrouded galaxies that do not need as much dark matter as previously thought to collect gas and burst into star formation.

 

copyright

http://www.esa.int/esaCP/SEMRQ3PT1KG_index_0.html

 

 

28-01-11

Hunt for dark matter closes in at Large Hadron Collider

 

Wednesday 26 January 2011


Physicists are closer than ever to finding the source of the Universe's mysterious dark matter, following a better than expected year of research at the Compact Muon Solenoid (CMS) particle detector, part of the Large Hadron Collider (LHC) at CERN in Geneva.

 

cern,lhc,cms,dark matter

 


copyright

http://commons.wikimedia.org/wiki/File:LHC,_CERN.jpg?usel...

Max Braun on Flickr

 

 

The scientists have now carried out the first full run of experiments that smash protons together at almost the speed of light.

 

When these sub-atomic particles collide at the heart of the CMS detector, the resultant energies and densities are similar to those that were present in the first instants of the Universe, immediately after the Big Bang some 13.7 billion years ago.

 

The unique conditions created by these collisions can lead to the production of new particles that would have existed in those early instants and have since disappeared.

 

The researchers say they are well on their way to being able to either confirm or rule out one of the primary theories that could solve many of the outstanding questions of particle physics, known as Supersymmetry (SUSY).

 

Many hope it could be a valid extension for the Standard Model of particle physics, which describes the interactions of known subatomic particles with astonishing precision but fails to incorporate general relativity, dark matter and dark energy.

 

Dark matter is an invisible substance that we cannot detect directly but whose presence is inferred from the rotation of galaxies.

 

Physicists believe that it makes up about a quarter of the mass of the Universe whilst the ordinary and visible matter only makes up about 5% of the mass of the Universe.

 

Its composition is a mystery, leading to intriguing possibilities of hitherto undiscovered physics.

 

Professor Geoff Hall from the Department of Physics at Imperial College London, who works on the CMS experiment, said:

"We have made an important step forward in the hunt for dark matter, although no discovery has yet been made.

 

These results have come faster than we expected because the LHC and CMS ran better last year than we dared hope and we are now very optimistic about the prospects of pinning down Supersymmetry in the next few years."

 


copyright :

 

http://www3.imperial.ac.uk/newsandeventspggrp/imperialcol...

 

 

 

16-01-11

Dark-Matter Galaxy Detected: Hidden Dwarf Lurks Nearby?

 

Richard A. Lovett in Seattle, Washington


for National Geographic News


Published January 14, 2011

 

Milky Way.jpg

 

Copyright :

http://upload.wikimedia.org/wikipedia/commons/f/fd/Our_Mi...

 

An entire galaxy may be lurking, unseen, just outside our own, scientists announced Thursday.

 


The invisibility of "Galaxy X"—as the purported body has been dubbed—may be due less to its apparent status as a dwarf galaxy than to its murky location and its overwhelming amount of dark matter, astronomer Sukanya Chakrabarti speculates.

 

Detectable only by the effects of its gravitational pull, dark matter is an invisible material that scientists think makes up more than 80 percent of the mass in the universe.

 

Chakrabarti, of the University of California, Berkeley, devised a technique similar to that used 160 years ago to predict the existence of Neptune, which was given away by the wobbles its gravity induced in Uranus's orbit.

 

Based on gravitational perturbations of gases on the fringes of our Milky Way galaxy, Chakrabarti came to her conclusion that there's a unknown dwarf galaxy about 260,000 light-years away.


With an estimated mass equal to only one percent the mass of the Milky Way, Galaxy X is still the third largest of the Milky Way's satellite galaxies, Chakrabarti predicts.


The two Magellanic are each about ten times larger.


If it exists, Galaxy X isn't likely to be composed entirely of dark matter.


It should also have a sprinkling of dim stars, Chakrabarti said.


"These should provide enough light for astronomers to see it, now that they know where to look," she said.


The reason the dark matter galaxy hasn't yet been seen, she added, is because it lies in the same plane as the Milky Way disc.


Clouds of gas and dust stand between us and Galaxy X, confounding telescopes.

 

 

 

Copyright : http://news.nationalgeographic.com/news/2011/01/110114-ga...

 

14-01-11

Harvard-Smithsonian Center For Astrophysics - Better Measuring Dark Energy

 

 

Press Release

Release No.: 2011-04

For Release: Thursday, January 13, 2011 09:00:00 AM EST

 

Dark Energy.jpg

 

Copyright : http://commons.wikimedia.org/wiki/File:Cosmological_compo...

 


The Best Way to Measure Dark Energy Just Got Better

 

Seattle, WA

 

Dark energy is a mysterious force that pervades all space, acting as a "push" to accelerate the Universe's expansion.

 

Despite being 70 percent of the Universe, dark energy was only discovered in 1998 by two teams observing Type Ia supernovae.

 

A Type 1a supernova is a cataclysmic explosion of a white dwarf star.

 

These supernovae are currently the best way to measure dark energy because they are visible across intergalactic space.

 

Also, they can function as "standard candles" in distant galaxies since the intrinsic brightness is known.

 

Just as drivers estimate the distance to oncoming cars at night from the brightness of their headlights, measuring the apparent brightness of a supernova yields its distance (fainter is farther).

 

Measuring distances tracks the effect of dark energy on the expansion of the Universe.

 

The best way of measuring dark energy just got better, thanks to a new study of Type Ia supernovae led by Ryan Foley of the Harvard-Smithsonian Center for Astrophysics. 

 

He has found a way to correct for small variations in the appearance of these supernovae, so that they become even better standard candles.

 

The key is to sort the supernovae based on their color.

 

"Dark energy is the biggest mystery in physics and astronomy today.

 

Now, we have a better way to tackle it," said Foley, who is a Clay Fellow at the Center.

 

He presented his findings in a press conference at the 217th meeting of the American Astronomical Society.

 

The new tool also will help astronomers to firm up the cosmic distance scale by providing more accurate distances to faraway galaxies.

 

Type Ia supernovae are used as standard candles, meaning they have a known intrinsic brightness.

 

However, they're not all equally bright.

 

Astronomers have to correct for certain variations.

 

In particular, there is a known correlation between how quickly the supernova brightens and dims (its light curve) and the intrinsic peak brightness.

 

Even when astronomers correct for this effect, their measurements still show some scatter, which leads to inaccuracies when calculating distances and therefore the effects of dark energy.

 

Studies looking for ways to make more accurate corrections have had limited success until now.

 

"We've been looking for this sort of 'second-order effect' for nearly two decades," said Foley.

 

Foley discovered that after correcting for how quickly Type Ia supernovae faded,

they show a distinct relationship between the speed of their ejected material and their color: the faster ones are slightly redder and the slower ones are bluer.

 

Previously, astronomers assumed that redder explosions only appeared that way because of intervening dust, which would also dim the explosion and make it appear farther than it was.

 

Trying to correct for this, they would incorrectly calculate that the explosion was closer than it appeared.

 

Foley's work shows that some of the color difference is intrinsic to the supernova itself.

 

The new study succeeded for two reasons.

 

First, it used a large sample of more than 100 supernovae.

 

More importantly, it went back to "first principles" and reexamined the assumption that Type Ia supernovae are one average color.

 

The discovery provides a better physical understanding of Type Ia supernovae and their intrinsic differences.

 

It also will allow cosmologists to improve their data analysis and make better measurements of dark energy - an important step on the road to learning what this mysterious force truly is, and what it means for the future of the cosmos.

 

Headquartered in Cambridge, Mass., the Harvard-Smithsonian Center for Astrophysics (CfA) is a joint collaboration between the Smithsonian Astrophysical Observatory and the Harvard College Observatory. CfA scientists, organized into six research divisions, study the origin, evolution and ultimate fate of the universe.

 


Copyright : http://www.cfa.harvard.edu/news/2011/pr201104.html

 

17-12-10

Physicists propose mechanism that explains the origins of both dark matter and 'normal' matter

 

December 10, 2010 by Lisa Zyga Enlarge

 

Defining_Dark_Matter_and_Energy_in_a_4th_Etheric_System.png

 

WIKIMEDIA COMMONS IMAGE

 

(PhysOrg.com) -- Through precise cosmological measurements, scientists know that about 4.6% of the energy of the Universe is made of baryonic matter (normal atoms), about 23% is made of dark matter, and the remaining 72% or so is dark energy.

 

Scientists also know that almost all the baryonic matter in the observable Universe is matter (with a positive baryon charge) rather than antimatter (with a negative baryon charge).

 

But exactly why this matter and energy came to be this way is still an open question.

 

In a recent study, physicists have proposed a new mechanism that can generate both the baryon asymmetry and the dark matter density of the Universe simultaneously.

 

 


copyright - credits :


http://www.physorg.com/news/2010-12-physicists-mechanism-...

 

14-12-10

No evidence of time before Big Bang.

Published online 10 December 2010 | Nature | doi:10.1038/news.2010.665

 

Latest research deflates the idea that the Universe cycles for eternity.

 

Edwin Cartlidge


Circular ripples in the cosmic microwave background have been making waves with theoreticians.

 

NASA

Our view of the early Universe may be full of mysterious circles — and even triangles — but that doesn't mean we're seeing evidence of events that took place before the Big Bang.

 

So says a trio of papers taking aim at a recent claim that concentric rings of uniform temperature within the cosmic microwave background — the radiation left over from the Big Bang — might, in fact, be the signatures of black holes colliding in a previous cosmic 'aeon' that existed before our Universe.

 

Dark_matter_halo.png

Dark Matter Halo

WIKIMEDIA COMMONS

 


copyright - credits : http://www.nature.com/news/2010/101210/full/news.2010.665...

26-11-10

Mini-oerknak resulteert in superhete vloeistof (LHC - CERN)

Copyright - credits :


http://allesoversterrenkunde.nl/nieuws/4274-Mini-oerknak-...

 

URL was niet volledig overgenomen op het weblog.

 

Sorry,

 

Uw webmaster,

 

Mini-oerknak resulteert in superhete vloeistof (LHC - CERN)

25 november 2010


allesoversterrenkunde.nl
 

 

IMAGE.jpg

 

copyright - credits


http://www.scienceparkamsterdam.nl/onderzoek/nieuwsberich...

 

Kort na de oerknal was het heelal een extreem dikke, superhete vloeistof.

 

Dat is de verrassende ontdekking die onderzoekers hebben gedaan met de Large Hadron Collider (LHC), de grote deeltjesversneller in Zwitserland.


Op 7 november begonnen wetenschappers een nieuw experiment met de LHC, waarbij zij de kernen van loodatomen met enorme snelheden tegen elkaar lieten botsen.


Bij die botsingen ontstonden kleine vuurballen van subatomaire deeltjes met een temperatuur van meer dan 10 biljoen graden.
 

Het idee achter dit experiment was om de 'oersoep' van deeltjes te reproduceren, het zogeheten quark-gluonenplasma, zoals die een miljoenste seconde na het
ontstaan van het heelal moet hebben bestaan.


Quarks en gluonen zijn de bouwstenen van de neutronen en protonen die de atomen vormen.


Volgens veel modellen die de deeltjesstroom van dit subatomaire vuurwerk beschrijven, zou deze oersoep zich als een gas moeten gedragen.


Maar uit de waarnemingen blijkt nu dat de oersoep, precies zoals de naam al aangeeft, meer weg had van een vloeistof.


Ook de dichtheid van de subatomaire deeltjes die bij de botsingen vrijkwamen, verrast de onderzoekers: bij de 'mini-oerknallen' werden veel meer van die
deeltjes gevormd dan verwacht.


Het is volgende wetenschappers overigens nog te vroeg om uit deze eerste resultaten verregaande conclusies te trekken over de structuur van het jonge heelal.

 

© Eddy Echternach

www.astronieuws.nl

 

copyright-credits

http://allesoversterrenkunde.nl/nieuws/4274-Mini-oerknak-...

 

 

25-11-10

What is Dark Energy ?

by Clara Moskowitz


27th april 2010


Dark energy is the name given to an unexplained force that is drawing galaxies away from each other, against the pull of gravity, at an accelerated pace.

 

Dark energy is a bit like anti-gravity. Where gravity pulls things together at the more local level, dark energy tugs them apart on the grander scale.

 

Dark Matter and Dark Energy.png


Dark Matter and Dark Energy Simplified Structure

 

Its existence isn't proven, but dark energy is many scientists' best guess to explain the confusing observation that the universe's expansion is speeding up.

 

Experts still don't know what's driving this force, but the quest to learn more about dark energy is one of cosmologists' top priorities.


Copyright - credits for article : http://www.space.com/scienceastronomy/090427-mm-dark-ener...


Copyright - credits photo : commons.wikimedia.org

 

URL Photo :

 

http://commons.wikimedia.org/wiki/File:Defining_Darkc_Mat...

22-11-10

Penrose: WMAP Shows Evidence of ‘Activity’ Before Big Bang

22nd November 2010


Have scientists seen evidence of time before the Big Bang, and perhaps a verification of the idea of the cyclical universe?


One of the great physicists of our time, Roger Penrose from the University of Oxford, has published a new paper saying that the circular patterns seen in the WMAP mission data on the Cosmic Microwave Background suggest that space and time perhaps did not originate at the Big Bang but that our universe continually cycles through a series of “aeons,” and we have an eternal, cyclical cosmos.


His paper also refutes the idea of inflation, a widely accepted theory of a period of very rapid expansion immediately following the Big Bang.

 

Sir Roger Penrose.jpg

 

Copyright - Credits : Universe Today

 

http://www.universetoday.com/79750/penrose-wmap-shows-evi... 

 

12-11-10

Hubble Provides Most Detailed Dark Matter Map Yet

 

11th November 2010

 

DarkMatterAbell.jpg

 

Nasa Hubble Space Telescope shows the distribution of dark matter in the center of the giant galaxy cluster Abell 1689. (more than 1000 galaxies with trillions of stars).

 

Credit: NASA, ESA, D. Coe (NASA Jet Propulsion Laboratory/California Institute of Technology,
and Space Telescope Science Institute), N. Benitez (Institute of Astrophysics of Andalusia, Spain), T. Broadhurst (University of the Basque Country, Spain), and H. Ford (Johns Hopkins University).

 

Credits :

 

http://www.universetoday.com/78309/hubble-provides-most-d...

 

11-11-10

Cosmology - animation photo from Big Bang To Present Time

FromBigBangtopresenttime.jpg

10-11-10

Cosmology Video - The Hubble Ultra Deep Field in 3D


 

Animation Credit:

 

Hubble Cosmological Redshift Animation Courtesy:

 

Mike Gallis

 

http://phys23p.sl.psu.edu/phys_anim/Phys_anim.htm

 

http://www.youtube.com/watch?v=e6G2Z6iD-9M

 

Music Used in this video was purchased from stockmusic.net and belongs to the Spirit Legends Collection.

 

The tunes I used were:

 

Voice Redo B

 

Voice in the Dark

 

Link to demos:

 

http://www.stockmusic.net/index.cfm/page/main.collectionD...

 

Category:

 

Science & Technology

 

 

05:56 Gepost in Web | Permalink | Commentaren (0) | Tags: hubble, ultra deep field |  Facebook |

08-11-10

Missing Milky Way Dark Matter

 

8 november 2010

DarkMatterintheMilkyWay.jpg

Although dark matter is inherently difficult to observe, an understanding of its properties (even if not its nature) allows astronomers to predict where

its effects should be felt.


The current understanding is that dark matter helped form the first galaxies by providing gravitational scaffolding in the early universe.


These galaxies were small and collapsed to form the larger galaxies we see today.


As galaxies grew large enough to shred incoming satellites and their dark matter, much of the dark matter should have been deposited in a flat structure in

spiral galaxies which would allow such galaxies to form dark components similar to the disk and halo.


However, a new study aimed at detecting the Milky Way‘s dark disk have come up empty.

 

copyrights,credits : http://www.universetoday.com/77662/missing-milky-way-dark...

 

30-10-10

Dark Matter - 27102010

 

 

Hooper and Goodenough’s findings !

 

The Milky Way’s galactic center.

 

A new paper reports that very-high-energy gamma rays coming from the center of the Milky Way originate from dark matter collisions.

 

Fermi Gamma-Ray Space Telescope.jpg

 

The burden of proof to claim new physics is high.

 

One must show that the surprising features in the data are not explained by systematic uncertainties or other plausible astrophysics.

 

It will take time for other dark matter experiments to confirm or deny Hooper and Goodenough’s findings.

 

copyright - credits

 

http://www.symmetrymagazine.org/breaking/2010/10/22/fermi...

 

 

25-09-10

Doorbraak of gelul in de ruimte ?

 

25 september 2010


de Volkskrant 
 

De Amerikaanse natuurkundige Greg Landsberg zegt een nieuwe theorie over verdwijnende ruimtelijke dimensies te hebben gevonden die het antwoord zou kunnen verschaffen op allerlei netelige vragen.

 

Nederlandse collega's regeren geërgerd. 'Toe maar, dit kan er ook wel bij.'


‘Een nieuw paradigma’ noemt hij het zelf. Speculatief, jazeker, maar daarom niet minder veelbelovend.

 

Greg Landsberg, natuurkundige aan de Amerikaanse Brown University, raakt er niet over uitgepraat.

 

Samen met vier collega’s leurt hij sinds een paar maanden met het idee dat het aantal ruimtelijke dimensies in het heelal afhankelijk is van de schaal waarop je de dingen bekijkt.

 

‘Misschien levert dit een oplossing voor allerlei netelige kwesties in de deeltjesfysica en de kosmologie,’ ratelt hij over de telefoon vanuit deeltjeslaboratorium CERN in Genève. ‘En wie weet lossen we het raadsel van de tijd er ook wel mee op.’

 

Netelige kwesties zijn er volop in de moderne natuurwetenschap. Waarom zijn er bijvoorbeeld drie deeltjesfamilies in plaats van één?

 

Wat is zwaartekracht? Waarom is er meer gewone materie dan antimaterie in het heelal? Hoe komt het dat het heelal steeds sneller uitdijt?

 

Waaruit bestaat de mysterieuze donkere materie? Valt de relativiteitstheorie ooit te rijmen met de quantumfysica?

 

En, inderdaad, wat is tijd eigenlijk? Wie het allemaal weet, mag het zeggen.

 

En wie het niet weet, hoeft kennelijk ook zijn mond niet te houden.

 

De meest uiteenlopende modellen, theorieën, concepten en luchtballonnetjes vinden de laatste jaren hun weg naar wetenschappelijke blogs, preprint servers, of zelfs naar de pagina’s van Physical Review Letters. Een vijfde kracht, schaduwmaterie, asymmetrische branen – het komt allemaal voorbij.

Dimensies.jpg

De onbewijsbare snaartheorie met zijn 10^500 heelallen, stevig gepromoot door niemand minder dan Stephen Hawking, is eigenlijk nog een van de serieuzere ideeën.

 

Van de ‘verdwijnende dimensies’ van Landsberg en zijn collega’s kijkt een theoretisch fysicus nauwelijks meer op.

 

‘Buitengewoon onaangenaam’ vindt kosmoloog Vincent Icke van de Leidse Sterrewacht deze wildgroei aan ‘loze speculaties’.

 

‘Ik sta positief tegenover dwarse denkers,’ zegt hij, ‘maar je moet wel met een verdomd goed onderbouwd idee komen, wil ik het serieus nemen.

 

Nu nemen mensen onbeperkt de vrijheid om maar te zeggen wat ze blieven.

 

Neem dat snaargelul, daar is al dertig jaar niets uitgekomen dan gebakken lucht en af en toe een wiskundeprijsje.

 

Ik vind dat laf.’ Theoretisch natuurkundige Gerard ’t Hooft van de Universiteit Utrecht, op werkbezoek in Turkije, is het met Icke eens.

 

‘Men schrijft er maar op los,’ mailt de Nobelprijswinnaar. ‘Verdwijnende dimensies, toe maar, het kan er ook wel bij.’

9_Dimensions.jpg

 

Landsberg – in 1967 in Moskou geboren – ziet dat natuurlijk heel anders. Er zijn inderdaad meer theorieën dan theoretici, grapt hij met een licht Russisch accent, maar nieuwe ideeën die misschien bevestigd zouden kunnen worden door toekomstige experimenten, kun je niet zomaar negeren.

 

Afgelopen zomer, tijdens de International Conference on High-Energy Physics in Parijs, was er weliswaar veel kritiek op het ‘nieuwe paradigma’, maar toch vooral veel belangstelling. Geen wonder, aldus Landsberg, want wie weet komt de nieuwe deeltjesversneller van CERN nog dit jaar met ondersteunende resultaten.

 

Dun rietje

 

Begin vorige eeuw speculeerden Theodor Kaluza en Oskar Klein al over extra dimensies, in een vruchteloze poging om zwaartekracht en elektromagnetisme in één beschrijving te verenigen.

 

Volgens de Kaluza-Kleintheorie bestaat er naast lengte, breedte en hoogte een vierde ruimtelijke dimensie.

 

Die zou echter niet oneindig uitgestrekt zijn, maar heel compact, waardoor je er alleen op miscroscopische schaal mee te maken krijgt.

 

Alsof je een eendimensionale lijn ziet, die bij nadere beschouwing een tweedimensionaal oppervlak blijkt te zijn, heel strak opgerold tot een extreem dun rietje.

 

‘In ons model is er echter geen sprake van extra dimensies, maar van ‘verdwijnende’ dimensies,’ zegt Landsberg.

 

Hoe nauwkeuriger je kijkt, hoe minder ruimtelijke dimensies er zijn.

 

Precies andersom dus dan bij Kaluza en Klein. Op een natuurkundeworkshop in Heidelberg, vorig jaar zomer, begon het balletje te rollen.

 

‘Tijdens een etentje met twee andere natuurkundigen en twee kosmologen bleek dat die vanishing dimensions wel eens een verklaring zouden kunnen vormen voor een aantal problemen in de moderne natuurwetenschap.’

 

Om uit te leggen hoe het werkt, vergelijkt Landsberg de ruimte met een opgefrommeld vloerkleed.

 

Dat is een driedimensionale structuur, maar als je beter kijkt zie je dat het om een tweedimensionaal kleed gaat, en pak je er een loep bij, dan blijkt het hele kleed geweven te zijn van één enkele eendimensionale draad.

 

‘Op de allergrootste schaal, vergelijkbaar met de afmetingen van het waarneembare heelal, zou onze driedimensionale ruimte ook weer geplooid en gevouwen kunnen zijn tot een vierdimensionaal geheel,’ aldus Landsberg.

 

Of er op nóg grotere schaal zelfs sprake kan zijn van een vijfde dimensie, durft hij niet te zeggen. ‘Alles is mogelijk.’

 

Maar daar zit ’m nou net de kneep, volgens de criticasters – alles lijkt maar te kunnen.

‘Ik neem een exotisch idee alleen serieus als er meetbare consequenties uit tevoorschijn komen,’ zegt Icke, ‘of als er fundamentele problemen mee verklaard worden.

 

Veel andere dingen dragen weinig of niets bij, of kunnen zelfs nooit door waarnemingen en experimenten worden onderbouwd of weerlegd.

 

Dan is zo’n theorie volslagen gratuit.’ Ook snaar-theoreticus Robbert Dijkgraaf van de Universiteit van Amsterdam is bepaald niet onder de indruk: ‘Het theoretische en experimentele laagje ijs waarop Landsberg en zijn collega’s schaatsen is erg dun.’

 

’t Hooft is bij nader inzien toch net iets milder. ‘Deze mensen weten in ieder geval waar ze over praten, en zien dus zelf de moeilijkheden ook wel in,’ zegt hij.

 

‘Maar ik vind de prijs die je betaalt voor deze theorie nogal hoog: allerlei waardevolle concepten lijken te sneuvelen, en er komt weinig bruikbaars voor in de plaats.’

 

Bovendien, aldus ’t Hooft, moet alles wel ‘streng logisch in elkaar zitten, en dat heb ik nog niet gezien.’ Overigens werkt hij zelf ook aan een ‘wild idee’ dat conforme gravitatie heet. ‘Maar dat is verre van uitgewerkt en nog niet wetenschappelijk onderbouwd.’

 

Landsberg blijft voorlopig onverminderd enthousiast. Als de driedimensionale ruimte op de grootste schaal gevouwen en geplooid is, kan een ander deel van het heelal zich vlak bij het onze bevinden, op zeer kleine afstand in de vierde dimensie.

 

Tussen die ‘naburige’ delen kunnen dan quantumeffecten optreden die een beetje vergelijkbaar zijn met het beroemde Casimir-effect.

 

Dat zou mogelijk een verklaring kunnen opleveren voor de onbegrepen donkere energie, die tot de versnellende uitdijing van het heelal leidt. ‘Maar daar moeten inderdaad nog realistische wiskundige modellen voor worden uitgewerkt,’ geeft hij toe.

 

Botsingsexperimenten

 

En wat als er op microscopische schaal inderdaad dimensies verdwijnen?

 

‘Dan gaan we dat misschien zien in botsingsexperimenten in de LHC-versneller van CERN,’ zegt Landsberg, die zelf aan een van de CERN-experimenten meewerkt.

 

‘Je verwacht dan dat de deeltjes die bij een extreem energierijke botsing geproduceerd worden voornamelijk in één vlak bewegen.

 

Voorzichtige aanwijzingen daarvoor blijken een jaar of tien geleden al eens te zijn waargenomen, maar die resultaten brachten het toen niet verder dan een vrij obscuur Russisch tijdschrift, waardoor ze nooit veel aandacht hebben gekregen.’

 

‘Natuurlijk kun je theoretici niet verbieden met vergezochte ideeën te komen,’ zegt Vincent Icke.

‘Het verbieden van een theorie komt altijd van waarnemingen en experimenten. De natuur zal wel uitmaken wat mag en wat niet.’

 

Maar, verzucht hij, als de LHC-metingen niets te zien geven, kunnen Landsberg en zijn collega’s zich altijd verschuilen achter de conclusie dat de effecten dan misschien pas bij een nóg veel hogere energie optreden.

 

‘In het Engels heet dat weaseling out. Dat vind ik het glibberige eraan. Ik houd meer van mouwen opstropen en rekenen.

 

Houd je eerst maar eens bezig met de dingen die wél meetbaar zijn.’

 

Robbert Dijkgraaf ziet veel meer in de snaartheorie als route naar een oplossing voor de crisis in de deeltjesfysica en de kosmologie.

 

‘Op kleine lengteschalen vervagen onze klassieke ideeën over ruimte en dimensie misschien wel, en moeten ze worden vervangen door quantumbegrippen,’ zegt hij.

 

Maar Gerard ’t Hooft loopt ook daar niet warm voor: ‘Stephen Hawking moet zelf weten waar hij zijn geld op zet, maar de snaartheorie komt vaak ook met flutverklaringen.’

 

Zo lang er nog zo veel onenigheid is over de betekenis van een ‘gevestigd’ idee als de snaartheorie, kun je het creatieve natuurkundigen als Greg Landsberg misschien niet kwalijk nemen dat ze plezier beleven aan het speculeren over verdwijnende dimensies.

 

'Misschien was er héél kort na de geboorte van het heelal wel sprake van slechts één ruimtelijke dimensie en één tijddimensie,’ filosofeert hij er dan ook vrolijk op los. ‘Wie weet komen we er op deze manier ooit nog eens achter waarom je in de ruimte wél alle kanten op kunt, terwijl de tijd maar één richting heeft.’

 

© Govert Schilling

 

Copyright

 

http://allesoversterrenkunde.nl/artikelen/1004-Doorbraak-...

 

 

18-09-10

Astronomen nemen afscheid van oerknalsatelliet WMAP !

 

13 september 2010

 

copyright

 

allesoversterrenkunde.nl

 

http://allesoversterrenkunde.nl/nieuws/4117-Astronomen-ne...

 

WMAP.jpg

 

Zonder veel ophef hebben astronomen op 8 september afscheid genomen van de Wilkinson Microwave Anisotropy Probe, beter bekend als WMAP.

 

De satelliet, die negen jaar lang de zogeheten kosmische achtergrondstraling heeft onderzocht, is met zijn eigen raketmotor in een veilige baan om de zon gemanoeuvreerd.

 

De WMAP-satelliet werd op 30 juni 2001 gelanceerd naar 'vaste' locatie die vanaf de zon gezien anderhalf miljoen kilometer achter de aarde ligt.

 

Enkele maanden later begon hij met het in kaart brengen van de kosmische achtergrondstraling - de straling die een overblijfsel is van de oerknal, die bijna veertien miljard jaar geleden het ontstaan van het heelal inluidde.

 

Al in 2003 werd WMAP door het wetenschappelijke tijdschrift Science uitgeroepen tot 'doorbraak van het jaar'.

 

De resultaten van de WMAP-metingen zijn in overeenstemming met het standaardmodel dat vrijwel alle astronomen voor het ontstaan van het heelal hanteren.

 

Vastgesteld is dat de oerknal waaruit ons heelal is voortgekomen 13,73 miljard jaar geleden moet hebben plaatsgevonden.

 

Ook is uit het onderzoek gebleken dat het heelal voor slechts 4,6 procent uit normale materie bestaat.

 

 

 

UniversePie.jpg

De overige 95,4 procent wordt gevormd door donkere materie, die geen enkele vorm van waarneembare straling uitzendt maar wel zwaartekracht uitoefent, en een mysterieuze donkere energie, die het heelal versneld laat uitdijen.

 

Toegevoegd door Eddy Echternach

 

www.astronieuws.nl

 

Links

 

http://nl.wikipedia.org/wiki/Wilkinson_Microwave_Anisotro...

 

http://map.gsfc.nasa.gov/

17-09-10

Big Bang Animation (no audio)

 

copyright :


http://hubblesite.org/newscenter/archive/releases/2003/27...


Credit: Dana Berry (Skyworks)

Lees meer...

12-09-10

Natuurwetten lijken niet overal gelijk

6 september 2010


allesoversterrenkunde.nl 
 

 

Krabnevel.jpg

 

 

De elektromagnetische kracht is niet overal in het heelal even sterk.


 

Dat concludeert een team astronomen van de universiteit van New South Wales (Australië) na nieuw onderzoek, dat vandaag tijdens een grote bijeenkomst van Europese astronomen in Lissabon wordt gepresenteerd.

 


Bij hun onderzoek hebben de astronomen gekeken naar zogeheten quasars: extreem verre sterrenstelsels met een superzwaar zwart gat in hun kern die enorme hoeveelheden licht uitzenden.

 

Tijdens zijn reis door het heelal wordt dit licht deels geabsorbeerd door de wolken van gas die het onderweg tegenkomt.

 


En uit dat absorptieproces kunnen astronomen afleiden hoe de natuurwetten zich op miljarden lichtjaren afstand van de aarde gedragen.

 

De resultaten van het onderzoek wijzen er op dat de zogeheten fijnstructuurconstante, die de sterkte van de elektromagnetische kracht karakteriseert, niet in alle richtingen waarin gekeken wordt gelijk is.

 


De wetten van de natuurkunde lijken dus niet zo onwrikbaar vast te liggen als doorgaans wordt aangenomen.


© Eddy Echternach (www.astronieuws.nl)

 

Copyright :


http://www.allesoversterrenkunde.nl/nieuws/4107-Natuurwet...

Laws of physics may change across the universe

 

18:29 08 September 2010 by Michael Brooks

 

New evidence supports the idea that we live in an area of the universe that is "just right" for our existence.

 

The controversial finding comes from an observation that one of the constants of nature appears to be different in different parts of the cosmos.

 

If correct, this result stands against Einstein's equivalence principle, which states that the laws of physics are the same everywhere.

 

"This finding was a real surprise to everyone," says John Webb of the University of New South Wales in Sydney, Australia.

 

Webb is lead author on the new paper, which has been submitted to Physical Review Letters.

 

Even more surprising is the fact that the change in the constant appears to have an orientation, creating a "preferred direction", or axis, across the cosmos.

 

That idea was dismissed more than 100 years ago with the creation of Einstein's special theory of relativity.

 

Sections of sky

 

At the centre of the new study is the fine structure constant, also known as alpha.

 

This number determines the strength of interactions between light and matter.

 

A decade ago, Webb used observations from the Keck telescope in Hawaii to analyse the light from distant galaxies called quasars.

 

The data suggested that the value of alpha was very slightly smaller when the quasar light was emitted 12 billion years ago than it appears in laboratories on Earth today.

 

Now Webb's colleague Julian King, also of the University of New South Wales, has analysed data from the Very Large Telescope (VLT) in Chile, which looks at a different region of the sky.

 

The VLT data suggests that the value of alpha elsewhere in the universe is very slightly bigger than on Earth.

 

The difference in both cases is around a millionth of the value alpha has in our region of space, and suggests that alpha varies in space rather than time. "

 

I'd quietly hoped we'd simply find the same thing that Keck found," King says. "This was a real shock."

 

 

Galaxies merging.jpg

 

 

 

 

 

 

 

 

 

 

 

Bar magnet

 

Moreover, the team's analysis of around 300 measurements of alpha in light coming from various points in the sky suggests the variation is not random but structured, like a bar magnet. The universe seems to have a large alpha on one side and a smaller alpha on the other.

 

This "dipole" alignment nearly matches that of a stream of galaxies mysteriously moving towards the edge of the universe.

 

It does not, however, line up with another unexplained dipole, dubbed the axis of evil, in the afterglow of the big bang.

Earth sits somewhere in the middle of the extremes for alpha. If correct, the result would explain why alpha seems to have the finely tuned value that allows chemistry – and thus life – to occur. Grow alpha by 4 per cent, for instance, and the stars would be unable to produce carbon, making our biochemistry impossible.

 

Extraordinary claim

 

Even if the result is accepted for publication, it is going to be hard to convince other scientists that the laws of physics might need a rewrite.

 

A spatial variation in the fine-structure constant would be "truly transformative", according to Lennox Cowie,

who works at the Institute for Astronomy in Hawaii.

 

But, he adds, extraordinary claims require extraordinary evidence: "That's way beyond what we have here."

 

He says the statistical significance of the new observations is too small to prove that alpha is changing.

 

If the interpretation of the light is correct, it is "a huge deal", agrees Craig Hogan, head of the Fermilab Center for Particle Astrophysics in Batavia, Illinois.

 

But like Cowie, he suspects there is a flaw somewhere in the analysis. "I think the result is not real," he says.

 

Another author on the paper, Michael Murphy of Swinburne University in Australia, understands the caution.

 

But he says the evidence for changing constants is piling up. "We just report what we find, and no one has been able to explain away these results in a decade of trying," Murphy told New Scientist.

 

"The fundamental constants being constant is an assumption. We're here to test physics, not to assume it."

 

Updated on 9 September: The analysis of VLT data was amended to credit Julian King

 


COPYRIGHT :


http://www.newscientist.com/article/dn19429-laws-of-physi...

20-08-10

First Use of Cosmic Lens to Probe Dark Energy

19082010

 

Dark Matter.jpg

 

 

Astronomers have devised a new method for measuring perhaps the greatest puzzle of our universe — dark energy. This mysterious force, discovered in 1998, is pushing our universe apart at ever-increasing speeds.

 


For the first time, astronomers using NASA's Hubble Space Telescope were able to take advantage of a giant magnifying lens in space — a massive cluster of galaxies — to narrow in on the nature of dark energy.

 

Their calculations, when combined with data from other methods, significantly increase the accuracy of dark energy measurements.

 

This may eventually lead to an explanation of what the elusive phenomenon really is.

 

"We have to tackle the dark energy problem from all sides," said Eric Jullo, an astronomer at NASA's Jet Propulsion Laboratory, Pasadena, Calif.

 

"It's important to have several methods, and now we've got a new, very powerful one." Jullo is lead author of a paper on the findings appearing in the Aug. 20 issue of the journal Science.

 

Scientists aren't clear about what dark energy is, but they do know that it makes up a large chunk of our universe, about 72 percent.

 

Another chunk, about 24 percent, is thought to be dark matter, also mysterious in nature but easier to study than dark energy because of its gravitational influence on matter that we can see. The rest of the universe, a mere 4 percent, is the stuff that makes up people, planets, stars, and everything made up of atoms.

 


In their new study, the science team used images from Hubble to examine a massive cluster of galaxies, named Abell 1689, which acts as a magnifying, or gravitational, lens. The gravity of the cluster causes galaxies behind it to be imaged multiple times into distorted shapes, sort of like a fun-house mirror reflection that warps your face.

 


Using these distorted images, the scientists were able to figure out how light from the more distant, background galaxies had been bent by the cluster — a characteristic that depends on the nature of dark energy.

 


Their method also depends on precise ground-based measurements of the distance and speed at which the background galaxies are traveling away from us.

 


The team used these data to quantify the strength of the dark energy that is causing our universe to accelerate.

 


"What I like about our new method is that it's very visual," said Jullo,

 


"You can literally see gravitation and dark energy bend the images of the background galaxies into arcs."

 


According to the scientists, their method required multiple, meticulous steps.

 


They spent the last several years developing specialized mathematical models and precise maps of the matter — both dark and "normal" — constituting the Abell 1689 cluster.

 


"We can now apply our technique to other gravitational lenses," said co-author Priya Natarajan, a cosmologist at Yale University, New Haven, Conn.

 


"We're exploiting a beautiful phenomenon in nature to learn more about the role that dark energy plays in our universe."

 

Copyright

 

http://hubblesite.org/newscenter/archive/releases/2010/26...