[url]http://www.tgdaily.com/space-features/66109-evidence-for-dark-energy-stacks-up-says-team[/url]
[quote]The astronomers, from the University of Portsmouth and LMU University Munich, say there's a 99.996 percent chance that the strange substance thought to be speeding up the expansion of the universe is really there.[/quote]
[quote]Over ten years ago, astronomers observing the brightness of distant supernovae realised that the expansion of the universe appeared to be accelerating. The phenomenon was attributed to the repulsive force associated with dark energy, now thought to make up about three-quarters of the cosmos.But while the researchers who made the discovery received the Nobel Prize for Physics in 2011, the existence of dark energy remained in dispute.
The strongest evidence came in the form of the Integrated Sachs Wolfe effect. In 1967, Rainer Sachs and Arthur Wolfe predicted that light from the Cosmic [URL="http://www.tgdaily.com/space-features/66109-evidence-for-dark-energy-stacks-up-says-team#"][COLOR=#346200]Microwave Background[/COLOR][/URL] - the radiation of the residual heat of the Big Bang - would become slightly bluer as it passed through the gravitational fields of matter, an effect known as gravitational redshift.
This effect was first detected in 2003 - and was immediately seen as corroborative evidence for dark energy. But the data is weak, and some scientists suggested it was caused by other sources, such as the dust in our galaxy.
In their new paper, though, the team has re-examined all the arguments against the Integrated Sachs Wolfe detection, as well as improving the cosmic maps used in the original work.
They conclude that there's a 99.996 per cent chance that dark energy is responsible for the hotter parts of the[URL="http://www.tgdaily.com/space-features/66109-evidence-for-dark-energy-stacks-up-says-team#"][COLOR=#346200]cosmic microwave background[/COLOR][/URL] maps - about the same level of significance as the recent discovery of the Higgs boson.
"This work also tells us about possible modifications to Einstein's theory of General Relativity," says lead author Tommaso Giannantonio.
"The next generation of cosmic microwave background and galaxy surveys should provide the definitive measurement, either confirming general relativity, including dark energy, or even more intriguingly, demanding a completely new understanding of how gravity works."[/quote]
well, it seems pretty clear that it exists now
So, now all we need to do is get it and use it.
So the dark side is stronger?
It could be gravity from another source in the universe...
So where's the 0.004%
I wouldn't mind having my own super gravity gun.
How exactly do we know how quickly the universe is expanding?
[QUOTE=DienDwemar;37642086]So, now all we need to do is get it and use it.[/QUOTE]
This sounds incredibly reckless.
But also incredibly cool, so I guess they balance each other out.
It's kind of irritating that all the cool shit in the universe is stuff we can't directly perceive, magnetism, gravity, microwaves, infrared, [I]anything[/I] on an atomic scale
[QUOTE=geel9;37642143]How exactly do we know how quickly the universe is expanding?[/QUOTE]
Redshift, probably.
[QUOTE=Rents;37642153]It's kind of irritating that all the cool shit in the universe is stuff we can't directly perceive, magnetism, gravity, microwaves, infrared, [I]anything[/I] on an atomic scale[/QUOTE]
You find it so interesting [b]because[/b] you can't directly perceive it.
[editline]12th September 2012[/editline]
[QUOTE=Dlaor-guy;37642159]Redshift, probably.[/QUOTE]
This doesn't really help.
[QUOTE=Rents;37642153]It's kind of irritating that all the cool shit in the universe is stuff we can't directly perceive, magnetism, gravity, microwaves, infrared, [I]anything[/I] on an atomic scale[/QUOTE]
Well, if we could directly perceive it then it probably wouldn't be so cool.
I mean maybe some creature that sees only in microwaves would say "These human fuckers can see yellow? What sons of bitches!" or "Holy fuck these guys are able to actually detect chemicals by smelling them! We can't do anything that fucking cool!"
[QUOTE=geel9;37642143]How exactly do we know how quickly the universe is expanding?[/QUOTE]
Reshift, the faster they move away, the redder they become.
It just like the blue shift... But other way round.
[QUOTE=geel9;37642167]You find it so interesting [b]because[/b] you can't directly perceive it.
[editline]12th September 2012[/editline]
This doesn't really help.[/QUOTE]
You know how the pitch of a sound changes when something speeds away from you? The same happens to light, that observable difference allows us to estimate how fast and if the universe is expanding.
Good, now all we have to do is figure out what it is.
...I'm thinking of dark [i]matter[/i], aren't I?
We only know its there, because if red shift.
We can't see it because it does not give off light in a way we can perceive (with normal matter).
There was a good example with lights in a swimming pool and ripples.. But I can remember which way around it goes.
Spazzy bouncing orbs are the future.
[QUOTE=yawmwen;37642184]Well, if we could directly perceive it then it probably wouldn't be so cool.
I mean maybe some creature that sees only in microwaves would say "These human fuckers can see yellow? What sons of bitches!" or "Holy fuck these guys are able to actually detect chemicals by smelling them! We can't do anything that fucking cool!"[/QUOTE]
Maybe, but we've looked at things we can see and had the same curiosity towards them, maybe it's just because I don't like not knowing things.
[QUOTE=Jookia;37642212]Good, now all we have to do is figure out what it is.
...I'm thinking of dark [i]matter[/i], aren't I?[/QUOTE]
Dark matter is stuff that's a pain in the ass to directly detect, but has mass, dark energy is a force that's pushing everything away.
[QUOTE=FrankOfArabia;37642128]It could be gravity from another source in the universe...[/QUOTE]
Gravity pulls things in... If what you just said was plausible in the slightest (as in gravity could effect the rate at which the universe expands) then surely the universe would not be expanding it would be contracting.
Unless you mean something [B]outside[/B] the universe is pulling it out?
[QUOTE=Rents;37642153]It's kind of irritating that all the cool shit in the universe is stuff we can't directly perceive, magnetism, gravity, microwaves, infrared, [I]anything[/I] on an atomic scale[/QUOTE]
Technically, you can perceive gravity pretty well. Otherwise you would have big trouble walking.
Sense of balance and that stuff.
You should also be glad we are the species on our planet that learned to perceive it indirectly.
My question is, how significant is that additional .004% in terms of astronomical findings?
[QUOTE=dingusnin;37642258]We only know its there, because if red shift.
We can't see it because it does not give off light in a way we can perceive (with normal matter).
There was a good example with lights in a swimming pool and ripples.. But I can remember which way around it goes.[/QUOTE]
The idea of dark energy comes from basically supernovae of certain types eg 1a. When comparing the redshift and brightness of supernovae (and determining its distance from its brightness), a graph is plotted between distance and velocity of stars, galaxies far away. The graph was not a straight line (which was expected) but it was a curve. This means the galaxies/stars had to moving away faster then expected, to explain this they came up with dark energy which they have no idea what it is and no idea how to end up with a theory which produces such a small energy density for dark energy. Keeping in mind dark energy takes up the form of negative energy (positive energy would add mass ( E=mc^2) and slow the expansion down).
[QUOTE=shian;37642135]So where's the 0.004%[/QUOTE]
It got trapped in a black hole, never to be seen again.
5σ result!
[QUOTE=Justin Case;37642317]Gravity pulls things in... If what you just said was plausible in the slightest (as in gravity could effect the rate at which the universe expands) then surely the universe would not be expanding it would be contracting.
Unless you mean something [B]outside[/B] the universe is pulling it out?[/QUOTE]
Exactly, perhaps the universe extends infinitely and dark energy is a result of all the energy that gravity creates from outside the observable universe.
Assuming the dark energy would diminish over time, wouldn't that mean gravity will eventually pull everything back in?
[QUOTE=FrankOfArabia;37642609]Exactly, perhaps the universe extends infinitely and dark energy is a result of all the energy that gravity creates from outside the observable universe.[/QUOTE]
Sounds like it might work, though if there's a force outside of the universe pulling on it, AND the universe extends infinitely, that would have to mean the force is possibly extradimensional; either another universe pulling on ours or the pulling force having more spatial dimensions than the readily-available 3 in ours.
However a thought pertaining to heat comes to mind; what if the nature of dark energy's universe-expanding power is down to it exciting the fabric of spacetime, making it expand or oscillate like what heat does to normal matter? If dark energy is to spacetime what heat is to matter, could that mean that in the chaotic churning expanse of the interversal space between dimensions, there are objects that radiate dark energy like some sort of dark star, causing the universes to expand?
If that kinda stuff is true, perhaps universes accelerate in growth as they absorb the dark radiation, with the amount they receive depending on the distance they are from their dark star; universes that stand too close gradually inflate into cold empty husks, whilst further-away 'verses receive too little dark radiation and shrink back into a Big Crunch, and a theoretical Goldilocks zone could exist where there is neither Big Crunch nor Big Freeze, though other fates could exist.
But for all we know, the metaphysics of dark matter and dimensional expansion could be completely different.
[QUOTE=shian;37642135]So where's the 0.004%[/QUOTE]
That all the missing matter as simply hiding behind other matter.
So, they're unsure it's real?
I wonder how did these scientists get exact percentage of probability
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